Remove completed roadmap documents

COPYRIGHT

@@ -18,8 +18,3 @@ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU Lesser General Public License for more details.
 
 Third-party code and assets are subject to their respective license terms.
-
-Policy documents adapted from Standard Repository Policies, the root AGENTS.md
-orientation, and the Policy Reading Guide in docs/development.md remain licensed
-under CC-BY-SA-4.0. See docs/oss/attribution.md for the affected material,
-upstream credit, and license links.

README.md

@@ -1,39 +1,18 @@
 # ConfigKit
 
-An opinionated Go library for applications that use YAML configuration files.
+ConfigKit loads YAML into your application's Go configuration type, combines the
+inputs you choose, and lets you inspect where the final values came from. You
+supply the types, defaults, and application rules; ConfigKit handles loading,
+combination, strict decoding, and inspection.
 
 Linux is release-validated; macOS support is best-effort. See the
-[platform support policy](docs/policy/release.md#platform-support) for details.
+[platform support policy](docs/policy/release.md#platform-support).
 
-ConfigKit's simple `Load` accepts one strict YAML source (or explicit
+## Load a configuration file
-defaults-only input). `LoadLayered` additionally combines explicit lower-priority
-source groups with an independently selected main input. Sources can be host
-files, native `fs.FS` files, labeled bytes or readers, or snapshotted mappings.
-Enabled path and glob imports compose strictly within their group; precedence
-between groups combines mappings recursively. Both entry points return a complete,
-validated configuration with detached metadata and safe diagnostics.
-Applications may perform audited defaulting and normalization through a resolver,
-then report domain errors and warnings through read-only semantic validation. Secret
-tags and a path predicate drive deterministic redacted effective YAML. Typed secret
-references resolve environment names before validation, and explicit
-secrets-directory bootstrap is available as a separate startup operation. Explicit
-CLI override records apply above overlays. Value explanation is available through
-detached structured records and deterministic redacted output. Built-in
-`extends` relationships let a mapping inherit from a named sibling during the
-same load, retaining explicit presence and source/derivation history. The root
-`Diff` API compares frozen effective values from two successful same-type loads;
-the [configuration contract](docs/config.md#effective-configuration-diffs) and
-[consumer guide](docs/consumers/README.md#effective-configuration-diffs) describe
-its safe changed-region records and maintained workflows.
-
-Sources can also be explicitly placed as sequence items, and definitions can
-register selected sequences to append records with distinct string IDs during
-strict composition. Higher-priority sequences still replace lower-priority
-sequences as whole values. See the [sequence contract](docs/config.md#strict-document-composition),
-[maintained prompt example](docs/consumers/README.md#identified-prompt-sequences),
-and [ADR 0014](docs/adr/0014-sequence-placement-and-composition.md).
 
 ```go
+import "go.maximumdirect.net/configkit"
+
 type Config struct {
     Enabled bool `yaml:"enabled"`
     Workers int  `yaml:"workers"`
@@ -48,47 +27,57 @@ func ReadConfig(path string) (Config, error) {
 }
 ```
 
+Existing consumers should follow the
+[module-path migration guidance](docs/consumers/README.md#vanity-module-path-migration).
+
+## Add the features you need
+
+Start with one file. Optional features use the same loading and inspection model:
+
+- [Choose inputs](docs/consumers/README.md#choosing-a-loading-entry-point): read
+  files, an application-owned `fs.FS`, bytes, a reader, or a Go mapping. Use
+  explicit search descriptions when the application should look in several places.
+- [Supply lower-priority settings](docs/consumers/README.md#native-filesystem-and-layered-input):
+  use `LoadLayered` for bundled defaults that application configuration can override.
+- [Combine configuration](docs/config.md#explicit-imports): add declared imports,
+  select one overlay, or pass values explicitly set by your CLI parser.
+- [Reuse settings](docs/config.md#sibling-inheritance): let one named entry inherit
+  from a sibling. [Identified lists](docs/config.md#strict-document-composition)
+  also support record inheritance and replace, append, or upsert operations.
+- [Apply application rules](docs/config.md#recorded-application-resolution): derive
+  or normalize values in a resolver, then check the final configuration in a validator.
+- [Handle credentials](docs/config.md#typed-secret-references): use environment-name
+  references and choose which configuration fields to hide in inspection output.
+- [Inspect a load](docs/config.md#layered-metadata): examine sources, presence,
+  history, safe YAML output, or [changes between two loads](docs/config.md#effective-configuration-diffs).
+
+The [consumer guide](docs/consumers/README.md) walks through these tasks and links
+to maintained examples. The [configuration reference](docs/config.md) defines the
+exact YAML, combination, and lifecycle rules.
+
 ## Design philosophy
 
-ConfigKit favors one coherent, predictable configuration model over flexibility
+ConfigKit favors consistent, predictable rules across applications. A load returns
-for reproducing each consumer's conventions. Its goal is to let applications
+the final configuration and metadata that distinguish supplied values such as
-load once, inspect where final values came from, and distinguish explicit values
+`false` and `0` from omissions. Applications keep their domain rules and runtime
-from omissions with minimal configuration bookkeeping. Applications retain their
+initialization.
-domain rules and execution responsibilities.
 
-Loading is synchronous and complete on return. Applications normally load once
+Within one layer, independent contributions combine strictly: conflicting
-near startup and then use the final configuration and metadata; ConfigKit stays
+values are errors. Across layers, higher-priority settings can replace
-inactive until explicitly called again. Applications may initiate additional
+lower-priority settings, while mappings combine by key. Identified lists have
-loads as needed. See the [loading lifecycle](docs/config.md#completion-and-resource-lifetime)
+their declared combination rules. See the [worked combination
-for completion and ownership details.
+examples](docs/config.md#strict-document-composition) for the details and
+exceptions.
 
-Within a configuration tier, independent contributions compose strictly: shared
+Loading finishes before the call returns. ConfigKit then stays inactive until you
-mappings combine, while overlapping non-mapping definitions are errors. Between
+call it again; inspection uses the saved result. See
-precedence tiers, mappings combine recursively, retaining omitted lower-priority
+[completion and resource lifetime](docs/config.md#completion-and-resource-lifetime).
-children; other values replace lower-priority values. The main document and its
-imports form one strictly composed tier. Explicit underlay groups sit below it
-and above typed defaults; a selected overlay and explicit CLI overrides sit
-above it. The [configuration contract](docs/config.md#strict-document-composition)
-owns the detailed combination rules and input-specific constraints. At
-definition-registered paths only, strict composition can append records with
-distinct explicit IDs; ordinary and unregistered sequences keep their conflict
-or whole-value replacement behavior.
 
-The [architecture goals](docs/policy/architecture.md#success-criteria) explain
+The [architecture goals](docs/policy/architecture.md#success-criteria) and
-these priorities and how genuine new needs can justify extending the shared
+[ADRs](docs/adr) explain design decisions, including shared import and inheritance
-model. The [future feature list](docs/roadmap/future.md) preserves candidates for
+ordering. [Future work](docs/roadmap/future.md) lists possible extensions.
-consideration in future releases.
+Contributors can start with the [development guide](docs/development.md);
-
+release maintainers use the [release procedure](docs/release.md).
-The [configuration contract](docs/config.md) describes implemented behavior,
-including [input destinations](docs/config.md#input-destinations). The
-[consumer adoption guide](docs/consumers/README.md) provides maintained simple,
-layered, mounted-collection, and identified-prompt examples alongside the
-migration shapes. Input placement decisions are recorded in
-[ADR 0011](docs/adr/0011-input-destinations.md) and sequence placement and
-composition in [ADR 0014](docs/adr/0014-sequence-placement-and-composition.md).
-See the [development guide](docs/development.md) for repository orientation and
-the [release procedure](docs/release.md) for maintainer-only candidate and
-publication steps.
 
 ConfigKit code is licensed under the [LGPL v3.0 or later](COPYRIGHT).
 

conversion.go

@@ -1,6 +1,6 @@
 package configkit
 
-import "gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+import "go.maximumdirect.net/configkit/internal/engine"
 
 func fromEngineLocation(value engine.Location) Location {
 	return Location{SourceID: value.SourceID, Line: value.Line, Column: value.Column}
@@ -43,32 +43,62 @@ func toEngineLocations(values []Location) []engine.Location {
 	return result
 }
 func fromEngineSourceInfo(value engine.SourceInfo) SourceInfo {
-	return SourceInfo{ID: value.ID, Label: value.Label, Path: value.Path, Destination: fromEnginePath(value.Destination), PlacementMode: PlacementMode(engine.SourceInfoPlacementModeForFacade(value)), DestinationUnresolved: engine.SourceInfoDestinationUnresolvedForFacade(value), Layer: Layer(value.Layer), Kind: SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex, ImportedFrom: fromEngineLocationPointer(value.ImportedFrom), VersionCheck: fromEngineSourceVersionCheck(value.VersionCheck)}
+	return SourceInfo{
+		ID: value.ID, Label: value.Label, Path: value.Path, Destination: fromEnginePath(value.Destination),
+		PlacementMode:         PlacementMode(engine.SourceInfoPlacementModeForFacade(value)),
+		DestinationIsFallback: engine.SourceInfoDestinationUnresolvedForFacade(value),
+		Layer:                 Layer(value.Layer), Kind: SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex,
+		ImportedFrom: fromEngineLocationPointer(value.ImportedFrom), VersionEvidence: fromEngineSourceVersionEvidence(value.VersionCheck),
+		EmptyImportSelections: fromEngineEmptyImportSelections(engine.SourceInfoImportSelectionsForFacade(value)),
+	}
 }
-func toEngineSourceInfo(value SourceInfo) engine.SourceInfo {
+func fromEngineEmptyImportSelections(values []engine.ImportSelectionForFacade) []EmptyImportSelection {
-	result := engine.SourceInfo{ID: value.ID, Label: value.Label, Path: value.Path, Destination: toEnginePath(value.Destination), Layer: engine.Layer(value.Layer), Kind: engine.SourceKind(value.Kind), UnderlayIndex: value.UnderlayIndex, ImportedFrom: toEngineLocationPointer(value.ImportedFrom), VersionCheck: toEngineSourceVersionCheck(value.VersionCheck)}
+	if values == nil {
-	return engine.SourceInfoWithPlacement(result, uint8(value.PlacementMode), value.DestinationUnresolved)
+		return nil
+	}
+	result := make([]EmptyImportSelection, len(values))
+	for index, value := range values {
+		result[index] = EmptyImportSelection{
+			Path: fromEnginePath(value.Path), Location: fromEngineLocation(value.Location),
+			Selector: ImportSelector(value.Selector),
+		}
+	}
+	return result
 }
-func fromEngineSourceVersionCheck(value *engine.SourceVersionCheck) *SourceVersionCheck {
+
+func toEngineOverrides(values []Override) []engine.Override {
+	if values == nil {
+		return nil
+	}
+	result := make([]engine.Override, len(values))
+	for index, value := range values {
+		result[index] = engine.Override{
+			Path: toEnginePath(value.Path), Value: value.Value, Flag: value.Flag,
+		}
+	}
+	return result
+}
+
+func toEngineImportDefaults(value ImportDefaults) engine.ImportDefaults {
+	return engine.ImportDefaults{
+		Required:  value.Required,
+		Follow:    value.FollowSymlinks,
+		Hidden:    value.IncludeHidden,
+		Recursive: value.Recursive,
+		Pattern:   value.Pattern,
+	}
+}
+
+func fromEngineSourceVersionEvidence(value *engine.SourceVersionCheck) *SourceVersionEvidence {
 	if value == nil {
 		return nil
 	}
-	return &SourceVersionCheck{
+	return &SourceVersionEvidence{
 		Path:     fromEnginePath(value.Path),
 		Version:  Version{Present: value.Version.Present, Null: value.Version.Null, Text: value.Version.Text},
 		Location: fromEngineLocationPointer(value.Location), Redacted: value.Redacted,
 	}
 }
-func toEngineSourceVersionCheck(value *SourceVersionCheck) *engine.SourceVersionCheck {
-	if value == nil {
-		return nil
-	}
-	return &engine.SourceVersionCheck{
-		Path:     toEnginePath(value.Path),
-		Version:  engine.Version{Present: value.Version.Present, Null: value.Version.Null, Text: value.Version.Text},
-		Location: toEngineLocationPointer(value.Location), Redacted: value.Redacted,
-	}
-}
 func fromEngineOrigin(value engine.Origin) Origin {
 	result := Origin{Layer: Layer(value.Layer), Locations: fromEngineLocations(value.Locations), Operation: ChangeKind(value.Operation)}
 	if value.Inheritance != nil {
@@ -82,19 +112,6 @@ func fromEngineOrigin(value engine.Origin) Origin {
 	}
 	return result
 }
-func toEngineOrigin(value Origin) engine.Origin {
-	result := engine.Origin{Layer: engine.Layer(value.Layer), Locations: toEngineLocations(value.Locations), Operation: engine.ChangeKind(value.Operation)}
-	if value.Inheritance != nil {
-		result.Inheritance = make([]engine.InheritanceStep, len(value.Inheritance))
-		for index, step := range value.Inheritance {
-			result.Inheritance[index] = engine.InheritanceStep{
-				From: toEnginePath(step.From), To: toEnginePath(step.To), Reference: toEnginePath(step.Reference),
-				Locations: toEngineLocations(step.Locations),
-			}
-		}
-	}
-	return result
-}
 func fromEngineDiagnostic(value engine.Diagnostic) Diagnostic {
 	return Diagnostic{Code: Code(value.Code), Severity: Severity(value.Severity), Path: fromEnginePath(value.Path), Message: value.Message, Primary: fromEngineLocationPointer(value.Primary), Related: fromEngineLocations(value.Related)}
 }

diagnostic.go

@@ -3,7 +3,7 @@ package configkit
 import (
 	"io"
 
-	"gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+	"go.maximumdirect.net/configkit/internal/engine"
 )
 
 // LoadError reports safe structured diagnostics for a failed configuration load.
@@ -50,6 +50,21 @@ func (e *LoadError) Sources() []SourceInfo {
 	return result
 }
 
+// Source returns a detached record from the sanitized source evidence retained
+// before loading failed, including placement evidence available at that point.
+// IDs are local to the failed load. It does not acquire sources or access the
+// filesystem. Empty or unknown IDs return false.
+func (e *LoadError) Source(id string) (SourceInfo, bool) {
+	if e == nil || e.value == nil {
+		return SourceInfo{}, false
+	}
+	value, ok := e.value.Source(id)
+	if !ok {
+		return SourceInfo{}, false
+	}
+	return fromEngineSourceInfo(value), true
+}
+
 // WriteDiagnostics writes diagnostics in canonical order. It escapes terminal
 // control characters and propagates writer errors, including short writes.
 func WriteDiagnostics(output io.Writer, diagnostics []Diagnostic) error {

diff.go

@@ -1,15 +1,14 @@
 package configkit
 
-import "gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
+import "go.maximumdirect.net/configkit/internal/engine"
 
-// Difference describes one canonical changed region between two successful
+// Difference describes one changed value or subtree between two successful loads.
-// loads. Left is the earlier value and Right is the later value. Each snapshot
+// Left is the earlier value and Right is the later value. Snapshots are copies;
-// is detached; Present distinguishes absence from an explicit null, and
+// Present distinguishes absence from explicit null. Redacted reports hiding
-// Redacted reports whether combined sensitivity affected that side. Mappings
+// based on sensitivity from either load. Mappings compare by key; a changed
-// are compared recursively, while sequences are reported as atomic values.
+// sequence is reported as a whole value. Records are ordered by canonical JSON
-// Records are ordered by canonical JSON pointer. HiddenChanged indicates that
+// pointer. HiddenChanged reports an actual hidden change, without identifying
-// a value concealed by combined sensitivity changed, without revealing which
+// the hidden member. Redaction alone does not set it.
-// concealed member changed.
 type Difference struct {
 	Path          Path
 	Left          ValueSnapshot
@@ -17,8 +16,9 @@ type Difference struct {
 	HiddenChanged bool
 }
 
-// Diff compares the frozen effective values of two successful loads of the
+// Diff compares the saved final values of two successful loads of the same
-// same configuration type. It does not reread sources, environment variables,
+// configuration type, independently of later changes to Result.Config.
+// It does not reread sources, environment variables,
 // or rerun defaults or resolvers. Equal values produce no records even when
 // their sources, defaults, or resolution histories differ. Credential contents
 // are not compared: typed secret references compare by reference name only.

discovery.go

@@ -0,0 +1,90 @@
+package configkit
+
+import "go.maximumdirect.net/configkit/internal/engine"
+
+// Search is an immutable ordered description of possible host-file inputs.
+// It is consumed only when passed to SearchConfig and used by a load.
+type Search struct{ value engine.Search }
+
+// FilenameGroup selects filenames in order for a directory search.
+// Construct groups with NamedFilenames, GenericFilenames, or CustomFilenames.
+type FilenameGroup struct{ value engine.FilenameGroup }
+
+// SearchOptions controls whether a search must select a file.
+type SearchOptions struct {
+	// Required reports a missing-source error if the complete search is exhausted.
+	Required bool
+}
+
+// DirectorySearchOptions selects the filename groups used by SearchDirectory.
+type DirectorySearchOptions struct {
+	// Filenames concatenates groups in order. A nil slice uses Named then Generic;
+	// a non-nil empty slice selects no filenames.
+	Filenames []FilenameGroup
+}
+
+// NamedFilenames selects <application>.yml followed by <application>.yaml.
+func NamedFilenames() FilenameGroup { return FilenameGroup{value: engine.NamedFilenames()} }
+
+// GenericFilenames selects config.yml, config.yaml, main.yml, and main.yaml.
+func GenericFilenames() FilenameGroup { return FilenameGroup{value: engine.GenericFilenames()} }
+
+// CustomFilenames selects literal filename components in the supplied order.
+// Names cannot be empty or contain a directory component.
+func CustomFilenames(names ...string) FilenameGroup {
+	return FilenameGroup{value: engine.CustomFilenames(names...)}
+}
+
+// SearchDirectory describes a search within directory. Omitted options or a nil
+// Filenames slice uses Named then Generic groups. Explicitly empty Filenames
+// selects no names and does not resolve the directory base.
+func SearchDirectory(directory string, supplied ...DirectorySearchOptions) Search {
+	options := make([]engine.DirectorySearchOptions, len(supplied))
+	for index, option := range supplied {
+		if option.Filenames == nil {
+			continue
+		}
+		options[index].Filenames = make([]engine.FilenameGroup, len(option.Filenames))
+		for groupIndex, group := range option.Filenames {
+			options[index].Filenames[groupIndex] = group.value
+		}
+	}
+	return Search{value: engine.SearchDirectory(directory, options...)}
+}
+
+// SearchPaths describes literal host-file candidates in the supplied order.
+func SearchPaths(paths ...string) Search { return Search{value: engine.Paths(paths...)} }
+
+// Searches concatenates descriptions in order and snapshots their entries.
+func Searches(searches ...Search) Search {
+	values := make([]engine.Search, len(searches))
+	for index, search := range searches {
+		values[index] = search.value
+	}
+	return Search{value: engine.Searches(values...)}
+}
+
+// UnixSystemDirectories describes the conventional Unix system directories.
+// Loading on an unsupported platform fails if this preset is reached.
+func UnixSystemDirectories() Search { return Search{value: engine.UnixSystemDirectories()} }
+
+// UserConfigDirectory describes searches rooted at the Go user-config directory.
+func UserConfigDirectory() Search { return Search{value: engine.UserConfigDirectory()} }
+
+// HomeDirectory describes searches rooted at the Go home directory.
+func HomeDirectory() Search { return Search{value: engine.HomeDirectory()} }
+
+// WorkingDirectory describes application-named files in the current directory.
+func WorkingDirectory() Search { return Search{value: engine.WorkingDirectory()} }
+
+// SearchConfig creates a source that selects the first matching host file when
+// consumed by Load or LoadLayered. Without Required, exhausting the search uses
+// the absent-input lifecycle. Description and option errors are reported while
+// loading.
+func SearchConfig(application string, search Search, supplied ...SearchOptions) Source {
+	options := make([]engine.SearchOptions, len(supplied))
+	for index, option := range supplied {
+		options[index] = engine.SearchOptions{Required: option.Required}
+	}
+	return Source{value: engine.SearchConfig(application, search.value, options...)}
+}

doc.go

@@ -1,9 +1,17 @@
-// Package configkit provides deterministic, application-owned configuration
+// Package configkit loads YAML into an application's Go configuration type and
-// loading for Go programs.
+// lets the application inspect where the final values came from.
 //
-// Load supports file, byte, reader, and explicit no-input sources with strict YAML,
+// Start with Load and a File, Bytes, Reader, Mapping, or Filesystem.File source.
-// typed defaults, imports, overlays, CLI overrides, schema-version checks, detached
+// Use NoSource for deliberately absent input or SearchConfig for an explicitly
-// metadata, recorded application resolution, typed secret references, safe effective
+// chosen search. Applications supply types, defaults, version rules, and callbacks
-// rendering, read-only semantic validation, and structured load errors. The
+// for deriving and validating values. LoadLayered adds lower-priority input groups.
-// configuration contract is documented in docs/config.md.
+//
+// A successful load returns the final configuration and saved inspection state.
+// Metadata tracks supplied values, including false and zero; explanations retain
+// safe earlier values. WriteEffective and Diff use the saved state even if the
+// application later changes Result.Config. Secret references resolve credentials
+// during loading, while inspection follows the configured hiding rules.
+//
+// The consumer guide is in docs/consumers/README.md. The exact YAML, combination,
+// lifecycle, and ownership rules are documented in docs/config.md.
 package configkit

docs/adr/0005-explicit-overrides-and-safe-explanation.md

@@ -1,6 +1,8 @@
 # ADR 0005: Record explicit CLI overrides and safe value explanation
 
-Status: accepted
+Status: Partially superseded by
+[ADR 0018](0018-cli-after-structural-resolution.md) for override-before-decoding
+ordering. The remaining ownership and safe explanation decisions remain accepted.
 
 Date: 2026-09-06
 

docs/adr/0007-source-backed-underlays.md

@@ -2,7 +2,9 @@
 
 ## Status
 
-Proposed draft for review. Completed planning and remediation records are
+Proposed draft for review; its whole-sequence precedence replacement rule is
+superseded by [ADR 0017](0017-collection-sequence-policy.md). The remainder
+retains its proposed status. Completed planning and remediation records are
 preserved in Git history at `b604aa1` under `docs/roadmap/`; the
 [configuration contract](../config.md#layered-loading) owns current behavior.
 

docs/adr/0009-sibling-inheritance.md

@@ -2,8 +2,14 @@
 
 ## Status
 
-Accepted and implemented. The [configuration contract](../config.md#sibling-inheritance)
+Partially superseded by [ADR 0017](0017-collection-sequence-policy.md) for
-owns current behavior. The completed implementation plan is preserved in Git
+sequence combination and the addition of identified-sequence sibling scopes,
+and [ADR 0018](0018-cli-after-structural-resolution.md) for CLI-before-inheritance
+ordering. Existing mapping-sibling scopes and the remaining ownership and
+inspection decisions remain accepted.
+
+The [configuration contract](../config.md#sibling-inheritance) owns implemented
+behavior. The completed implementation plan is preserved in Git
 history at `83c59ea`.
 
 ## Date

docs/adr/0014-sequence-placement-and-composition.md

@@ -2,8 +2,12 @@
 
 ## Status
 
-Accepted and implemented. The [configuration contract](../config.md#strict-document-composition)
+Partially superseded by [ADR 0017](0017-collection-sequence-policy.md) for
-defines current behavior, and the [consumer guide](../consumers/README.md#identified-prompt-sequences)
+identity ownership and sequence combination. Explicit source placement remains
+accepted.
+
+The [configuration contract](../config.md#strict-document-composition)
+defines implemented behavior, and the [consumer guide](../consumers/README.md#identified-prompt-sequences)
 shows the maintained example. The completed roadmap, implementation plan, and
 resolved remediation record are preserved in Git history at `008d2ba` under
 `docs/roadmap/`; see the [development guide](../development.md) for retrieval

docs/adr/0015-shared-dependency-ready-ordering.md

@@ -0,0 +1,68 @@
+# ADR 0015: Share Dependency-Ready Ordering Across Imports and Inheritance
+
+## Status
+
+Accepted. Implemented behavior is described in the
+[configuration contract](../config.md#explicit-imports) and
+[internal import overview](../internal/imports.md).
+
+## Date
+
+2026-10-19
+
+## Context
+
+Imports and sibling inheritance both resolve relationships between configuration
+contributions. Their existing resolvers use different traversal rules, making
+ordering depend on which mechanism expresses a dependency. Ordering affects
+sequence contributions, provenance, and diagnostics, so a consistent rule is
+part of ConfigKit's configuration model.
+
+The resolvers also serve distinct purposes. Imports strictly compose sources;
+inheritance overlays a child on its resolved parent after source assembly.
+Item-local contributions and nested inheritance introduce scope boundaries that
+resolution must preserve.
+
+## Decision
+
+ConfigKit owns one shared dependency-ready scheduler for imports and sibling
+inheritance. Both resolvers use Kahn's algorithm with a stable ordering key,
+selecting the smallest currently eligible node after its dependencies have
+completed. The shared scheduler owns eligibility, deterministic tie-breaking,
+and dependency-cycle identification. Each resolver owns construction of its
+dependency relationships and application of its domain operations.
+
+Apply the common scheduling rule within the scopes where dependencies are
+available. Complete item-local contributions before item placement and resolve
+enclosing inheritance before relationships in the resulting nested scopes.
+Source discovery supplies the import graph; the scheduler determines resolution
+order.
+
+Strict composition, inheritance overlay, and precedence tiers retain their
+existing ownership and meanings under [ADR 0001](0001-separate-composition-and-overlay.md).
+The lifecycle and scope decisions in
+[ADR 0009](0009-sibling-inheritance.md) continue to govern inheritance. Import
+admission retains its cycle and repeated-source rules.
+
+## Alternatives Considered
+
+- **Deterministic depth-first postorder.** Keeps dependency branches together,
+  but gives traversal branch selection an additional role in ordering.
+- **Dependency rounds.** Groups nodes by readiness rounds, but delays newly
+  eligible nodes until the current round finishes.
+- **Descending longest-path depth.** Prioritizes the furthest dependencies,
+  but adds distance from the root as an ordering policy.
+- **Separate resolver algorithms.** Allows local specialization, but leaves
+  consumers and maintainers with different rules for analogous dependencies.
+
+## Consequences
+
+Both resolvers follow one deterministic ordering model and share responsibility
+for maintaining that model. Resolver-specific scopes, combination semantics,
+and source-admission rules remain explicit at their integration boundaries.
+
+Independent branches may interleave as nodes become eligible. Adopting this
+rule changes existing traversal-dependent sequence positions and reporting
+order, requiring coordinated review of source assembly, provenance, and
+inheritance behavior. The configuration contract owns the implemented ordering
+details.

docs/adr/0016-independent-import-controls.md

@@ -0,0 +1,83 @@
+# ADR 0016: Separate Import Selection, Traversal, and Presence Requirements
+
+## Status
+
+Accepted. Implemented behavior is described in the
+[configuration contract](../config.md#explicit-imports), the
+[public API declarations](../../lifecycle.go), and the
+[internal import overview](../internal/imports.md).
+
+## Date
+
+2026-10-19
+
+## Context
+
+Consumers assemble configurations from named files and collections whose layout
+varies between installations. Simple imports should require little setup, while
+larger collections need control over discovery, recursion, filtering, and
+required contributions. Combining those choices implicitly makes declarations
+harder to interpret and pushes source-selection work into applications.
+
+Discovery can also reach a candidate through overlapping searches or encounter
+different names for one canonical source. Selection and source admission need
+distinct identities to support useful search unions while preserving ConfigKit's
+existing source-integrity rules.
+
+## Decision
+
+ConfigKit owns import discovery and selection within its source-loading
+lifecycle. Support explicit files, directory searches, and path globs as
+distinct selection forms. Keep traversal, filename filtering, and presence
+requirements independently expressible. Discovery determines the selected
+contributions; the shared scheduler in
+[ADR 0015](0015-shared-dependency-ready-ordering.md) determines their resolution
+order.
+
+Use optional-by-default imports with explicit requiredness controls. Selected
+sources remain subject to ConfigKit's validity, containment, resource, and
+composition contracts. This applies the library's
+[simplicity and defaults principles](../policy/architecture.md#simplicity-defaults-and-explicit-controls)
+to import absence while retaining meaningful errors for invalid contributions.
+
+Applications own their selected import defaults. Authored declaration values
+take precedence over application defaults, which take precedence over library
+defaults. Each declaration resolves applicable controls independently,
+including declarations in imported sources. This gives applications a shared
+baseline while preserving explicit choices in individual declarations.
+
+Keep declaration-local candidate identity separate from canonical source
+identity. Search unions coalesce repeated candidate paths within a source
+namespace before symlink resolution; filename filtering uses the selected or
+discovered name. Source admission continues to use canonical identity and the
+existing repeated-source rules. Distinct aliases retain their separate
+inclusion routes.
+
+## Alternatives Considered
+
+- **Use path globs for all discovery.** Offers one selection form, but makes
+  collection traversal depend on path-pattern structure and complicates
+  independently controlling recursion and filename filtering.
+- **Offer only explicit files and directory searches.** Reduces the selector
+  vocabulary, but moves wildcard directory selection into repeated declarations
+  or application-side discovery.
+- **Require every import by default.** Detects absent contributions immediately,
+  but requires repeated opt-outs for installations with optional components.
+- **Make application settings override authored declarations.** Provides central
+  enforcement, but prevents declarations from expressing local exceptions.
+- **Deduplicate selections globally by canonical source identity.** Coalesces
+  aliases and separate inclusion routes, but changes the existing repeated-source
+  contract and obscures independently authored contributions.
+
+## Consequences
+
+Consumers can express simple imports and more selective collection searches
+through the same loading lifecycle. Applications choose defaults and validate
+their required effective configuration; ConfigKit owns consistent selection,
+source admission, composition, and inspection.
+
+Optional absence can conceal misspelled selectors, so requiredness and
+inspection provide explicit ways to detect and explain missing contributions.
+Declaration-local deduplication requires the loader to preserve candidate
+identity alongside canonical source identity. The configuration and public API
+contracts own the implemented behavior.

docs/adr/0017-collection-sequence-policy.md

@@ -0,0 +1,143 @@
+# ADR 0017: Define Identity and Merge Rules for Each Collection
+
+## Status
+
+Accepted.
+
+This supersedes the decisions about who declares identity and how
+sequences combine in [ADR 0014](0014-sequence-placement-and-composition.md),
+and the rule that inheritance always replaces sequences in
+[ADR 0009](0009-sibling-inheritance.md). It also extends that ADR's sibling
+scopes to identified sequences. Existing mapping-sibling scopes and source
+placement continue to apply. It supersedes the whole-sequence
+precedence replacement rule in the proposed
+[ADR 0007](0007-source-backed-underlays.md).
+
+## Date
+
+2026-10-22
+
+## Context
+
+ConfigKit can load separate files as records in a sequence. Applications can
+register an identity key so records with different identities combine and
+duplicates fail. However, a higher configuration layer or an inheriting mapping
+currently replaces the whole sequence. Applications that need to extend a
+catalog across layers must write their own merging code and keep source and
+history information consistent with its results.
+
+Configuration authors need to choose how records are identified and whether a
+layer adds records, updates records, or replaces the collection. Applications
+also need a way to require unique identities in the final loaded configuration.
+These rules must work consistently for imported records, inline sequences,
+overlays, and inheritance.
+
+Records in a sequence may also share settings. Authors need to reuse those
+settings through inheritance while keeping each record's own identity.
+
+## Decision
+
+ConfigKit manages identity and merge rules for each collection during loading.
+Configuration files can declare those rules for imported and inline sequences,
+including sequences in selected overlays. Applications can require a particular
+identity definition, and configuration declarations must agree with it. Source
+placement determines where each contribution enters the configuration.
+
+Keep the distinction between contributions at the same priority and overrides
+from a higher layer, as established in
+[ADR 0001](0001-separate-composition-and-overlay.md). Within one tier, records
+with distinct identities combine; duplicate identities and conflicting
+declarations fail. Determine the applicable rules before combining those
+contributions, including any identity established in lower tiers.
+
+Across layers, support three operations: replace the whole sequence, append
+records while rejecting duplicate identities, or replace whole records by
+identity (`upsert`). Source layering and sibling inheritance use the same
+operations. For inheritance, the rules at the inheriting destination determine
+which operation applies.
+
+An identified sequence is also a sibling scope for inheritance. A record may
+inherit from one other record in the same sequence, selected by its complete
+identity. Each record supplies its own identity before inheritance. The child
+keeps that identity and combines its settings with the parent's other fields,
+using the existing mapping and collection rules. Parents remain ordinary records
+subject to normal validation.
+
+Resolve these relationships after source assembly, using the same dependency
+ordering as mapping-sibling inheritance. Resolve nested relationships at each
+inheriting destination. Preserve the assembled sequence order. Whole-record
+upsert keeps its existing meaning; inheritance then uses the records that remain.
+Typed defaults, CLI overrides, and application resolution follow the lifecycle
+in [ADR 0018](0018-cli-after-structural-resolution.md).
+
+An explicitly selected operation remains in effect at its destination until a
+higher layer changes it. When no explicit operation applies, use upsert if an
+identity definition is available; otherwise replace the whole sequence. Authors
+can declare identity and an operation before supplying any records. Keep source
+acquisition order separate from layer priority and the dependency ordering
+established by [ADR 0015](0015-shared-dependency-ready-ordering.md).
+
+Rules declared inside a record belong to that record. Retaining the record
+retains its local rules; replacing it discards them. Replacing a whole collection
+can discard its previous YAML identity definition, while application requirements
+still apply. Inheritance can copy collection identity, but the inheriting
+destination chooses its operation. Application registrations continue to govern
+the paths where they were registered. The same ownership rules apply to
+declarations made before a sequence exists.
+
+Check YAML-declared identity when combining collections during source assembly
+and inheritance. Application registrations also require the final loaded
+sequences to satisfy their identity rules, including after typed defaults, CLI
+overrides, and application resolution. This guarantee checks sequences that
+exist; the application schema and validation decide whether a collection must
+exist and which value types are allowed. The guarantee applies when loading
+completes, rather than to every intermediate callback state or changes made by
+the caller afterward.
+
+Preserve explicit presence, source attribution, history, sensitivity, and
+resource context through these operations, following
+[ADR 0003](0003-preserve-presence-and-resolution-history.md). Typed defaults,
+CLI assignments, and application resolution keep their own rules for changing
+values. The public API provides registration and inspection; the implementation
+chooses how to store and track collection rules internally.
+
+## Alternatives Considered
+
+- **Keep identity application-owned and always replace sequences across layers.**
+  Keeps the current design small, but reusable catalogs require application
+  changes or custom merging code.
+- **Put merge rules on each import.** Keeps the rules beside the imported source,
+  but inline sequences and overlays need a separate way to declare them. It also
+  makes rules for a collection spread across several imports harder to reconcile.
+- **Merge individual fields of records with matching identities.** Allows partial
+  record updates, but adds rules for field conflicts and retained values.
+  Replacing the whole record makes the update's scope clear.
+- **Keep inheritance limited to mapping siblings.** Keeps parent lookup simpler,
+  but authors of sequence records must duplicate shared settings or applications
+  must implement inheritance themselves. Collection identity provides a way to
+  select a parent within the existing loading process.
+- **Check every YAML identity again at the end of loading.** Gives YAML declarations
+  authority over values changed by defaults, CLI assignments, and application
+  resolution. This extends the lifetime of those declarations; application
+  registration provides that final guarantee when needed.
+
+## Consequences
+
+Consumers can build and customize catalogs in one load while retaining useful
+inspection information. Configuration authors choose how collections combine
+within application requirements. Duplicate identities among contributions at
+the same priority remain errors.
+
+Existing registered collections use upsert across layers by default unless an
+explicit operation selects otherwise. Correct loading now requires tracking
+which declarations still apply as records are replaced, copied, or moved to new
+positions. Lower-tier identity must be available before combining higher-tier
+contributions.
+
+Record inheritance also requires parent lookup by identity and checking for
+missing parents and cycles. Copied settings retain the same source, history,
+and sensitivity information as mapping-sibling inheritance.
+
+The [configuration contract](../config.md#strict-document-composition) defines
+declaration syntax, identity comparison, omission and empty-value behavior, and
+diagnostics for the implemented feature.

docs/adr/0018-cli-after-structural-resolution.md

@@ -0,0 +1,84 @@
+# ADR 0018: Apply CLI Overrides After Inheritance and Decoding
+
+## Status
+
+Accepted.
+
+This supersedes the rule that CLI overrides apply before decoding in
+[ADR 0005](0005-explicit-overrides-and-safe-explanation.md) and the
+rule that they apply before inheritance in [ADR 0009](0009-sibling-inheritance.md).
+Their remaining ownership, inheritance scope, and safe inspection decisions
+continue to apply.
+
+## Date
+
+2026-10-22
+
+## Context
+
+Explicit command-line values are the operator's highest-priority input. If they
+apply before inheritance, a sequence supplied as a replacement could gain
+inherited records afterward. Its final contents would then differ from the
+operator's assignment.
+
+The application also needs these values when it fills missing settings,
+normalizes values, or computes derived settings. ConfigKit needs a clear loading
+order that preserves both CLI precedence and the application's role in resolving
+the final configuration.
+
+## Decision
+
+ConfigKit uses this loading order:
+
+1. Combine sources within tiers and apply precedence between layers.
+2. Resolve sibling inheritance, apply typed defaults, and decode the configuration
+   into the application's types.
+3. Apply explicit CLI overrides and check them against the application schema.
+4. Run application resolution using the overridden configuration.
+5. Look up effective secret references, validate the final configuration, and
+   return it.
+
+CLI overrides are the highest-priority input to application resolution. A CLI
+sequence replaces the whole sequence; mappings combine recursively. Collection
+merge rules apply during the earlier source and inheritance steps. Inheritance
+and typed defaulting do not run again after CLI overrides.
+
+Keep track of which values were explicitly supplied and which CLI input supplied
+them. Applications continue to parse command-line arguments; ConfigKit applies
+and validates the overrides and makes their effects inspectable. Reject
+structural directives in override paths and values, so instructions such as
+inheritance relationships remain part of source processing.
+
+Application resolution keeps its existing rules for defaults and recorded
+changes under [ADR 0003](0003-preserve-presence-and-resolution-history.md).
+It receives CLI values together with their presence and source information.
+Defaults that only fill missing settings preserve explicit CLI values.
+Application normalization and derived-value calculations can still change them,
+with those changes recorded. Secret lookup and final validation use the resulting
+configuration.
+
+## Alternatives Considered
+
+- **Apply CLI overrides before inheritance.** Preserves existing ordering, but
+  later merging needs special handling to preserve CLI replacement intent while
+  still combining ordinary source contributions.
+- **Apply CLI overrides after inheritance but before typed decoding.** Allows an
+  override to fix a source value that would otherwise fail decoding, but leaves
+  typed defaulting after the operator's assignment. Completing defaulting and
+  decoding first gives CLI overrides an already resolved configuration to modify.
+- **Apply CLI overrides after application resolution.** Applies assignments after
+  the application's changes, but derived settings still reflect earlier values
+  unless resolution runs again.
+
+## Consequences
+
+CLI overrides change a configuration whose inheritance and typed defaults are
+already resolved. The application can then derive settings from the operator's
+values. The final values, source information, history, and sensitivity handling
+must remain consistent throughout loading.
+
+CLI input can no longer add or cancel inheritance relationships or bypass an
+earlier error in source assembly or inheritance. It also cannot fix a value that
+fails the earlier decoding step. Semantic validation still runs after overrides
+and application resolution. The [configuration contract](../config.md#explicit-cli-overrides)
+and [consumer guidance](../consumers/README.md) describe this behavior.

docs/adr/0019-explicit-configuration-discovery.md

@@ -0,0 +1,68 @@
+# ADR 0019: Keep Configuration Discovery Explicit and Inside Loading
+
+## Status
+
+Accepted.
+
+## Date
+
+2026-10-24
+
+## Context
+
+Applications often need a small ordered convention for choosing a main
+configuration file. Keeping that choice entirely in each application repeats
+path selection and file-loading plumbing. Moving the convention into ConfigKit
+without an explicit declaration would make ordinary loads search paths that a
+consumer did not choose, obscuring both precedence and filesystem access.
+
+ConfigKit already owns synchronous source acquisition, parsing, composition,
+decoding, validation, and inspection. A selected host file can therefore enter
+that lifecycle as the existing file source, preserving its source identity,
+resource context, and diagnostics. Optional exhaustion can use the same absent
+main lifecycle as an explicitly absent source.
+
+## Decision
+
+Consumers choose and order the main-file conventions they want to use. They may
+describe literal paths, directory filename groups, and supported directory
+presets, and may mark the complete search as required. Search descriptions are
+explicit inputs to loading; no preset or convention is activated implicitly.
+
+During synchronous loading, ConfigKit resolves the description to one real host
+file or to absence before parsing. The selected file follows the existing source
+acquisition and processing rules. A selected-file access, parse, version,
+composition, decode, or validation failure is terminal and does not resume the
+search. Optional exhaustion shares the absent-main lifecycle; required
+exhaustion reports a missing-source diagnostic. No candidate-attempt history is
+added to public metadata.
+
+This keeps convention choice with applications while moving repeated selection
+and loading plumbing into the library's established lifecycle. It preserves
+explicit control, ordinary source behavior, and complete-on-return ownership.
+
+## Alternatives Considered
+
+- **Keep all search and fallback loading in each application.** This preserves
+  consumer ownership but repeats the file-selection and load coordination that
+  ConfigKit already owns, and risks divergent handling of selected-file errors.
+- **Search conventional locations implicitly during every load.** This reduces
+  setup, but activates filesystem access and precedence the consumer did not
+  select and makes ordinary source behavior less predictable.
+- **Return candidate paths for the application to load one by one.** This keeps
+  selection outside the load lifecycle and encourages repeated complete loads,
+  potentially rerunning defaults, callbacks, and validation during fallback.
+
+## Consequences
+
+The public search description must be immutable and root-owned, with private
+engine conversion and selection. The contract documents candidate ordering,
+selection, exhaustion, context, and provenance; the API declaration documents
+the public symbols. Dynamic bases and file availability are observed when each
+load consumes the description. Applications remain responsible for selecting
+conventions and for their schema and domain requirements.
+
+The [configuration contract](../config.md) owns implemented behavior, and the
+[component overview](../internal/overview.md) describes implementation ownership.
+The completed implementation plan and remediation record are preserved in Git
+history at `0369111` under `docs/roadmap/`.

docs/consumers/README.md

@@ -1,66 +1,142 @@
 # Consumer Adoption Guide
 
-ConfigKit removes parser setup, strict decoding, presence bookkeeping, import and
+ConfigKit loads configuration into your application's Go types. You provide
-selected-overlay traversal, precedence, provenance, secret lookup, and safe inspection from
+those types, defaults, and application rules. ConfigKit reads and combines the
-applications. Consumers still own their configuration structs, defaults, semantic
+selected inputs, checks their types, and returns values with source information.
-validation, schema-version policy, CLI parsing, runtime matching and conversion,
+Your application still owns CLI parsing, resource reads, remote acquisition, and
-resource checks, remote acquisition, and service initialization.
+runtime initialization.
 
-The maintained [`examples/consumers`](../../examples/consumers) package demonstrates
+Import `"go.maximumdirect.net/configkit"`; the package name is `configkit`.
-sanitized shapes using only ConfigKit and the Go standard library:
+Start with one file, then choose the tasks your application needs:
 
-| Shape | Demonstrated fit | Application code deliberately retained |
+| Task | Start here |
-| --- | --- | --- |
+| --- | --- |
-| Narratio-like | Fresh defaults, explicit partial imports, artifact maps, recorded inherited defaults, normalization, and source ownership | Artifact meaning and the separate `model_profile` domain field |
+| Load one file | [Happy path](#happy-path) and the [README example](../../README.md#load-a-configuration-file) |
-| Notarius-like | Canonical object bindings, a string-backed schema version accepting string or integer YAML, strict dynamic options, and `int64` dynamic integers | Catalog selection, allowed option keys, range-checked conversion to runtime `int` |
+| Supply fixed defaults and check application rules | [Defaults and application rules](#defaults-and-application-rules) |
-| WeatherReporter-like | Defaults-only loading, report maps, canonical module objects, typed option unions, explicit CLI records, and typed secret startup | Report/module compatibility, rejection of explicitly empty domain lists, CLI parsing, and startup ordering |
+| Add bundled defaults beneath application settings | [Native filesystem and layered input](#native-filesystem-and-layered-input) |
-| Seriatim-like | Independent strict ordered speaker and autocorrect rule files | First-match and ordered replacement algorithms; no central application configuration file |
+| Select files or an overlay | [Discovery](#explicit-main-file-discovery), [import defaults](#import-defaults-and-selection-inspection), and the [overlay reference](../config.md#selected-overlays) |
-| Bundled file | Simple native `fs.FS` source through ordinary `Load` | Selection and lifetime of the application-owned embedded filesystem |
+| Reuse settings or combine record lists | [Inheritance](#named-sibling-inheritance) and [identified sequences](#identified-prompt-sequences) |
-| Layered catalog | Embedded defaults with an import, a mapping underlay, an independent host main file, explicit false/zero input, and source-relative resource access | Domain validation and opening/interpreting the template resource |
+| Handle credentials | [Typed-secret reference](../config.md#typed-secret-references) and the [startup example](../../examples/consumers/consumers_test.go) |
-| Mounted collections | Entry-declared relative destinations, nested metadata/prompt/profile imports, local inheritance, and a version-only higher-tier override | Collection IDs, profile meaning, and opening/interpreting prompt resources |
+| Inspect sources, earlier values, or changes | [Inspect a completed load](#inspect-a-completed-load) and [diffs](#effective-configuration-diffs) |
-| Named presets | One-load sibling inheritance, explicit false, nested destination resolution, and source/derivation inspection | Choosing and executing a preset |
+| Upgrade an existing consumer | [Migration guidance](#intentional-migration-changes) |
-| Effective configuration diff | Same-type frozen effective comparisons for two selected files or base-versus-overlay impact | Source/options selection and consumer-owned safe presentation |
-| Shared source-version checks | One `Definition.Version` policy for accepted declarations across participating source documents, with optional or required declarations and sanitized evidence | Choosing which declarations the application accepts; final assembled schema and domain validation |
-| Identified prompt sequences | Explicit item path/glob imports, helper-supplied IDs, reusable single-field registration, and main-tier replacement of a lower-priority collection | Prompt meaning and final domain validation |
 
-The YAML under [`testdata`](../../examples/consumers/testdata) is loaded by the
+## Choosing a loading entry point
-executable examples and ordinary tests. It contains no private application data,
-credentials, network calls, or dependency on a sibling checkout.
 
-The Notarius-shaped fixtures deliberately load both `version: 4` and
+- Use [`Load`](../../lifecycle.go) with one source for an ordinary configuration.
-`version: "4"` into the same string-backed application field. Its version checker
+  [`SearchConfig`](../../discovery.go) is also a source; pass it to `Load` or use
-still owns the supported identifier; fractional numeric input and unsupported
+  it as the main input to [`LoadLayered`](../../layered.go).
-integer identifiers remain negative examples.
+- Use `LoadLayered` when several inputs should supply lower-priority defaults
+  beneath the main source. Each underlay group combines its inputs strictly.
+  Each [`Input`](../../layered.go) owns its source, filesystem, destination, and
+  import choice. The overlay filesystem context is selected independently in
+  [`LayeredOptions`](../../layered.go).
+- Load-wide rules belong to [`Options`](../../lifecycle.go) or
+  [`LayeredOptions`](../../layered.go): the application definition (including
+  version policy), import defaults, and explicit overrides. These do not turn
+  on imports or discovery by themselves. See the
+  [configuration contract](../config.md#layered-loading) and
+  [discovery contract](../config.md#configuration-discovery) for exact rules.
+
+The root [README example](../../README.md) shows the small `Load` path.
+[`layered.go`](../../examples/consumers/layered.go) demonstrates the bundled
+file and layered cases. For import-focused adoption, see the
+[prompt catalog](../../examples/consumers/prompt_catalog.go); for explicit
+discovery composed with sequences, see the
+[sequence catalog](../../examples/consumers/sequence_catalog.go).
 
 ## Happy path
 
-An application defines ordinary types and passes one explicit source. Optional
+Define the Go configuration type, choose one source, and call `Load`. Handle a
-features appear only when the application needs them:
+load error before starting the application with `result.Config`. The
+[README example](../../README.md#load-a-configuration-file) shows this complete
+minimal loading function. An explicitly missing file is an error; use `NoSource`
+when you deliberately want defaults without a main document.
+
+### Defaults and application rules
+
+Using the README's `Config` type, an application can add reusable rules:
 
 ```go
-result, err := configkit.Load[Config](configkit.File(path), configkit.Options[Config]{
+definition := configkit.Definition[Config]{
-    Definition: rules,
+    Defaults: func() Config { return Config{Enabled: true, Workers: 2} },
-    Imports:    useDeclaredImports,
+    Validate: func(value *Config, validation *configkit.Validation) {
-    Overlay:    selectedConfigOverlay,
+        if value.Workers < 0 {
-    Overrides:  explicitlySetFlags,
+            validation.Error(configkit.Keys("workers"), "must be nonnegative")
-})
+        }
-if err != nil {
+    },
-    return err
 }
-return start(result.Config)
 ```
 
-Simple consumers use neither imports nor selected overlays. A complex consumer can opt into
+Pass this definition in `Options[Config]{Definition: definition}` when calling
-both without redefining their syntax. ConfigKit overlays are configuration overlays;
+`Load`. Supplied `enabled: false` or `workers: 0` replaces those defaults.
-they do not select or replace an application's LLM, model, pipeline, report, or
+Use `Resolve` when a value must be derived or normalized before validation, and
-execution profile concepts.
+record that change with the provided helpers. The
+[callback reference](../config.md#recorded-application-resolution) compares the
+helpers; [executable examples](../../example_test.go) show full definitions.
+
+### Inspect a completed load
+
+Keep the result when you need to explain configuration. Use
+`result.Metadata().Lookup(configkit.Keys("workers"))` to inspect whether input
+supplied the value and which source or application step supplied it. Follow an
+origin's source ID with `result.Source(id)` when you need its source record.
+
+Use `Explain` for earlier values, `WriteExplanation` for a readable explanation,
+and `WriteEffective` for safe YAML describing the final saved state. These
+operations describe the completed load even if your application later changes
+`result.Config`. The [inspection reference](../config.md#layered-metadata)
+explains returned values, copies, and hidden information.
+
+Add imports, a selected overlay, or explicitly set CLI values through options
+only when needed. An overlay changes configuration; choosing an LLM, report, or
+execution profile remains application logic.
+
+## Explicit main-file discovery
+
+Applications choose the search conventions and their precedence, then pass the
+resulting `SearchConfig` source to the same `Load` or `LoadLayered` entry
+point. For example, the maintained sequence catalog puts a caller-selected
+file before a custom directory fallback while keeping its underlay and overlay
+choices independent. See
+[`sequence_catalog.go`](../../examples/consumers/sequence_catalog.go) and its
+[behavior tests](../../examples/consumers/sequence_catalog_test.go), plus the
+[working-directory executable
+example](../../examples/consumers/discovery_test.go). Together, the [discovery
+API](../../discovery.go) and [configuration discovery
+contract](../config.md#configuration-discovery) explain the order of attempted
+files, what happens when no file is found, and why a selected-file failure
+stops the search. [ADR 0019](../adr/0019-explicit-configuration-discovery.md)
+records why discovery is explicitly selected.
+
+## Import defaults and selection inspection
+
+`Options.ImportDefaults` and `LayeredOptions.ImportDefaults` apply one
+load-wide policy to enabled main, underlay, and transitive imports. Each field
+is resolved independently: a declaration's explicit value wins, then the
+application default, then the library default. `Required`, `FollowSymlinks`,
+`IncludeHidden`, and `Recursive` use nil pointers for unspecified values.
+`Pattern` applies to
+directory searches: nil leaves filenames unrestricted, while a non-nil empty
+slice selects no files. A declaration's own `pattern` replaces the application
+default. The defaults do not enable imports or change selected-overlay behavior.
+The Go fields `FollowSymlinks` and `IncludeHidden` correspond to the unchanged
+YAML keys `follow` and `hidden`.
+
+`Result.Sources`, `LoadError.Sources`, and `Resolution.Source` expose each
+declaring source's `EmptyImportSelections`. `Result.Source(id)` and
+`LoadError.Source(id)` retrieve one retained record directly when its load-local
+ID is known. These records identify the source-local declaration path, its
+authored location and selector;
+they do not include candidate names or a guessed reason for absence. Returned
+records are detached snapshots. The [configuration contract](../config.md#explicit-imports)
+owns selector applicability and exact absence semantics.
 
 ## Shared source-version checks
 
 [`LoadVersionedService`](../../examples/consumers/source_version.go) demonstrates
 if-present and required modes with one `Definition.Version` rule across a mounted
 main input and an underlay. The example reads only sanitized
-`SourceInfo.VersionCheck` fields; its executable test is in
+`SourceInfo.VersionEvidence` fields; its executable test is in
 [`layered_test.go`](../../examples/consumers/layered_test.go). The
 [configuration contract](../config.md#shared-source-version-checks) defines
 participation, source-local lookup and diagnostics, non-main header consumption,
@@ -78,13 +154,14 @@ priority values remain present. Its resolver records a derived endpoint URL afte
 overlay application, and its nested typed secret reference is classified before
 the resulting records are presented.
 
-The maintained [behavior tests and executable examples](../../examples/consumers/diff_test.go)
+The maintained [behavior tests and executable
-use temporary files and disposable secret values. Presenters should use
+examples](../../examples/consumers/diff_test.go) use temporary files and
-`ValueSnapshot.Present` for absence, record membership for change, and
+disposable secret values. Presenters should use `ValueSnapshot.Present` for
-`HiddenChanged` for a withheld change indicator. Do not parse the redaction marker
+absence, record membership for change, and `HiddenChanged` for a withheld
-or add separately rendered full contexts that lack combined sensitivity. The
+change indicator. Do not parse the redaction marker or add separately rendered
-[configuration contract](../config.md#effective-configuration-diffs) owns shared
+full contexts that lack combined sensitivity. The [configuration
-equality, granularity, and disclosure semantics.
+contract](../config.md#effective-configuration-diffs) owns shared equality,
+granularity, and disclosure semantics.
 
 ## Named sibling inheritance
 
@@ -166,21 +243,35 @@ import, source-location, and ownership behavior.
 
 ## Identified prompt sequences
 
-[`LoadPromptCatalog`](../../examples/consumers/prompt_catalog.go) uses one
+[`LoadPromptCatalog`](../../examples/consumers/prompt_catalog.go) shows the
-definition registration for the literal `prompts` path and `id` field. Its main
+smaller import-focused adoption path: a registered `prompts.id` identity,
-file imports one prompt by path and others by glob, placing each source as an
+directory and glob selection, a helper import that supplies an item's ID, and
-item. A nested ordinary helper import supplies an item's ID. The main tier
+resource lookup through the effective source context. Its executable examples
-strictly appends the distinct records in contribution order; its completed
+and tests are in
-sequence replaces the lower-priority default collection as one value.
+[`prompt_catalog_test.go`](../../examples/consumers/prompt_catalog_test.go), with
+complete [catalog](../../examples/consumers/testdata/prompt-catalog/config.yml)
+and [required-file](../../examples/consumers/testdata/prompt-catalog/simple.yml)
+fixtures.
 
-The example's `validatePromptCatalog` remains application-owned. It checks that
+[`LoadSequenceCatalog`](../../examples/consumers/sequence_catalog.go) integrates
-prompt names and message lists satisfy this consumer's requirements after
+an underlay declaration, imported main fragments, identified-record inheritance,
-ConfigKit has composed, projected, and decoded the configuration. It does not
+selected overlay `append`, `upsert`, and `replace`, a typed CLI override, and
-add recursive record merging, identity-based overlay, or final uniqueness checks
+recorded application resolution. Its tests and runnable example demonstrate
-after defaults and resolution. See the [strict composition contract](../config.md#strict-document-composition),
+stable output order, whole-record upsert, provenance/history inspection,
-[import syntax](../config.md#explicit-imports), and
+resource lookup for inherited records, and secret-safe explanation in
-[ADR 0014](../adr/0014-sequence-placement-and-composition.md) for the exact
+[`sequence_catalog_test.go`](../../examples/consumers/sequence_catalog_test.go).
-boundaries.
+[`LoadNamespacedMapCatalog`](../../examples/consumers/sequence_catalog.go) adds
+an exact root registration and a wildcard namespace registration, showing that
+each concrete sequence has an independent identity scope. The same tests show
+that a YAML identity declaration without an application registration does not
+create final-result identity enforcement.
+
+The examples keep prompt meaning and domain checks in the consuming application.
+The [configuration contract](../config.md#strict-document-composition) owns
+declaration, identity, operation, ownership, and final-validation semantics;
+[sibling inheritance](../config.md#sibling-inheritance) defines record
+relationships, and the [CLI contract](../config.md#explicit-cli-overrides) owns
+override ordering.
 
 Known module catalogs should use canonical object entries with a module identifier
 and typed options. A small union struct is sufficient when the available option
@@ -193,14 +284,13 @@ conversion API.
 ## Source-aware application path policy
 
 [`LoadNotariusPaths`](../../examples/consumers/consumers.go) is the maintained
-path-bearing example. Its application resolver uses `Resolution.InputInfo` and
+path-bearing example. Its application resolver uses `Resolution.EntryInfo` and
 `Resolution.Source` before normalizing: relative CLI input uses an explicitly
 supplied invocation directory, retained defaults use the canonical main source,
 and a file-authored scalar uses its one declaring source. Absolute paths remain
-unchanged. Its executable test covers the matching effective YAML and explanation
+unchanged. Its executable test checks the resulting YAML and explanation
-history, source-file ownership, and a symlink opened through an alias; canonical
+history. When the configuration filename is a symlink, this example uses the
-target-file directories, rather than the alias directory or process working
+actual target file's directory as the base for file-authored paths.
-directory, are the selected bases.
 
 The selected example policy leaves a relative value unchanged and emits a warning
 when a CLI base is absent or file provenance is missing or composite. That is an
@@ -210,7 +300,15 @@ existence checks nor confinement checks.
 
 ## Intentional migration changes
 
-The examples preserve domain meaning while adopting one configuration convention:
+When upgrading, start with the changes relevant to your dependency and inputs:
+
+1. Update the module requirement and Go imports together as described below.
+2. Replace old public names using the old/new table.
+3. Update any layer or diagnostic-code strings stored or compared by your code.
+4. Review YAML and startup changes that apply to your application, then rebuild
+   and run its configuration tests.
+
+The maintained examples illustrate these configuration changes:
 
 - Explicit empty strings, lists, zeroes, false values, and nulls remain intentional.
   ConfigKit accepts an empty list structurally; WeatherReporter-shaped validation
@@ -230,10 +328,70 @@ The examples preserve domain meaning while adopting one configuration convention
   parsers translate only explicitly set configuration flags into `Override` records.
   Separate invocation state remains outside configuration.
 - Credential fields migrate to environment-name `Secret` references. Applications
-  explicitly call `LoadSecretsDir` before `Load` when they choose file bootstrap;
+  explicitly call `LoadSecretsIntoEnvironment` before `Load` when they choose
+  file bootstrap;
   blocked empty variables remain blocked, and ordinary `Load` never changes the
   process environment.
 
+### Vanity module path migration
+
+ConfigKit's module identifier changed from
+`gitea.maximumdirect.net/eric/ConfigKit` to `go.maximumdirect.net/configkit` before
+v1.0.0. Update the dependency requirement in your application's `go.mod` and its
+Go imports together, selecting a revision or release that declares the new module
+path. The package name remains `configkit`; the configuration model and public
+symbol names are unchanged by this identity migration.
+
+Go treats the old and new import paths as different packages, with different
+named types. For example, if another library returns a ConfigKit `Path` or
+`Secret` using the old import, your application cannot use it as the new
+package's type just by changing a module requirement. Coordinate migration
+with dependencies that pass ConfigKit values to or from your application. The
+maintained examples use the new path, but other repositories must manage their
+own migrations.
+
+Historical tags keep their original module declarations and contents. Older
+releases such as v0.10.2 still use the old path and cannot be installed under the
+vanity identifier simply because discovery can find their repository. A matching
+migrated revision is needed; no old-path compatibility module is supplied here.
+
+### Pre-v1 public API cleanup
+
+The pre-v1 API cleanup replaces these names outright; it does not retain
+compatibility aliases:
+
+| Previous API | Current API |
+| --- | --- |
+| `Resolution.InputInfo(path)` | `Resolution.EntryInfo(path)` |
+| `Definition.Secret` | `Definition.Sensitive` |
+| `SourceVersionModeDefault` | `SourceVersionModeMainOnly` |
+| `SourceVersionCheck` | `SourceVersionEvidence` |
+| `SourceInfo.VersionCheck` | `SourceInfo.VersionEvidence` |
+| `ImportSelection` | `EmptyImportSelection` |
+| `SourceInfo.ImportSelections` | `SourceInfo.EmptyImportSelections` |
+| `SourceInfo.DestinationUnresolved` | `SourceInfo.DestinationIsFallback` |
+| `ImportDefaults.Follow` / `.Hidden` | `FollowSymlinks` / `IncludeHidden` |
+| `Paths(paths...)` | `SearchPaths(paths...)` |
+| `LoadSecretsDir(directory)` | `LoadSecretsIntoEnvironment(directory)` |
+| `LayerBase` | `LayerMain` |
+| `CodeExplainLimitExceeded` | `CodeHistoryLimitExceeded` |
+| `CodeResolveInvalidKind` / `CodeOptionsUnavailable` | Removed; no replacement |
+| `ImportSelection.Outcome`, `ImportSelectionOutcome`, `ImportSelectionNone` | Removed; empty-selection records no longer carry an outcome |
+| `Resolution.Record(path, ChangeDerivedDefault, reason, deps...)` | `Resolution.RecordDerivedDefault(path, reason, deps...)` |
+| `Resolution.Record(path, ChangeNormalization, reason, deps...)` | `Resolution.RecordNormalization(path, reason, deps...)` |
+| Enumerating `Result.Sources()` / `LoadError.Sources()` to find one ID | `Result.Source(id)` / `LoadError.Source(id)` |
+| Provenance string `"base"` | `"main"` |
+| History diagnostic string `"explain.limit_exceeded"` | `"history.limit_exceeded"` |
+
+The YAML import keys `follow` and `hidden`, the `configkit:"secret"` tag, and
+typed `Secret` references are unchanged. If your application compares or
+stores layer names or diagnostic codes as strings, update those strings
+alongside Go references. This repository guidance does not claim that
+downstream applications have migrated and does not select a release version
+for this breaking pre-v1 change. `ChangeKind` and its inspection constants
+remain; use `Default` and `Normalize` when the helper should both assign and
+record a value.
+
 ### Selected-overlay migration
 
 To adopt the current selected-overlay API, rename `Options.Profile`,
@@ -244,10 +402,40 @@ The [configuration contract](../config.md#selected-overlays) is the canonical
 behavioral reference. Application-owned profile concepts, such as `model_profile`,
 are unchanged, and any CLI flag rename remains the application's decision.
 
-These examples are migration evidence, not completed changes to Narratio, Notarius,
+### Background on the examples
-WeatherReporter, or Seriatim. Updating those repositories, their deployed YAML, CLI
+
-wiring, runtime catalogs, and operational documentation remains separate downstream
+These examples demonstrate migration shapes. They do not claim that Narratio,
-work.
+Notarius, WeatherReporter, or Seriatim has been migrated. Updating those
+repositories, their deployed YAML, CLI wiring, runtime catalogs, and
+operational documentation remains separate downstream work.
+
+## Example background
+
+The maintained [`examples/consumers`](../../examples/consumers) package demonstrates
+sanitized shapes using only ConfigKit and the Go standard library:
+
+| Shape | Demonstrated fit | Application code deliberately retained |
+| --- | --- | --- |
+| Artifact defaults and normalization (Narratio-like) | Fresh defaults, explicit partial imports, artifact maps, recorded inherited defaults, normalization, and source ownership | Artifact meaning and the separate `model_profile` domain field |
+| Versions and dynamic options (Notarius-like) | Canonical object bindings, a string-backed schema version accepting string or integer YAML, strict dynamic options, and `int64` dynamic integers | Catalog selection, allowed option keys, range-checked conversion to runtime `int` |
+| Module validation and credential startup (WeatherReporter-like) | Defaults-only loading, report maps, canonical module objects, typed option unions, explicit CLI records, and typed secret startup | Report/module compatibility, rejection of explicitly empty domain lists, CLI parsing, and startup ordering |
+| Independent ordered rule files (Seriatim-like) | Independent strict ordered speaker and autocorrect rule files | First-match and ordered replacement algorithms; no central application configuration file |
+| Bundled file | Simple native `fs.FS` source through ordinary `Load` | Selection and lifetime of the application-owned embedded filesystem |
+| Layered catalog | Embedded defaults with an import, a mapping underlay, an independent host main file, explicit false/zero input, and source-relative resource access | Domain validation and opening/interpreting the template resource |
+| Mounted collections | Entry-declared relative destinations, nested metadata/prompt/profile imports, local inheritance, and a version-only higher-tier override | Collection IDs, profile meaning, and opening/interpreting prompt resources |
+| Named presets | One-load sibling inheritance, explicit false, nested destination resolution, and source/derivation inspection | Choosing and executing a preset |
+| Effective configuration diff | Same-type frozen effective comparisons for two selected files or base-versus-overlay impact | Source/options selection and consumer-owned safe presentation |
+| Shared source-version checks | One `Definition.Version` policy for accepted declarations across participating source documents, with optional or required declarations and sanitized evidence | Choosing which declarations the application accepts; final assembled schema and domain validation |
+| Sequence catalogs | Declared collection operations, record inheritance, typed CLI and resolution, inspection, exact and wildcard application registrations | Catalog meaning and final domain validation |
+
+The YAML under [`testdata`](../../examples/consumers/testdata) is loaded by the
+executable examples and ordinary tests. It contains no private application data,
+credentials, network calls, or dependency on a sibling checkout.
+
+The Notarius-shaped fixtures deliberately load both `version: 4` and
+`version: "4"` into the same string-backed application field. Its version checker
+still owns the supported identifier; fractional numeric input and unsupported
+integer identifiers remain negative examples.
 
 ## Maintained API examples
 
@@ -259,7 +447,7 @@ focused behavioral owner:
 | `Load`, `NoSource`, validation, versions, resolution, `SecretEnv`, overrides, and explanation | Executable examples in [`example_test.go`](../../example_test.go) |
 | Source/import/selected-overlay pipeline rules and artifact defaults | Narratio-shaped executable example and fixture |
 | Canonical module objects and dynamic option handling | WeatherReporter- and Notarius-shaped examples and migration tests |
-| `LoadSecretsDir`, bootstrap reporting, typed lookup, CLI explanation | `Example_weatherStartup` |
+| `LoadSecretsIntoEnvironment`, bootstrap reporting, typed lookup, CLI explanation | `Example_weatherStartup` |
 | Native filesystem, grouped underlays, programmatic mapping, retained resource context | `Example_nativeFilesystem`, `Example_layeredCatalog`, and their focused consumer tests |
 | Literal input destinations, root-default compatibility, and mounted peer collections | `Example_inputDestination`, `LoadCollectionBundle`, and `destinations_test.go` |
 | Named sibling inheritance, presence, and derivation | `Example_inheritedPresets` and `TestPresetCatalogOneLoadAndDerivation` |

docs/development.md

@@ -59,6 +59,11 @@ Accepted decisions:
 - [Keep the public facade root-owned](adr/0006-public-facade.md)
 - [Compare frozen effective configuration snapshots](adr/0010-effective-configuration-diff.md)
 - [Place inputs at literal application mapping paths](adr/0011-input-destinations.md)
+- [Share dependency-ready ordering](adr/0015-shared-dependency-ready-ordering.md)
+- [Separate import selection controls](adr/0016-independent-import-controls.md)
+- [Define identity and merge rules for each collection](adr/0017-collection-sequence-policy.md)
+- [Apply CLI overrides after inheritance and decoding](adr/0018-cli-after-structural-resolution.md)
+- [Keep main-file discovery explicit and composable](adr/0019-explicit-configuration-discovery.md)
 
 For cross-cutting changes, follow every applicable row. Completed implementation
 and remediation plans are preserved in Git history at `cb5b435`; use current
@@ -108,7 +113,7 @@ git show 8e91a2b:docs/roadmap/startup-benchmark.md
 ```
 
 Remaining optimization candidates belong to
-[future performance experiments](roadmap/future.md#3-performance-experiments).
+[future performance experiments](roadmap/future.md#5-performance-experiments).
 
 The completed effective-configuration diff roadmap, implementation plan, and
 resolved review findings are preserved in Git history at `1c2610c` under
@@ -131,12 +136,13 @@ Current behavior belongs to the configuration contract's
 [input destinations](config.md#input-destinations),
 [imports](config.md#explicit-imports), and
 [shared source-version checks](config.md#shared-source-version-checks) sections.
-Explicit sequence-item placement and registered strict composition are owned by
+Explicit sequence-item placement, collection operations, identity registration,
-the [strict composition](config.md#strict-document-composition) and
+and final registered-identity validation are owned by the
-[imports](config.md#explicit-imports) sections. The
+[strict composition](config.md#strict-document-composition) section;
-[maintained prompt catalog](consumers/README.md#identified-prompt-sequences)
+[imports](config.md#explicit-imports) owns acquisition and scheduling. The
-shows the current consumer boundary, and [ADR 0014](adr/0014-sequence-placement-and-composition.md)
+[maintained sequence catalog](consumers/README.md#identified-prompt-sequences)
-records the decision.
+shows the consumer boundary, and [ADR 0017](adr/0017-collection-sequence-policy.md)
+records the collection decision.
 
 The completed sequence-composition roadmap, implementation plan, and resolved
 remediation record are preserved in Git history at `008d2ba` under
@@ -148,7 +154,77 @@ git show 008d2ba:docs/roadmap/implementation.md
 git show 008d2ba:docs/roadmap/remediation.md
 ```
 
+The completed import-discovery roadmap, implementation plan, and resolved
+remediation record are preserved in Git history at `5747ec4` under
+`docs/roadmap/`. For example:
+
+```sh
+git show 5747ec4:docs/roadmap/imports.md
+git show 5747ec4:docs/roadmap/implementation.md
+git show 5747ec4:docs/roadmap/remediation.md
+```
+
+The subsequent import-integration audit and completed remediation record are
+preserved at `6903c9e:docs/roadmap/remediation.md`; retrieve them with
+`git show 6903c9e:docs/roadmap/remediation.md`.
+
+The completed sequence-identity/collection-policy roadmap and implementation
+plan are preserved in Git history at `d0a605a`:
+
+```sh
+git show d0a605a:docs/roadmap/sequences.md
+git show d0a605a:docs/roadmap/implementation.md
+```
+
+Current behavior belongs to the configuration contract's
+[strict composition](config.md#strict-document-composition),
+[sibling inheritance](config.md#sibling-inheritance), and
+[CLI overrides](config.md#explicit-cli-overrides) sections.
+The completed remediation record, including the algorithm-audit findings, is
+preserved at `ea46001:docs/roadmap/remediation.md`.
+
+The completed configuration-discovery roadmap, implementation plan, and
+remediation record are preserved in Git history at `0369111`, for example
+`git show 0369111:docs/roadmap/remediation.md`. Current behavior belongs to
+[configuration discovery](config.md#configuration-discovery); the public
+[discovery declarations](../discovery.go) own the Go API.
+
+The completed consolidation proposal, implementation plan, and resolved audit
+findings are preserved in Git history at `34cbc0d` under `docs/roadmap/`. For
+example:
+
+```sh
+git show 34cbc0d:docs/roadmap/implementation.md
+git show 34cbc0d:docs/roadmap/remediation.md
+```
+
 Potential enhancements are tracked in [future features](roadmap/future.md).
+The completed audit-remediation, internal-boundary simplification, shared-history,
+and public API cleanup roadmaps, reviews, and resolved findings are preserved at
+`68400ff` under `docs/roadmap/`. For example:
+
+```sh
+git show 68400ff:docs/roadmap/api.md
+git show 68400ff:docs/roadmap/remediation.md
+```
+
+Their earlier completed implementation plans are preserved at
+`bb5540b:docs/roadmap/implementation.md` (audit remediation),
+`f6d54a0:docs/roadmap/implementation.md` (internal-boundary simplification), and
+`07e4ae5:docs/roadmap/implementation.md` (shared history). The plan at
+`68400ff:docs/roadmap/implementation.md` records the public API cleanup.
+Current behavior and migration information belong to the
+[configuration contract](config.md), public declaration comments, and
+[consumer guide](consumers/README.md#pre-v1-public-api-cleanup).
+
+The consolidated audit, including
+findings, evidence, and settled scope decisions, is preserved at
+`453da68:docs/roadmap/audit.md`; the original nine reports are preserved at
+`ecd5d5d` under `docs/roadmap/`. Retrieve the consolidated record with:
+
+```sh
+git show 453da68:docs/roadmap/audit.md
+```
 
 Install the Go version required by `go.mod` or a compatible newer toolchain.
 Acquire declared dependencies explicitly before entering an offline
@@ -196,21 +272,25 @@ code changes. Use the component overview to find the corresponding implementatio
 | Task | Behavioral test owners | Focused command |
 | --- | --- | --- |
 | YAML syntax, diagnostics, parser limits | [Adapter tests](../internal/yaml/parse_test.go), [source translation](../internal/engine/parse_test.go) | `go test ./internal/yaml` and `go test ./internal/engine -run '^TestParseSource'` |
-| File/reader access, imports, globs, containment | [Sources](../internal/engine/source_test.go), [FIFO](../internal/engine/source_fifo_test.go), [imports](../internal/engine/imports_test.go), [relative destinations](../internal/engine/destination_import_test.go), [globs](../internal/engine/glob_test.go) | `go test ./internal/engine -run 'Source\|Import\|Glob\|Filesystem\|Nonregular\|RegularFile'` |
+| File/reader access, imports, globs, containment | [Import internals](internal/imports.md), [source acquisition](../internal/engine/source_test.go), [FIFO](../internal/engine/source_fifo_test.go), [import traversal](../internal/engine/imports_test.go), [import evidence](../internal/engine/import_evidence_test.go), [relative destinations](../internal/engine/destination_import_test.go), [globs](../internal/engine/glob_test.go) | `go test ./internal/engine -run 'Source\|Import\|Glob\|Filesystem\|Nonregular\|RegularFile'` |
+| Explicit main-file discovery and absent-input loading | [Candidate selection](../internal/engine/discovery_test.go), [load integration](../internal/engine/discovery_load_test.go), [public facade](../facade_discovery_test.go), and maintained [catalog](../examples/consumers/sequence_catalog_test.go) and [preset](../examples/consumers/discovery_test.go) examples | `go test ./internal/engine -run 'Discovery\|Search'`, `go test . -run 'Search'`, and `go test ./examples/consumers -run 'WorkingDirectoryPreset\|SequenceCatalog'` |
+| Import defaults, empty-selection evidence, and dependency-ready ordering | [Defaults and facade evidence](../facade_import_defaults_test.go), [engine import evidence](../internal/engine/import_evidence_test.go), [scheduler](../internal/engine/dependency_order_test.go), [scheduling integrations](../internal/engine/imports_test.go) | `go test ./internal/engine -run 'Import\|ScheduleDependencies\|Inheritance'`, `go test . -run 'ImportDefaults\|FacadeImport'`, and `go test ./examples/consumers` |
 | Native filesystem and mapping sources | [Native acquisition](../internal/engine/native_filesystem_test.go), [filesystem facade](../facade_filesystem_test.go), [mapping facade](../facade_mapping_test.go) | `go test ./internal/engine -run 'NativeFilesystem'` and `go test . -run 'TestFacade'` |
 | Composition, selected overlays, CLI precedence | [Composition](../internal/engine/compose_test.go), [overlay](../internal/engine/overlay_test.go), [selected overlays](../internal/engine/selected_overlay_test.go), [overrides](../internal/engine/override_test.go) | `go test ./internal/engine -run 'Compose\|Overlay\|Override'` |
-| Sibling inheritance, provenance, history, sensitivity | [Expansion](../internal/engine/inheritance_test.go), [destination scopes](../internal/engine/inheritance_walk_test.go), [origins](../internal/engine/inheritance_origin_test.go), [history](../internal/engine/inheritance_history_test.go), [secrets](../internal/engine/inheritance_secret_test.go), [public loading](../facade_inheritance_test.go) | `go test ./internal/engine -run 'Inheritance\|Inherited'` and `go test . -run '^TestFacadeInheritance\|^TestFacadeInheritedSecrets'` |
+| Sequence identity, declarations, and operations | [Identity](../internal/engine/sequence_identity_test.go), [registrations](../internal/engine/sequence_registration_test.go), [declarations](../internal/engine/sequence_declaration_test.go), [combination](../internal/engine/sequence_combine_test.go), [final facade validation](../facade_final_sequence_identity_test.go), and [consumer catalog](../examples/consumers/sequence_catalog_test.go) | `go test ./internal/engine -run 'Sequence\|Collection'`, `go test . -run 'SequenceIdentity\|SequenceRegistration'`, and `go test ./examples/consumers` |
+| Sibling inheritance, provenance, history, sensitivity | [Implementation flow](internal/overview.md#implementation-flow), [expansion](../internal/engine/inheritance_test.go), [destination scopes](../internal/engine/inheritance_walk_test.go), [origins](../internal/engine/inheritance_origin_test.go), [history](../internal/engine/inheritance_history_test.go), [secrets](../internal/engine/inheritance_secret_test.go), [public loading](../facade_inheritance_test.go) | `go test ./internal/engine -run 'Inheritance\|Inherited'` and `go test . -run '^TestFacadeInheritance\|^TestFacadeInheritedSecrets'` |
 | Layered loading and source equivalence | [Grouped lifecycle](../internal/engine/load_request_test.go), [layered facade](../facade_layered_test.go), [equivalence](../facade_equivalence_test.go) | `go test ./internal/engine -run '^TestGrouped'`, `go test . -run '^TestFacadeLayered'`, and `go test . -run '^TestEquivalentSourceForms'` |
-| Input and relative-import destinations, mounted sources, and source ownership | [Destination engine tests](../internal/engine/destination_test.go), [tier tests](../internal/engine/destination_tiers_test.go), [import traversal and version tests](../internal/engine/destination_import_test.go), [accounting tests](../internal/engine/destination_accounting_test.go), [lifecycle inspection tests](../internal/engine/destination_import_lifecycle_test.go), [public source/error tests](../facade_destination_test.go), [resource contexts](../facade_resource_context_test.go), and [consumer examples](../examples/consumers/destinations_test.go) | `go test ./internal/engine -run 'Destination|Import|Glob|Mounted'`, `go test . -run 'Destination|Import|SourceContext|FacadeMounted'`, and `go test ./examples/consumers` |
+| Input and relative-import destinations, mounted sources, and source ownership | [Destination engine tests](../internal/engine/destination_test.go), [tier tests](../internal/engine/destination_tiers_test.go), [import traversal and version tests](../internal/engine/destination_import_test.go), [accounting tests](../internal/engine/destination_accounting_test.go), [lifecycle inspection tests](../internal/engine/destination_import_lifecycle_test.go), [public source/error tests](../facade_destination_test.go), [resource contexts](../facade_resource_context_test.go), and [consumer examples](../examples/consumers/destinations_test.go) | `go test ./internal/engine -run 'Destination\|Import\|Glob\|Mounted'`, `go test . -run 'Destination\|Import\|SourceContext\|FacadeMounted'`, and `go test ./examples/consumers` |
 | Shared source-version modes and evidence | [Engine source-version tests](../internal/engine/source_version_test.go), [public facade tests](../facade_source_version_mode_test.go), and [consumer example tests](../examples/consumers/layered_test.go) | `go test ./internal/engine -run 'SourceVersion'`, `go test . -run 'SourceVersion'`, and `go test ./examples/consumers` |
-| Schema, defaults, projection, cloning | [Schema](../internal/engine/schema_test.go), [decoding](../internal/engine/decode_test.go), [projection](../internal/engine/projection_test.go) | `go test ./internal/engine -run 'Schema\|Decode\|Projection\|Clone\|Inline\|CompareDocument'` |
+| Schema, defaults, projection, cloning | [Implementation flow](internal/overview.md#implementation-flow), [schema](../internal/engine/schema_test.go), [decoding](../internal/engine/decode_test.go), [projection and typed cloning](../internal/engine/projection_test.go) | `go test ./internal/engine -run 'Schema\|Decode\|Projection\|Clone\|Inline\|CompareDocument'` |
 | Lifecycle, resolution, validation, callback ownership | [Loading](../internal/engine/load_test.go), [resolution](../internal/engine/resolution_test.go), [validation](../internal/engine/validation_test.go), [ownership](../internal/engine/callback_ownership_test.go), [independence](../internal/engine/independence_test.go) | `go test ./internal/engine -run 'Load\|Resolution\|Validation\|Validator\|Hook\|Callback\|Parallel'` |
 | Paths, metadata, provenance | [Paths](../internal/engine/path_test.go), [metadata](../internal/engine/metadata_test.go), [provenance](../internal/engine/provenance_test.go) | `go test ./internal/engine -run 'Path\|Metadata\|Provenance\|Queries'` |
 | Passive resource contexts | [Engine contexts](../internal/engine/resource_context_test.go), [public contexts](../facade_resource_context_test.go) | `go test ./internal/engine -run 'Resource'` and `go test . -run 'SourceContext'` |
 | Secrets, bootstrap, redaction, explanation | [References](../internal/engine/secret_reference_test.go), [bootstrap](../internal/engine/secrets_test.go), [rendering](../internal/engine/render_test.go), [explanation](../internal/engine/explain_test.go) | `go test ./internal/engine -run 'Secret\|Bootstrap\|Effective\|Explain\|Explanation\|History\|Sensitivity'` |
-| Effective configuration diff | [Engine comparison and masking tests](../internal/engine/diff_test.go), [engine operation tests](../internal/engine/diff_operation_test.go), [root facade tests](../facade_diff_test.go), and [consumer examples](../examples/consumers/diff_test.go) | `go test ./internal/engine -run 'Diff|Explain|History|Secret|Independent'`, `go test . -run 'Diff|FacadeInspection|PublicFacadeBoundary|DependencyImportBoundary'`, `go test ./examples/consumers`, and `go test . -run '^ExampleDiff$'` |
+| Effective configuration diff | [Engine comparison and masking tests](../internal/engine/diff_test.go), [engine operation tests](../internal/engine/diff_operation_test.go), [root facade tests](../facade_diff_test.go), and [consumer examples](../examples/consumers/diff_test.go) | `go test ./internal/engine -run 'Diff\|Explain\|History\|Secret\|Independent'`, `go test . -run 'Diff\|FacadeInspection\|PublicFacadeBoundary\|DependencyImportBoundary'`, `go test ./examples/consumers`, and `go test . -run '^ExampleDiff$'` |
 | Consumer examples and migration fixtures | [Consumer tests](../examples/consumers/consumers_test.go), [native, layered, and ordinary relative-import examples](../examples/consumers/layered_test.go), [mounted collection examples](../examples/consumers/destinations_test.go), [API examples](../example_test.go) | `go test ./examples/consumers` and `go test . -run '^Example'` |
 | Assembly and layered scaling evidence | [Assembly benchmarks](../internal/engine/assembly_bench_test.go), [layered benchmarks](../internal/engine/underlay_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkUnderlay' -benchmem`; repeat with `^BenchmarkCompose` and `^BenchmarkOverlay` |
+| Identified-sequence scaling evidence | [Mixed-upsert benchmark](../internal/engine/sequence_combine_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkSequenceMixedUpsert$' -benchmem` |
 | Inheritance scaling evidence | [Expansion benchmarks](../internal/engine/inheritance_bench_test.go) | `go test ./internal/engine -run '^$' -bench '^BenchmarkInheritance' -benchmem` |
 | Documentation links and dependency isolation | [Link checks](../documentation_test.go), [import boundary](../import_boundary_test.go), [public boundary](../public_boundary_test.go) | `go test . -run 'TestLocalDocumentationLinks\|TestDependencyImportBoundary\|TestPublicFacadeBoundary'` |
 | Development check behavior | [Development checker test](../development_check_test.go) | `go test . -run '^TestDevelopmentCheckHandlesFilenamesAndStopsOnFailure$'` |

docs/internal/imports.md

@@ -0,0 +1,125 @@
+# Import Discovery and Scheduling Internals
+
+The [configuration contract](../config.md#explicit-imports) owns selector syntax,
+defaults, requiredness, placement, inspection evidence, and observable ordering.
+This note records implementation flow and private identities for maintainers.
+
+## Discovery and acquisition
+
+Each source's root directive is parsed into presence-aware declarations and
+resolved against load-wide defaults. `acquisition.go` owns shared acquisition
+policy, load-wide accounting, and tier-scoped repetition/namespace state;
+`import_acquisition.go` owns reading candidate bytes, declaration traversal,
+and import admission. Candidate
+selection in `import_selection.go` preserves a normalized
+namespace path separately from canonical access identity: overlapping roots
+coalesce the same candidate spelling in that namespace, while aliases reached
+through distinct spellings retain separate inclusion routes for admission.
+Directory searches walk each distinct normalized root once, apply all filename
+patterns to discovered names, and form a set union of matching candidates across
+overlapping roots. Exclusions are applied as set difference after discovery and
+candidate normalization. They do not suppress discovery or resource errors.
+
+Directory traversal tracks canonical directories on the active traversal path.
+It adds an identity when descending and removes it when the frame is popped, so
+only a back-edge to an active directory is a traversal cycle; a later alias is
+not mistaken for one. This is separate from import dependency-cycle detection.
+For host sources, discovery uses rooted `Lstat` and canonical containment.
+`filesystem_context.go` owns resolved access facts and live access setup; the
+acquisition operation closes its live handles before composition. Native sources
+use `fs.ReadLinkFS` inspection when supplied; otherwise traversal follows the
+capabilities and behavior of the provided `fs.FS`, without claiming a general
+sandbox guarantee. `source_context.go` derives passive resource contexts from
+resolved sources for later caller-owned reads; those records do not retain live
+acquisition handles.
+
+Host and native link bindings share one iterative link-frame evaluator. It
+tracks active links for cycle detection and reuses successfully completed link
+targets while resolving the remaining path components; each binding retains its
+own namespace and target-containment rules. Directory reads distinguish an
+initial-open failure from failures after opening: only an initial missing
+directory can be treated as optional, while enumeration and close failures
+remain selection errors, including errors from the standard `fs.ReadDir`
+fallback.
+
+Glob selection keeps traversal coordination in `selectGlobImportCandidates`:
+it advances literal and patterned segments, reads directories, unions and sorts
+candidates, validates final targets, then applies exclusions and requiredness.
+For each patterned directory entry, `prepareGlobEntry` handles matching and
+hidden filtering, containment, target and link inspection, intermediate-directory
+eligibility, host/native access-path selection, and candidate identity and label.
+It returns a candidate, an ordinary skip, or a diagnostic without mutating the
+selector's candidate set or traversal state. Directory entry preparation remains
+separate because its matching, absence, recursion, and traversal-state rules
+differ.
+
+Acquisition remains authored: declarations are visited in source order and each
+selected candidate set in namespace-path lexical order. This preserves source
+records, IDs, source-local version checks, and callback ordering. The acquired
+inclusion graph is retained separately from composition scopes so cycles that
+cross item boundaries remain detectable. Source discovery does not itself choose
+sequence assembly order.
+
+## Stable keys and scheduling
+
+The shared scheduler compares immutable tuples component by component using Go's
+bytewise string order; if one tuple is a prefix of another, the shorter tuple
+sorts first. The import key is
+`(namespace-kind, namespace-anchor, resource-kind, resource-path)`:
+
+- Namespace kind is `host` or `native`. Host resource paths are canonical
+  absolute paths rendered with slash separators; native paths retain their
+  namespace-relative identity.
+- Anchors come from explicit input positions, not discovery order: main is
+  `(0,0)` and underlay/input positions are `(group+1,input+1)`, each encoded as
+  fixed-width decimal. Host accesses in one scheduled tier share its host anchor.
+  A native filesystem namespace uses its earliest explicit selecting position
+  in that tier. Filesystem tokens distinguish namespace equality, not sort order,
+  so separately constructed filesystems with the same label remain distinct.
+- Resource kind is `file` or `synthetic`. A synthetic root uses its explicit
+  input anchor and an empty resource path rather than a display label or token
+  address.
+
+Inheritance keys are
+`("definition", scope-pointer, definition-pointer)`, where both pointers use
+canonical escaped semantic path spelling. Source IDs are not part of the key.
+
+Both integrations use the same Kahn scheduler: it deduplicates dependency edges,
+keeps currently ready nodes in a min-heap, and selects the smallest ready key
+after every completion. Its scheduling cost is `O(E + V log V)` time and
+`O(V + E)` additional memory, excluding key construction, tuple copying, and
+tuple comparisons. On a stalled graph, deterministic DFS over the residual graph
+returns a closed cycle rotated to its smallest key; blocked dependents are not
+reported as cycle members.
+
+Import edge preparation builds an importer-to-target adjacency index once for
+an acquisition's outer and item-local scheduling, and once for grouped
+scheduling. Each scope gathers edges from its participating identities and
+retains only edges with both endpoints in its local slots. The retained
+inclusion graph still owns cycle diagnostics and source relationships.
+
+Import composition schedules a main tier or one underlay group as a single
+strict-scope graph. Applicable collection declarations are gathered for the
+scope before peer composition, including identity inherited from lower tiers.
+Identified peer sequences then combine distinct records in assembled source and
+list order; after the strict scope completes, layered assembly applies the
+resolved collection operation against the lower value, as defined by the
+[configuration contract](../config.md#strict-document-composition). Item
+contributions own nested local strict-mapping scopes; their helpers complete
+before the item is placed in its outer scope. Inheritance uses the same
+ready-node rule inside each sibling mapping scope, while preserving the authored
+mapping order in its output.
+These scopes do not flatten into one global graph, and independent precedence
+tiers remain separate.
+
+The owners are [`acquisition.go`](../../internal/engine/acquisition.go),
+[`import_selection.go`](../../internal/engine/import_selection.go),
+[`import_acquisition.go`](../../internal/engine/import_acquisition.go),
+[`directory_walk.go`](../../internal/engine/directory_walk.go),
+[`import_graph.go`](../../internal/engine/import_graph.go),
+[`import_projection.go`](../../internal/engine/import_projection.go),
+[`dependency_order.go`](../../internal/engine/dependency_order.go), and
+[`inheritance_schedule.go`](../../internal/engine/inheritance_schedule.go).
+Their focused behavior is covered by import-selection, acquisition, scheduler,
+and scheduling integration tests under `internal/engine`; see the
+[development test map](../development.md#task-to-test-map).

docs/internal/overview.md

@@ -7,28 +7,41 @@ private state; public signatures and fields do not expose engine types.
 
 Implemented component owners:
 
-- `internal/engine` owns host and native-filesystem source acquisition,
+- `internal/engine` owns host and native-filesystem source acquisition and
-  grouped strict composition, recursive precedence assembly, per-input mapping
+  explicitly selected configuration discovery. A search resolves once during
-  and sequence-item placement, definition-registered distinct-ID sequence
+  shared acquisition; the selected concrete file or absent-input state then
-  composition within strict tiers, and immediate-parent-relative import
+  follows the existing composition, metadata, and resource-context lifecycle.
-  placement within that assembly. Higher-priority sequences replace lower
+  It also owns grouped strict composition, recursive precedence assembly,
-  sequences as whole values. The engine also owns destination-local sibling
+  per-input mapping and sequence-item placement, YAML collection declarations
-  inheritance before typed decoding, plus shared source-version checking with
+  and operations for identified sequences, and application identity registrations for strict
-  sanitized declaration evidence.
+  composition, inheritance, and final validation. It applies the selected
+  collection operation at precedence boundaries and owns dependency-ready,
+  destination-local inheritance before typed decoding. CLI assignment follows
+  inheritance and decoding, before application resolution. The engine also owns
+  shared source-version checking with sanitized declaration evidence.
+  Explicit import discovery supports declared paths, directory searches, and
+  globs; root-owned defaults are converted to the engine's single defaults input
+  and snapshotted during load preflight before acquisition, while source-local
+  empty-selection evidence crosses the facade without changing acquisition
+  order. The root constructs placement directly on engine options and inputs
+  using explicit enum conversion; public types and fields remain root-owned.
+  Import and inheritance resolution share dependency-ready scheduling within
+  their composition scopes.
   It retains each source's effective placement alongside physical source
   identity and owns schema
   inspection, lifecycle coordination, callback auditing,
   provenance/history, passive source-context retention, secret resolution and
-  bootstrap, safe inspection rendering, and effective-value comparison over
+  bootstrap, operation-local secret failure-location attribution, safe
+  inspection rendering, and effective-value comparison over
   frozen inspection snapshots. It never imports the root package.
 - Root `Source`, `Filesystem`, `Input`, `Underlay`, `Path`, `Secret`, records,
   lifecycle callbacks, results, and bootstrap reports are root-defined wrappers
   or records. Callback wrappers pass only live engine context during a callback;
   `Result.Config` is detached and its private inspection remains frozen
   independently.
-- Root conversion files explicitly cross the path, record, callback, secret, and
+- Root conversion files explicitly cross the path, record, callback, secret,
-  error boundaries. There are no public aliases, anonymous engine embeddings, or
+  search-description, and error boundaries. There are no public aliases,
-  public engine bridge methods.
+  anonymous engine embeddings, or public engine bridge methods.
 - Root `Diff` and `Difference` provide the public comparison boundary and
   convert detached engine records to root-owned paths and snapshots; consumer
   examples own presentation of the safe changed regions.
@@ -48,13 +61,16 @@ these constraints and rejects exported aliases, fields, or signatures involving
 internal types.
 
 The [configuration contract](../config.md) owns implemented YAML and lifecycle
-semantics, including [input destinations](../config.md#input-destinations),
+semantics, including
+[configuration discovery](../config.md#configuration-discovery),
+[input destinations](../config.md#input-destinations),
 [shared source-version checks](../config.md#shared-source-version-checks), and
 [effective configuration diffs](../config.md#effective-configuration-diffs).
 The [strict composition contract](../config.md#strict-document-composition)
-owns sequence placement, registration, replacement, and history behavior; the
+owns sequence declarations, identity, operations, ownership, and final
-[consumer guide](../consumers/README.md#identified-prompt-sequences) shows the
+validation; [CLI overrides](../config.md#explicit-cli-overrides) own override
-maintained example.
+ordering. The [consumer guide](../consumers/README.md#identified-prompt-sequences)
+links maintained workflow examples.
 The [consumer adoption guide](../consumers/README.md) owns application guidance.
 The [architecture policy](../policy/architecture.md) owns contributor
 boundaries; [ADR 0006](../adr/0006-public-facade.md) records the facade decision
@@ -67,4 +83,105 @@ post-assembly structural operation. [ADR 0012](../adr/0012-relative-import-desti
 records the relative-import extension; [ADR 0013](../adr/0013-shared-source-version-checks.md)
 records the source-version decision.
 [ADR 0014](../adr/0014-sequence-placement-and-composition.md) records explicit
-sequence placement and composition.
+sequence placement and composition. [ADR 0015](../adr/0015-shared-dependency-ready-ordering.md)
+records the shared dependency-ready ordering decision; [ADR
+0016](../adr/0016-independent-import-controls.md) records the independent
+selection controls. [ADR 0017](../adr/0017-collection-sequence-policy.md) and
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md) record collection
+operations and CLI ordering. [ADR 0019](../adr/0019-explicit-configuration-discovery.md)
+records explicit main-file discovery. The [import internals](imports.md)
+document candidate and namespace identities, discovery and scheduling, and the
+bounded algorithms.
+
+## Implementation flow
+
+The root facade converts caller-owned values into engine-owned requests. Its
+`ImportDefaults` conversion maps fields without taking ownership; engine load
+preflight snapshots the defaults once before source acquisition or callbacks.
+Ordinary and grouped loading then carry that read-only value through their
+normalized `loadRequest` and acquisition policy, while declaration resolution
+copies values needed by its independently owned effective policy. Placement is
+constructed directly on the engine's options and input records after explicit
+root-to-engine enum conversion. See
+[`lifecycle.go`](../../lifecycle.go), [`layered.go`](../../layered.go), and
+[`load_request.go`](../../internal/engine/load_request.go). Load-wide definition,
+version, default-import, and override policy stays distinct from each input's
+source, filesystem, destination, and import settings.
+
+[`acquisition.go`](../../internal/engine/acquisition.go) defines acquisition
+policy, load-wide accounting, and tier-scoped repetition/namespace state. Each
+input is acquired under that policy; grouped requests retain acquired underlay
+scopes until their tier is composed in
+[`load_request.go`](../../internal/engine/load_request.go). Completed tiers then
+share one assembly handoff that applies collection declarations and projects
+only that tier's source/version evidence; the caller keeps main-version
+protection and its projection explicit. Live
+filesystem access handles are confined to acquisition and closed there. Resolved
+filesystem facts used to authorize access are separate from passively retained
+resource contexts. Non-import validation retains those facts on `assembledInput`
+for passive-context construction and ordinary-overlay handling: see
+[`filesystem_context.go`](../../internal/engine/filesystem_context.go) and
+[`source_context.go`](../../internal/engine/source_context.go).
+
+Import responsibilities are split across candidate selection and path
+normalization in [`import_selection.go`](../../internal/engine/import_selection.go),
+source reading and traversal admission in
+[`import_acquisition.go`](../../internal/engine/import_acquisition.go),
+directory walking in [`directory_walk.go`](../../internal/engine/directory_walk.go),
+dependency graph scheduling in [`import_graph.go`](../../internal/engine/import_graph.go),
+and projection of acquired evidence into final source coordinates in
+[`import_projection.go`](../../internal/engine/import_projection.go). The
+[import internals](imports.md) page describes the boundaries and identities.
+
+After acquisition handles are closed, grouped composition and inheritance run on
+the retained ordered documents. `inheritance.go` coordinates traversal and
+[`inheritance_schedule.go`](../../internal/engine/inheritance_schedule.go) applies
+dependency-ready templates;
+[`inheritance_prepare.go`](../../internal/engine/inheritance_prepare.go)
+prepares child and parent inputs,
+[`inheritance_combine.go`](../../internal/engine/inheritance_combine.go)
+returns the combined value with its origin, policy, sequence, and diagnostic
+evidence, and [`inheritance_finalize.go`](../../internal/engine/inheritance_finalize.go)
+accounts for and finalizes the result. Projection and schema work have separate
+operation owners: [`value_operation.go`](../../internal/engine/value_operation.go)
+holds per-operation state, [`projection.go`](../../internal/engine/projection.go)
+builds projected values, [`schema.go`](../../internal/engine/schema.go) owns
+descriptor caching and type policy, and
+[`schema_fields.go`](../../internal/engine/schema_fields.go) owns ordinary and
+inline field assembly. [`decode.go`](../../internal/engine/decode.go) consumes
+those descriptors for typed decoding.
+
+History and inspection use one private evidence owner. The
+[`history_model.go`](../../internal/engine/history_model.go) builder receives
+baseline, source-composition, inheritance, typed-checkpoint, and CLI evidence
+in [`preparePostDecodeOverrideContext`](../../internal/engine/override_context.go),
+before application resolution begins. The callback retains its separate fixed
+entry view; it does not read a builder that continues to change. After successful
+resolution auditing, [`resolveLoadInput`](../../internal/engine/load_result.go)
+adds the original resolution records and their net replay groups. At the existing
+pre-secret admission boundary, [`prepareInspectionHistory`](../../internal/engine/load_result.go)
+freezes that builder and counts the retained document roots before secret lookup
+and validation.
+
+The frozen model is shared by `Metadata` and `Inspection`. Its shape-aware
+selection in [`history_select.go`](../../internal/engine/history_select.go)
+drives metadata history, explanation, and historical-path membership; the model
+also supplies historical diagnostic locations and sensitivity/dependency
+evidence. `Inspection` replays selected payloads to produce detached, safely
+rendered values, while metadata queries return detached attribution records.
+History and explanation behavior is covered by focused `history_*_test.go`
+tests alongside metadata, secret, inheritance, and facade integration tests.
+
+Behavioral ownership follows the same handoffs: imports and grouped lifetimes are
+covered by `imports_test.go`, `load_request_test.go`, and focused source,
+discovery, and destination tests; inheritance by the inheritance test files;
+reflection behavior by `schema_test.go`, `projection_test.go`, and
+`decode_test.go`. The [development test map](../development.md#task-to-test-map)
+links focused commands. [`clone.go`](../../internal/engine/clone.go) owns typed
+copying, using the shared descriptors and per-operation traversal helpers.
+
+Each schema operation builds its private reflection descriptor graph with
+operation-local caching; there is no global mutable descriptor cache. Decoding,
+projection, and cloning reuse these descriptors so field bindings agree. The
+public reference describes the resulting type, output, and ownership behavior;
+this descriptor storage is an implementation detail.

docs/policy/architecture.md

@@ -2,7 +2,7 @@
 
 **Base Policy Version:** 1.3
 
-**Last Updated**: 2026-10-16
+**Last Updated**: 2026-10-22
 
 **Upstream Source:** [Standard Repository Policies](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/docs/policy/architecture.md)
 
@@ -32,6 +32,12 @@ structure as implemented when its changes land.
 Constraints must reflect deliberately selected requirements and decisions.
 Do not promote incidental implementation choices into architectural invariants.
 
+The implemented collection-policy and CLI-ordering constraints below reflect
+accepted [ADR 0017](../adr/0017-collection-sequence-policy.md) and
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md). The configuration
+contract owns their current behavior; these architectural constraints describe
+the system boundaries and guarantees that guide changes to that behavior.
+
 ## Success Criteria
 
 ConfigKit prioritizes a coherent configuration model: consistency and
@@ -91,13 +97,59 @@ boundaries, and keep simple consumers independent of optional composition
 features. The [consumer adoption guide](../consumers/README.md) demonstrates the
 implemented surface against representative simple and complex shapes.
 
+## Simplicity, Defaults, And Explicit Controls
+
+These principles apply throughout ConfigKit: to configuration syntax, the public
+Go API, defaults, and feature design. Evaluate their effects on both configuration
+authors and consuming applications.
+
+**Keep straightforward workflows straightforward.** Common configuration
+workflows should require little configuration text and minimal API setup.
+Support more demanding workflows through explicit, composable options, without
+requiring simple consumers to understand or configure those options.
+
+**Prefer simple, permissive defaults with explicit controls.** Choose predictable
+defaults that minimize required setup and accommodate valid configurations
+without unnecessary restrictions. Provide selectable options for workflows that
+need additional capabilities, narrower behavior, or stronger requirements.
+
+Measure simplicity by what consumers must understand and maintain, including
+configuration text and application-side plumbing. Concise syntax is useful, but
+hidden inference and interacting meanings can make a shorter declaration harder
+to understand. Prefer explicitness where it makes behavior more predictable.
+A terse configuration format that requires substantial application-side
+infrastructure does not satisfy the simplicity principle.
+
+Define what permissiveness means for each behavior. Allowing an optional
+contribution to be absent or accepting valid inputs without an unnecessary
+filename restriction can reduce required setup. Invalid declarations, ambiguous
+composition, and unreadable selected sources must still produce meaningful
+errors under the applicable contracts. Permissiveness does not authorize silent
+recovery from invalid supplied configuration or weaken configuration integrity.
+
+Options should express coherent choices with understandable purposes and fit
+ConfigKit's shared configuration model. Support powerful controls when they
+serve concrete needs; these principles do not require a switch for every
+implementation behavior or conceivable consumer preference.
+
+Defaults require judgment when simplicity and permissiveness pull in different
+directions. Broader discovery can accommodate more layouts while increasing the
+implicit search scope. Evaluate such tradeoffs explicitly; these principles do
+not mechanically select the broadest behavior for every option. Changes to
+existing defaults remain subject to compatibility review, and proposed behavior
+remains in the roadmap until implemented.
+
 ## Responsibility Boundaries
 
 ConfigKit owns configuration input processing and the coordination of decoding,
 resolution, validation, and inspection. Applications own their configuration
 types, field meanings, defaults, normalization, semantic validation, and schema
-version policy. Applications also own main-file search conventions, CLI wiring,
+version policy. Applications choose and order their main-file search conventions;
-remote acquisition, runtime initialization, and resource checks.
+ConfigKit provides explicitly selected search descriptions that resolve during
+loading. Applications also own CLI wiring, remote acquisition, runtime
+initialization, and resource checks. See the [configuration discovery
+contract](../config.md#configuration-discovery) and [ADR
+0019](../adr/0019-explicit-configuration-discovery.md).
 
 The engine applies each input's mapping destination within the existing source
 assembly, applies immediate-parent-relative YAML destinations to imports, and
@@ -109,8 +161,18 @@ placement, and [ADR 0012](../adr/0012-relative-import-destinations.md) records
 the import extension.
 
 Library code must not depend on consuming applications or initialize their
-runtime resources. It must not perform implicit network access, discover
+runtime resources. It must not perform implicit network access, implicitly
-application-specific paths, or change process-global state during ordinary `Load`.
+discover application-specific paths, or change process-global state during
+ordinary `Load`.
+Import discovery is available only through declarations in selected sources:
+explicit `path`, `dir`, and `glob` selectors may search their declared scope, but
+ConfigKit does not search conventional application paths unless the application
+explicitly supplies a discovery description, and it never discovers a main
+configuration file implicitly. Imports and sibling inheritance share
+dependency-ready scheduling within their existing scopes; acquisition order and
+precedence-tier boundaries remain distinct. The [configuration contract](../config.md#explicit-imports)
+owns observable behavior; [ADR 0015](../adr/0015-shared-dependency-ready-ordering.md)
+and [ADR 0016](../adr/0016-independent-import-controls.md) record the decisions.
 The explicit secrets-directory bootstrap is a narrow, opt-in exception: applications
 invoke it during startup, and it reports writes, skips and partial failures. It
 must never run implicitly as part of configuration loading.
@@ -133,6 +195,29 @@ The [configuration contract](../config.md#completion-and-resource-lifetime) owns
 the precise completion and ownership behavior. The proposed decision record is
 [ADR 0008](../adr/0008-complete-on-return-loading.md).
 
+### Accepted Processing Order
+
+Complete source composition and precedence, including selected overlays, before
+sibling inheritance. Then apply typed defaults and decode the configuration.
+Apply explicit CLI overrides to that configuration and check their types before
+running application resolution. Effective secret lookup and final validation
+follow resolution, before publication. [ADR 0018](../adr/0018-cli-after-structural-resolution.md)
+records this ordering.
+
+CLI overrides are the highest-priority input to application resolution. Supplied
+sequences replace whole sequences, and mappings combine recursively. Inheritance
+and typed defaulting do not run again after CLI application. CLI paths and values
+must not introduce structural directives; earlier source, inheritance, and
+decoding failures remain errors even if a CLI assignment would replace the value.
+Semantic validation assesses the final configuration after overrides and resolution.
+
+Applications own flag parsing and domain resolution. ConfigKit owns override
+application, validation, and source attribution. Resolution receives CLI values
+with their explicit-presence and source information. Absence-based defaults
+preserve explicit values; recorded normalization and derivation can still change
+them. Typed defaults and application resolution retain their own assignment
+semantics, independently of collection operations during source assembly.
+
 ## Public API And Dependency Direction
 
 Keep one small, coherent public surface for the supported lifecycle. Simple
@@ -161,41 +246,44 @@ framework on this library.
 
 ## Configuration Integrity
 
-Within a configuration tier, independent contributions use strict composition:
+Within a configuration tier, independent contributions use strict composition.
-shared mappings combine recursively, while overlapping non-mapping definitions
+Shared mappings combine recursively. Sequences with an applicable identity
-are conflicts, including equal values, except that sequences at explicitly
+combine distinct records and reject duplicate identities, including equal
-registered paths append records with distinct present string identities. Between
+records. Other overlapping non-mapping values remain conflicts, including equal
-precedence tiers, intentional overlay combines mappings recursively, retains
+values. Conflicting identity or operation declarations among peers also fail.
-omitted lower-priority children,
+Traversal order establishes stable reporting and record order; it does not grant
-and replaces other present values according to the existing overlay rules.
+precedence to peers. [ADR 0001](../adr/0001-separate-composition-and-overlay.md)
-Tier precedence is explicit; traversal order within a tier establishes stable
+records the distinction between strict composition and intentional overrides.
-reporting, not permission to override. The distinction and its rationale are
-recorded in [ADR 0001](../adr/0001-separate-composition-and-overlay.md).
-
-Sequence-item placement and sequence registration are explicit source and
-definition controls; registration does not change precedence replacement. The
-[configuration contract](../config.md#strict-document-composition) defines the
-behavior, [ADR 0014](../adr/0014-sequence-placement-and-composition.md) records
-the decision, and the [consumer guide](../consumers/README.md#identified-prompt-sequences)
-shows the implemented subset. This feature does not authorize arbitrary
-configurable merge strategies.
 
 The main document and its imports form a strictly composed tier. Explicit
-underlay groups compose strictly within each group, then combine recursively
+underlay groups compose strictly within each group, then combine from lowest to
-from lowest to highest beneath the main tier. Source acquisition kind does not
+highest beneath the main tier. Between tiers, mappings combine recursively and
-determine its precedence role. Input-specific constraints, including CLI path
+retain omitted lower-priority children. Sequence values follow collection policy;
-rules and opt-in version ownership, remain part of the configuration contract. Consistent combination
+other present values retain the established replacement rules. Source acquisition
-semantics do not require identical acquisition or lifetime behavior from every
+kind does not determine precedence. Input-specific constraints, including version
-source kind.
+ownership and path protections, remain part of the configuration contract.
+Consistent combination semantics do not require identical acquisition or lifetime
+behavior from every source kind.
 
-After source precedence is complete, built-in sibling `extends` relationships
+Built-in sibling `extends` relationships resolve after source precedence in the
-resolve structurally in the same parser-independent representation, using the
+parser-independent document representation. Preserve existing mapping-sibling
-existing recursive overlay rules. This adds neither an acquired source nor a
+scopes and allow an identified sequence to provide a sibling scope for its
-consumer registration mechanism. Enclosing relationships precede nested
+records. A record may inherit from one parent in that sequence, selected by
-destination-local resolution; typed defaults, application resolution, and
+complete identity. The child supplies and keeps its own identity while inheriting
-secret lookup retain their existing lifecycle roles. The [configuration
+the parent's other settings. Parents remain ordinary records subject to normal
-contract](../config.md#sibling-inheritance) owns the exact syntax and presence
+validation.
-rules, and [ADR 0009](../adr/0009-sibling-inheritance.md) records the rationale.
+
+Use the shared dependency ordering and preserve assembled sequence order.
+Resolve enclosing relationships before nested destination-local relationships.
+Mappings combine recursively; sequences use the inheriting collection's policy.
+Whole-record upsert replaces records during combination; explicit inheritance
+uses the records that remain. Inheritance remains built-in and creates no
+acquired source.
+[ADR 0009](../adr/0009-sibling-inheritance.md) records the
+original scope and continuing ownership decisions, with sequence combination
+and identified-sequence inheritance defined by
+[ADR 0017](../adr/0017-collection-sequence-policy.md) and CLI ordering by
+[ADR 0018](../adr/0018-cli-after-structural-resolution.md).
 
 ConfigKit must define supported YAML semantics explicitly rather than inherit
 parser defaults. Processing order and diagnostics must be deterministic for the
@@ -204,13 +292,14 @@ configuration. Do not run application hooks on invalid typed configuration.
 
 User-controlled precedence is application defaults, ordered underlays, composed
 main input, selected overlay, then explicitly supplied CLI overrides.
-Applications own flag parsing; ConfigKit owns overlay semantics and provenance.
+This priority order is distinct from processing order: typed defaults are applied
-Domain resolution follows these
+at decoding, and application resolution follows CLI input under the lifecycle
-inputs and must remain recorded, not become a hidden override channel.
+rules above.
 
-Preserve node-based composition until the effective input is ready for typed
+Preserve node-based composition through source assembly and inheritance until
-decoding. Preserve presence and source information through processing. Ordinary Go zero
+typed decoding. Preserve presence and source information through later CLI and
-values must not be used to infer whether input was absent. Final configuration,
+application-resolution changes as well. Ordinary Go zero values must not be used
+to infer whether input was absent. Final configuration,
 metadata, and effective inspection must agree, including application resolution
 changes; see [ADR 0003](../adr/0003-preserve-presence-and-resolution-history.md).
 Safe historical values and an explanation renderer are part of the implemented contract,
@@ -227,6 +316,72 @@ comparison and disclosure behavior, the [component overview](../internal/overvie
 owns implementation responsibility, and [ADR 0010](../adr/0010-effective-configuration-diff.md)
 records the accepted decision.
 
+## Collection Identity And Combination
+
+ConfigKit owns a common collection policy for imported records, inline sequences,
+selected overlays, and sibling inheritance. Configuration authors may declare
+identity and combination rules; applications may register authoritative identity
+constraints. Configuration declarations must agree with application constraints.
+Keep source placement explicit and separate from policy, retaining the placement
+decision in [ADR 0014](../adr/0014-sequence-placement-and-composition.md).
+[ADR 0017](../adr/0017-collection-sequence-policy.md) owns the rationale for
+collection policy and its relationship to application authority.
+
+Gather declarations for the relevant destination and source or item-local scope
+before strict composition. Applicable identity from accumulated lower tiers must
+be available when composing higher-tier peers. Higher-tier declarations cannot
+repair invalid lower-tier composition. Preserve the distinction between source
+acquisition, dependency-ready scheduling within scopes, and precedence order.
+
+Strictly compose each tier's contributions before applying one operation for the
+collection against its lower value. Support whole-sequence replacement,
+duplicate-rejecting append, and whole-record replacement by identity (`upsert`).
+Append and upsert require identity; do not infer it from record fields or position.
+Duplicate identities among peers fail under every mode. Source precedence and
+inheritance use the same operations and deterministic ordering rules. Whole-record
+upsert replaces the matching record's fields together; recursive record merging
+and unkeyed sequence concatenation are outside this operation model.
+
+An explicit mode persists at its applicable destination until a higher explicit
+mode changes it. With no explicit mode, effective identity selects upsert and
+its absence selects whole-sequence replacement. Inferred defaults do not become
+persistent instructions. The inheriting destination chooses its operation; copying
+a parent collection does not automatically copy its mode to that destination.
+
+Track YAML identity and explicit modes according to their separate lifetimes.
+Actual whole-value replacement discards lower YAML identity while preserving
+application constraints and any new identity declaration. Item-local policies
+belong to their records: retaining a record retains its rules, and discarding it
+discards those rules. Policies independently applicable at a destination remain
+in effect. Inheritance can copy YAML identity subject to agreement and replacement
+rules; application registrations continue to constrain their registered paths.
+Numeric positions alone do not establish policy ownership.
+
+Allow declarations without accompanying records. A key declaration validates a
+retained sequence immediately or remains pending in its owning scope when no
+sequence exists. A mode-only declaration affects later combinations without
+recombining earlier tiers. Neither declaration alone clears a collection, and
+declaring replace alone does not authorize changing a retained collection's
+identity. These rules do not independently impose path-existence or shape
+requirements.
+
+Enforce YAML identity during source composition, precedence, and identified
+inheritance operations. Application registrations additionally constrain final
+effective sequences after defaults, CLI overrides, and application resolution.
+The application schema and validation own existence, nullability, and allowed
+shape. The final identity guarantee covers actual sequences on successful load;
+it does not cover every intermediate callback state or later caller mutations.
+YAML-only declarations carry no such final guarantee through defaults, CLI
+assignments, or application resolution.
+
+Preserve source attribution, presence, history, sensitivity, and resource context
+as records survive, move, or are replaced. Identity diagnostics use paths and
+available origin information without exposing identity values. The guarantee
+requires no new mutation-history system or exact reconstruction of causes for
+records supplied by defaults or callbacks. Exact identity equality, declaration
+syntax, presence cases, and operation tables belong in the
+[configuration contract](../config.md#strict-document-composition).
+
 ## Ownership And Confidentiality
 
 Returned configuration and metadata must not share mutable state across loads.

docs/release.md

@@ -1,16 +1,23 @@
 # ConfigKit Release Procedure
 
 This is the maintainer runbook for ConfigKit's [release policy](policy/release.md).
-ConfigKit publishes a source-only Go module. The immutable annotated tag and
+A release publishes the Go source under a new Git tag, with a matching release
-matching checked-in release note are the deliverables; there is no binary,
+note committed in the repository. The tag is annotated: it includes the release
-container image, generated package, or separate registry publication.
+note text and points to the released commit. Published tags and contents are
+immutable. There is no binary, container image, generated package, or separate
+registry publication.
+
+A **candidate** is the committed revision you intend to release. The
+**authoritative remote** is the repository where ConfigKit publishes releases;
+its exact push URL is listed below. The **consumer minimum** is the oldest Go
+version supported for applications using ConfigKit.
 
 ## Release identity and support
 
-- Module: `gitea.maximumdirect.net/eric/ConfigKit`
+- Module: `go.maximumdirect.net/configkit`
 - Primary branch: `main`
 - Authoritative remote: `origin`
-- Authoritative push URL: `https://gitea.maximumdirect.net/eric/ConfigKit.git`
+- Authoritative push URL: `ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git`
 - Tags: stable Semantic Versions such as `v0.5.0`; no prereleases
 - Minimum Go version: the first stable patch of the selected Go series, or a
   higher patch when required by a dependency or specific correctness fix, as
@@ -20,10 +27,15 @@ container image, generated package, or separate registry publication.
 - Best-effort targets: macOS amd64 and arm64, under the
   [platform support policy](policy/release.md#platform-support)
 
-Release validation runs one offline race-enabled Go suite, one full vet pass,
+Release validation runs the offline Go test suite once with the race detector,
-and CGO-disabled package compilation for both Linux targets. macOS and CI are
+then a full vet pass and package compilation for both Linux targets with cgo
+disabled (`CGO_ENABLED=0`). macOS and CI are
 not release gates; do not wait for or poll CI.
 
+The vanity module path is the name applications put in Go imports. Source/tag
+browser links and public Go retrieval use the Forge HTTPS repository
+independently of SSH publication.
+
 ## 1. Select Go and prepare the tool
 
 Use a clean checkout with Git, Bash 3.2 or newer, and a native compiler for race
@@ -33,10 +45,10 @@ For a patch release, retain the series recorded in `go.mod` and leave its consum
 minimum unchanged. Follow the
 [toolchain selection policy](policy/release.md#configkit-toolchain-selection).
 
-Put the selected series' latest locally available compatible patch first on
+Choose the latest compatible patch installed locally in that Go series. Put
-`PATH`, ensuring it meets `go.mod`'s minimum. The same `go` executable must build
+its `go` executable first on `PATH` and ensure it meets the minimum in
-ReleaseKit and run its child validation commands. Set local toolchain selection
+`go.mod`. The same `go` executable must build ReleaseKit and run its child
-and verify it:
+validation commands. Set local toolchain selection and verify it:
 
 ```sh
 export GOTOOLCHAIN=local
@@ -61,8 +73,17 @@ use that required version instead and document the reason. When the series is
 unchanged, leave the minimum unchanged unless a minor or major release
 deliberately changes it under the
 [consumer minimum policy](policy/release.md#consumer-minimum-and-release-toolchain).
-For example, validating with Go 1.26.8 leaves `go 1.26.0` unchanged. There is no
+For example:
-separate requirement to validate with Go 1.26.0.
+
+| Release situation | Go used for validation | Consumer minimum |
+| --- | --- | --- |
+| Patch release in the 1.26 series | Latest compatible patch installed locally, such as 1.26.8 | Keep the existing `go.mod` minimum unchanged. |
+| Minor/major release staying in 1.26 | Latest compatible patch installed locally | Normally retain the minimum; any deliberate change follows the linked policy. |
+| Minor/major release adopting a newer installed stable series | Latest compatible patch installed locally in that series | Normally declare that series' initial stable patch, or the higher patch required by a dependency or identified fix. |
+
+Using Go 1.26.8 for validation can therefore leave `go 1.26.0` unchanged. Users
+need the declared minimum, while maintainers validate with their selected patch.
+There is no separate requirement to validate with Go 1.26.0.
 
 Prepare dependencies whether or not the minimum changes:
 
@@ -70,7 +91,8 @@ Prepare dependencies whether or not the minimum changes:
 go mod download
 ```
 
-Build the tool selected by `go.mod` into temporary storage outside the checkout.
+Build the ReleaseKit version recorded in `go.mod` into temporary storage outside
+the checkout.
 Ensure `$TMPDIR` names a system temporary location, not the repository. These
 commands never install another ReleaseKit version:
 
@@ -82,8 +104,8 @@ go list -m gitea.maximumdirect.net/eric/ReleaseKit
 "$releasekit_bin" version
 ```
 
-The module-selected executable is ReleaseKit v0.4.1. Use the built executable
+This repository selects ReleaseKit v0.4.2. Use the compiled program above for
-for publication to preserve its exit status and publication-state diagnostics.
+publication so its exit status and publication report reach you unchanged.
 `go run` maps a nonzero child exit status to 1. ReleaseKit's child Go commands
 use the `go` found on `PATH` with `GOTOOLCHAIN=local`; keep the selected
 executable first on `PATH` through the publication command.
@@ -91,7 +113,7 @@ executable first on `PATH` through the publication command.
 Verify access to the authoritative remote without displaying credentials:
 
 ```sh
-git ls-remote https://gitea.maximumdirect.net/eric/ConfigKit.git HEAD refs/heads/main
+git ls-remote ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git HEAD refs/heads/main
 ```
 
 Publication requires explicit authorization. Local implementation commits do
@@ -99,10 +121,10 @@ not authorize a push or release.
 
 ## 2. Prepare and commit the candidate
 
-Choose an unused stable version locally and on the authoritative remote. Compare
+Choose a stable version that has not been used locally or on the publication
-the candidate with the previous tag and review exported Go signatures and
+remote. Compare the candidate with the previous tag. Review public Go APIs and
-ownership, YAML and resolution semantics, diagnostic contracts, minimum Go
+value ownership, YAML and resolution rules, diagnostic contracts, the minimum
-version, and platform support. Review maintained consumer examples and the
+Go version, and platform support. Review maintained consumer examples and the
 migration guidance. Explain any consumer-minimum increase and required consumer
 action under the
 [consumer minimum policy](policy/release.md#consumer-minimum-and-release-toolchain).
@@ -111,7 +133,7 @@ Create `docs/releases/<version>.md`. Its first line must be exactly
 `# ConfigKit <version>`, and it must end with the license and attribution footer:
 
 ```markdown
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/VERSION/docs/oss/attribution.md)
+[COPYRIGHT](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/COPYRIGHT) | [LICENSE](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/LICENSE) | [ATTRIBUTION](https://forge.maximumdirect.net/base-layer/configkit/src/tag/VERSION/docs/oss/attribution.md)
 ```
 
 Replace `VERSION` with the full tag and confirm the three target files exist in
@@ -127,7 +149,7 @@ Push only that committed candidate to the literal authoritative URL. This does
 not follow local tags:
 
 ```sh
-git push --no-follow-tags https://gitea.maximumdirect.net/eric/ConfigKit.git HEAD:refs/heads/main
+git push --no-follow-tags ssh://git@forge.maximumdirect.net:22222/base-layer/configkit.git HEAD:refs/heads/main
 ```
 
 ReleaseKit requires authoritative `main` to equal this candidate before it
@@ -139,32 +161,40 @@ candidate to `main`, and invoke validation again.
 
 ## 4. Publish the committed candidate
 
-With the authorized candidate already on authoritative `main`, invoke the
+Once publication is authorized and the candidate is on the publication remote's
-module-selected native executable exactly once:
+`main`, run the compiled ReleaseKit program once to validate and publish it:
 
 ```sh
 "$releasekit_bin" publish vMAJOR.MINOR.PATCH
 ```
 
 Replace the placeholder with the selected version. ReleaseKit checks the
-effective push URL against `expected_push_url`, verifies the candidate on
+push URL Git will actually use, after URL rewrites, against `expected_push_url`.
+It verifies the candidate on
 `main`, and checks the release-note H1 for the product and version. It then
 runs the selected race-enabled standard suite once with test-time vet disabled,
 one full vet pass, and CGO-disabled package compilation for Linux amd64 and
 arm64. It publishes only the annotated tag for that candidate. Confirmed
 publication of the intended tag completes the release. The tag points to the
 captured commit and uses the complete checked-in note as its annotation message.
-The optional `check`
+Use the optional `check` command for diagnosis when useful. It validates without
-command is available for diagnosis but is not a separate required pass:
+publishing and is not required before `publish`, which performs its own checks:
 
 ```sh
 "$releasekit_bin" check vMAJOR.MINOR.PATCH
 ```
 
-Status 0 confirms publication, status 1 reports a known publication failure or
+For `publish`, interpret the program's exit status as follows:
-conflict, status 2 reports usage, profile, or version errors, and status 3 means
+
-the push outcome remains unknown. Preserve both the native exit status and its
+| Status | Meaning | Next action |
-diagnostics.
+| --- | --- | --- |
+| `0` | Publication succeeded. | The release is complete. Optional verification can follow. |
+| `1` | A known publication failure or conflict was reported. | Read the report and correct the stated problem. Preserve any published tag. |
+| `2` | The command, profile, or version is invalid. | Correct the command or configuration before trying again. |
+| `3` | The tag push outcome is still unknown. | Follow the recovery procedure below before retrying or declaring success. |
+
+Keep both the program's exit status and its diagnostic report. Using `go run`
+would lose the distinction between its nonzero exit statuses.
 
 The command does not push or repair `main`, wait for CI, or publish binaries or
 a hosted release page. A successful intended-tag publication does not require
@@ -173,12 +203,17 @@ remote read-back or consumer retrieval; those checks remain optional.
 ## 5. Recover from a failed or uncertain tag push
 
 The executable reports the publication state, phase, version, candidate commit,
-tag-object ID, effective endpoint, and error on standard error. It performs one
+tag-object ID, effective endpoint, and error on standard error. After a failed
-bounded authoritative reconciliation after a failed tag push. Exit status 3
+tag push, it makes one bounded check of the exact publication remote to find out
+whether the tag arrived. Exit status 3
 means the tag outcome remains unknown; do not blindly retry or move a tag.
 
-For an uncertain result, use the exact endpoint, candidate commit, version, and
+An annotated tag is a Git object containing the release note and a pointer to
-tag-object ID from the report. Copy the captured endpoint into the variable
+the source commit. Its tag-object ID identifies that complete object. Checking
+only the commit ID would not establish that the intended tag object arrived.
+
+For an uncertain result, use the exact endpoint (remote URL), candidate commit,
+version, and tag-object ID from the report. Copy the captured endpoint into the variable
 below using normal shell quoting. Check that Git still resolves it to itself,
 then query the authoritative refs once:
 
@@ -195,7 +230,8 @@ cannot establish absence at the captured endpoint.
 
 Compare the `main` object ID with the reported candidate commit and the tag
 object ID with the reported tag-object ID. `--refs` returns the annotated tag
-object itself, not merely its peeled commit. If the tag object matches, the
+object itself. A peeled commit is the source commit reached by following that
+tag; it is a different identity. If the tag object matches, the
 release is published. If the query fails, the result is conflicting, or the
 endpoint or candidate differs, stop and resolve the state before retrying. If
 the endpoint is reachable, the tag is confirmed absent, and `main` still equals
@@ -228,8 +264,8 @@ consumer_dir=$(mktemp -d)
 (
   cd "$consumer_dir"
   go mod init example.invalid/configkit-release-check
-  GOPRIVATE=gitea.maximumdirect.net GOPROXY=direct go get "gitea.maximumdirect.net/eric/ConfigKit@$release_version"
+  GOWORK=off GOPROXY=direct go get "go.maximumdirect.net/configkit@$release_version"
-  go list -m -f '{{.Path}} {{.Version}}' gitea.maximumdirect.net/eric/ConfigKit
+  GOWORK=off go list -m -f '{{.Path}} {{.Version}}' go.maximumdirect.net/configkit
 )
 ```
 

docs/releases/v0.10.0.md

@@ -0,0 +1,77 @@
+# ConfigKit v0.10.0
+
+This minor release adds explicit, composable discovery of a configuration file.
+Applications choose the search conventions and their order; ConfigKit selects one
+file during loading and returns the final configuration with its normal metadata.
+Optional searches that find no file share the expanded `NoSource()` lifecycle.
+
+## Changes
+
+- Add `SearchConfig`, immutable `Search` and `FilenameGroup` descriptions, and
+  search-wide requiredness through `SearchOptions`. Compose explicit `Paths`,
+  custom `SearchDirectory` descriptions, and built-in Unix system, user-config,
+  home, or working-directory presets with `Searches`. See the
+  [public declarations](../../discovery.go) and
+  [discovery contract](../config.md#configuration-discovery).
+- Expand searches in supplied order, trying a directory's filename groups before
+  moving to the next directory. Named and generic groups provide conventional
+  YAML filenames; custom groups provide literal names. Directory searches
+  distinguish omitted filename selection from an explicitly empty selection.
+  Constructors perform no filesystem access, and each load observes current
+  directory bases and file availability.
+- Select the first existing candidate. Access errors and failures while loading
+  the selected file terminate the load rather than trying another configuration.
+  Selected files retain physical source identity, placement, provenance, imports,
+  and relative-resource context. Discovery works with ordinary loading and
+  layered inputs, including underlays, without adding a precedence tier.
+- Permit enabled imports with an absent main input: there are no main import
+  declarations to traverse, while actual underlay sources retain normal imports.
+  Support ordinary selected overlays with an absent main and explicit filesystem
+  context, including a root-only host context. Layered overlays retain their
+  independent `OverlayFilesystem` requirement. See
+  [single-source loading](../config.md#single-source-loading) and
+  [layered loading](../config.md#layered-loading).
+- Preserve ordinary file-context behavior after discovery and include the
+  failing candidate's file identity in access diagnostics. Use Go's
+  platform-aware Windows component rules and native drive-root-relative path
+  resolution. Isolate user-config tests according to the host Go conventions.
+
+## Compatibility and upgrade
+
+Existing explicit source constructors and loading APIs remain available.
+`File(path)` remains an exclusive selection that fails for a missing file;
+discovery is activated only by explicitly supplying `SearchConfig`.
+
+Searches are optional by default. Set `SearchOptions{Required: true}` when the
+application must find a file. An exhausted optional search contributes no main
+document or source record; application version checks, defaults, resolution,
+and validation still run under their existing rules and may reject incomplete
+configuration. A selected overlay is still required to exist.
+
+The former `NoSource()` rejections of enabled imports and explicit filesystem
+context are relaxed. An active ordinary overlay with no main file now loads
+when explicit context is supplied. Applications that relied on those combinations
+being rejected should review their option handling. Selected host files derive
+their own base directory; do not supply an explicit `BaseDir` or native filesystem
+context for a search that selects a host file.
+
+Applications may replace their own fallback-loading loops with the new search
+descriptions. The maintained [consumer examples](../consumers/README.md#explicit-main-file-discovery)
+show simple preset selection and custom-first discovery alongside existing
+configuration tiers. Composition, collection operations, inheritance, CLI
+precedence, and the complete-on-return ownership model retain their existing
+semantics.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.0
+```
+
+The consumer minimum remains Go 1.26.0. Release validation uses Go 1.26.10.
+The YAML dependency remains `go.yaml.in/yaml/v4 v4.0.0-rc.6`, and the maintainer
+tool remains ReleaseKit v0.4.1. Linux amd64 and arm64 remain release-validated
+targets; macOS remains best-effort. Publication follows the existing
+[release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.0/docs/oss/attribution.md)

docs/releases/v0.10.1.md

@@ -0,0 +1,42 @@
+# ConfigKit v0.10.1
+
+This patch release consolidates ConfigKit's internal loading machinery and
+reduces repeated import bookkeeping. Public APIs and configuration semantics
+remain unchanged from v0.10.0.
+
+## Changes
+
+- Consolidate ordinary and layered input acquisition, including import requests
+  and selected-overlay handling, while retaining their distinct context and
+  precedence rules. Remove unused private reverse conversions.
+- Separate import acquisition, scoped composition, and evidence projection;
+  clarify inheritance preparation, combination, and finalization; and simplify
+  reflective projection and schema-field assembly responsibilities.
+- Retain resolved filesystem facts from non-import validation for later passive
+  resource contexts and ordinary overlays. Remove duplicate absent-host context
+  derivation while preserving validation timing and handle cleanup.
+- Record empty optional-import selections directly against their declaring
+  source, avoiding repeated searches through acquired sources. Index import
+  dependencies for scope-local edge preparation instead of scanning the whole
+  inclusion graph for every item scope. Stable dependency-ready ordering,
+  provenance, and source destinations are preserved.
+- Expand regression coverage for import evidence ownership, scope boundaries,
+  and broad main/underlay item imports. Improve
+  [consumer loading guidance](../consumers/README.md) and internal documentation.
+
+## Compatibility and upgrade
+
+No consumer code or configuration migration is required. Composition, collection
+operations, inheritance, discovery, CLI precedence, source-version checks, and
+inspection retain their existing contracts.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.1
+```
+
+The consumer minimum remains Go 1.26.0. Dependencies and platform support are
+unchanged. Publication follows the existing [release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.1/docs/oss/attribution.md)

docs/releases/v0.10.2.md

@@ -0,0 +1,70 @@
+# ConfigKit v0.10.2
+
+This patch release fixes edge-case loading failures, resource cleanup, and limit
+accounting, and simplifies ConfigKit's internal loading machinery. Public APIs
+and documented configuration semantics remain unchanged from v0.10.1.
+
+## Fixes
+
+- Terminate pointer-only recursive type traversal safely during decoding and
+  schema-path resolution, preserving nullable values and supported recursive
+  structures. Roll back failed dynamic descriptor construction so subsequent
+  operations do not reuse incomplete state or panic.
+- Accept finite, non-cyclic slice views that share backing storage while
+  retaining cycle detection and detached output.
+- Deactivate resolution, validation, and version-check contexts when callbacks
+  panic, and close library-owned import roots during panic unwinding. The
+  original application panic continues to propagate.
+- Report directory enumeration and close failures instead of treating them as
+  optional absence, including failures reported as not-exist after a successful
+  open. Genuinely missing optional directories retain their existing behavior.
+- Reuse completed symlink dependencies during host and native import discovery,
+  avoiding exponential repeated expansion of finite link graphs while retaining
+  cycle detection and containment checks.
+- Check existing projection budgets before bulk container allocation and account
+  for the complete retained inspection-history graph, including replay and
+  separately copied inheritance evidence.
+- Apply the documented append/upsert sequence requirements to non-sequence
+  contributions at retained collection-policy destinations.
+
+## Internal improvements
+
+- Index collection-policy retirement and prepare sparse incoming policy changes
+  instead of repeatedly scanning or copying unrelated retained policy.
+- Reuse successful dynamic-type eligibility checks within an operation and index
+  tier-history lookups, compound identity restoration, and secret-failure source
+  attribution to avoid repeated scans.
+- Remove unused snapshots, evidence, helpers, fields, and test-only production
+  paths. Clarify acquisition handoffs and separate collection preparation,
+  application, and finalization while sharing sequence-history construction.
+- Separate patterned glob entry preparation from traversal. Consolidate engine
+  import defaults, snapshot them during load preflight, and construct placement
+  directly across the facade while keeping public types root-owned.
+- Add regression coverage for the corrected failures, public historical paths,
+  defaults snapshots, and resource ownership. Strengthen fuzz detachment checks
+  and replace redundant or implementation-coupled assertions.
+- Update release tooling from ReleaseKit v0.4.1 to v0.4.2.
+
+These changes remove redundant work and improve scaling in the identified paths;
+no end-to-end performance improvement has been quantified.
+
+## Compatibility and upgrade
+
+No consumer API or configuration-format migration is required. The
+[configuration contract](../config.md) remains authoritative.
+
+Loads that previously succeeded despite directory acquisition failures, invalid
+append/upsert contributions, or incomplete retained-history accounting may now
+return the documented structured errors. These corrections enforce existing
+requirements and limits rather than introducing new ones.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.10.2
+```
+
+The consumer minimum remains Go 1.26.0. The YAML dependency and platform support
+are unchanged. Publication follows the existing [release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.10.2/docs/oss/attribution.md)

docs/releases/v0.6.0.md

@@ -30,7 +30,7 @@ adopts ReleaseKit for source publication, and raises the consumer Go minimum to
   successful-tag-push completion point remain unchanged; CI is not a gate.
 - Adopt release policy 1.6, distinguishing the consumer Go minimum from the
   validation toolchain. Retire completed planning and measurement records into
-  Git history while preserving [performance candidates](../roadmap/future.md#3-performance-experiments).
+  Git history while preserving [performance candidates](../roadmap/future.md#5-performance-experiments).
 
 ## Compatibility and upgrade
 

docs/releases/v0.9.0.md

@@ -0,0 +1,111 @@
+# ConfigKit v0.9.0
+
+This minor release expands import selection, adds author-declared collection
+identity and operations, and supports inheritance between identified records.
+It also moves CLI assignments after inheritance and typed decoding. These changes
+include breaking API and configuration behavior changes from v0.8.0; review the
+migration guidance below before upgrading.
+
+## Changes
+
+- Extend imports with named-file and directory lists, directory filename patterns,
+  exclusions, recursion and depth controls, and explicit hidden-file and symlink
+  discovery controls. Add `ImportDefaults` to ordinary and layered options, with
+  authored declarations taking precedence over application defaults. Imports are
+  optional by default. `SourceInfo.ImportSelections` exposes completed optional
+  declarations that selected no sources. See the
+  [import contract](../config.md#explicit-imports) and
+  [consumer guidance](../consumers/README.md#import-defaults-and-selection-inspection).
+- Use shared dependency-ready ordering for import composition and sibling
+  inheritance. Dependencies complete before dependents, with deterministic
+  selection among currently eligible contributions. Source acquisition and
+  callback order remain separate from assembly order. See the
+  [ordering decision](../adr/0015-shared-dependency-ready-ordering.md).
+- Add root `configkit.sequences` declarations for collection identity and
+  `replace`, `append`, or `upsert` operations, including in selected overlays.
+  Strict peers combine distinct identities and reject duplicates; precedence
+  and inheritance apply the destination's collection operation. Upsert replaces
+  a whole matching record at its retained position. Identity supports compound
+  field sets and scalar strings, numbers, booleans, and null. See the
+  [collection contract](../config.md#strict-document-composition).
+- Add `Definition.SequenceIdentities`, exact `SequenceIdentityAt` registrations,
+  and dynamic `SequenceIdentityMatching` selectors. Application registrations
+  govern structural collection operations and check existing matching final
+  typed sequences, including values from defaults, CLI assignments, and
+  application resolution. YAML-only declarations govern structural operations
+  without adding that final-result check.
+- Support record inheritance within an identified sequence using an `extends`
+  mapping containing the parent's complete identity. The child retains its own
+  identity, relationships use surviving assembled records, and output sequence
+  order is preserved. See [sibling inheritance](../config.md#sibling-inheritance)
+  and the maintained [sequence catalog](../consumers/README.md#identified-prompt-sequences).
+- Apply explicit CLI overrides to the decoded configuration before application
+  resolution. Mappings retain omitted fields and their presence metadata;
+  sequences replace whole lists independently of collection operations. See the
+  [CLI contract](../config.md#explicit-cli-overrides).
+- Correct native import alias and contained-symlink handling, source-version
+  path projection, and provenance/history through collection movement,
+  replacement, inheritance, and CLI assignment. Reduce repeated scans,
+  accumulated policy copying, and sparse-projection storage during construction.
+
+## Compatibility and upgrade
+
+This pre-v1 minor release intentionally changes the v0.8.0 contracts:
+
+1. **Migrate import requiredness.** The YAML `optional` field is removed and is
+   rejected. Replace `optional: true` with `required: false`; omission is equivalent
+   when the application does not default imports to required. Replace
+   `optional: false` with `required: true`. Imports that previously relied on
+   implicit requiredness now need `required: true`, or an application
+   `ImportDefaults.Required` default set to true. Review discovery filters:
+   `follow` and `hidden` default to true, and directory searches select all
+   filenames unless a pattern is supplied.
+2. **Replace sequence registrations.** `SequenceComposition` and
+   `Definition.SequenceCompositions` are removed without compatibility aliases.
+   For a previous registration at `prompts` using `id`, use:
+
+   ```go
+   rules.SequenceIdentities = []configkit.SequenceIdentity{
+       configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+   }
+   ```
+
+   These registrations now also enforce identity in final typed sequences. Fix
+   missing or duplicate identities introduced by defaults, CLI assignments, or
+   application resolution. Registration does not require a collection to exist
+   or determine its allowed shape; schema and application validation retain
+   those responsibilities.
+3. **Review collection precedence and ordering.** An identified collection now
+   defaults to upsert across layers and inheritance when no explicit mode
+   applies, rather than unconditional whole-sequence replacement. Declare
+   `mode: replace` at the relevant destination where replacement is intended.
+   With append or upsert, `[]` contributes no records and does not clear the
+   collection; null is invalid. Use `mode: replace` with `[]` to clear it.
+   An explicit mode persists at its destination until changed; a parent's mode
+   does not transfer to a different inheriting destination. Unidentified
+   sequences retain strict peer conflicts and whole-value precedence
+   replacement. Dependency-ready assembly can change sequence positions and
+   diagnostic or history order compared with the former traversal order.
+4. **Review CLI recovery and inheritance assumptions.** CLI overrides can no
+   longer repair values that fail earlier decoding, bypass source or inheritance
+   errors, or add or cancel inheritance relationships. Supply structural
+   directives in source configuration. Application resolution still receives
+   explicit CLI values and may record subsequent normalization or derivation.
+5. **Update affected Go literals and diagnostic handling.** Use keyed literals
+   for expanded option and source-information structs. Collection validation adds
+   `CodeSequenceInvalid` (`sequence.invalid`) and `CodeSequenceConflict`
+   (`sequence.conflict`); update diagnostic handling where applicable.
+
+Select this version and rebuild:
+
+```sh
+go get gitea.maximumdirect.net/eric/ConfigKit@v0.9.0
+```
+
+The consumer minimum remains Go 1.26.0. The YAML dependency remains
+`go.yaml.in/yaml/v4 v4.0.0-rc.6`, and the maintainer tool dependency remains
+ReleaseKit v0.4.1. Linux amd64 and arm64 remain release-validated targets;
+macOS remains best-effort. Publication follows the existing
+[release procedure](../release.md).
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.9.0/docs/oss/attribution.md)

docs/roadmap/future.md

@@ -1,112 +1,26 @@
-# Potential Future Features
+# Potential Future Work
 
-This document lists potential enhancements for consideration in future ConfigKit
+This document lists potential enhancements and maintenance work for consideration
-releases. Entries are not accepted contracts, implementation plans, or release
+in future ConfigKit releases. Entries are not accepted contracts, implementation
-commitments. Adopting a candidate requires an explicit design decision and a
+plans, or release commitments. Adopting a candidate requires an explicit design
-separate plan. Significant architectural exclusions and their rationale belong
+decision and a separate plan. Significant architectural exclusions and their rationale belong
 in ADRs; this document does not maintain a list of rejected proposals.
 
-## 1. Identified record sequences
+## 3. Recursive body merging for identified records
 
-Status: deferred. PromptKit proposed this capability from its retired proposal 2,
+Status: deferred. The implemented
-**Namespaced Collections As Identified Records**. The original proposal is in the
+[collection policy](../config.md#strict-document-composition) uses `upsert` to
-PromptKit repository at
+replace a complete matched record. Recursive merging of fields inside matching
-`b5866dd:docs/roadmap/configuration-collections-identified-records.md`.
+records remains a separate candidate and would revisit the whole-record update
-PromptKit selected mounted mappings instead; this feature is not a dependency
+boundary selected by [ADR 0017](../adr/0017-collection-sequence-policy.md).
-of that design or a request to restore multiple installed prompt versions.
 
-A narrower [sequence placement and composition feature](../config.md#strict-document-composition)
+Consider this only in response to a concrete consumer need. A proposal would need
-is implemented: consumers can place imported mappings as sequence items and
+to define conflicts for overlapping body fields, removal of omitted fields,
-register a single literal string identity field for duplicate-rejecting strict
+presence and ordering, and how provenance, history, sensitivity, and resource
-composition. Precedence still replaces sequences as whole values. This entry
+context follow partially retained records. Any change requires a new decision and
-tracks broader identified-record behavior that remains deferred and is not part
+implementation plan; this entry does not alter current upsert behavior.
-of that implemented contract.
 
-### Motivation and proposed behavior
+## 4. Required version declarations for selected sources
-
-Allow applications to declare that selected sequences contain records identified
-by explicit fields, while retaining sequence-shaped output for slice decoding
-and effective YAML. This could make composite identities and independently
-authored catalogs more convenient than encoding identity in nested mapping keys.
-Current [composition](../config.md#strict-document-composition) appends distinct
-records only at explicitly registered paths; other sequences remain atomic.
-Selected [overlays](../config.md#selected-overlays) always treat sequences
-atomically.
-
-The proposed broader opt-in registration would extend the current reusable
-application definition from one identity field to a composite identity made of
-an ordered, nonempty set of distinct direct string-field names. For example,
-records at `profiles` could be identified by `(namespace, id)`. Records
-`(provider, brief)`
-and `(application, brief)` would coexist, and a later layer could update the
-provider record's temperature while retaining its backend and model.
-
-The requested semantics, all still subject to design review, are:
-
-- Match exact string tuples, preserving component boundaries and spelling,
-  including empty strings. Every contribution supplies its complete identity;
-  defaults, inheritance, filenames, and normalization do not supply it.
-- Retain distinct identities. Matching records from strict peers recursively
-  compose disjoint body fields and conflict on overlapping non-mapping body
-  values, even equal values. Equal identity fields act as structural keys rather
-  than conflicts and retain their contributing source evidence.
-- Higher layers recursively overlay matching bodies. A changed identity denotes
-  a different record, not a rename. Proposed ordering is first contribution in
-  precedence-assembly order; matching records keep position and new ones append.
-- Reject malformed identities, non-mapping records, non-null non-sequence values
-  at registered paths, and duplicate tuples within one source sequence. Later
-  layers cannot repair malformed structural identity in an acquired contribution.
-- Treat an empty registered sequence as contributing no records; whole-path null
-  retains ordinary conflict/replacement semantics. Unregistered sequences,
-  including nested message lists, retain existing atomic behavior.
-- Support record inheritance within the same registered sequence using an
-  `extends` mapping containing the complete parent tuple. Resolve only final
-  active relationships after precedence, preserve the child's identity, overlay
-  its body on the parent's body, and consume the directive before decoding.
-  Preserve cancellation, missing-parent/cycle errors, and declaring resource
-  contexts. Existing string-based mapping-sibling inheritance stays unchanged.
-
-Integrate ordinary and layered loads, imports, mounted paths, selected overlays,
-and whole-sequence CLI overrides. Keep origins, presence, history, sensitivity,
-and resource contexts attached to the correct record despite different source
-and final indexes. Diagnostics must retain source locations without exposing
-sensitive identity values. Final inspection may use snapshot-specific sequence
-indexes; existing atomic sequence diffs need not become identity-aware.
-
-Successful results would have valid, unique identities, including after defaults
-and application resolution, without a second merge or inheritance pass. Existing
-source-version checks remain independent; consumed headers cannot supply missing
-record identities. No identity-selector path syntax, arbitrary merge callbacks,
-wildcard registration, per-record deletion/rename operator, multiple inheritance,
-or cross-path parent references are requested.
-
-### Questions to resolve before implementation
-
-- **Need and delivery scope:** does an active consumer benefit enough to justify
-  the added semantics over keyed mappings? Are composite identities required?
-  Staging composition before inheritance is possible but would leave part of
-  the request incomplete.
-- **Defaults and callbacks:** do default records merge by identity or retain
-  existing sequence-replacement behavior? How are callback-created duplicates,
-  identity edits, and reordering validated and reflected in provenance?
-- **Null, empty, and order:** what happens when null clears a collection and a
-  later layer reintroduces records? How do absent and explicitly empty sequences
-  interact with defaults and first-contribution order?
-- **Inheritance references:** how do peers compose relationship declarations,
-  and how are complete references enforced without assembling partial tuples
-  accidentally? What happens if identity fields overlap structural controls?
-- **Registration paths:** how do overlapping registrations and paths beneath
-  sequence indexes behave when assembly changes those indexes?
-- **Evidence and lifecycle:** how are record identities mapped between source
-  trees, history, inheritance, callback snapshots, and final indexes without
-  mixing records' provenance or sensitivity? Where do identity checks run relative
-  to header consumption and other structural processing?
-
-Keep the feature deferred until its consumer value and full lifecycle design
-justify reconsidering the sequence-merging exclusion. A correct final sequence
-alone would not establish correct inspection or disclosure behavior.
-
-## 2. Required version declarations for selected sources
 
 Status: deferred. PromptKit requested a way to require version declarations on
 a selected subset of source files while permitting other fragments to omit them.
@@ -142,7 +56,7 @@ compatible version or replace final configuration validation.
   behavior for absent optional inputs and preserve source-local diagnostics,
   inspection evidence, and existing sensitivity handling.
 
-## 3. Performance experiments
+## 5. Performance experiments
 
 Status: deferred pending evidence. The completed performance audit identified
 four internal optimization candidates for separate investigation:
@@ -169,3 +83,22 @@ evidence are preserved in Git history at `8e91a2b` under `docs/roadmap/`.
   across loads without introducing aliasing?
 - What cache lifetime and concurrency design would make schema reuse worthwhile
   without excessive retained memory?
+
+## 6. Public path comparison
+
+Status: deferred pending a concrete consumer need. This preserves A2 from the
+completed API review at `68400ff:docs/roadmap/review.md`.
+
+`Path.String()` is a JSON Pointer spelling, not a complete semantic identity:
+an explicit numeric mapping key and a sequence index can share it. The public
+type is opaque and currently non-comparable.
+
+If consumers need comparison, consider a small exact-representation operation
+rather than exposing mutable segments or introducing a pattern language. A
+proposal must distinguish exact segment representation, including parsed versus
+explicit segments and invalid state, from resolution against a document. Pointer
+string equality must not be presented as semantic equality.
+
+Keeping `Path` solely as an opaque query/building value remains an alternative.
+No current contract changes or implementation commitment follow from this entry;
+a comparison operation can be added compatibly later.

example_test.go

@@ -6,7 +6,7 @@ import (
 	"os"
 	"strings"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func ExampleLoad() {
@@ -19,6 +19,28 @@ func ExampleLoad() {
 	// Output: {true 3} <nil>
 }
 
+func ExampleLoad_sequenceDeclaration() {
+	type Item struct {
+		ID string `yaml:"id"`
+	}
+	type Config struct {
+		Items []Item `yaml:"items"`
+	}
+	result, err := configkit.Load[Config](configkit.Bytes("catalog.yml", []byte(`configkit:
+  sequences:
+    - destination: [items]
+      key: id
+items:
+  - id: prompt
+`)))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	fmt.Println(result.Config.Items[0].ID)
+	// Output: prompt
+}
+
 func ExampleNoSource() {
 	type Config struct {
 		Workers int `yaml:"workers"`
@@ -154,10 +176,18 @@ func ExampleOverride() {
 		})
 	}
 	result, err := configkit.Load(configkit.NoSource(), configkit.Options[Config]{
-		Definition: configkit.Definition[Config]{Defaults: func() Config { return Config{Workers: 4} }},
+		Definition: configkit.Definition[Config]{
-		Overrides:  overrides,
+			Defaults: func() Config { return Config{Workers: 4} },
+			Resolve: func(configuration *Config, resolution *configkit.Resolution) error {
+				configkit.Default(resolution, configkit.Keys("workers"), &configuration.Workers, 100,
+					"preserve an explicitly supplied worker count")
+				return nil
+			},
+		},
+		Overrides: overrides,
 	})
-	fmt.Println(result.Config.Workers, result.Sources()[0].Label, err)
+	source, _ := result.Source("source-1")
+	fmt.Println(result.Config.Workers, source.Label, err)
 	// Output: 0 --workers <nil>
 }
 

examples/consumers/consumers.go

@@ -9,7 +9,7 @@ import (
 	"strings"
 	"time"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // Artifact is a Narratio-shaped generated output declaration.
@@ -167,7 +167,7 @@ func LoadNotariusPaths(path, invocationDir string, overrides ...configkit.Overri
 				resolveNotariusReference(configuration, resolution, invocationDir)
 				return nil
 			},
-			Secret: func(path configkit.Path) bool { return path.String() == "/sensitive" },
+			Sensitive: func(path configkit.Path) bool { return path.String() == "/sensitive" },
 		},
 	})
 }
@@ -177,7 +177,7 @@ func resolveNotariusReference(configuration *NotariusPathConfig, resolution *con
 	if configuration.Reference == "" || filepath.IsAbs(configuration.Reference) {
 		return
 	}
-	info, found := resolution.InputInfo(path)
+	info, found := resolution.EntryInfo(path)
 	if !found {
 		resolution.Warning(path, "relative reference has no entry provenance")
 		return

examples/consumers/consumers_test.go

@@ -11,8 +11,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_narratio() {
@@ -82,7 +82,7 @@ func Example_weatherStartup() {
 	defer os.RemoveAll(directory)
 	_ = os.WriteFile(filepath.Join(directory, blockedName), []byte("unused-example-value\n"), 0o600)
 	_ = os.WriteFile(filepath.Join(directory, tokenName), []byte("disposable-example-credential\n"), 0o600)
-	report, bootstrapErr := configkit.LoadSecretsDir(directory)
+	report, bootstrapErr := configkit.LoadSecretsIntoEnvironment(directory)
 	var reportOutput bytes.Buffer
 	_, reportWriteErr := report.WriteTo(&reportOutput)
 

examples/consumers/destinations.go

@@ -6,7 +6,7 @@ import (
 	"io/fs"
 	"path"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // CollectionBundleConfig is a representative application-owned collection
@@ -86,7 +86,7 @@ func resolveCollectionResources(configuration *CollectionBundleConfig, resolutio
 				continue
 			}
 			contentPath := configkit.Keys("collections", collectionID, "prompts", promptID, "content_file")
-			info, found := resolution.InputInfo(contentPath)
+			info, found := resolution.EntryInfo(contentPath)
 			if !found || len(info.Origin.Locations) != 1 {
 				return fmt.Errorf("prompt resource has no single declaring source")
 			}
@@ -104,9 +104,9 @@ func resolveCollectionResources(configuration *CollectionBundleConfig, resolutio
 			}
 			prompt.ResourceText = string(data)
 			collection.Prompts[promptID] = prompt
-			resolution.Record(
+			resolution.RecordNormalization(
 				configkit.Keys("collections", collectionID, "prompts", promptID, "resource_text"),
-				configkit.ChangeNormalization, "read source-relative prompt content", contentPath,
+				"read source-relative prompt content", contentPath,
 			)
 		}
 		configuration.Collections[collectionID] = collection

examples/consumers/destinations_test.go

@@ -5,8 +5,8 @@ import (
 	"fmt"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_inputDestination() {
@@ -60,7 +60,7 @@ func TestCollectionBundleAssemblesMountedPeersAndResources(t *testing.T) {
 	}
 
 	versionInfo, ok := result.Metadata().Lookup(configkit.Keys("version"))
-	if !ok || !versionInfo.Explicit || versionInfo.Origin.Layer != configkit.LayerBase || len(versionInfo.Origin.Locations) != 1 {
+	if !ok || !versionInfo.Explicit || versionInfo.Origin.Layer != configkit.LayerMain || len(versionInfo.Origin.Locations) != 1 {
 		t.Fatalf("main-owned version metadata = %#v, %v", versionInfo, ok)
 	}
 	collectionVersionPath := configkit.Keys("collections", "weatherreporter", "version")

examples/consumers/diff.go

@@ -5,7 +5,7 @@ import (
 	"strconv"
 	"strings"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // FileComparisonConfig is a small application-owned shape for comparing
@@ -101,8 +101,8 @@ func resolveRollout(configuration *RolloutConfig, resolution *configkit.Resoluti
 	url := fmt.Sprintf("https://%s:%d", endpoint.Host, endpoint.Port)
 	if endpoint.URL != url {
 		endpoint.URL = url
-		resolution.Record(configkit.Keys("service", "endpoint", "url"),
+		resolution.RecordNormalization(configkit.Keys("service", "endpoint", "url"),
-			configkit.ChangeNormalization, "derived endpoint URL",
+			"derived endpoint URL",
 			configkit.Keys("service", "endpoint", "host"),
 			configkit.Keys("service", "endpoint", "port"))
 	}

examples/consumers/diff_test.go

@@ -7,8 +7,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func ExampleCompareFiles() {

examples/consumers/discovery_test.go

@@ -0,0 +1,46 @@
+package consumers_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+type workingDirectoryPresetConfig struct {
+	Name string `yaml:"name"`
+}
+
+func Example_workingDirectoryPreset() {
+	original, err := os.Getwd()
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer func() { _ = os.Chdir(original) }()
+	root, err := os.MkdirTemp("", "configkit-working-search-")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer os.RemoveAll(root)
+	if err := os.Chdir(root); err != nil {
+		fmt.Println(err)
+		return
+	}
+	if err := os.WriteFile(filepath.Join(root, "service.yml"), []byte("name: example\n"), 0o600); err != nil {
+		fmt.Println(err)
+		return
+	}
+	result, err := configkit.Load[workingDirectoryPresetConfig](
+		configkit.SearchConfig("service", configkit.WorkingDirectory()),
+	)
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	source, _ := result.Source("source-1")
+	fmt.Println(result.Config.Name, filepath.Base(source.Path))
+	// Output: example service.yml
+}

examples/consumers/inheritance.go

@@ -1,6 +1,6 @@
 package consumers
 
-import configkit "gitea.maximumdirect.net/eric/ConfigKit"
+import configkit "go.maximumdirect.net/configkit"
 
 // PresetCatalog is ordinary application data; no inheritance fields or
 // registration hooks are required in the typed configuration.

examples/consumers/inheritance_test.go

@@ -3,8 +3,8 @@ package consumers_test
 import (
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func TestPresetCatalogOneLoadAndDerivation(t *testing.T) {

examples/consumers/layered.go

@@ -6,7 +6,7 @@ import (
 	"io/fs"
 	"path"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 //go:embed testdata/native-source testdata/layered-bundle testdata/collection-bundle testdata/ordinary-imports testdata/source-version

examples/consumers/layered_test.go

@@ -6,8 +6,8 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_nativeFilesystem() {
@@ -26,7 +26,7 @@ func Example_rootRelativeImports() {
 		fmt.Println(err)
 		return
 	}
-	source := result.Sources()[2]
+	source, _ := result.Source("source-3")
 	fmt.Println(result.Config.Name, result.Config.Version, result.Config.Prompts["brief"].Summary, source.Destination.String(), err)
 	// Output: Root import example 1.0 A root-loaded prompt. /prompts <nil>
 }
@@ -68,7 +68,7 @@ func Example_sourceVersionAdoption() {
 	}
 	checks, redacted := 0, true
 	for _, source := range result.Sources() {
-		if check := source.VersionCheck; check != nil {
+		if check := source.VersionEvidence; check != nil {
 			checks++
 			redacted = redacted && check.Redacted && check.Version.Text == ""
 		}
@@ -95,7 +95,7 @@ func TestVersionedServiceModesAndMountedProtection(t *testing.T) {
 			t.Fatalf("versioned service sources = %#v", sources)
 		}
 		for _, source := range sources {
-			check := source.VersionCheck
+			check := source.VersionEvidence
 			if check == nil || check.Path.String() != "/version" || !check.Version.Present ||
 				!check.Redacted || check.Version.Text != "" {
 				t.Fatalf("safe source version evidence = %#v", sources)
@@ -119,7 +119,7 @@ func TestCatalogRetainsPresenceAndSourceContext(t *testing.T) {
 	}
 	for _, key := range []string{"enabled", "workers"} {
 		info, found := result.Metadata().Lookup(configkit.Keys(key))
-		if !found || !info.Explicit || info.Origin.Layer != configkit.LayerBase {
+		if !found || !info.Explicit || info.Origin.Layer != configkit.LayerMain {
 			t.Fatalf("%s presence = %#v, %v", key, info, found)
 		}
 	}

examples/consumers/prompt_catalog.go

@@ -3,7 +3,7 @@ package consumers
 import (
 	"strings"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // PromptCatalogConfig is an application-owned prompt collection shape.
@@ -16,9 +16,10 @@ type PromptRecord struct {
 	ID       string   `yaml:"id"`
 	Name     string   `yaml:"name"`
 	Messages []string `yaml:"messages"`
+	Resource string   `yaml:"resource"`
 }
 
-// LoadPromptCatalog composes explicitly registered prompt records in the main
+// LoadPromptCatalog discovers explicitly registered prompt records in the main
 // tier and replaces the lower-priority default collection as a whole.
 func LoadPromptCatalog(mainPath string) (*configkit.Result[PromptCatalogConfig], error) {
 	return configkit.LoadLayered(configkit.Input{
@@ -28,16 +29,29 @@ func LoadPromptCatalog(mainPath string) (*configkit.Result[PromptCatalogConfig],
 		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
 			Source: configkit.Bytes("default prompts", []byte("prompts:\n  - id: default\n    name: Default prompt\n    messages: [Default message]\n")),
 		}}}},
-		Definition: configkit.Definition[PromptCatalogConfig]{
+		ImportDefaults: configkit.ImportDefaults{
-			SequenceCompositions: []configkit.SequenceComposition{{
+			Pattern: []string{"curated*.yml", "generated-*.yml"},
-				Path:          configkit.Keys("prompts"),
-				IdentityField: "id",
-			}},
-			Validate: validatePromptCatalog,
 		},
+		Definition: promptCatalogDefinition(),
 	})
 }
 
+// LoadRequiredPromptCatalog keeps the common one-file import shape small.
+func LoadRequiredPromptCatalog(mainPath string) (*configkit.Result[PromptCatalogConfig], error) {
+	return configkit.Load(configkit.File(mainPath), configkit.Options[PromptCatalogConfig]{
+		Imports: true, Definition: promptCatalogDefinition(),
+	})
+}
+
+func promptCatalogDefinition() configkit.Definition[PromptCatalogConfig] {
+	return configkit.Definition[PromptCatalogConfig]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+		},
+		Validate: validatePromptCatalog,
+	}
+}
+
 func validatePromptCatalog(configuration *PromptCatalogConfig, validation *configkit.Validation) {
 	for index, prompt := range configuration.Prompts {
 		if strings.TrimSpace(prompt.Name) == "" {

examples/consumers/prompt_catalog_test.go

@@ -3,11 +3,13 @@ package consumers_test
 import (
 	"errors"
 	"fmt"
+	"io/fs"
+	pathpkg "path"
 	"path/filepath"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
-	"gitea.maximumdirect.net/eric/ConfigKit/examples/consumers"
+	"go.maximumdirect.net/configkit/examples/consumers"
 )
 
 func Example_identifiedPromptCatalog() {
@@ -20,8 +22,26 @@ func Example_identifiedPromptCatalog() {
 	for _, prompt := range result.Config.Prompts {
 		ids = append(ids, prompt.ID)
 	}
-	fmt.Println(ids, err)
+	emptySearches := 0
-	// Output: [main curated weather welcome] <nil>
+	for _, source := range result.Sources() {
+		for _, selection := range source.EmptyImportSelections {
+			if selection.Selector == configkit.ImportSelectorDirectory {
+				emptySearches++
+			}
+		}
+	}
+	fmt.Println(ids, emptySearches, err)
+	// Output: [weather curated welcome main] 1 <nil>
+}
+
+func Example_requiredPromptCatalog() {
+	result, err := consumers.LoadRequiredPromptCatalog(fixture("prompt-catalog", "simple.yml"))
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	fmt.Println(result.Config.Prompts[0].ID, err)
+	// Output: required <nil>
 }
 
 func TestPromptCatalogImportsRegisteredItemsAndReplacesDefaults(t *testing.T) {
@@ -36,7 +56,7 @@ func TestPromptCatalogImportsRegisteredItemsAndReplacesDefaults(t *testing.T) {
 	if len(result.Config.Prompts) != 4 {
 		t.Fatalf("prompt records = %#v", result.Config.Prompts)
 	}
-	ids := []string{"main", "curated", "weather", "welcome"}
+	ids := []string{"weather", "curated", "welcome", "main"}
 	for index, id := range ids {
 		if result.Config.Prompts[index].ID != id {
 			t.Fatalf("prompt %d ID = %q, want %q", index, result.Config.Prompts[index].ID, id)
@@ -46,12 +66,15 @@ func TestPromptCatalogImportsRegisteredItemsAndReplacesDefaults(t *testing.T) {
 		if prompt.ID == "default" {
 			t.Fatalf("lower-priority default survived main sequence replacement: %#v", result.Config.Prompts)
 		}
+		if prompt.ID == "ignored" {
+			t.Fatalf("excluded generated prompt was selected: %#v", result.Config.Prompts)
+		}
 	}
 
 	var itemImports, helperImports int
 	for _, source := range result.Sources() {
 		switch filepath.Base(source.Path) {
-		case "curated.yml", "generated-weather.yml", "generated-welcome.yml":
+		case "curated.yml", "weather-feature.yml", "generated-welcome.yml":
 			if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/prompts" {
 				t.Fatalf("item source placement = %#v", source)
 			}
@@ -71,6 +94,36 @@ func TestPromptCatalogImportsRegisteredItemsAndReplacesDefaults(t *testing.T) {
 	}
 }
 
+func TestPromptCatalogMountsResourceFromScheduledPromptOrigin(t *testing.T) {
+	result, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "config.yml"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Config.Prompts[2].ID != "welcome" || result.Config.Prompts[2].Resource != "welcome.txt" {
+		t.Fatalf("scheduled resource prompt = %#v", result.Config.Prompts)
+	}
+	resourcePath := configkit.Keys("prompts").Index(2).Key("resource")
+	info, ok := result.Metadata().Lookup(resourcePath)
+	if !ok || len(info.Origin.Locations) != 1 {
+		t.Fatalf("resource origin = %#v, %v", info, ok)
+	}
+	context, ok := result.SourceContext(info.Origin.Locations[0].SourceID)
+	if !ok || context.FS == nil || filepath.Base(context.BaseDir) != "prompts" {
+		t.Fatalf("resource source context = %#v, %v", context, ok)
+	}
+	contents, err := fs.ReadFile(context.FS, pathpkg.Join(context.BaseDir, result.Config.Prompts[2].Resource))
+	if err != nil || string(contents) != "Welcome resource text.\n" {
+		t.Fatalf("mounted resource = %q, %v", contents, err)
+	}
+}
+
+func TestRequiredPromptCatalogUsesOneRequiredFile(t *testing.T) {
+	result, err := consumers.LoadRequiredPromptCatalog(fixture("prompt-catalog", "simple.yml"))
+	if err != nil || len(result.Config.Prompts) != 1 || result.Config.Prompts[0].ID != "required" {
+		t.Fatalf("simple required prompt = %#v, %v", result, err)
+	}
+}
+
 func TestPromptCatalogLeavesDomainValidationWithConsumer(t *testing.T) {
 	_, err := consumers.LoadPromptCatalog(fixture("prompt-catalog", "invalid.yml"))
 	var loadError *configkit.LoadError

examples/consumers/sequence_catalog.go

@@ -0,0 +1,145 @@
+package consumers
+
+import (
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+// SequenceCatalogConfig is a source-backed prompt catalog with an application
+// supplied run label and a value derived from that label during resolution.
+type SequenceCatalogConfig struct {
+	RunLabel      string                 `yaml:"run_label"`
+	ResolvedLabel string                 `yaml:"resolved_label"`
+	Prompts       []SequenceCatalogEntry `yaml:"prompts"`
+}
+
+// SequenceCatalogEntry keeps prompt meaning, resources, and credentials in the
+// consuming application while ConfigKit handles collection assembly.
+type SequenceCatalogEntry struct {
+	ID          string           `yaml:"id"`
+	Name        string           `yaml:"name"`
+	Description string           `yaml:"description"`
+	Messages    []string         `yaml:"messages"`
+	Resource    string           `yaml:"resource"`
+	Credential  configkit.Secret `yaml:"credential"`
+}
+
+// LoadSequenceCatalog searches its caller-selected main path before a custom
+// fallback directory, assembles imported fragments over a file-backed underlay,
+// applies one selected collection overlay, then resolves and validates once.
+func LoadSequenceCatalog(mainPath, overlayName, runLabel string) (*configkit.Result[SequenceCatalogConfig], error) {
+	absoluteMain, err := filepath.Abs(mainPath)
+	if err != nil {
+		return nil, err
+	}
+	root := filepath.Dir(absoluteMain)
+	filesystem := configkit.NewFilesystem("sequence catalog", os.DirFS(root))
+	filesystemContext := &configkit.FilesystemContext{BaseDir: ".", Root: ".", FS: &filesystem}
+	mainSearch := configkit.SearchConfig("", configkit.Searches(
+		configkit.SearchPaths(absoluteMain),
+		configkit.SearchDirectory(filepath.Join(root, "fallback"), configkit.DirectorySearchOptions{
+			Filenames: []configkit.FilenameGroup{configkit.CustomFilenames(filepath.Base(absoluteMain))},
+		}),
+	), configkit.SearchOptions{Required: true})
+	definition := configkit.Definition[SequenceCatalogConfig]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+		},
+		Resolve: func(configuration *SequenceCatalogConfig, resolution *configkit.Resolution) error {
+			configuration.ResolvedLabel = "for:" + configuration.RunLabel
+			resolution.RecordNormalization(configkit.Keys("resolved_label"),
+				"derive the resolved label from the selected run label", configkit.Keys("run_label"))
+			return nil
+		},
+		Validate: validateSequenceCatalog,
+	}
+	return configkit.LoadLayered(configkit.Input{
+		Source:     mainSearch,
+		Imports:    true,
+		Filesystem: &configkit.FilesystemContext{Root: root},
+	}, configkit.LayeredOptions[SequenceCatalogConfig]{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+			Source: filesystem.File("underlay.yml"),
+		}}}},
+		Overlay:           overlayName,
+		OverlayFilesystem: filesystemContext,
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("run_label"), Value: runLabel, Flag: "--run-label",
+		}},
+		Definition: definition,
+	})
+}
+
+// ReadSequenceCatalogResource follows the final prompt field's source context,
+// including when record inheritance retained a resource from an underlay.
+func ReadSequenceCatalogResource(result *configkit.Result[SequenceCatalogConfig], promptID string) (string, error) {
+	if result == nil {
+		return "", errors.New("sequence catalog result is nil")
+	}
+	for index, prompt := range result.Config.Prompts {
+		if prompt.ID != promptID {
+			continue
+		}
+		resourcePath := configkit.Keys("prompts").Index(index).Key("resource")
+		info, found := result.Metadata().Lookup(resourcePath)
+		if !found || len(info.Origin.Locations) != 1 {
+			return "", errors.New("prompt resource has no single declaring source")
+		}
+		context, found := result.SourceContext(info.Origin.Locations[0].SourceID)
+		if !found {
+			return "", errors.New("prompt resource source context is unavailable")
+		}
+		data, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, prompt.Resource))
+		if err != nil {
+			return "", fmt.Errorf("read prompt resource: %w", err)
+		}
+		return string(data), nil
+	}
+	return "", fmt.Errorf("prompt %q is unavailable", promptID)
+}
+
+func validateSequenceCatalog(configuration *SequenceCatalogConfig, validation *configkit.Validation) {
+	for index, prompt := range configuration.Prompts {
+		if strings.TrimSpace(prompt.Name) == "" {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("name"), "must not be empty")
+		}
+		if len(prompt.Messages) == 0 {
+			validation.Error(configkit.Keys("prompts").Index(index).Key("messages"), "must contain at least one message")
+		}
+	}
+	if len(configuration.Prompts) == 0 {
+		validation.Error(configkit.Keys("prompts"), "must contain at least one prompt")
+	}
+}
+
+// NamespacedMapCatalogConfig demonstrates typed application maps whose
+// independent prompt sequences use root and dynamic namespace registrations.
+type NamespacedMapCatalogConfig struct {
+	Prompts     []map[string]any          `yaml:"prompts"`
+	Collections map[string]map[string]any `yaml:"collections"`
+}
+
+// LoadNamespacedMapCatalog applies the same scalar identity constraint to one
+// root collection and each namespace's independently scoped collection.
+func LoadNamespacedMapCatalog(source configkit.Source) (*configkit.Result[NamespacedMapCatalogConfig], error) {
+	selector := configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("prompts"),
+	}
+	return configkit.Load(source, configkit.Options[NamespacedMapCatalogConfig]{
+		Definition: configkit.Definition[NamespacedMapCatalogConfig]{
+			SequenceIdentities: []configkit.SequenceIdentity{
+				configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id"),
+				configkit.SequenceIdentityMatching(selector, "id"),
+			},
+		},
+	})
+}

examples/consumers/sequence_catalog_test.go

@@ -0,0 +1,239 @@
+package consumers_test
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+	"go.maximumdirect.net/configkit/examples/consumers"
+)
+
+func Example_sequenceCatalog() {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	restoreOld, restoreNew := preserveEnvironment(oldSecret), preserveEnvironment(newSecret)
+	defer restoreOld()
+	defer restoreNew()
+	_ = os.Setenv(oldSecret, "disposable-old-example-credential")
+	_ = os.Setenv(newSecret, "disposable-new-example-credential")
+
+	result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), "upsert", "preview")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	ids := make([]string, 0, len(result.Config.Prompts))
+	for _, prompt := range result.Config.Prompts {
+		ids = append(ids, prompt.ID)
+	}
+	shared := configkit.Keys("prompts").Index(1).Key("name")
+	info, _ := result.Metadata().Lookup(shared)
+	resource, resourceErr := consumers.ReadSequenceCatalogResource(result, "concise")
+	fmt.Println(ids, result.Config.ResolvedLabel, info.Explicit, len(result.Metadata().History(shared)), resource, resourceErr == nil, err)
+	// Output: [foundation shared welcome concise extra] for:preview true 2 Foundation resource text.
+	//  true <nil>
+}
+
+func TestSequenceCatalogSelectedOverlayOperations(t *testing.T) {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	t.Setenv(oldSecret, "sequence-catalog-old-canary")
+	t.Setenv(newSecret, "sequence-catalog-new-canary")
+
+	tests := []struct {
+		name    string
+		wantIDs []string
+		shared  *consumers.SequenceCatalogEntry
+	}{
+		{name: "append", wantIDs: []string{"foundation", "shared", "welcome", "concise", "extra"}},
+		{name: "upsert", wantIDs: []string{"foundation", "shared", "welcome", "concise", "extra"}, shared: &consumers.SequenceCatalogEntry{ID: "shared", Name: "Shared replacement", Messages: []string{"Replacement message"}, Credential: configkit.SecretEnv(newSecret)}},
+		{name: "replace", wantIDs: []string{"replacement", "last"}},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), test.name, "test")
+			if err != nil {
+				var loadError *configkit.LoadError
+				if errors.As(err, &loadError) {
+					t.Fatalf("load selected overlay: %v (%#v)", err, loadError.Diagnostics())
+				}
+				t.Fatal(err)
+			}
+			gotIDs := make([]string, 0, len(result.Config.Prompts))
+			for _, prompt := range result.Config.Prompts {
+				gotIDs = append(gotIDs, prompt.ID)
+			}
+			if strings.Join(gotIDs, ",") != strings.Join(test.wantIDs, ",") {
+				t.Fatalf("prompt order = %v, want %v", gotIDs, test.wantIDs)
+			}
+			if test.shared == nil {
+				return
+			}
+			shared := result.Config.Prompts[1]
+			if shared.ID != test.shared.ID || shared.Name != test.shared.Name || len(shared.Messages) != 1 ||
+				shared.Messages[0] != test.shared.Messages[0] || shared.Description != "" || shared.Resource != "" || shared.Credential.EnvName() != newSecret {
+				t.Fatalf("upsert did not replace the complete matched record: %#v", shared)
+			}
+		})
+	}
+}
+
+func TestSequenceCatalogInspectionTracksResourcesAndSecretHistory(t *testing.T) {
+	const oldSecret = "CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET"
+	const newSecret = "CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET"
+	const oldCanary = "sequence-catalog-old-canary"
+	const newCanary = "sequence-catalog-new-canary"
+	t.Setenv(oldSecret, oldCanary)
+	t.Setenv(newSecret, newCanary)
+
+	result, err := consumers.LoadSequenceCatalog(fixture("sequence-catalog", "config.yml"), "upsert", "history")
+	if err != nil {
+		var loadError *configkit.LoadError
+		if errors.As(err, &loadError) {
+			t.Fatalf("load sequence catalog: %v (%#v)", err, loadError.Diagnostics())
+		}
+		t.Fatal(err)
+	}
+	resourcePath := configkit.Keys("prompts").Index(3).Key("resource")
+	resourceInfo, found := result.Metadata().Lookup(resourcePath)
+	if !found || len(resourceInfo.Origin.Locations) != 1 || len(resourceInfo.Origin.Inheritance) != 1 {
+		t.Fatalf("inherited resource inspection = %#v, %v", resourceInfo, found)
+	}
+	resource, err := consumers.ReadSequenceCatalogResource(result, "concise")
+	if err != nil || resource != "Foundation resource text.\n" {
+		t.Fatalf("resource from inherited source context = %q, %v", resource, err)
+	}
+	if len(result.Metadata().History(configkit.Keys("resolved_label"))) == 0 {
+		t.Fatal("recorded CLI-driven resolution was absent from final inspection")
+	}
+	credentialPath := configkit.Keys("prompts").Index(1).Key("credential")
+	credentialHistory := result.Metadata().History(credentialPath)
+	if len(credentialHistory) == 0 {
+		t.Fatal("upsert did not retain the replaced secret reference in history")
+	}
+	var explanation bytes.Buffer
+	if err := result.WriteExplanation(&explanation, credentialPath); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(explanation.String(), oldCanary) || strings.Contains(explanation.String(), newCanary) {
+		t.Fatalf("secret explanation exposed a credential value: %s", explanation.String())
+	}
+}
+
+func TestNamespacedTypedMapIdentityScopesAreIndependent(t *testing.T) {
+	source := configkit.Bytes("namespaced maps", []byte(`
+prompts:
+  - id: shared
+    text: root prompt
+collections:
+  team:
+    prompts:
+      - id: shared
+        text: team prompt
+  operations:
+    prompts:
+      - id: shared
+        text: operations prompt
+`))
+	result, err := consumers.LoadNamespacedMapCatalog(source)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if result.Config.Prompts[0]["text"] != "root prompt" ||
+		result.Config.Collections["team"]["prompts"].([]any)[0].(map[string]any)["text"] != "team prompt" ||
+		result.Config.Collections["operations"]["prompts"].([]any)[0].(map[string]any)["text"] != "operations prompt" {
+		t.Fatalf("typed map collections = %#v", result.Config)
+	}
+}
+
+func TestNamespacedTypedMapIdentityFindsCollectionsIntroducedByInheritance(t *testing.T) {
+	result, err := consumers.LoadNamespacedMapCatalog(configkit.Bytes("inherited namespace", []byte(`
+collections:
+  source:
+    prompts:
+      - id: shared
+        text: inherited prompt
+  copied:
+    extends: source
+`)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	copied := result.Config.Collections["copied"]["prompts"].([]any)
+	if len(copied) != 1 || copied[0].(map[string]any)["text"] != "inherited prompt" {
+		t.Fatalf("inherited typed-map collection = %#v", result.Config.Collections["copied"])
+	}
+}
+
+func Example_yamlDeclaredIdentityOnly() {
+	result, err := configkit.Load(configkit.Bytes("YAML identity only", []byte(`
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+prompts:
+  - id: initial
+`)), configkit.Options[map[string]any]{
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("prompts"),
+			Value: []any{
+				map[string]any{"id": "same"},
+				map[string]any{"id": "same"},
+			},
+			Flag: "--prompts",
+		}},
+	})
+	fmt.Println(len(result.Config["prompts"].([]any)), err)
+	// Output: 2 <nil>
+}
+
+func TestYAMLDeclaredIdentityDoesNotRegisterFinalTypedConstraint(t *testing.T) {
+	result, err := configkit.Load(configkit.Bytes("YAML identity only", []byte(`
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+prompts:
+  - id: initial
+`)), configkit.Options[map[string]any]{
+		Overrides: []configkit.Override{{
+			Path: configkit.Keys("prompts"),
+			Value: []any{
+				map[string]any{"id": "same"},
+				map[string]any{"id": "same"},
+			},
+			Flag: "--prompts",
+		}},
+	})
+	if err != nil {
+		t.Fatalf("YAML-only identity incorrectly became an application constraint: %v", err)
+	}
+	prompts := result.Config["prompts"].([]any)
+	if len(prompts) != 2 || prompts[0].(map[string]any)["id"] != prompts[1].(map[string]any)["id"] {
+		t.Fatalf("CLI result = %#v", result.Config)
+	}
+}
+
+func TestNamespacedTypedMapRejectsDuplicatesWithinOneCollection(t *testing.T) {
+	_, err := consumers.LoadNamespacedMapCatalog(configkit.Bytes("duplicate namespace", []byte(`
+collections:
+  team:
+    prompts:
+      - id: duplicate
+      - id: duplicate
+`)))
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 ||
+		loadError.Diagnostics()[0].Code != configkit.CodeComposeConflict ||
+		loadError.Diagnostics()[0].Path.String() != "/collections/team/prompts" {
+		diagnostics := []configkit.Diagnostic(nil)
+		if loadError != nil {
+			diagnostics = loadError.Diagnostics()
+		}
+		t.Fatalf("duplicate namespaced identity error = %v (%#v)", err, diagnostics)
+	}
+}

examples/consumers/source_version.go

@@ -4,7 +4,7 @@ import (
 	"errors"
 	"io/fs"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 // VersionedServiceConfig demonstrates a mounted main input whose source-local
@@ -47,7 +47,7 @@ func LoadVersionedService(mode configkit.SourceVersionMode, overrides ...configk
 				return nil
 			},
 		},
-		Secret: func(path configkit.Path) bool {
+		Sensitive: func(path configkit.Path) bool {
 			return path.String() == "/service/version"
 		},
 	}

examples/consumers/testdata/prompt-catalog/config.yml

@@ -1,11 +1,18 @@
 configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
   imports:
-    - path: prompts/curated.yml
+    - dir: prompts
+      exclude: [generated-ignored.yml]
       destination: [prompts]
       placement: sequence-item
-    - glob: prompts/generated-*.yml
+    - dir: featured
+      pattern: [weather-*.yml]
       destination: [prompts]
       placement: sequence-item
+    - dir: optional
 prompts:
   - id: main
     name: Main authored prompt

examples/consumers/testdata/prompt-catalog/invalid.yml

@@ -1,3 +1,8 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
 prompts:
   - id: invalid
     name: Invalid prompt

examples/consumers/testdata/prompt-catalog/optional/ignored.txt

@@ -0,0 +1 @@
+This file does not match the application import defaults.

examples/consumers/testdata/prompt-catalog/prompts/curated.yml

@@ -1,6 +1,6 @@
 configkit:
   imports:
-    - path: curated-id.yml
+    - path: helpers/curated-id.yml
 name: Curated summary
 messages:
   - Summarize the supplied content.

examples/consumers/testdata/prompt-catalog/prompts/generated-ignored.yml

@@ -0,0 +1,3 @@
+id: ignored
+name: Excluded generated prompt
+messages: [This record is excluded.]

examples/consumers/testdata/prompt-catalog/prompts/generated-welcome.yml

@@ -2,3 +2,4 @@ id: welcome
 name: Welcome
 messages:
   - Welcome the user.
+resource: welcome.txt

examples/consumers/testdata/prompt-catalog/prompts/required.yml

@@ -0,0 +1,3 @@
+id: required
+name: Required prompt
+messages: [Use the required prompt.]

examples/consumers/testdata/prompt-catalog/prompts/welcome.txt

@@ -0,0 +1 @@
+Welcome resource text.

examples/consumers/testdata/prompt-catalog/simple.yml

@@ -0,0 +1,7 @@
+configkit:
+  imports:
+    - path: prompts/required.yml
+      required: true
+      destination: [prompts]
+      placement: sequence-item
+prompts: []

examples/consumers/testdata/sequence-catalog/config.yml

@@ -0,0 +1,7 @@
+run_label: source-default
+configkit:
+  imports:
+    - dir: fragments
+      pattern: '*.yml'
+      destination: [prompts]
+      placement: sequence-item

examples/consumers/testdata/sequence-catalog/foundation.txt

@@ -0,0 +1 @@
+Foundation resource text.

examples/consumers/testdata/sequence-catalog/fragments/01-welcome.yml

@@ -0,0 +1,4 @@
+id: welcome
+name: Welcome
+messages: [Welcome message]
+credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/fragments/02-concise.yml

@@ -0,0 +1,3 @@
+id: concise
+extends: {id: foundation}
+name: Concise

examples/consumers/testdata/sequence-catalog/overlays/append.yml

@@ -0,0 +1,10 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: append
+prompts:
+  - id: extra
+    name: Extra
+    messages: [Extra message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/overlays/replace.yml

@@ -0,0 +1,14 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: replace
+prompts:
+  - id: replacement
+    name: Replacement
+    messages: [Replacement message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET
+  - id: last
+    name: Last
+    messages: [Last message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/overlays/upsert.yml

@@ -0,0 +1,14 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: upsert
+prompts:
+  - id: shared
+    name: Shared replacement
+    messages: [Replacement message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_NEW_SECRET
+  - id: extra
+    name: Extra
+    messages: [Extra message]
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

examples/consumers/testdata/sequence-catalog/underlay.yml

@@ -0,0 +1,18 @@
+configkit:
+  sequences:
+    - destination: [prompts]
+      key: id
+      mode: append
+prompts:
+  - id: foundation
+    name: Foundation
+    description: Shared foundation instruction
+    messages: [Foundation message]
+    resource: foundation.txt
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET
+  - id: shared
+    name: Shared draft
+    description: This field must not survive a whole-record replacement
+    messages: [Draft message]
+    resource: shared.txt
+    credential: CONFIGKIT_SEQUENCE_CATALOG_OLD_SECRET

facade_candidate_test.go

@@ -11,7 +11,7 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 var (
@@ -23,7 +23,7 @@ var (
 
 func TestFacadeValuesRemainRootOwned(t *testing.T) {
 	t.Parallel()
-	const packagePath = "gitea.maximumdirect.net/eric/ConfigKit"
+	const packagePath = "go.maximumdirect.net/configkit"
 	for _, candidate := range []reflect.Type{
 		reflect.TypeFor[configkit.Path](), reflect.TypeFor[configkit.Source](),
 		reflect.TypeFor[configkit.Secret](), reflect.TypeFor[configkit.Diagnostic](),
@@ -140,7 +140,7 @@ func TestFacadeSecretsBootstrapUsesFacadeRecords(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	report, err := configkit.LoadSecretsDir(directory)
+	report, err := configkit.LoadSecretsIntoEnvironment(directory)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -164,7 +164,7 @@ func TestFacadeSecretsBootstrapUsesFacadeRecords(t *testing.T) {
 		t.Fatalf("report rendering = %q, %v", rendered.String(), err)
 	}
 
-	failedReport, err := configkit.LoadSecretsDir("")
+	failedReport, err := configkit.LoadSecretsIntoEnvironment("")
 	var secretsError *configkit.SecretsError
 	if failedReport == nil || !errors.As(err, &secretsError) || len(secretsError.Diagnostics()) != 1 || secretsError.Diagnostics()[0].Code != configkit.CodeSecretsInvalidPath {
 		t.Fatalf("bootstrap failure = %#v / %#v", failedReport, err)
@@ -203,7 +203,7 @@ func TestFacadeLoadBridgesLifecycleCallbacks(t *testing.T) {
 			if !resolution.IsExplicit(configkit.Keys("input")) {
 				resolution.Error(configkit.Keys("input"), "input is required")
 			}
-			input, ok := resolution.InputInfo(configkit.Keys("input"))
+			input, ok := resolution.EntryInfo(configkit.Keys("input"))
 			if !ok || !input.Explicit {
 				resolution.Error(configkit.Keys("input"), "missing input provenance")
 			}
@@ -245,6 +245,8 @@ func TestFacadeLoadBridgesLifecycleCallbacks(t *testing.T) {
 	}
 	for _, context := range []func(){
 		func() { retainedResolution.IsExplicit(configkit.Keys("input")) },
+		func() { retainedResolution.RecordDerivedDefault(configkit.Keys("input"), "too late") },
+		func() { retainedResolution.RecordNormalization(configkit.Keys("input"), "too late") },
 		func() { retainedValidation.Warning(configkit.Keys("input"), "too late") },
 	} {
 		func() {

facade_compatibility_test.go

@@ -5,10 +5,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"reflect"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 var (
@@ -27,23 +26,6 @@ type facadeCompatibilityConfig struct {
 func TestFacadeCompatibility(t *testing.T) {
 	t.Parallel()
 
-	const packagePath = "gitea.maximumdirect.net/eric/ConfigKit"
-	for _, candidate := range []struct {
-		name  string
-		type_ reflect.Type
-	}{
-		{"Path", reflect.TypeFor[configkit.Path]()},
-		{"Source", reflect.TypeFor[configkit.Source]()},
-		{"Secret", reflect.TypeFor[configkit.Secret]()},
-		{"Definition", reflect.TypeFor[configkit.Definition[facadeCompatibilityConfig]]()},
-		{"Options", reflect.TypeFor[configkit.Options[facadeCompatibilityConfig]]()},
-		{"Result", reflect.TypeFor[configkit.Result[facadeCompatibilityConfig]]()},
-	} {
-		if candidate.type_.PkgPath() != packagePath {
-			t.Errorf("%s belongs to %q, want %q", candidate.name, candidate.type_.PkgPath(), packagePath)
-		}
-	}
-
 	constructed := configkit.Options[facadeCompatibilityConfig]{
 		Definition: configkit.Definition[facadeCompatibilityConfig]{},
 		Filesystem: &configkit.FilesystemContext{BaseDir: "configs", Root: "configs"},
@@ -56,11 +38,6 @@ func TestFacadeCompatibility(t *testing.T) {
 	if got := constructed.Overrides[0].Path.String(); got != "/value" {
 		t.Fatalf("constructed override path = %q, want /value", got)
 	}
-	publicResult := configkit.Result[facadeCompatibilityConfig]{Config: facadeCompatibilityConfig{Value: "constructed"}}
-	if publicResult.Config.Value != "constructed" {
-		t.Fatal("constructed result lost its public configuration")
-	}
-
 	result, err := configkit.Load(configkit.Bytes("facade.yml", []byte("value: input\n")), configkit.Options[facadeCompatibilityConfig]{
 		Definition: configkit.Definition[facadeCompatibilityConfig]{
 			Resolve: func(configuration *facadeCompatibilityConfig, resolution *configkit.Resolution) error {

facade_container_origin_test.go

@@ -0,0 +1,41 @@
+package configkit_test
+
+import (
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestOverlayExplanationUsesQueryScopedOrigin(t *testing.T) {
+	t.Parallel()
+	filesystem := configkit.NewFilesystem("origin", fstest.MapFS{
+		"main.yml":         {Data: []byte("a: base\ngroup: {x: X, y: Y}\n")},
+		"overlays/dev.yml": {Data: []byte("a: overlay\ngroup: {x: O}\n")},
+	})
+	result, err := configkit.Load[map[string]any](filesystem.File("main.yml"), configkit.Options[map[string]any]{Overlay: "dev"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, test := range []struct {
+		path         configkit.Path
+		line, column int
+	}{
+		{configkit.Keys(), 1, 1},
+		{configkit.Keys("group"), 2, 8},
+		{configkit.Keys("group", "x"), 2, 12},
+	} {
+		explanation, found := result.Explain(test.path)
+		if !found || len(explanation.History) == 0 {
+			t.Fatalf("missing explanation for %s", test.path)
+		}
+		origin := explanation.History[len(explanation.History)-1].Origin
+		if origin.Layer != configkit.LayerOverlay || len(origin.Locations) != 1 {
+			t.Fatalf("overlay origin for %s = %#v", test.path, origin)
+		}
+		location := origin.Locations[0]
+		if location.SourceID != "source-2" || location.Line != test.line || location.Column != test.column {
+			t.Fatalf("overlay location for %s = %#v; want line %d column %d", test.path, location, test.line, test.column)
+		}
+	}
+}

facade_context_test.go

@@ -3,7 +3,7 @@ package configkit_test
 import (
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func TestFacadeInactiveContextsPreserveClosedFailure(t *testing.T) {
@@ -24,10 +24,11 @@ func TestFacadeInactiveContextsPreserveClosedFailure(t *testing.T) {
 				call func()
 			}{
 				{"IsExplicit", func() { state.resolution.IsExplicit(path) }},
-				{"InputInfo", func() { state.resolution.InputInfo(path) }},
+				{"EntryInfo", func() { state.resolution.EntryInfo(path) }},
 				{"Source", func() { state.resolution.Source("source") }},
 				{"SourceContext", func() { state.resolution.SourceContext("source") }},
-				{"Record", func() { state.resolution.Record(path, configkit.ChangeNormalization, "reason") }},
+				{"RecordDerivedDefault", func() { state.resolution.RecordDerivedDefault(path, "reason") }},
+				{"RecordNormalization", func() { state.resolution.RecordNormalization(path, "reason") }},
 				{"Resolution.Error", func() { state.resolution.Error(path, "message") }},
 				{"Resolution.Warning", func() { state.resolution.Warning(path, "message") }},
 				{"Default", func() { configkit.Default(state.resolution, path, &target, 1, "reason") }},

facade_destination_test.go

@@ -14,7 +14,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func TestFacadeInputDestinationsAcrossSourceKinds(t *testing.T) {
@@ -352,7 +352,7 @@ func TestFacadeMountedMainAndUnderlayInspectionResourcesAndDiff(t *testing.T) {
 				Resolve: func(configuration *map[string]any, resolution *configkit.Resolution) error {
 					callbacks.resolve++
 					resourcePath := configkit.Keys("catalog", "entries", "item", "resource")
-					input, ok := resolution.InputInfo(resourcePath)
+					input, ok := resolution.EntryInfo(resourcePath)
 					if !ok || len(input.Origin.Locations) != 1 {
 						return fmt.Errorf("mounted resource input has no single source origin")
 					}
@@ -370,11 +370,11 @@ func TestFacadeMountedMainAndUnderlayInspectionResourcesAndDiff(t *testing.T) {
 					}
 					entry := facadeDestinationMap(t, facadeDestinationMap(t, facadeDestinationMap(t, *configuration, "catalog"), "entries"), "item")
 					entry["resource_text"] = string(data)
-					resolution.Record(configkit.Keys("catalog", "entries", "item", "resource_text"), configkit.ChangeNormalization, "read source-relative summary", resourcePath)
+					resolution.RecordNormalization(configkit.Keys("catalog", "entries", "item", "resource_text"), "read source-relative summary", resourcePath)
 					return nil
 				},
-				Validate: func(*map[string]any, *configkit.Validation) { callbacks.validate++ },
+				Validate:  func(*map[string]any, *configkit.Validation) { callbacks.validate++ },
-				Secret:   func(candidate configkit.Path) bool { return candidate.String() == tokenPath.String() },
+				Sensitive: func(candidate configkit.Path) bool { return candidate.String() == tokenPath.String() },
 			},
 		})
 		if err != nil {
@@ -405,7 +405,7 @@ func TestFacadeMountedMainAndUnderlayInspectionResourcesAndDiff(t *testing.T) {
 		if err != nil || string(data) != "source-relative summary" {
 			t.Fatalf("completed relative resource = %q, %v", data, err)
 		}
-		if info, ok := result.Metadata().Lookup(titlePath); !ok || info.Origin.Layer != configkit.LayerBase {
+		if info, ok := result.Metadata().Lookup(titlePath); !ok || info.Origin.Layer != configkit.LayerMain {
 			t.Fatalf("mounted title metadata = %#v, %v", info, ok)
 		}
 		if history := result.Metadata().History(titlePath); len(history) < 2 {

facade_diagnostic_order_test.go

@@ -0,0 +1,95 @@
+package configkit_test
+
+import (
+	"bytes"
+	"errors"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeCompositionConflictKeepsClaimantOrder(t *testing.T) {
+	filesystem := configkit.NewFilesystem("bundle", fstest.MapFS{
+		"a.yml": &fstest.MapFile{Data: []byte(`configkit:
+  imports:
+    - path: z.yml
+`)},
+		"b.yml": &fstest.MapFile{Data: []byte("x: b\n")},
+		"c.yml": &fstest.MapFile{Data: []byte("x: c\n")},
+		"z.yml": &fstest.MapFile{Data: []byte("x: z\n")},
+	})
+	main := configkit.Mapping("main", map[string]any{
+		"configkit": map[string]any{"imports": []any{
+			map[string]any{"path": "a.yml"},
+			map[string]any{"path": "b.yml"},
+			map[string]any{"path": "c.yml"},
+		}},
+	})
+	_, err := configkit.Load[map[string]any](main, configkit.Options[map[string]any]{
+		Imports: true,
+		Filesystem: &configkit.FilesystemContext{
+			FS: &filesystem, Root: ".", BaseDir: ".",
+		},
+	})
+	var loadError *configkit.LoadError
+	if !errors.As(err, &loadError) {
+		t.Fatalf("Load error = %v, want composition LoadError", err)
+	}
+	diagnostics := loadError.Diagnostics()
+	if len(diagnostics) != 1 {
+		t.Fatalf("diagnostics = %#v, want one composition conflict", diagnostics)
+	}
+	diagnostic := diagnostics[0]
+	if diagnostic.Code != configkit.CodeComposeConflict || diagnostic.Path.String() != "/x" || diagnostic.Primary == nil {
+		t.Fatalf("composition diagnostic = %#v", diagnostic)
+	}
+
+	pathsByID := make(map[string]string)
+	var acquisitionOrder []string
+	for _, source := range loadError.Sources() {
+		pathsByID[source.ID] = source.Path
+		for _, name := range []string{"z.yml", "b.yml", "c.yml"} {
+			if source.Path == name || strings.HasSuffix(source.Path, "/"+name) {
+				acquisitionOrder = append(acquisitionOrder, strings.TrimSuffix(name, ".yml"))
+				break
+			}
+		}
+	}
+	if strings.Join(acquisitionOrder, ",") != "z,b,c" {
+		t.Fatalf("claimant acquisition order = %v, want z,b,c", acquisitionOrder)
+	}
+	claimant := func(location configkit.Location) string {
+		for _, name := range []string{"b.yml", "c.yml", "z.yml"} {
+			if pathsByID[location.SourceID] == name || strings.HasSuffix(pathsByID[location.SourceID], "/"+name) {
+				return strings.TrimSuffix(name, ".yml")
+			}
+		}
+		return ""
+	}
+	if got := claimant(*diagnostic.Primary); got != "b" {
+		t.Fatalf("primary claimant = %q, want b (sources: %#v)", got, pathsByID)
+	}
+	if len(diagnostic.Related) != 2 || claimant(diagnostic.Related[0]) != "c" || claimant(diagnostic.Related[1]) != "z" {
+		t.Fatalf("related claimants = %#v, want c then z", diagnostic.Related)
+	}
+
+	var output bytes.Buffer
+	if err := configkit.WriteDiagnostics(&output, diagnostics); err != nil {
+		t.Fatal(err)
+	}
+	positions := []int{
+		strings.Index(output.String(), diagnostic.Primary.SourceID),
+		strings.Index(output.String(), diagnostic.Related[0].SourceID),
+		strings.Index(output.String(), diagnostic.Related[1].SourceID),
+	}
+	if positions[0] < 0 || positions[1] <= positions[0] || positions[2] <= positions[1] {
+		t.Fatalf("rendered claimant order = %v in %q", positions, output.String())
+	}
+
+	diagnostics[0].Related[0].SourceID = "mutated"
+	if got := claimant(loadError.Diagnostics()[0].Related[0]); got != "c" {
+		t.Fatalf("LoadError.Diagnostics retained caller mutation; first claimant = %q", got)
+	}
+}

facade_diff_test.go

@@ -7,7 +7,7 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type facadeDiffConfig struct {
@@ -29,10 +29,10 @@ func TestFacadeDiffKeepsPublicSequenceChangesWithHistoricalDescendants(t *testin
 		t.Helper()
 		result, err := configkit.Load(configkit.Bytes("historical-sequence.yml", []byte("items: [{secret: disposable-canary}, "+public+"]\n")),
 			configkit.Options[configuration]{Definition: configkit.Definition[configuration]{
-				Secret: func(path configkit.Path) bool { return path.String() == "/items/0/secret" },
+				Sensitive: func(path configkit.Path) bool { return path.String() == "/items/0/secret" },
 				Resolve: func(current *configuration, resolution *configkit.Resolution) error {
 					current.Items[0] = "public scalar"
-					resolution.Record(configkit.Keys("items"), configkit.ChangeNormalization, "normalize first item")
+					resolution.RecordNormalization(configkit.Keys("items"), "normalize first item")
 					return nil
 				},
 			}})
@@ -71,10 +71,10 @@ func TestFacadeDiffKeepsPublicScalarAcrossHistoricalAbsence(t *testing.T) {
 		Dynamic map[string]any `yaml:"dynamic"`
 	}
 	options := configkit.Options[configuration]{Definition: configkit.Definition[configuration]{
-		Secret: func(path configkit.Path) bool { return path.String() == "/dynamic/entry/token" },
+		Sensitive: func(path configkit.Path) bool { return path.String() == "/dynamic/entry/token" },
 		Resolve: func(current *configuration, resolution *configkit.Resolution) error {
 			delete(current.Dynamic, "entry")
-			resolution.Record(configkit.Keys("dynamic", "entry"), configkit.ChangeNormalization, "remove entry")
+			resolution.RecordNormalization(configkit.Keys("dynamic", "entry"), "remove entry")
 			return nil
 		},
 	}}
@@ -221,7 +221,7 @@ func TestFacadeDiffIgnoresSourceAndResolutionHistory(t *testing.T) {
 	resolve := func(value string) configkit.Options[config] {
 		return configkit.Options[config]{Definition: configkit.Definition[config]{Resolve: func(current *config, resolution *configkit.Resolution) error {
 			current.Count = len(value) + 8
-			resolution.Record(configkit.Keys("count"), configkit.ChangeNormalization, "set effective count")
+			resolution.RecordNormalization(configkit.Keys("count"), "set effective count")
 			return nil
 		}}}
 	}
@@ -281,7 +281,7 @@ func TestFacadeDiffUsesFrozenFilesAndRunsCallbacksOnlyDuringLoad(t *testing.T) {
 
 func TestFacadeDiffCombinesSecretSensitivityAndLoadErrors(t *testing.T) {
 	t.Setenv("FACADE_DIFF_SECRET", "credential-one")
-	secretOptions := configkit.Options[facadeDiffSecretConfig]{Definition: configkit.Definition[facadeDiffSecretConfig]{Secret: func(path configkit.Path) bool {
+	secretOptions := configkit.Options[facadeDiffSecretConfig]{Definition: configkit.Definition[facadeDiffSecretConfig]{Sensitive: func(path configkit.Path) bool {
 		return path.String() == "/secret"
 	}}}
 	left, err := configkit.Load[facadeDiffSecretConfig](configkit.Bytes("left.yml", []byte("secret: FACADE_DIFF_SECRET\n")), secretOptions)

facade_discovery_test.go

@@ -0,0 +1,316 @@
+package configkit
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+	"testing/fstest"
+)
+
+type facadeDiscoveryConfig struct {
+	Value    string            `yaml:"value"`
+	Settings map[string]string `yaml:"settings"`
+}
+
+type facadeDiscoveryLifecycleConfig struct {
+	Value    string `yaml:"value"`
+	Resolved string `yaml:"resolved"`
+}
+
+type facadeDiscoveryPlacementConfig struct {
+	Items []facadeDiscoveryPlacementItem `yaml:"items"`
+}
+
+type facadeDiscoveryPlacementItem struct {
+	Name string `yaml:"name"`
+}
+
+func TestFacadeSearchPresetUsesCurrentWorkingDirectory(t *testing.T) {
+	original, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	root := t.TempDir()
+	if err := os.Chdir(root); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() {
+		if err := os.Chdir(original); err != nil {
+			t.Errorf("restore working directory: %v", err)
+		}
+	})
+	writeFacadeImportFile(t, root, "myapp.yml", "value: working\n")
+
+	result, err := Load[facadeDiscoveryConfig](SearchConfig("myapp", WorkingDirectory()))
+	if err != nil || result.Config.Value != "working" {
+		t.Fatalf("working-directory search = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, filepath.Join(root, "myapp.yml")) {
+		t.Fatalf("working-directory sources = %#v", sources)
+	}
+}
+
+func TestFacadeSearchCustomGenericNamesAndEmptyFilenameSelection(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	filename := writeFacadeImportFile(t, root, "config.yml", "value: found\n")
+	custom := SearchDirectory(root, DirectorySearchOptions{
+		Filenames: []FilenameGroup{CustomFilenames("config.yml")},
+	})
+	result, err := Load[facadeDiscoveryConfig](SearchConfig("", custom))
+	if err != nil || result.Config.Value != "found" {
+		t.Fatalf("custom generic-only search with empty slug = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, filename) {
+		t.Fatalf("custom generic-only sources = %#v", sources)
+	}
+
+	defaults := func() facadeDiscoveryConfig { return facadeDiscoveryConfig{Value: "default"} }
+	empty := SearchDirectory(root, DirectorySearchOptions{Filenames: []FilenameGroup{}})
+	absent, err := Load(SearchConfig("myapp", empty), Options[facadeDiscoveryConfig]{
+		Definition: Definition[facadeDiscoveryConfig]{Defaults: defaults},
+	})
+	if err != nil || absent.Config.Value != "default" || len(absent.Sources()) != 0 {
+		t.Fatalf("explicit empty filename selection = %#v, %v", absent, err)
+	}
+	omitted, err := Load[facadeDiscoveryConfig](SearchConfig("myapp", SearchDirectory(root)))
+	if err != nil || omitted.Config.Value != "found" {
+		t.Fatalf("omitted filename selection did not use defaults = %#v, %v", omitted, err)
+	}
+}
+
+func TestFacadeSearchOrderingRequirednessAndSnapshots(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "config.yml", "value: selected\n")
+	laterPath := writeFacadeImportFile(t, root, "later.yml", "value: later\n")
+	paths := []string{filepath.Join(root, "missing.yml")}
+	names := []string{"config.yml"}
+	groups := []FilenameGroup{CustomFilenames(names...)}
+	directoryOptions := []DirectorySearchOptions{{Filenames: groups}}
+	search := Searches(SearchPaths(paths...), SearchDirectory(root, directoryOptions...), SearchPaths(laterPath))
+	source := SearchConfig("", search, SearchOptions{Required: true})
+
+	paths[0] = laterPath
+	names[0] = "later.yml"
+	groups[0] = CustomFilenames("later.yml")
+	directoryOptions[0].Filenames[0] = CustomFilenames("later.yml")
+	search = SearchPaths(laterPath)
+
+	result, err := Load[facadeDiscoveryConfig](source)
+	if err != nil || result.Config.Value != "selected" {
+		t.Fatalf("ordered required search after caller mutation = %#v, %v", result, err)
+	}
+	if sources := result.Sources(); len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, selectedPath) {
+		t.Fatalf("ordered search sources = %#v", sources)
+	}
+
+	_, err = Load[facadeDiscoveryConfig](SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml")), SearchOptions{Required: true}))
+	var loadErr *LoadError
+	if !errors.As(err, &loadErr) {
+		t.Fatalf("required exhausted search error = %v, want *LoadError", err)
+	}
+	foundMissing := false
+	for _, diagnostic := range loadErr.Diagnostics() {
+		foundMissing = foundMissing || diagnostic.Code == CodeSourceMissing
+	}
+	if !foundMissing {
+		t.Fatalf("required exhausted search diagnostics = %#v", loadErr.Diagnostics())
+	}
+}
+
+func TestFacadeSearchWorksForLayeredMainAndUnderlay(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	mainPath := writeFacadeImportFile(t, root, "main.yml", "settings: {main: value}\n")
+	underlayPath := writeFacadeImportFile(t, root, "underlay/base.yml", "settings: {underlay: value}\n")
+	result, err := LoadLayered(
+		Input{Source: SearchConfig("", SearchPaths(mainPath))},
+		LayeredOptions[facadeDiscoveryConfig]{Underlays: []Underlay{{Inputs: []Input{{
+			Source: SearchConfig("", SearchDirectory(filepath.Dir(underlayPath), DirectorySearchOptions{
+				Filenames: []FilenameGroup{CustomFilenames("base.yml")},
+			})),
+		}}}}},
+	)
+	if err != nil || !reflect.DeepEqual(result.Config.Settings, map[string]string{"main": "value", "underlay": "value"}) {
+		t.Fatalf("layered search = %#v, %v", result, err)
+	}
+	sources := result.Sources()
+	if len(sources) != 2 || sources[0].Path != canonicalFacadePath(t, mainPath) || sources[0].Layer != LayerMain ||
+		sources[1].Path != canonicalFacadePath(t, underlayPath) || sources[1].Layer != LayerUnderlay {
+		t.Fatalf("layered search sources = %#v", sources)
+	}
+}
+
+func TestFacadeSearchSelectedAndAbsentUseRootOnlyContext(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	mainPath := writeFacadeImportFile(t, root, "main.yml", "value: main\n")
+	writeFacadeImportFile(t, root, "overlays/testing.yml", "value: overlay\n")
+	filesystem := &FilesystemContext{Root: root}
+	options := Options[facadeDiscoveryConfig]{Overlay: "testing", Filesystem: filesystem}
+
+	selected, err := Load(SearchConfig("", SearchPaths(mainPath)), options)
+	if err != nil || selected.Config.Value != "overlay" {
+		t.Fatalf("selected search with root-only context = %#v, %v", selected, err)
+	}
+	sources := selected.Sources()
+	if len(sources) != 2 || sources[0].Path != canonicalFacadePath(t, mainPath) || sources[0].ID != "source-1" ||
+		sources[1].ID != "source-2" || sources[1].Layer != LayerOverlay {
+		t.Fatalf("selected search source evidence = %#v", sources)
+	}
+	mainContext, ok := selected.SourceContext("source-1")
+	if !ok || mainContext.BaseDir != "." {
+		t.Fatalf("selected file base context = %#v, %v", mainContext, ok)
+	}
+
+	missing := SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml")))
+	searchedAbsent, err := Load(missing, options)
+	if err != nil {
+		t.Fatalf("exhausted search with root-only overlay context: %v", err)
+	}
+	explicitAbsent, err := Load(NoSource(), options)
+	if err != nil {
+		t.Fatalf("NoSource with root-only overlay context: %v", err)
+	}
+	if !reflect.DeepEqual(searchedAbsent.Config, explicitAbsent.Config) ||
+		!reflect.DeepEqual(searchedAbsent.Sources(), explicitAbsent.Sources()) {
+		t.Fatalf("searched absence differs from NoSource: %#v / %#v", searchedAbsent, explicitAbsent)
+	}
+	left, leftOK := searchedAbsent.Metadata().Lookup(Keys("value"))
+	right, rightOK := explicitAbsent.Metadata().Lookup(Keys("value"))
+	if leftOK != rightOK || !reflect.DeepEqual(left, right) || !leftOK {
+		t.Fatalf("searched absence metadata = %#v, %v; NoSource metadata = %#v, %v", left, leftOK, right, rightOK)
+	}
+	if sources := searchedAbsent.Sources(); len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Layer != LayerOverlay {
+		t.Fatalf("absent search created unexpected source evidence = %#v", sources)
+	}
+}
+
+func TestFacadeSearchRejectsSelectedContextWithoutFallback(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	inside := writeFacadeImportFile(t, root, "inside.yml", "value: fallback\n")
+	outsideRoot := t.TempDir()
+	outside := writeFacadeImportFile(t, outsideRoot, "outside.yml", "value: selected\n")
+	search := SearchConfig("", SearchPaths(outside, inside))
+
+	_, err := Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{Root: root}})
+	var loadErr *LoadError
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeImportOutsideRoot) {
+		t.Fatalf("selected outside-root file error = %v, want containment failure", err)
+	}
+
+	_, err = Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{BaseDir: root, Root: root}})
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeOptionsInvalid) {
+		t.Fatalf("selected file with explicit base error = %v, want option failure", err)
+	}
+
+	native := NewFilesystem("native", fstest.MapFS{})
+	_, err = Load(search, Options[facadeDiscoveryConfig]{Filesystem: &FilesystemContext{FS: &native, BaseDir: ".", Root: "."}})
+	if !errors.As(err, &loadErr) || !hasFacadeDiagnostic(loadErr, CodeOptionsInvalid) {
+		t.Fatalf("selected file with native context error = %v, want option failure", err)
+	}
+}
+
+func TestFacadeSearchRunsCallbacksOnceAndKeepsInspectionWithSelectedFile(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "selected.yml", "value: selected\n")
+	writeFacadeImportFile(t, root, "later.yml", "value: later\n")
+	defaultsCalls, resolveCalls, validateCalls := 0, 0, 0
+	result, err := Load(SearchConfig("", SearchPaths(selectedPath, filepath.Join(root, "later.yml"))), Options[facadeDiscoveryLifecycleConfig]{
+		Definition: Definition[facadeDiscoveryLifecycleConfig]{
+			Defaults: func() facadeDiscoveryLifecycleConfig {
+				defaultsCalls++
+				return facadeDiscoveryLifecycleConfig{}
+			},
+			Resolve: func(configuration *facadeDiscoveryLifecycleConfig, resolution *Resolution) error {
+				resolveCalls++
+				configuration.Resolved = "from:" + configuration.Value
+				resolution.RecordNormalization(Keys("resolved"), "derive from selected value", Keys("value"))
+				return nil
+			},
+			Validate: func(_ *facadeDiscoveryLifecycleConfig, _ *Validation) { validateCalls++ },
+		},
+	})
+	if err != nil || result.Config.Value != "selected" || result.Config.Resolved != "from:selected" {
+		t.Fatalf("search lifecycle result = %#v, %v", result, err)
+	}
+	if defaultsCalls != 1 || resolveCalls != 1 || validateCalls != 1 {
+		t.Fatalf("search callbacks ran defaults=%d resolve=%d validate=%d times", defaultsCalls, resolveCalls, validateCalls)
+	}
+	sources := result.Sources()
+	if len(sources) != 1 || sources[0].Path != canonicalFacadePath(t, selectedPath) || sources[0].ID != "source-1" {
+		t.Fatalf("selected source evidence = %#v", sources)
+	}
+	valueInfo, found := result.Metadata().Lookup(Keys("value"))
+	if !found || len(valueInfo.Origin.Locations) != 1 || valueInfo.Origin.Locations[0].SourceID != sources[0].ID {
+		t.Fatalf("selected value metadata = %#v, %v", valueInfo, found)
+	}
+	var rendered strings.Builder
+	if err := result.WriteEffective(&rendered); err != nil || !strings.Contains(rendered.String(), "value: selected") || strings.Contains(rendered.String(), "later") {
+		t.Fatalf("effective output = %q, %v", rendered.String(), err)
+	}
+}
+
+func TestFacadeSearchSequenceItemAndAbsentInputPlacement(t *testing.T) {
+	t.Parallel()
+
+	root := t.TempDir()
+	selectedPath := writeFacadeImportFile(t, root, "item.yml", "name: selected\n")
+	options := Options[facadeDiscoveryPlacementConfig]{
+		Destination:   Keys("items"),
+		PlacementMode: PlacementModeSequenceItem,
+	}
+	selected, err := Load(SearchConfig("", SearchPaths(selectedPath)), options)
+	if err != nil || len(selected.Config.Items) != 1 || selected.Config.Items[0].Name != "selected" {
+		t.Fatalf("selected sequence item = %#v, %v", selected, err)
+	}
+	if sources := selected.Sources(); len(sources) != 1 || sources[0].Destination.String() != "/items" || sources[0].PlacementMode != PlacementModeSequenceItem {
+		t.Fatalf("selected sequence-item source = %#v", sources)
+	}
+
+	defaults := func() facadeDiscoveryPlacementConfig {
+		return facadeDiscoveryPlacementConfig{Items: []facadeDiscoveryPlacementItem{}}
+	}
+	absent, err := Load(SearchConfig("", SearchPaths(filepath.Join(root, "missing.yml"))), Options[facadeDiscoveryPlacementConfig]{
+		Definition:    Definition[facadeDiscoveryPlacementConfig]{Defaults: defaults},
+		Destination:   options.Destination,
+		PlacementMode: options.PlacementMode,
+	})
+	if err != nil || len(absent.Config.Items) != 0 || len(absent.Sources()) != 0 {
+		t.Fatalf("absent search created a sequence item: %#v, %v", absent, err)
+	}
+}
+
+func hasFacadeDiagnostic(err *LoadError, code Code) bool {
+	for _, diagnostic := range err.Diagnostics() {
+		if diagnostic.Code == code {
+			return true
+		}
+	}
+	return false
+}
+
+func canonicalFacadePath(t *testing.T, path string) string {
+	t.Helper()
+	absolute, err := filepath.Abs(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	canonical, err := filepath.EvalSymlinks(absolute)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return canonical
+}

facade_dynamic_redaction_test.go

@@ -0,0 +1,53 @@
+package configkit_test
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFinalDynamicTagRedactsEqualValuedResolution(t *testing.T) {
+	t.Parallel()
+	type classified struct {
+		Token string `yaml:"token" configkit:"secret"`
+	}
+	type configuration struct {
+		Value any `yaml:"value"`
+	}
+	const canary = "DYNAMIC-TAG-CANARY"
+	result, err := configkit.Load(configkit.Bytes("input", []byte("value: {token: "+canary+"}\n")), configkit.Options[configuration]{
+		Definition: configkit.Definition[configuration]{
+			Resolve: func(c *configuration, _ *configkit.Resolution) error {
+				// No canonical value changes, so no normalization record is needed.
+				c.Value = classified{Token: canary}
+				return nil
+			},
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var effective bytes.Buffer
+	if err := result.WriteEffective(&effective); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Contains(effective.String(), canary) || !strings.Contains(effective.String(), "[REDACTED]") {
+		t.Fatal("effective rendering did not preserve the final dynamic tag")
+	}
+	explanation, found := result.Explain(configkit.Keys("value", "token"))
+	if !found || !explanation.Effective.Redacted || strings.Contains(explanation.Effective.YAML, canary) {
+		t.Fatal("effective explanation did not preserve the final dynamic tag")
+	}
+	if len(explanation.History) == 0 {
+		t.Fatal("source history is absent")
+	}
+	for _, change := range explanation.History {
+		for _, value := range []configkit.ValueSnapshot{change.Before, change.After} {
+			if value.Present && (!value.Redacted || strings.Contains(value.YAML, canary)) {
+				t.Fatal("historical explanation did not preserve the final dynamic tag")
+			}
+		}
+	}
+}

facade_equivalence_test.go

@@ -9,7 +9,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type equivalentConfig struct {
@@ -23,6 +23,9 @@ type equivalentConfig struct {
 
 func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 	const yaml = "version: 1\nname: retained\nenabled: false\ncount: 0\nitems: []\noptional: null\n"
+	bytesData := []byte(yaml)
+	bytesSource := configkit.Bytes("memory", bytesData)
+	bytesData[0] = 'X'
 	hostPath := filepath.Join(t.TempDir(), "main.yml")
 	if err := os.WriteFile(hostPath, []byte(yaml), 0o600); err != nil {
 		t.Fatal(err)
@@ -37,7 +40,7 @@ func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 	}{
 		{"host", configkit.File(hostPath), nil, configkit.SourceKindFile},
 		{"native", namespace.File("main.yml"), nil, configkit.SourceKindFilesystem},
-		{"bytes", configkit.Bytes("memory", []byte(yaml)), context, configkit.SourceKindBytes},
+		{"bytes", bytesSource, context, configkit.SourceKindBytes},
 		{"reader", configkit.Reader("stream", strings.NewReader(yaml)), context, configkit.SourceKindReader},
 		{"mapping", configkit.Mapping("programmatic", map[string]any{
 			"version": uint64(1), "name": "retained", "enabled": false, "count": 0,
@@ -66,7 +69,7 @@ func TestEquivalentSourceFormsPreserveInputSemantics(t *testing.T) {
 			}
 			for _, field := range []string{"version", "name", "enabled", "count", "items", "optional"} {
 				info, ok := result.Metadata().Lookup(configkit.Keys(field))
-				if !ok || !info.Explicit || info.Origin.Layer != configkit.LayerBase || info.Null != (field == "optional") {
+				if !ok || !info.Explicit || info.Origin.Layer != configkit.LayerMain || info.Null != (field == "optional") {
 					t.Errorf("%s input info = %#v, %v", field, info, ok)
 				}
 			}
@@ -112,6 +115,15 @@ func TestRepeatedImportsAcrossTiersAndReaderConsumption(t *testing.T) {
 	if got := layeredErrorCode(t, err); got != configkit.CodeSourceReaderUsed {
 		t.Fatalf("reader re-consumption = %s", got)
 	}
+	copiedReader := configkit.Reader("copied-single-use", strings.NewReader("name: retained\n"))
+	readerCopy := copiedReader
+	if _, err := configkit.Load[config](readerCopy, configkit.Options[config]{}); err != nil {
+		t.Fatal(err)
+	}
+	_, err = configkit.Load[config](copiedReader, configkit.Options[config]{})
+	if got := layeredErrorCode(t, err); got != configkit.CodeSourceReaderUsed {
+		t.Fatalf("copied reader re-consumption = %s", got)
+	}
 }
 
 func TestReplacedSecretRemainsAbsentFromSafeOutput(t *testing.T) {
@@ -120,7 +132,7 @@ func TestReplacedSecretRemainsAbsentFromSafeOutput(t *testing.T) {
 	}
 	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main", []byte("secret: new-secret-canary\n"))}, configkit.LayeredOptions[config]{
 		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"secret": "old-secret-canary"})}}}},
-		Definition: configkit.Definition[config]{Secret: func(path configkit.Path) bool { return path.String() == "/secret" }},
+		Definition: configkit.Definition[config]{Sensitive: func(path configkit.Path) bool { return path.String() == "/secret" }},
 	})
 	if err != nil || result.Config.Secret != "new-secret-canary" {
 		t.Fatalf("secret load = %#v, %v", result, err)

facade_filesystem_test.go

@@ -9,7 +9,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 //go:embed testdata/filesystem

facade_final_sequence_identity_test.go

@@ -0,0 +1,249 @@
+package configkit_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"go.maximumdirect.net/configkit"
+)
+
+func TestFinalSequenceIdentityTreatsLateExtendsFieldsAsPayload(t *testing.T) {
+	for _, phase := range []string{"defaults", "resolution"} {
+		for _, component := range []any{"application-data", nil} {
+			for _, duplicate := range []bool{false, true} {
+				t.Run(fmt.Sprintf("%s/%v/duplicate=%t", phase, component, duplicate), func(t *testing.T) {
+					items := []any{map[string]any{"extends": component}}
+					if duplicate {
+						items = append(items, map[string]any{"extends": component})
+					}
+					definition := configkit.Definition[map[string]any]{
+						SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "extends")},
+						Defaults: func() map[string]any {
+							if phase == "defaults" {
+								return map[string]any{"items": items}
+							}
+							return map[string]any{}
+						},
+					}
+					if phase == "resolution" {
+						definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+							(*value)["items"] = items
+							resolution.RecordNormalization(configkit.Keys("items"), "supply application payload")
+							return nil
+						}
+					}
+					loaded, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{Definition: definition})
+					if duplicate {
+						loadErr := requireFacadeLoadError(t, err)
+						diagnostics := loadErr.Diagnostics()
+						if loaded != nil || len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict || diagnostics[0].Path.String() != "/items" {
+							t.Fatalf("duplicate effective payload diagnostics = %#v", diagnostics)
+						}
+						return
+					}
+					if err != nil || loaded == nil {
+						t.Fatalf("ordinary effective identity was interpreted as a directive: %v", err)
+					}
+					value := loaded.Config["items"].([]any)[0].(map[string]any)
+					if actual, present := value["extends"]; !present || actual != component {
+						t.Fatalf("effective payload = %#v", value)
+					}
+				})
+			}
+		}
+	}
+}
+
+func TestFinalSequenceIdentityValidatesLateValues(t *testing.T) {
+	identity := configkit.SequenceIdentityAt(configkit.Keys("items"), "id")
+	for _, source := range []string{"defaults", "CLI", "resolution"} {
+		for _, shape := range []string{"duplicate", "missing", "non-scalar"} {
+			t.Run(source+"/"+shape, func(t *testing.T) {
+				items := finalIdentityRecords(shape)
+				definition := configkit.Definition[map[string]any]{
+					SequenceIdentities: []configkit.SequenceIdentity{identity},
+					Defaults: func() map[string]any {
+						if source == "defaults" {
+							return map[string]any{"items": items}
+						}
+						return map[string]any{}
+					},
+				}
+				options := configkit.Options[map[string]any]{Definition: definition}
+				switch source {
+				case "CLI":
+					options.Overrides = []configkit.Override{{Path: configkit.Keys("items"), Value: items, Flag: "--items"}}
+				case "resolution":
+					options.Definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+						(*value)["items"] = items
+						resolution.RecordNormalization(configkit.Keys("items"), "create effective records")
+						return nil
+					}
+				}
+				result, err := configkit.Load(configkit.NoSource(), options)
+				if result != nil {
+					t.Fatalf("invalid final identities returned a result: %#v", result.Config)
+				}
+				loadErr := requireFacadeLoadError(t, err)
+				if len(loadErr.Diagnostics()) != 1 {
+					t.Fatalf("diagnostics = %#v", loadErr.Diagnostics())
+				}
+				diagnostic := loadErr.Diagnostics()[0]
+				wantCode, wantPath := configkit.CodeSequenceInvalid, "/items/0/id"
+				if shape == "duplicate" {
+					wantCode, wantPath = configkit.CodeSequenceConflict, "/items"
+				}
+				if diagnostic.Code != wantCode || diagnostic.Path.String() != wantPath {
+					t.Fatalf("diagnostic = %#v, want %s at %s", diagnostic, wantCode, wantPath)
+				}
+				if source == "CLI" && (diagnostic.Primary == nil || diagnostic.Primary.SourceID != "source-1") {
+					t.Fatalf("CLI identity diagnostic lost its source: %#v", diagnostic)
+				}
+			})
+		}
+	}
+}
+
+func TestFinalSequenceIdentityMatchesLateDynamicNamespaces(t *testing.T) {
+	selector := configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("items"),
+	}
+	for _, source := range []string{"defaults", "CLI", "resolution"} {
+		t.Run(source, func(t *testing.T) {
+			name := map[string]string{"defaults": "team", "CLI": "cloud", "resolution": "orbit"}[source]
+			path := configkit.Keys("collections", name, "items")
+			items := finalIdentityRecords("duplicate")
+			definition := configkit.Definition[map[string]any]{
+				SequenceIdentities: []configkit.SequenceIdentity{
+					configkit.SequenceIdentityMatching(selector, "id"),
+				},
+				Defaults: func() map[string]any {
+					if source == "defaults" {
+						return map[string]any{"collections": map[string]any{name: map[string]any{"items": items}}}
+					}
+					return map[string]any{}
+				},
+			}
+			options := configkit.Options[map[string]any]{Definition: definition}
+			switch source {
+			case "CLI":
+				options.Overrides = []configkit.Override{{Path: path, Value: items, Flag: "--items"}}
+			case "resolution":
+				options.Definition.Resolve = func(value *map[string]any, resolution *configkit.Resolution) error {
+					(*value)["collections"] = map[string]any{name: map[string]any{"items": items}}
+					resolution.RecordNormalization(configkit.Keys("collections"), "create namespaced records")
+					return nil
+				}
+			}
+			result, err := configkit.Load(configkit.NoSource(), options)
+			if result != nil {
+				t.Fatalf("invalid dynamic identity returned a result: %#v", result.Config)
+			}
+			loadErr := requireFacadeLoadError(t, err)
+			if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict || diagnostics[0].Path.String() != path.String() {
+				t.Fatalf("dynamic identity diagnostics = %#v", diagnostics)
+			}
+		})
+	}
+}
+
+func TestFinalSequenceIdentityAppliesToLayeredLoads(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+		Defaults: func() map[string]any {
+			return map[string]any{"items": finalIdentityRecords("duplicate")}
+		},
+	}
+	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.NoSource()}, configkit.LayeredOptions[map[string]any]{Definition: definition})
+	if result != nil {
+		t.Fatalf("invalid layered final identities returned a result: %#v", result.Config)
+	}
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("layered identity diagnostics = %#v", diagnostics)
+	}
+}
+
+func TestFinalSequenceIdentityUsesTypedNumbersAndIgnoresUnmatchedShapes(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{
+		SequenceIdentities: []configkit.SequenceIdentity{
+			configkit.SequenceIdentityAt(configkit.Keys("items"), "id"),
+			configkit.SequenceIdentityAt(configkit.Keys("unmatched"), "id"),
+		},
+	}
+	_, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{
+		Definition: configkit.Definition[map[string]any]{
+			SequenceIdentities: definition.SequenceIdentities,
+			Defaults: func() map[string]any {
+				return map[string]any{"items": []any{
+					map[string]any{"id": int64(1)}, map[string]any{"id": float64(1)},
+				}}
+			},
+		},
+	})
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("typed numeric identity diagnostics = %#v", diagnostics)
+	}
+
+	valid, err := configkit.Load(configkit.Mapping("valid", map[string]any{
+		"items": []any{
+			map[string]any{"id": nil}, map[string]any{"id": true},
+			map[string]any{"id": int64(1)}, map[string]any{"id": "one"},
+		},
+		"other": []any{map[string]any{"id": "same"}, map[string]any{"id": "same"}},
+	}), configkit.Options[map[string]any]{Definition: definition})
+	if err != nil || valid == nil {
+		t.Fatalf("valid scalar identities and unmatched duplicate sequence = %#v, %v", valid, err)
+	}
+	if _, err := configkit.Load(configkit.Mapping("other-shapes", map[string]any{"items": nil}), configkit.Options[map[string]any]{Definition: definition}); err != nil {
+		t.Fatalf("null at a registered path was validated as an identity sequence: %v", err)
+	}
+}
+
+func TestFinalSequenceIdentityDiagnosticDoesNotRevealResolvedSecrets(t *testing.T) {
+	const canary = "FINAL-IDENTITY-CREDENTIAL-CANARY"
+	const secretName = "CONFIGKIT_FINAL_IDENTITY_SECRET"
+	t.Setenv(secretName, canary)
+	type item struct {
+		ID    string           `yaml:"id"`
+		Token configkit.Secret `yaml:"token"`
+	}
+	type config struct {
+		Items []item `yaml:"items"`
+	}
+	definition := configkit.Definition[config]{
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+		Defaults: func() config {
+			return config{Items: []item{
+				{ID: "duplicate", Token: configkit.SecretEnv(secretName)},
+				{ID: "duplicate", Token: configkit.SecretEnv(secretName)},
+			}}
+		},
+	}
+	result, err := configkit.Load(configkit.NoSource(), configkit.Options[config]{Definition: definition})
+	if result != nil {
+		t.Fatalf("duplicate identity returned a result: %#v", result.Config)
+	}
+	if err == nil || strings.Contains(err.Error(), canary) {
+		t.Fatalf("identity diagnostic leaked a resolved secret: %v", err)
+	}
+	loadErr := requireFacadeLoadError(t, err)
+	if diagnostics := loadErr.Diagnostics(); len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeSequenceConflict {
+		t.Fatalf("secret-bearing identity diagnostics = %#v", diagnostics)
+	}
+}
+
+func finalIdentityRecords(shape string) []any {
+	switch shape {
+	case "duplicate":
+		return []any{map[string]any{"id": "same"}, map[string]any{"id": "same"}}
+	case "missing":
+		return []any{map[string]any{"other": "value"}}
+	default:
+		return []any{map[string]any{"id": map[string]any{"nested": "value"}}}
+	}
+}

facade_historical_paths_test.go

@@ -0,0 +1,120 @@
+package configkit_test
+
+import (
+	"reflect"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestPublicHistoricalPathsEnumerateContextualShapes(t *testing.T) {
+	loaded, err := configkit.Load[map[string]any](configkit.Bytes("main", []byte(
+		"retired: {child: 1}\nshape: {'0': base}\n'a/b~': {'': 2}\n",
+	)), configkit.Options[map[string]any]{Overrides: []configkit.Override{
+		{Path: configkit.Keys("retired"), Value: nil, Flag: "--retired"},
+		{Path: configkit.Keys("shape"), Value: []any{"replacement"}, Flag: "--shape"},
+	}})
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+
+	metadata := loaded.Metadata()
+	paths := metadata.HistoricalPaths()
+	got := make([]string, len(paths))
+	for index, path := range paths {
+		got[index] = path.String()
+		if len(metadata.History(path)) == 0 {
+			t.Errorf("enumerated path %s has no history", path)
+		}
+	}
+	want := []string{"", "/a~1b~0", "/a~1b~0/", "/retired", "/retired/child", "/shape", "/shape/0"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("historical paths = %v, want sorted unique pointers %v", got, want)
+	}
+	if _, ok := metadata.Lookup(paths[4]); ok {
+		t.Fatal("removed descendant remains effective")
+	}
+	if _, ok := metadata.Lookup(paths[6]); !ok {
+		t.Fatal("enumerated numeric path did not follow the effective sequence shape")
+	}
+	if len(metadata.History(paths[6])) == 0 {
+		t.Fatal("enumerated numeric path lost history")
+	}
+	assertPublicShapeHistory(t, metadata, configkit.LayerCLI)
+	if _, ok := metadata.Lookup(configkit.Keys("shape", "0")); ok {
+		t.Fatal("mapping-key path resolved against the effective sequence")
+	}
+	if len((configkit.Metadata{}).HistoricalPaths()) != 0 {
+		t.Fatal("zero metadata contains historical paths")
+	}
+	if (configkit.Metadata{}).History(configkit.Keys("shape")) != nil {
+		t.Fatal("zero metadata contains history")
+	}
+
+	paths[1] = configkit.Keys("mutated")
+	if again := metadata.HistoricalPaths(); !reflect.DeepEqual(pathStrings(again), want) {
+		t.Fatalf("returned path slice mutated retained metadata: %v", pathStrings(again))
+	}
+}
+
+func TestPublicHistoryUsesResolutionShapeAttribution(t *testing.T) {
+	loaded, err := configkit.Load[map[string]any](configkit.Bytes("main", []byte("shape: {'0': base}\n")), configkit.Options[map[string]any]{
+		Definition: configkit.Definition[map[string]any]{
+			Resolve: func(configuration *map[string]any, resolution *configkit.Resolution) error {
+				(*configuration)["shape"] = []any{"replacement"}
+				resolution.RecordNormalization(configkit.Keys("shape"), "replace numeric mapping key")
+				return nil
+			},
+		},
+	})
+	if err != nil {
+		t.Fatalf("Load: %v", err)
+	}
+	assertPublicShapeHistory(t, loaded.Metadata(), configkit.LayerResolution)
+}
+
+func assertPublicShapeHistory(t *testing.T, metadata configkit.Metadata, operationLayer configkit.Layer) {
+	t.Helper()
+
+	keyPath := configkit.Keys("shape", "0")
+	indexPath := configkit.Keys("shape").Index(0)
+	keyHistory := metadata.History(keyPath)
+	indexHistory := metadata.History(indexPath)
+	if len(keyHistory) == 0 || len(indexHistory) == 0 {
+		t.Fatalf("explicit shape histories = key %#v, index %#v", keyHistory, indexHistory)
+	}
+	var keyDefinition, keyReplacement, indexReplacement bool
+	for _, change := range keyHistory {
+		keyDefinition = keyDefinition || change.Origin.Layer == configkit.LayerMain
+		keyReplacement = keyReplacement || change.Origin.Layer == operationLayer && change.Path.String() == "/shape"
+	}
+	for _, change := range indexHistory {
+		if change.Origin.Layer == configkit.LayerMain {
+			t.Fatalf("introduced index inherited mapping-key history: %#v", indexHistory)
+		}
+		indexReplacement = indexReplacement || change.Origin.Layer == operationLayer && change.Path.String() == "/shape"
+		for _, previous := range change.Previous {
+			if previous.Layer == configkit.LayerMain {
+				t.Fatalf("introduced index inherited mapping-key previous origin: %#v", change)
+			}
+		}
+	}
+	if !keyDefinition || !keyReplacement || !indexReplacement {
+		t.Fatalf("shape histories missed applicable definitions or replacement: key %#v, index %#v", keyHistory, indexHistory)
+	}
+	parsed, err := configkit.ParsePath("/shape/0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if parsedHistory := metadata.History(parsed); len(parsedHistory) == 0 {
+		t.Fatal("parsed numeric query lost contextual history")
+	}
+}
+
+func pathStrings(paths []configkit.Path) []string {
+	result := make([]string, len(paths))
+	for index, path := range paths {
+		result[index] = path.String()
+	}
+	return result
+}

facade_import_alias_test.go

@@ -0,0 +1,99 @@
+package configkit_test
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeNativeDiscoveryPreservesAliasIdentity(t *testing.T) {
+	root := t.TempDir()
+	for name, contents := range map[string]string{
+		"data/item.yml":        "configkit:\n  imports:\n    - path: helper.yml\nvalue: item\n",
+		"data/helper.yml":      "owner: target\nresource: resource.txt\n",
+		"aliases/helper.yml":   "owner: alias\nresource: resource.txt\n",
+		"data/resource.txt":    "target resource",
+		"aliases/resource.txt": "alias resource",
+	} {
+		filename := filepath.Join(root, filepath.FromSlash(name))
+		if err := os.MkdirAll(filepath.Dir(filename), 0o700); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(filename, []byte(contents), 0o600); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for name, target := range map[string]string{"aliases/item.yml": "../data/item.yml", "linked": "data"} {
+		if err := os.Symlink(target, filepath.Join(root, filepath.FromSlash(name))); err != nil {
+			t.Skipf("symlinks unavailable: %v", err)
+		}
+	}
+	filesystem := configkit.NewFilesystem("aliases", os.DirFS(root))
+	type configuration struct {
+		Value    string `yaml:"value"`
+		Owner    string `yaml:"owner"`
+		Resource string `yaml:"resource"`
+	}
+	for _, test := range []struct {
+		name, declaration, item, helper, owner, resource string
+	}{
+		{"file/path", "path: aliases/item.yml", "aliases/item.yml", "aliases/helper.yml", "alias", "alias resource"},
+		{"file/dir", "dir: aliases\n      pattern: item.yml", "aliases/item.yml", "aliases/helper.yml", "alias", "alias resource"},
+		{"file/glob", "glob: 'aliases/ite*.yml'", "aliases/item.yml", "aliases/helper.yml", "alias", "alias resource"},
+		{"directory/path", "path: linked/item.yml", "linked/item.yml", "linked/helper.yml", "target", "target resource"},
+		{"directory/dir", "dir: linked\n      pattern: item.yml", "linked/item.yml", "linked/helper.yml", "target", "target resource"},
+		{"directory/glob", "glob: 'lin*/ite*.yml'", "linked/item.yml", "linked/helper.yml", "target", "target resource"},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+test.declaration+"\n")), configkit.Options[configuration]{
+				Imports: true, Filesystem: &configkit.FilesystemContext{FS: &filesystem, Root: ".", BaseDir: "."},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if result.Config.Owner != test.owner || result.Config.Value != "item" {
+				t.Fatalf("configuration = %#v", result.Config)
+			}
+			sources := result.Sources()
+			if len(sources) != 3 || sources[1].Path != test.item || sources[2].Path != test.helper {
+				t.Fatalf("source identities = %#v", sources)
+			}
+			for field, source := range map[string]configkit.SourceInfo{"value": sources[1], "resource": sources[2]} {
+				info, ok := result.Metadata().Lookup(configkit.Keys(field))
+				if !ok || len(info.Origin.Locations) != 1 || info.Origin.Locations[0].SourceID != source.ID {
+					t.Fatalf("%s origin = %#v", field, info)
+				}
+				context, ok := result.SourceContext(source.ID)
+				if !ok || context.BaseDir != path.Dir(source.Path) {
+					t.Fatalf("%s context = %#v", field, context)
+				}
+				contents, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, result.Config.Resource))
+				if err != nil || string(contents) != test.resource {
+					t.Fatalf("%s resource = %q, %v", field, contents, err)
+				}
+			}
+		})
+	}
+	// The same native path is still a repeat when separately included. An alias
+	// to a leaf file remains a different native namespace path, as for path imports.
+	for _, selector := range []string{"path: aliases/item.yml", "dir: aliases\n      pattern: item.yml", "glob: 'aliases/ite*.yml'"} {
+		_, err := configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+selector+"\n    - path: aliases/item.yml\n")), configkit.Options[configuration]{
+			Imports: true, Filesystem: &configkit.FilesystemContext{FS: &filesystem, Root: ".", BaseDir: "."},
+		})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != configkit.CodeImportRepeated {
+			t.Fatalf("repeated source: %v", err)
+		}
+		_, err = configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+selector+"\n    - path: data/item.yml\n")), configkit.Options[configuration]{
+			Imports: true, Filesystem: &configkit.FilesystemContext{FS: &filesystem, Root: ".", BaseDir: "."},
+		})
+		if !errors.As(err, &loadError) || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeComposeConflict {
+			t.Fatalf("distinct native alias paths should reach composition: %v", err)
+		}
+	}
+}

facade_import_defaults_test.go

@@ -0,0 +1,306 @@
+package configkit
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestImportDepthChecksSuffixAfterSaturation(t *testing.T) {
+	for _, test := range []struct {
+		depth string
+		valid bool
+	}{
+		{"999999999999999999999999.5", false},
+		{"999999999999999999999999e1", false},
+		{"999999999999999999999999", true},
+		{"-0", true},
+	} {
+		t.Run(test.depth, func(t *testing.T) {
+			main := writeFacadeImportFile(t, t.TempDir(), "main.yml", "value: true\nconfigkit:\n  imports:\n    - dir: absent\n      recursive: true\n      depth: "+test.depth+"\n")
+			result, err := Load[map[string]any](File(main), Options[map[string]any]{Imports: true})
+			if test.valid {
+				if err != nil || result.Config["value"] != true {
+					t.Fatalf("valid depth: %v", err)
+				}
+				return
+			}
+			var loadError *LoadError
+			if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 {
+				t.Fatalf("invalid depth accepted: %v", err)
+			}
+			if diagnostic := loadError.Diagnostics()[0]; diagnostic.Code != CodeImportInvalid || diagnostic.Path.String() != "/configkit/imports/0/depth" {
+				t.Fatalf("invalid depth diagnostic = %#v", diagnostic)
+			}
+		})
+	}
+}
+
+func TestImportDefaultsApplyToTransitiveAndUnderlayImports(t *testing.T) {
+	type config struct {
+		Main        string `yaml:"main"`
+		Transitive  string `yaml:"transitive"`
+		Exception   string `yaml:"exception"`
+		Underlay    string `yaml:"underlay"`
+		IgnoredDeep string `yaml:"ignored_deep"`
+	}
+	directory := t.TempDir()
+	mainPath := writeFacadeImportFile(t, directory, "main.yml", `configkit:
+  imports:
+    - path: parent/parent.yml
+main: main
+`)
+	writeFacadeImportFile(t, directory, "parent/parent.yml", `configkit:
+  imports:
+    - dir: generated
+    - dir: explicit
+      pattern: '*.yaml'
+      recursive: false
+`)
+	transitivePath := writeFacadeImportFile(t, directory, "parent/generated/deep/transitive.cfg", "transitive: selected\n")
+	writeFacadeImportFile(t, directory, "parent/generated/ignored.yaml", "ignored_deep: wrong-pattern\n")
+	explicitPath := writeFacadeImportFile(t, directory, "parent/explicit/exception.yaml", "exception: declaration\n")
+	writeFacadeImportFile(t, directory, "parent/explicit/deep/ignored.yaml", "ignored_deep: wrong-depth\n")
+	writeFacadeImportFile(t, directory, "parent/explicit/ignored.cfg", "ignored_deep: wrong-explicit-pattern\n")
+	underlayPath := writeFacadeImportFile(t, directory, "underlay.yml", `configkit:
+  imports:
+    - dir: underlay-files
+`)
+	underlayImportPath := writeFacadeImportFile(t, directory, "underlay-files/underlay.cfg", "underlay: selected\n")
+	recursive := true
+	loaded, err := LoadLayered(Input{Source: File(mainPath), Imports: true}, LayeredOptions[config]{
+		ImportDefaults: ImportDefaults{Recursive: &recursive, Pattern: []string{"*.cfg"}},
+		Underlays:      []Underlay{{Inputs: []Input{{Source: File(underlayPath), Imports: true}}}},
+	})
+	if err != nil {
+		t.Fatalf("LoadLayered: %v", err)
+	}
+	if loaded.Config.Main != "main" || loaded.Config.Transitive != "selected" || loaded.Config.Exception != "declaration" || loaded.Config.Underlay != "selected" || loaded.Config.IgnoredDeep != "" {
+		t.Fatalf("configuration = %#v", loaded.Config)
+	}
+	paths := make(map[string]bool)
+	for _, source := range loaded.Sources() {
+		paths[source.Path] = true
+	}
+	for _, selected := range []string{transitivePath, explicitPath, underlayImportPath} {
+		if !paths[canonicalFacadeImportPath(t, selected)] {
+			t.Errorf("selected source %q missing from source records", selected)
+		}
+	}
+}
+
+func TestImportDefaultsPreserveEmptyPatternAndRequiredness(t *testing.T) {
+	type config struct {
+		Value  string `yaml:"value"`
+		Hidden string `yaml:"hidden"`
+	}
+	directory := t.TempDir()
+	mainPath := writeFacadeImportFile(t, directory, "main.yml", `configkit:
+  imports:
+    - dir: snippets
+`)
+	writeFacadeImportFile(t, directory, "snippets/value.cfg", "value: imported\n")
+	writeFacadeImportFile(t, directory, "snippets/.hidden.cfg", "hidden: imported\n")
+
+	unrestricted, err := Load(File(mainPath), Options[config]{Imports: true})
+	if err != nil || unrestricted.Config.Value != "imported" {
+		t.Fatalf("unspecified pattern = %#v, %v", unrestricted, err)
+	}
+	includeHidden := false
+	visibleOnly, err := Load(File(mainPath), Options[config]{Imports: true, ImportDefaults: ImportDefaults{IncludeHidden: &includeHidden}})
+	if err != nil || visibleOnly.Config.Value != "imported" || visibleOnly.Config.Hidden != "" {
+		t.Fatalf("hidden-file default = %#v, %v", visibleOnly, err)
+	}
+	empty, err := Load(File(mainPath), Options[config]{Imports: true, ImportDefaults: ImportDefaults{Pattern: []string{}}})
+	if err != nil || empty.Config.Value != "" {
+		t.Fatalf("empty pattern = %#v, %v", empty, err)
+	}
+	emptySources := empty.Sources()
+	if len(emptySources) != 1 || len(emptySources[0].EmptyImportSelections) != 1 || emptySources[0].EmptyImportSelections[0].Path.String() != "/configkit/imports/0" || emptySources[0].EmptyImportSelections[0].Selector != ImportSelectorDirectory {
+		t.Fatalf("empty-pattern evidence = %#v", emptySources)
+	}
+	required := true
+	_, err = Load(File(mainPath), Options[config]{Imports: true, ImportDefaults: ImportDefaults{Required: &required, Pattern: []string{}}})
+	var loadError *LoadError
+	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != CodeImportMissing {
+		t.Fatalf("required empty selection error = %T %v", err, err)
+	}
+	if sources := loadError.Sources(); len(sources) != 1 || len(sources[0].EmptyImportSelections) != 0 {
+		t.Fatalf("required empty selection was recorded as optional: %#v", sources)
+	}
+}
+
+func TestImportDefaultsAreSnapshottedBeforeOrdinaryAndLayeredCallbacks(t *testing.T) {
+	type config struct {
+		Version  string `yaml:"version"`
+		Imported string `yaml:"imported"`
+	}
+	for _, layered := range []bool{false, true} {
+		t.Run(map[bool]string{false: "ordinary", true: "layered"}[layered], func(t *testing.T) {
+			directory := t.TempDir()
+			mainPath := writeFacadeImportFile(t, directory, "main.yml", `version: v1
+configkit:
+  imports:
+    - dir: parts
+`)
+			writeFacadeImportFile(t, directory, "parts/nested/value.cfg", "imported: selected\n")
+
+			recursive := true
+			patterns := []string{"*.cfg"}
+			definition := Definition[config]{Version: &VersionRule{
+				Path: Keys("version"),
+				Check: func(version Version, _ *Validation) error {
+					if version != (Version{Present: true, Text: "v1"}) {
+						t.Errorf("version callback received %#v", version)
+					}
+					recursive = false
+					patterns[0] = "*.skip"
+					return nil
+				},
+			}}
+			load := func() (*Result[config], error) {
+				defaults := ImportDefaults{Recursive: &recursive, Pattern: patterns}
+				if layered {
+					return LoadLayered(Input{Source: File(mainPath), Imports: true}, LayeredOptions[config]{
+						Definition: definition, SourceVersionMode: SourceVersionModeIfPresent, ImportDefaults: defaults,
+					})
+				}
+				return Load(File(mainPath), Options[config]{
+					Definition: definition, SourceVersionMode: SourceVersionModeIfPresent, Imports: true, ImportDefaults: defaults,
+				})
+			}
+
+			first, err := load()
+			if err != nil || first.Config.Imported != "selected" {
+				t.Fatalf("load with pre-callback defaults = %#v, %v", first, err)
+			}
+			if recursive || patterns[0] != "*.skip" {
+				t.Fatalf("version callback did not mutate caller defaults: recursive=%v pattern=%q", recursive, patterns[0])
+			}
+
+			second, err := load()
+			if err != nil || second.Config.Imported != "" {
+				t.Fatalf("subsequent load reused earlier defaults: %#v, %v", second, err)
+			}
+		})
+	}
+}
+
+func TestInvalidImportDefaultsPreflightBeforeOrdinaryAndLayeredReads(t *testing.T) {
+	type config struct {
+		Value string `yaml:"value"`
+	}
+	for _, layered := range []bool{false, true} {
+		input := strings.NewReader("value: read\n")
+		underlayInput := strings.NewReader("value: underlay\n")
+		defaultsCalled := false
+		resolveCalled := false
+		definition := Definition[config]{
+			Defaults: func() config { defaultsCalled = true; return config{} },
+			Resolve:  func(*config, *Resolution) error { resolveCalled = true; return nil },
+		}
+		defaults := ImportDefaults{Pattern: []string{"["}}
+		var err error
+		if layered {
+			_, err = LoadLayered(Input{Source: Reader("reader.yml", input)}, LayeredOptions[config]{
+				Definition: definition, ImportDefaults: defaults,
+				Underlays: []Underlay{{Inputs: []Input{{Source: Reader("underlay.yml", underlayInput)}}}},
+			})
+		} else {
+			_, err = Load(Reader("reader.yml", input), Options[config]{Definition: definition, ImportDefaults: defaults})
+		}
+		var loadError *LoadError
+		if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != CodeOptionsInvalid {
+			if loadError != nil {
+				t.Fatalf("layered=%v diagnostics = %#v", layered, loadError.Diagnostics())
+			}
+			t.Fatalf("layered=%v error = %T %v", layered, err, err)
+		}
+		if input.Len() != len("value: read\n") || underlayInput.Len() != len("value: underlay\n") || defaultsCalled || resolveCalled {
+			t.Fatalf("layered=%v consumed input or called application hooks: remaining=%d underlay=%d defaults=%v resolve=%v", layered, input.Len(), underlayInput.Len(), defaultsCalled, resolveCalled)
+		}
+	}
+}
+
+func TestPublicImportSelectionSnapshotsAreDetachedAcrossResultErrorAndResolution(t *testing.T) {
+	type config struct {
+		Value string `yaml:"value"`
+	}
+	directory := t.TempDir()
+	mainPath := writeFacadeImportFile(t, directory, "main.yml", `configkit:
+  imports:
+    - dir: absent
+value: loaded
+`)
+	callbackPath := ""
+	loaded, err := Load(File(mainPath), Options[config]{Imports: true, Definition: Definition[config]{Resolve: func(_ *config, resolution *Resolution) error {
+		first, ok := resolution.Source("source-1")
+		if !ok || len(first.EmptyImportSelections) != 1 {
+			t.Fatalf("resolution source = %#v, %v", first, ok)
+		}
+		first.EmptyImportSelections[0].Path = Keys("callback mutation")
+		second, ok := resolution.Source("source-1")
+		if !ok || second.EmptyImportSelections[0].Path.String() != "/configkit/imports/0" {
+			t.Fatalf("resolution snapshot changed after mutation: %#v", second)
+		}
+		callbackPath = second.EmptyImportSelections[0].Path.String()
+		return nil
+	}}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if callbackPath != "/configkit/imports/0" {
+		t.Fatalf("callback path = %q", callbackPath)
+	}
+	sources := loaded.Sources()
+	if len(sources) != 1 || len(sources[0].EmptyImportSelections) != 1 || sources[0].EmptyImportSelections[0].Location.SourceID != sources[0].ID || sources[0].EmptyImportSelections[0].Selector != ImportSelectorDirectory {
+		t.Fatalf("result source evidence = %#v", sources)
+	}
+	sources[0].EmptyImportSelections[0].Path = Keys("result mutation")
+	if got := loaded.Sources()[0].EmptyImportSelections[0].Path.String(); got != "/configkit/imports/0" {
+		t.Fatalf("result snapshot changed after mutation: %q", got)
+	}
+
+	failurePath := writeFacadeImportFile(t, directory, "failure.yml", `configkit:
+  imports:
+    - dir: absent
+    - path: required-missing.yml
+      required: true
+`)
+	_, err = Load(File(failurePath), Options[config]{Imports: true})
+	var loadError *LoadError
+	if !errors.As(err, &loadError) {
+		t.Fatalf("failed load error = %T %v", err, err)
+	}
+	errorSources := loadError.Sources()
+	if len(errorSources) != 1 || len(errorSources[0].EmptyImportSelections) != 1 || errorSources[0].EmptyImportSelections[0].Path.String() != "/configkit/imports/0" {
+		t.Fatalf("error source evidence = %#v", errorSources)
+	}
+	errorSources[0].EmptyImportSelections[0].Path = Keys("error mutation")
+	if got := loadError.Sources()[0].EmptyImportSelections[0].Path.String(); got != "/configkit/imports/0" {
+		t.Fatalf("error snapshot changed after mutation: %q", got)
+	}
+}
+
+func writeFacadeImportFile(t *testing.T, root, name, contents string) string {
+	t.Helper()
+	filename := filepath.Join(root, name)
+	if err := os.MkdirAll(filepath.Dir(filename), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filename, []byte(contents), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	return filename
+}
+
+func canonicalFacadeImportPath(t *testing.T, filename string) string {
+	t.Helper()
+	canonical, err := filepath.EvalSymlinks(filename)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return filepath.ToSlash(canonical)
+}

facade_import_lifecycle_test.go

@@ -0,0 +1,143 @@
+package configkit
+
+import (
+	"errors"
+	"io/fs"
+	"path"
+	"strings"
+	"testing"
+	"testing/fstest"
+)
+
+func TestDiscoveredItemHelpersPreserveNestedInheritedResourceEvidence(t *testing.T) {
+	const canary = "PRIVATE-CONSUMED-HEADER-CANARY"
+	filesystem := NewFilesystem("bundle", fstest.MapFS{
+		"bundle/config/main.yml": {Data: []byte(`configkit:
+  imports:
+    - dir: records
+      pattern: '*-item.yml'
+      destination: [services, records]
+      placement: sequence-item
+services:
+  records:
+    - id: authored
+      version: authored
+`)},
+		"bundle/config/records/a-item.yml": {Data: []byte(`configkit:
+  imports:
+    - path: helper.yml
+version: ` + canary + `
+entries:
+  parent:
+    resource: icon.txt
+  child:
+    extends: parent
+`)},
+		"bundle/config/records/helper.yml": {Data: []byte("id: helper-supplied\n")},
+		"bundle/config/records/icon.txt":   {Data: []byte("icon payload")},
+	})
+	result, err := Load(filesystem.File("bundle/config/main.yml"), Options[map[string]any]{
+		Imports:    true,
+		Filesystem: &FilesystemContext{Root: "bundle", FS: &filesystem},
+		Definition: Definition[map[string]any]{
+			Version:            &VersionRule{Path: Keys("version"), Check: func(Version, *Validation) error { return nil }},
+			SequenceIdentities: []SequenceIdentity{SequenceIdentityAt(Keys("services", "records"), "id")},
+			Sensitive: func(candidate Path) bool {
+				return candidate.String() == "/services/records/0/version"
+			},
+		},
+		SourceVersionMode: SourceVersionModeIfPresent,
+	})
+	if err != nil {
+		var loadError *LoadError
+		if errors.As(err, &loadError) {
+			t.Fatalf("load discovered item: %v; diagnostics: %#v", err, loadError.Diagnostics())
+		}
+		t.Fatalf("load discovered item: %v", err)
+	}
+	services := result.Config["services"].(map[string]any)
+	records := services["records"].([]any)
+	if len(records) != 2 || records[0].(map[string]any)["id"] != "helper-supplied" || records[0].(map[string]any)["version"] != nil || records[1].(map[string]any)["version"] != "authored" {
+		t.Fatalf("nested records = %#v", records)
+	}
+	childPath := Keys("services", "records").Index(0).Key("entries").Key("child").Key("resource")
+	child := records[0].(map[string]any)["entries"].(map[string]any)["child"].(map[string]any)
+	if child["resource"] != "icon.txt" {
+		t.Fatalf("inherited relative resource = %#v", child)
+	}
+
+	sources := result.Sources()
+	if len(sources) < 3 || sources[0].Layer != LayerMain || string(sources[0].Layer) != "main" {
+		t.Fatalf("main source attribution = %#v", sources)
+	}
+	for _, source := range sources[1:] {
+		if source.ImportedFrom != nil && (source.Layer != LayerMain || string(source.Layer) != "main") {
+			t.Errorf("imported main source attribution = %#v", source)
+		}
+	}
+	filesByID := make(map[string]string, len(sources))
+	for _, source := range sources {
+		filesByID[source.ID] = source.Path
+	}
+	var itemSource SourceInfo
+	for _, source := range sources {
+		if source.Path == "bundle/config/records/a-item.yml" {
+			itemSource = source
+		}
+	}
+	if itemSource.VersionEvidence == nil || !itemSource.VersionEvidence.Version.Present || !itemSource.VersionEvidence.Redacted || itemSource.VersionEvidence.Version.Text != "" {
+		t.Fatalf("consumed header inspection = %#v", itemSource.VersionEvidence)
+	}
+	idInfo, ok := result.Metadata().Lookup(Keys("services", "records").Index(0).Key("id"))
+	if !ok || len(idInfo.Origin.Locations) != 1 || filesByID[idInfo.Origin.Locations[0].SourceID] != "bundle/config/records/helper.yml" {
+		t.Fatalf("assigned helper ID origin = %#v", idInfo)
+	}
+	resourceInfo, ok := result.Metadata().Lookup(childPath)
+	if !ok || len(resourceInfo.Origin.Locations) != 1 || filesByID[resourceInfo.Origin.Locations[0].SourceID] != "bundle/config/records/a-item.yml" {
+		t.Fatalf("inherited resource metadata = %#v", resourceInfo)
+	}
+	explanation, ok := result.Explain(childPath)
+	if !ok || explanation.Effective.YAML != "icon.txt\n" || len(explanation.Origin.Locations) != 1 || explanation.Origin.Locations[0].SourceID != resourceInfo.Origin.Locations[0].SourceID {
+		t.Fatalf("inherited resource explanation = %#v", explanation)
+	}
+	context, ok := result.SourceContext(resourceInfo.Origin.Locations[0].SourceID)
+	if !ok || context.FS == nil || context.BaseDir != "config/records" {
+		t.Fatalf("inherited resource context = %#v, %v", context, ok)
+	}
+	contents, err := fs.ReadFile(context.FS, path.Join(context.BaseDir, child["resource"].(string)))
+	if err != nil || string(contents) != "icon payload" {
+		t.Fatalf("inherited resource read = %q, %v", contents, err)
+	}
+
+	_, err = Load(filesystem.File("bundle/config/main.yml"), Options[map[string]any]{
+		Imports:    true,
+		Filesystem: &FilesystemContext{Root: "bundle", FS: &filesystem},
+		Definition: Definition[map[string]any]{
+			Version:            &VersionRule{Path: Keys("version"), Check: func(Version, *Validation) error { return nil }},
+			SequenceIdentities: []SequenceIdentity{SequenceIdentityAt(Keys("services", "records"), "version")},
+			Sensitive: func(candidate Path) bool {
+				return candidate.String() == "/services/records/0/version"
+			},
+		},
+		SourceVersionMode: SourceVersionModeIfPresent,
+	})
+	loadError, ok := err.(*LoadError)
+	if !ok || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != CodeComposeInvalid {
+		t.Fatalf("consumed header supplied an identity: %v", err)
+	}
+	if strings.Contains(err.Error(), canary) {
+		t.Fatalf("diagnostic exposed the consumed secret header: %v", err)
+	}
+	var failedItemSource SourceInfo
+	foundFailedItem := false
+	for _, source := range loadError.Sources() {
+		if source.Path == "bundle/config/records/a-item.yml" {
+			failedItemSource = source
+			foundFailedItem = true
+			break
+		}
+	}
+	if !foundFailedItem || failedItemSource.VersionEvidence == nil || failedItemSource.VersionEvidence.Version.Text != "" || !failedItemSource.VersionEvidence.Redacted {
+		t.Fatalf("failed-load source inspection exposed or omitted header evidence: %#v", failedItemSource)
+	}
+}

facade_import_root_test.go

@@ -0,0 +1,119 @@
+package configkit_test
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeDirectoryRootBelowContainedAbsoluteSymlink(t *testing.T) {
+	root, err := filepath.EvalSymlinks(t.TempDir())
+	if err != nil {
+		t.Fatal(err)
+	}
+	parts := filepath.Join(root, "real", "parts")
+	if err := os.MkdirAll(parts, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	partPath := filepath.Join(parts, "part.yml")
+	if err := os.WriteFile(partPath, []byte("value: included\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink(filepath.Join(root, "real"), filepath.Join(root, "absolute")); err != nil {
+		t.Skipf("symlinks unavailable: %v", err)
+	}
+	for _, follow := range []bool{true, false} {
+		t.Run(fmt.Sprintf("follow=%t", follow), func(t *testing.T) {
+			mainPath := filepath.Join(root, "main.yml")
+			contents := fmt.Sprintf("configkit:\n  imports:\n    - dir: absolute/parts\n      pattern: '*.yml'\n      follow: %t\n", follow)
+			if err := os.WriteFile(mainPath, []byte(contents), 0o600); err != nil {
+				t.Fatal(err)
+			}
+			result, err := configkit.Load[map[string]any](configkit.File(mainPath), configkit.Options[map[string]any]{Imports: true})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if result.Config["value"] != "included" {
+				t.Fatalf("configuration = %#v", result.Config)
+			}
+			if sources := result.Sources(); len(sources) != 2 || sources[1].Path != partPath {
+				t.Fatalf("canonical imported source = %#v", sources)
+			}
+		})
+	}
+}
+
+func TestFacadeNativeDiscoveryWithNestedRoot(t *testing.T) {
+	root := t.TempDir()
+	parts := filepath.Join(root, "nested/root/parts")
+	if err := os.MkdirAll(parts, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(parts, "value.yml"), []byte("value: 1\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink("parts", filepath.Join(root, "nested/root/linked")); err != nil {
+		t.Skipf("symlinks unavailable: %v", err)
+	}
+	filesystem := configkit.NewFilesystem("nested", os.DirFS(root))
+	context := &configkit.FilesystemContext{FS: &filesystem, Root: "nested/root", BaseDir: "nested/root"}
+	for _, selector := range []string{
+		"dir: parts", "glob: 'parts/*.yml'", "dir: linked", "glob: 'lin*/*.yml'",
+	} {
+		t.Run(selector, func(t *testing.T) {
+			result, err := configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+selector+"\n")), configkit.Options[map[string]any]{Imports: true, Filesystem: context})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if result.Config["value"] != int64(1) {
+				t.Fatalf("configuration = %#v", result.Config)
+			}
+		})
+	}
+	if err := os.WriteFile(filepath.Join(root, "nested/outside.yml"), []byte("value: outside\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink("../../outside.yml", filepath.Join(parts, "escape.yml")); err != nil {
+		t.Fatal(err)
+	}
+	for _, selector := range []string{"dir: parts", "glob: 'parts/*.yml'"} {
+		_, err := configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+selector+"\n")), configkit.Options[map[string]any]{Imports: true, Filesystem: context})
+		var loadError *configkit.LoadError
+		if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != configkit.CodeImportOutsideRoot {
+			t.Fatalf("escaping %s: %v", selector, err)
+		}
+	}
+}
+
+func TestFacadeDiscoveryAllowsFiniteLinkReuse(t *testing.T) {
+	root := t.TempDir()
+	if err := os.Mkdir(filepath.Join(root, "parts"), 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "parts/value.yml"), []byte("value: 1\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.Symlink("..", filepath.Join(root, "parts/up")); err != nil {
+		t.Skipf("symlinks unavailable: %v", err)
+	}
+	filesystem := configkit.NewFilesystem("finite", os.DirFS(root))
+	for _, native := range []bool{false, true} {
+		for _, selector := range []string{"dir: parts/up/parts/up/parts\n      pattern: '*.yml'", "glob: 'parts/up/parts/up/parts/*.yml'"} {
+			context := &configkit.FilesystemContext{Root: root, BaseDir: root}
+			if native {
+				context = &configkit.FilesystemContext{FS: &filesystem, Root: ".", BaseDir: "."}
+			}
+			result, err := configkit.Load(configkit.Bytes("main", []byte("configkit:\n  imports:\n    - "+selector+"\n")), configkit.Options[map[string]any]{Imports: true, Filesystem: context})
+			if err != nil {
+				t.Fatalf("native=%v selector=%s: %v", native, selector, err)
+			}
+			if result.Config["value"] != int64(1) {
+				t.Fatalf("configuration = %#v", result.Config)
+			}
+		}
+	}
+}

facade_inheritance_test.go

@@ -8,7 +8,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type inheritedEntry struct {
@@ -42,7 +42,7 @@ func TestFacadeInheritancePreservesPresenceOriginsAndHistory(t *testing.T) {
 			if !resolution.IsExplicit(configkit.Keys("entries", "child", "enabled")) {
 				t.Error("inherited false is not explicit")
 			}
-			info, found := resolution.InputInfo(configkit.Keys("entries", "child", "enabled"))
+			info, found := resolution.EntryInfo(configkit.Keys("entries", "child", "enabled"))
 			if !found || len(info.Origin.Inheritance) != 1 {
 				t.Errorf("resolver inherited origin = %#v, %v", info, found)
 			}
@@ -91,6 +91,214 @@ func TestFacadeInheritancePreservesPresenceOriginsAndHistory(t *testing.T) {
 	}
 }
 
+func TestFacadeIdentifiedInheritanceResolvesChainsAndNestedCollections(t *testing.T) {
+	const secretName = "CONFIGKIT_IDENTIFIED_INHERITANCE_SECRET"
+	const canary = "IDENTIFIED-INHERITANCE-SECRET-CANARY"
+	t.Setenv(secretName, canary)
+	type step struct {
+		ID    string `yaml:"id"`
+		Value string `yaml:"value"`
+	}
+	type job struct {
+		ID         string                       `yaml:"id"`
+		Name       string                       `yaml:"name"`
+		Credential configkit.Secret             `yaml:"credential"`
+		Resource   string                       `yaml:"resource"`
+		Steps      []step                       `yaml:"steps"`
+		Settings   map[string]map[string]string `yaml:"settings"`
+	}
+	type configuration struct {
+		Jobs []job `yaml:"jobs"`
+	}
+	input := []byte(`jobs:
+- id: child
+  extends: {id: parent}
+  name: child-name
+- id: parent
+  extends: {id: base}
+- id: base
+  name: base-name
+  credential: CONFIGKIT_IDENTIFIED_INHERITANCE_SECRET
+  resource: icon.txt
+  steps:
+    - id: base-step
+      value: base-step-value
+    - id: second-step
+      value: second-step-value
+  settings:
+    primary: {value: base-setting}
+    secondary: {extends: primary}
+`)
+	filesystem := configkit.NewFilesystem("identified-bundle", fstest.MapFS{
+		"config/identified.yml": &fstest.MapFile{Data: input},
+		"config/icon.txt":       &fstest.MapFile{Data: []byte("identified-parent-resource")},
+	})
+	registrations := []configkit.SequenceIdentity{
+		configkit.SequenceIdentityAt(configkit.Keys("jobs"), "id"),
+	}
+	result, err := configkit.Load(filesystem.File("config/identified.yml"), configkit.Options[configuration]{
+		Definition: configkit.Definition[configuration]{
+			SequenceIdentities: registrations,
+			Sensitive: func(path configkit.Path) bool {
+				return path.String() == "/jobs/0/credential" || path.String() == "/jobs/1/credential" || path.String() == "/jobs/2/credential"
+			},
+		},
+	})
+	if err != nil {
+		if loadError, ok := err.(*configkit.LoadError); ok {
+			t.Fatalf("load identified inheritance: %v (%#v)", err, loadError.Diagnostics())
+		}
+		t.Fatal(err)
+	}
+	if len(result.Config.Jobs) != 3 || result.Config.Jobs[0].ID != "child" || result.Config.Jobs[1].ID != "parent" || result.Config.Jobs[2].ID != "base" {
+		t.Fatalf("inherited job positions and identities = %#v", result.Config.Jobs)
+	}
+	child := result.Config.Jobs[0]
+	if child.Name != "child-name" || child.Credential.Value() != canary || child.Resource != "icon.txt" || len(child.Steps) != 2 {
+		t.Fatalf("inherited child = %#v", child)
+	}
+	if got := []string{child.Steps[0].ID, child.Steps[1].ID}; strings.Join(got, ",") != "base-step,second-step" {
+		t.Fatalf("inherited nested steps = %v", got)
+	}
+	if child.Steps[0].Value != "base-step-value" || child.Steps[1].Value != "second-step-value" || child.Settings["secondary"]["value"] != "base-setting" {
+		t.Fatalf("inherited nested collection and mapping = %#v", child)
+	}
+	credentialPath := configkit.Keys("jobs").Index(0).Key("credential")
+	credentialInfo, found := result.Metadata().Lookup(credentialPath)
+	if !found || len(credentialInfo.Origin.Inheritance) != 2 {
+		t.Fatalf("inherited secret provenance = %#v, %v", credentialInfo, found)
+	}
+	resourceInfo, found := result.Metadata().Lookup(configkit.Keys("jobs").Index(0).Key("resource"))
+	if !found || len(resourceInfo.Origin.Inheritance) != 2 || len(resourceInfo.Origin.Locations) != 1 {
+		t.Fatalf("inherited resource provenance = %#v, %v", resourceInfo, found)
+	}
+	context, found := result.SourceContext(resourceInfo.Origin.Locations[0].SourceID)
+	if !found || context.BaseDir != "config" || context.FS == nil {
+		t.Fatalf("inherited resource context = %#v, %v", context, found)
+	}
+	resource, readErr := fs.ReadFile(context.FS, context.BaseDir+"/"+child.Resource)
+	if readErr != nil || string(resource) != "identified-parent-resource" {
+		t.Fatalf("inherited resource = %q, %v", resource, readErr)
+	}
+	resourceHistory, found := result.Explain(configkit.Keys("jobs").Index(0).Key("resource"))
+	if !found || len(resourceHistory.History) == 0 {
+		t.Fatalf("inherited resource history = %#v, %v", resourceHistory, found)
+	}
+	credentialHistory, found := result.Explain(credentialPath)
+	if !found || !credentialHistory.Effective.Redacted {
+		t.Fatalf("inherited secret explanation = %#v, %v", credentialHistory, found)
+	}
+	identityInfo, found := result.Metadata().Lookup(configkit.Keys("jobs").Index(0).Key("id"))
+	if !found || !identityInfo.Explicit || len(identityInfo.Origin.Inheritance) != 0 ||
+		len(identityInfo.Origin.Locations) != 1 {
+		t.Fatalf("child identity origin and presence = %#v, %v", identityInfo, found)
+	}
+	if _, found := result.Metadata().Lookup(configkit.Keys("jobs").Index(0).Key("extends")); found {
+		t.Fatal("identified record relationship remained in effective metadata")
+	}
+	var rendered bytes.Buffer
+	if err := result.WriteEffective(&rendered); err != nil || strings.Contains(rendered.String(), canary) || strings.Contains(rendered.String(), "extends:") {
+		t.Fatalf("effective inherited configuration = %q, %v", rendered.String(), err)
+	}
+}
+
+func TestFacadeIdentifiedInheritanceFailureDoesNotRevealSecretCanary(t *testing.T) {
+	const secretName = "CONFIGKIT_IDENTIFIED_INHERITANCE_FAILURE_SECRET"
+	const canary = "IDENTIFIED-INHERITANCE-FAILURE-CANARY"
+	t.Setenv(secretName, canary)
+	type job struct {
+		ID         string           `yaml:"id"`
+		Credential configkit.Secret `yaml:"credential"`
+	}
+	type configuration struct {
+		Jobs []job `yaml:"jobs"`
+	}
+	input := []byte(`jobs:
+- id: child
+  extends: {id: missing}
+  credential: CONFIGKIT_IDENTIFIED_INHERITANCE_FAILURE_SECRET
+`)
+	_, err := configkit.Load(configkit.Bytes("identified-failure.yml", input), configkit.Options[configuration]{
+		Definition: configkit.Definition[configuration]{
+			SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("jobs"), "id")},
+			Sensitive:          func(path configkit.Path) bool { return path.String() == "/jobs/0/credential" },
+		},
+	})
+	if err == nil || strings.Contains(err.Error(), canary) {
+		t.Fatalf("identified inheritance failure = %v; secret canary must remain undisclosed", err)
+	}
+}
+
+func TestFacadeLayeredIdentifiedInheritanceUsesSurvivingRecords(t *testing.T) {
+	policy := func(mode string) string {
+		return "configkit:\n  sequences:\n    - destination: [jobs]\n      key: id\n      mode: " + mode + "\n"
+	}
+	tests := []struct {
+		name        string
+		lower       string
+		higher      string
+		wantCode    configkit.Code
+		wantValue   string
+		wantSuccess bool
+	}{
+		{
+			name:      "upserted parent supplies its final payload",
+			lower:     policy("upsert") + "jobs: [{id: parent, value: lower}]\n",
+			higher:    policy("upsert") + "jobs: [{id: parent, value: higher}, {id: child, extends: {id: parent}}]\n",
+			wantValue: "higher", wantSuccess: true,
+		},
+		{
+			name:     "replacement removes a lower parent before lookup",
+			lower:    policy("upsert") + "jobs: [{id: parent, value: lower}]\n",
+			higher:   policy("replace") + "jobs: [{id: child, extends: {id: parent}}]\n",
+			wantCode: configkit.CodeInheritanceMissing,
+		},
+		{
+			name:      "upserted child without a directive replaces the invalid lower child",
+			lower:     policy("upsert") + "jobs: [{id: child, extends: {id: missing}, value: lower}]\n",
+			higher:    policy("upsert") + "jobs: [{id: child, value: higher}]\n",
+			wantValue: "higher", wantSuccess: true,
+		},
+		{
+			name:     "self-reference cannot resolve through a lower predecessor",
+			lower:    policy("upsert") + "jobs: [{id: parent, value: lower}]\n",
+			higher:   policy("upsert") + "jobs: [{id: parent, extends: {id: parent}, value: higher}]\n",
+			wantCode: configkit.CodeInheritanceCycle,
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			result, err := configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main.yml", []byte(test.higher))}, configkit.LayeredOptions[map[string]any]{
+				Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Bytes("lower.yml", []byte(test.lower))}}}},
+			})
+			if test.wantSuccess {
+				if err != nil {
+					t.Fatal(err)
+				}
+				jobs, ok := result.Config["jobs"].([]any)
+				if !ok || len(jobs) == 0 {
+					t.Fatalf("assembled jobs = %#v", result.Config["jobs"])
+				}
+				child, ok := jobs[len(jobs)-1].(map[string]any)
+				if !ok || child["value"] != test.wantValue {
+					t.Fatalf("surviving record = %#v, want inherited value %q", jobs[len(jobs)-1], test.wantValue)
+				}
+				return
+			}
+			loadError, ok := err.(*configkit.LoadError)
+			if !ok {
+				t.Fatalf("load error = %v, want code %s", err, test.wantCode)
+			}
+			for _, diagnostic := range loadError.Diagnostics() {
+				if diagnostic.Code == test.wantCode {
+					return
+				}
+			}
+			t.Fatalf("load diagnostics = %#v, want code %s", loadError.Diagnostics(), test.wantCode)
+		})
+	}
+}
+
 func TestFacadeInheritanceLayeredPrecedenceAndSourceContext(t *testing.T) {
 	filesystem := configkit.NewFilesystem("bundle", fstest.MapFS{
 		"config/main.yml":          &fstest.MapFile{Data: []byte("entries: {child: {extends: parent}}\n")},
@@ -206,27 +414,24 @@ func TestFacadeInheritanceFailureStopsLaterCallbacks(t *testing.T) {
 	}
 }
 
-func TestFacadeInheritanceResolvesAfterImportsAndCLIReferenceChange(t *testing.T) {
+func TestFacadeCLIOverridesCannotChangeInheritanceRelationship(t *testing.T) {
 	filesystem := configkit.NewFilesystem("bundle", fstest.MapFS{
 		"main.yml":   &fstest.MapFile{Data: []byte("configkit: {imports: [{path: parent.yml}]}\nentries: {child: {extends: first}}\n")},
 		"parent.yml": &fstest.MapFile{Data: []byte("entries: {first: {count: 1}, second: {count: 2}}\n")},
 	})
-	result, err := configkit.Load(filesystem.File("main.yml"), configkit.Options[inheritedConfiguration]{
+	_, err := configkit.Load(filesystem.File("main.yml"), configkit.Options[inheritedConfiguration]{
 		Imports: true, Overrides: []configkit.Override{{Path: configkit.Keys("entries", "child", "extends"), Value: "second", Flag: "--extends"}},
 	})
-	if err != nil || result.Config.Entries["child"].Count != 2 {
+	loadError, ok := err.(*configkit.LoadError)
-		t.Fatalf("import and CLI reference = %#v, %v", result, err)
+	if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeOverrideDirective {
-	}
+		t.Fatalf("CLI inheritance relationship change = %v", err)
-	history := result.Metadata().History(configkit.Keys("entries", "child", "extends"))
-	if len(history) < 3 || history[len(history)-1].Origin.Operation != configkit.ChangeInheritance {
-		t.Fatalf("superseded reference history = %#v", history)
 	}
 	conflicting := configkit.NewFilesystem("bundle", fstest.MapFS{
 		"main.yml":   &fstest.MapFile{Data: []byte("configkit: {imports: [{path: parent.yml}]}\nentries: {child: {extends: first}, first: {count: 3}}\n")},
 		"parent.yml": &fstest.MapFile{Data: []byte("entries: {first: {count: 1}}\n")},
 	})
 	_, err = configkit.Load[inheritedConfiguration](conflicting.File("main.yml"), configkit.Options[inheritedConfiguration]{Imports: true})
-	loadError, ok := err.(*configkit.LoadError)
+	loadError, ok = err.(*configkit.LoadError)
 	if !ok || len(loadError.Diagnostics()) == 0 || loadError.Diagnostics()[0].Code != configkit.CodeComposeConflict {
 		t.Fatalf("strict conflict before expansion = %v", err)
 	}
@@ -263,7 +468,7 @@ func TestFacadeInheritedSecretsStayRedactedAfterLookup(t *testing.T) {
 		Entries map[string]entry `yaml:"entries"`
 	}
 	result, err := configkit.Load[configuration](configkit.Bytes("secret.yml", []byte("entries: {parent: {credential: CONFIGKIT_INHERITED_TEST_SECRET, plain: visible}, child: {extends: parent}}\n")), configkit.Options[configuration]{Definition: configkit.Definition[configuration]{
-		Secret: func(path configkit.Path) bool { return path.String() == "/entries/parent/credential" },
+		Sensitive: func(path configkit.Path) bool { return path.String() == "/entries/parent/credential" },
 	}})
 	if err != nil || result.Config.Entries["child"].Credential.Value() != canary {
 		t.Fatalf("inherited credential = %#v, %v", result, err)

facade_internal_test.go

@@ -1,52 +0,0 @@
-package configkit
-
-import (
-	"errors"
-	"reflect"
-	"strings"
-	"testing"
-
-	"gitea.maximumdirect.net/eric/ConfigKit/internal/engine"
-)
-
-func TestWrappedSourcesPreserveEngineOwnership(t *testing.T) {
-	t.Parallel()
-
-	type config struct {
-		Value string `yaml:"value"`
-	}
-	data := []byte("value: retained\n")
-	source := Bytes("snapshot.yml", data)
-	data[7] = 'X'
-	result, err := engine.Load[config](source.toEngine(), engine.SecretBinding{})
-	if err != nil || result.Config.Value != "retained" {
-		t.Fatalf("snapshotted source = %#v, %v", result, err)
-	}
-
-	readerSource := Reader("reader.yml", strings.NewReader("value: once\n"))
-	first := readerSource
-	if _, err := engine.Load[config](first.toEngine(), engine.SecretBinding{}); err != nil {
-		t.Fatal(err)
-	}
-	_, err = engine.Load[config](readerSource.toEngine(), engine.SecretBinding{})
-	var loadError *engine.LoadError
-	if !errors.As(err, &loadError) || len(loadError.Diagnostics()) != 1 || loadError.Diagnostics()[0].Code != engine.CodeSourceReaderUsed {
-		t.Fatalf("copied reader source error = %#v", err)
-	}
-}
-
-func TestWrappedPathsRetainEngineSegmentIntent(t *testing.T) {
-	t.Parallel()
-
-	parsed, err := ParsePath("/0")
-	if err != nil {
-		t.Fatal(err)
-	}
-	keyed, indexed := Keys("0"), Path{}.Index(0)
-	if parsed.String() != "/0" || keyed.String() != "/0" || indexed.String() != "/0" {
-		t.Fatalf("path spellings = %q, %q, %q", parsed, keyed, indexed)
-	}
-	if reflect.DeepEqual(parsed.value, keyed.value) || reflect.DeepEqual(parsed.value, indexed.value) || reflect.DeepEqual(keyed.value, indexed.value) {
-		t.Fatal("path wrappers collapsed parsed, mapping-key, and index segments")
-	}
-}

facade_item_registration_scope_test.go

@@ -0,0 +1,69 @@
+package configkit_test
+
+import (
+	"fmt"
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeItemScopesDoNotReinterpretGlobalRegistrations(t *testing.T) {
+	t.Parallel()
+	for _, layered := range []bool{false, true} {
+		for _, dynamic := range []bool{false, true} {
+			for _, missingOuterID := range []bool{false, true} {
+				t.Run(fmt.Sprintf("layered=%t/dynamic=%t/missing-outer-id=%t", layered, dynamic, missingOuterID), func(t *testing.T) {
+					payload := "prompts: [{text: helper}]\n"
+					unused := configkit.SequenceIdentityAt(configkit.Keys("prompts"), "id")
+					if dynamic {
+						payload = "catalog: {local: {prompts: [{text: helper}]}}\n"
+						unused = configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+							configkit.SequenceLiteralKey("catalog"), configkit.SequenceAnyMappingKey(), configkit.SequenceLiteralKey("prompts"),
+						}, "id")
+					}
+					item := "configkit: {imports: [{path: helper.yml}, {path: child.yml, destination: [children], placement: sequence-item}]}\n"
+					if !missingOuterID {
+						item += "id: outer\n"
+					}
+					files := configkit.NewFilesystem("items", fstest.MapFS{
+						"main.yml": {Data: []byte("configkit: {imports: [{path: item.yml, destination: [items], placement: sequence-item}]}\n")},
+						"item.yml": {Data: []byte(item)}, "helper.yml": {Data: []byte(payload)},
+						"child.yml":        {Data: []byte("id: child\nconfigkit: {imports: [{path: child-helper.yml}]}\n")},
+						"child-helper.yml": {Data: []byte(payload)},
+					})
+					definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+						unused, configkit.SequenceIdentityAt(configkit.Keys("items"), "id"),
+					}}
+					var result *configkit.Result[map[string]any]
+					var err error
+					if layered {
+						result, err = configkit.LoadLayered(configkit.Input{Source: files.File("main.yml"), Imports: true}, configkit.LayeredOptions[map[string]any]{Definition: definition})
+					} else {
+						result, err = configkit.Load(files.File("main.yml"), configkit.Options[map[string]any]{Imports: true, Definition: definition})
+					}
+					if missingOuterID {
+						failure := requireFacadeLoadError(t, err)
+						if result != nil || len(failure.Diagnostics()) != 1 || failure.Diagnostics()[0].Code != configkit.CodeComposeInvalid || failure.Diagnostics()[0].Path.String() != "/items/0/id" {
+							t.Fatalf("outer constraint diagnostics = %#v", failure.Diagnostics())
+						}
+						return
+					}
+					if err != nil {
+						t.Fatal(err)
+					}
+					for _, record := range []configkit.Path{configkit.Keys("items").Index(0), configkit.Keys("items").Index(0).Key("children").Index(0)} {
+						path := record
+						if dynamic {
+							path = path.Key("catalog").Key("local")
+						}
+						info, found := result.Metadata().Lookup(path.Key("prompts").Index(0).Key("text"))
+						if !found || !info.Explicit {
+							t.Fatalf("nested helper payload lost at %s", path)
+						}
+					}
+				})
+			}
+		}
+	}
+}

facade_item_version_test.go

@@ -0,0 +1,64 @@
+package configkit_test
+
+import (
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeItemDomainVersionsKeepEffectiveScope(t *testing.T) {
+	for _, test := range []struct {
+		name, item, child, helper string
+		underlay, mainItem        bool
+	}{
+		{name: "item", item: "id: item\nversion: domain\n"},
+		{name: "helper", item: "id: item\nconfigkit: {imports: [{path: helper.yml}]}\n", helper: "version: domain\n"},
+		{name: "nested", item: "id: parent\nconfigkit: {imports: [{path: child.yml, destination: [children], placement: sequence-item}]}\n", child: "id: child\nversion: domain\n"},
+		{name: "underlay", item: "id: item\nversion: domain\n", underlay: true},
+		{name: "main-item", item: "id: parent\nconfigkit: {imports: [{path: child.yml, destination: [children], placement: sequence-item}]}\n", child: "id: child\nversion: domain\n", mainItem: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			files := fstest.MapFS{
+				"main.yml":     {Data: []byte("version: 1\nconfigkit: {imports: [{path: item.yml, destination: [items], placement: sequence-item}]}\n")},
+				"item.yml":     {Data: []byte(test.item)},
+				"child.yml":    {Data: []byte(test.child)},
+				"helper.yml":   {Data: []byte(test.helper)},
+				"underlay.yml": {Data: []byte("configkit: {imports: [{path: item.yml, destination: [items], placement: sequence-item}]}\n")},
+			}
+			filesystem := configkit.NewFilesystem("items", files)
+			definition := configkit.Definition[map[string]any]{Version: &configkit.VersionRule{
+				Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { return nil },
+			}}
+			var result *configkit.Result[map[string]any]
+			var err error
+			switch {
+			case test.underlay:
+				result, err = configkit.LoadLayered(configkit.Input{Source: configkit.Mapping("main", map[string]any{"version": "1"})}, configkit.LayeredOptions[map[string]any]{
+					Definition: definition, Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: filesystem.File("underlay.yml"), Imports: true}}}},
+				})
+			case test.mainItem:
+				result, err = configkit.Load(filesystem.File("item.yml"), configkit.Options[map[string]any]{
+					Imports: true, Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem, Definition: definition,
+				})
+			default:
+				result, err = configkit.Load(filesystem.File("main.yml"), configkit.Options[map[string]any]{Imports: true, Definition: definition})
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			item := result.Config["items"].([]any)[0].(map[string]any)
+			fieldPath := configkit.Keys("items").Index(0).Key("version")
+			if test.child != "" {
+				item = item["children"].([]any)[0].(map[string]any)
+				fieldPath = configkit.Keys("items").Index(0).Key("children").Index(0).Key("version")
+			}
+			if item["version"] != "domain" {
+				t.Fatalf("domain version = %#v", item)
+			}
+			if info, ok := result.Metadata().Lookup(fieldPath); !ok || !info.Explicit {
+				t.Fatalf("version metadata = %#v, %v", info, ok)
+			}
+		})
+	}
+}

facade_layered_test.go

@@ -10,7 +10,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type layeredFacadeConfig struct {
@@ -59,8 +59,8 @@ func TestFacadeLayeredMixedSourcesAndInspection(t *testing.T) {
 				configkit.Default(resolution, configkit.Keys("derived"), &config.Derived, config.Settings["native"], "derive from native", configkit.Keys("settings", "native"))
 				return nil
 			},
-			Validate: func(config *layeredFacadeConfig, validation *configkit.Validation) { checks.validation++ },
+			Validate:  func(config *layeredFacadeConfig, validation *configkit.Validation) { checks.validation++ },
-			Secret:   func(path configkit.Path) bool { return path.String() == "/settings/secret" },
+			Sensitive: func(path configkit.Path) bool { return path.String() == "/settings/secret" },
 		},
 	})
 	if err != nil {
@@ -80,7 +80,7 @@ func TestFacadeLayeredMixedSourcesAndInspection(t *testing.T) {
 	if len(sources) != 8 {
 		t.Fatalf("sources = %#v", sources)
 	}
-	wantLayers := []configkit.Layer{configkit.LayerBase, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerOverlay, configkit.LayerCLI}
+	wantLayers := []configkit.Layer{configkit.LayerMain, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerUnderlay, configkit.LayerOverlay, configkit.LayerCLI}
 	wantIndexes := []int{0, 1, 1, 1, 1, 2, 0, 0}
 	wantKinds := []configkit.SourceKind{configkit.SourceKindFile, configkit.SourceKindFilesystem, configkit.SourceKindFilesystem, configkit.SourceKindMapping, configkit.SourceKindFilesystem, configkit.SourceKindMapping, configkit.SourceKindFilesystem, configkit.SourceKindCLI}
 	for index, source := range sources {

facade_mapping_test.go

@@ -7,7 +7,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type mappingFacadeConfig struct {
@@ -36,7 +36,7 @@ func TestFacadeMappingSnapshotsAndMatchesYAML(t *testing.T) {
 		if !reflect.DeepEqual(result.Config, want) {
 			t.Fatalf("mapping config = %#v, want %#v", result.Config, want)
 		}
-		if sources := result.Sources(); len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Kind != configkit.SourceKindMapping || sources[0].Layer != configkit.LayerBase || sources[0].Path != "" {
+		if sources := result.Sources(); len(sources) != 1 || sources[0].ID != "source-1" || sources[0].Kind != configkit.SourceKindMapping || sources[0].Layer != configkit.LayerMain || sources[0].Path != "" {
 			t.Fatalf("mapping sources = %#v", sources)
 		}
 		info, ok := result.Metadata().Lookup(configkit.Keys("name"))
@@ -89,7 +89,7 @@ func TestFacadeMappingImportsUseExplicitContext(t *testing.T) {
 	if err != nil || result.Config.Name != "imported" || !result.Config.Enabled {
 		t.Fatalf("mapping import = %#v, %v", result, err)
 	}
-	if sources := result.Sources(); len(sources) != 2 || sources[0].Kind != configkit.SourceKindMapping || sources[1].Kind != configkit.SourceKindFilesystem || sources[1].Layer != configkit.LayerBase {
+	if sources := result.Sources(); len(sources) != 2 || sources[0].Kind != configkit.SourceKindMapping || sources[1].Kind != configkit.SourceKindFilesystem || sources[1].Layer != configkit.LayerMain {
 		t.Fatalf("mapping import sources = %#v", sources)
 	}
 	checkMappingCode(t, source, configkit.Options[mappingFacadeConfig]{Imports: true}, configkit.CodeOptionsInvalid)

facade_resolution_presence_test.go

@@ -0,0 +1,63 @@
+package configkit_test
+
+import (
+	"errors"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeResolutionPresenceUsesDynamicEntryShape(t *testing.T) {
+	t.Parallel()
+
+	type configuration struct {
+		Shape any `yaml:"shape"`
+	}
+	tests := []struct {
+		name       string
+		input      string
+		keyPresent bool
+	}{
+		{name: "mapping key", input: "shape: {'0': input}\n", keyPresent: true},
+		{name: "sequence index", input: "shape: [input]\n", keyPresent: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			parsed, err := configkit.ParsePath("/shape/0")
+			if err != nil {
+				t.Fatal(err)
+			}
+			_, err = configkit.Load(configkit.Bytes("dynamic.yml", []byte(test.input)), configkit.Options[configuration]{
+				Definition: configkit.Definition[configuration]{
+					Resolve: func(_ *configuration, resolution *configkit.Resolution) error {
+						check := func(path configkit.Path, want bool) error {
+							info, found := resolution.EntryInfo(path)
+							explicit := resolution.IsExplicit(path)
+							if found != want || explicit != want || (found && info.Explicit != explicit) {
+								return errors.New("resolution presence disagrees with dynamic entry shape")
+							}
+							return nil
+						}
+						for _, checkPath := range []struct {
+							path configkit.Path
+							want bool
+						}{
+							{path: configkit.Keys("shape", "0"), want: test.keyPresent},
+							{path: configkit.Keys("shape").Index(0), want: !test.keyPresent},
+							{path: parsed, want: true},
+							{path: configkit.Keys("shape", "missing"), want: false},
+						} {
+							if err := check(checkPath.path, checkPath.want); err != nil {
+								return err
+							}
+						}
+						return nil
+					},
+				},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+		})
+	}
+}

facade_resolution_recording_test.go

@@ -0,0 +1,43 @@
+package configkit
+
+import "testing"
+
+func TestFacadeResolutionRecordingIntents(t *testing.T) {
+	type configuration struct {
+		Derived    string `yaml:"derived"`
+		Normalized string `yaml:"normalized"`
+	}
+
+	result, err := Load(Bytes("recording.yml", []byte("derived: explicit\nnormalized: before\n")), Options[configuration]{
+		Definition: Definition[configuration]{Resolve: func(value *configuration, resolution *Resolution) error {
+			value.Derived = "changed explicit input"
+			resolution.RecordDerivedDefault(Keys("derived"), "derive explicit input")
+			value.Normalized = "after"
+			resolution.RecordNormalization(Keys("normalized"), "normalize configured input")
+			return nil
+		}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, test := range []struct {
+		path Path
+		kind ChangeKind
+	}{
+		{path: Keys("derived"), kind: ChangeDerivedDefault},
+		{path: Keys("normalized"), kind: ChangeNormalization},
+	} {
+		info, ok := result.Metadata().Lookup(test.path)
+		if !ok || info.Origin.Operation != test.kind {
+			t.Errorf("metadata %s = %#v, %v; want operation %q", test.path, info, ok, test.kind)
+		}
+		history := result.Metadata().History(test.path)
+		if len(history) == 0 || history[len(history)-1].Origin.Operation != test.kind {
+			t.Errorf("history %s = %#v; want final operation %q", test.path, history, test.kind)
+		}
+	}
+	if !result.Metadata().IsExplicit(Keys("derived")) {
+		t.Fatal("recording a derived default suppressed explicit-input provenance")
+	}
+}

facade_resource_context_test.go

@@ -12,7 +12,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type observedResourceFS struct {

facade_sequence_identity_test.go

@@ -0,0 +1,240 @@
+package configkit_test
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestFacadeSequenceIdentitySnapshotsSelectorsAndFields(t *testing.T) {
+	fields := []string{"namespace", "id", "id"}
+	selector := configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("prompts"),
+	}
+	identity := configkit.SequenceIdentityMatching(selector, fields...)
+	selector[1] = configkit.SequenceLiteralKey("other")
+	fields[0] = "changed"
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{identity}}
+
+	underlay := configkit.Mapping("underlay", map[string]any{"collections": map[string]any{
+		"team": map[string]any{"prompts": []any{map[string]any{"namespace": "team", "id": "kept"}}},
+	}})
+	main := configkit.Mapping("main", map[string]any{"collections": map[string]any{
+		"team": map[string]any{"prompts": []any{map[string]any{"namespace": "team", "id": "added"}}},
+	}})
+	loaded, err := configkit.LoadLayered(configkit.Input{Source: main}, configkit.LayeredOptions[map[string]any]{
+		Definition: definition,
+		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: underlay}}}},
+	})
+	if err != nil {
+		t.Fatalf("load after mutating constructor inputs: %v", err)
+	}
+	prompts := loaded.Config["collections"].(map[string]any)["team"].(map[string]any)["prompts"].([]any)
+	if len(prompts) != 2 {
+		t.Fatalf("registered compound identity did not append records: %#v", prompts)
+	}
+}
+
+func TestFacadeSequenceIdentityUsesExactAndDynamicSelectors(t *testing.T) {
+	dynamic := configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+		configkit.SequenceLiteralKey("collections"),
+		configkit.SequenceAnyMappingKey(),
+		configkit.SequenceLiteralKey("prompts"),
+	}, "id")
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityAt(configkit.Keys("prompts"), "namespace", "id"),
+		dynamic,
+	}}
+	underlay := configkit.Mapping("underlay", map[string]any{
+		"prompts": []any{map[string]any{"namespace": "alpha", "id": "same"}},
+		"collections": map[string]any{
+			"team":  map[string]any{"prompts": []any{map[string]any{"id": "team-one"}}},
+			"cloud": map[string]any{"prompts": []any{map[string]any{"id": "cloud-one"}}},
+		},
+	})
+	main := configkit.Mapping("main", map[string]any{
+		"prompts": []any{map[string]any{"namespace": "beta", "id": "same"}},
+		"collections": map[string]any{
+			"team":  map[string]any{"prompts": []any{map[string]any{"id": "team-two"}}},
+			"cloud": map[string]any{"prompts": []any{map[string]any{"id": "cloud-two"}}},
+		},
+	})
+	loaded, err := configkit.LoadLayered(configkit.Input{Source: main}, configkit.LayeredOptions[map[string]any]{
+		Definition: definition,
+		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: underlay}}}},
+	})
+	if err != nil {
+		t.Fatalf("load mixed exact and dynamic registrations: %v", err)
+	}
+	rootRecords := loaded.Config["prompts"].([]any)
+	if len(rootRecords) != 2 {
+		t.Fatalf("compound root identities = %#v", rootRecords)
+	}
+	collections := loaded.Config["collections"].(map[string]any)
+	for _, name := range []string{"team", "cloud"} {
+		prompts := collections[name].(map[string]any)["prompts"].([]any)
+		if len(prompts) != 2 {
+			t.Errorf("dynamic prompts for %q = %#v", name, prompts)
+		}
+	}
+}
+
+func TestFacadeSequenceIdentityLiteralStarIsNotWildcard(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+			configkit.SequenceLiteralKey("collections"),
+			configkit.SequenceLiteralKey("*"),
+			configkit.SequenceLiteralKey("prompts"),
+		}, "id"),
+	}}
+	underlay := configkit.Mapping("underlay", map[string]any{"collections": map[string]any{
+		"*":    map[string]any{"prompts": []any{map[string]any{"id": "one"}}},
+		"team": map[string]any{"prompts": []any{map[string]any{"id": "team-one"}}},
+	}})
+	main := configkit.Mapping("main", map[string]any{"collections": map[string]any{
+		"*":    map[string]any{"prompts": []any{map[string]any{"id": "two"}}},
+		"team": map[string]any{"prompts": []any{map[string]any{"id": "team-two"}}},
+	}})
+	_, err := configkit.LoadLayered(configkit.Input{Source: configkit.Mapping("main", map[string]any{})}, configkit.LayeredOptions[map[string]any]{
+		Definition: definition,
+		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: underlay}, {Source: main}}}},
+	})
+	loadErr := requireFacadeLoadError(t, err)
+	if len(loadErr.Diagnostics()) == 0 || loadErr.Diagnostics()[0].Path.String() != "/collections/team/prompts" {
+		t.Fatalf("literal star registration also matched another key: %#v", loadErr.Diagnostics())
+	}
+
+	wildcard := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+			configkit.SequenceLiteralKey("collections"),
+			configkit.SequenceAnyMappingKey(),
+			configkit.SequenceLiteralKey("prompts"),
+		}, "id"),
+	}}
+	loaded, err := configkit.LoadLayered(configkit.Input{Source: configkit.Mapping("main", map[string]any{})}, configkit.LayeredOptions[map[string]any]{
+		Definition: wildcard,
+		Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: underlay}, {Source: main}}}},
+	})
+	if err != nil {
+		t.Fatalf("wildcard registration did not match mapping keys: %v", err)
+	}
+	for name, raw := range loaded.Config["collections"].(map[string]any) {
+		if got := len(raw.(map[string]any)["prompts"].([]any)); got != 2 {
+			t.Errorf("wildcard result for %q has %d records", name, got)
+		}
+	}
+}
+
+func TestFacadeSequenceIdentityRejectsInvalidDefinitionsBeforeReadingSource(t *testing.T) {
+	tests := []struct {
+		name     string
+		identity configkit.SequenceIdentity
+		wantPath string
+	}{
+		{
+			name:     "index path",
+			identity: configkit.SequenceIdentityAt(configkit.Keys("records").Index(0), "id"),
+			wantPath: "/records/0",
+		},
+		{
+			name:     "empty fields",
+			identity: configkit.SequenceIdentityAt(configkit.Keys("records")),
+			wantPath: "/records",
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			reader := strings.NewReader("records: []\n")
+			_, err := configkit.Load(configkit.Reader("input.yml", reader), configkit.Options[map[string]any]{
+				Definition: configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{test.identity}},
+			})
+			loadErr := requireFacadeLoadError(t, err)
+			if len(loadErr.Diagnostics()) != 1 || loadErr.Diagnostics()[0].Code != configkit.CodeOptionsInvalid || loadErr.Diagnostics()[0].Path.String() != test.wantPath {
+				t.Fatalf("definition diagnostics = %#v", loadErr.Diagnostics())
+			}
+			if reader.Len() == 0 {
+				t.Fatal("source was read before registration validation")
+			}
+		})
+	}
+}
+
+func TestFacadeSequenceIdentityOverlapFailsBeforeSourceAccess(t *testing.T) {
+	selector := configkit.SequenceSelector{configkit.SequenceLiteralKey("collections"), configkit.SequenceAnyMappingKey()}
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityMatching(selector, "id"),
+		configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+			configkit.SequenceLiteralKey("collections"), configkit.SequenceLiteralKey("team"),
+		}, "slug"),
+	}}
+	reader := strings.NewReader("collections: {}\n")
+	_, err := configkit.Load(configkit.Reader("input.yml", reader), configkit.Options[map[string]any]{Definition: definition})
+	loadErr := requireFacadeLoadError(t, err)
+	if len(loadErr.Diagnostics()) == 0 || loadErr.Diagnostics()[0].Code != configkit.CodeOptionsInvalid {
+		t.Fatalf("overlap diagnostics = %#v", loadErr.Diagnostics())
+	}
+	if reader.Len() == 0 {
+		t.Fatal("source was read before overlapping registrations were rejected")
+	}
+}
+
+func TestFacadeSequenceIdentityConstraintsApplyAtInheritedDestinations(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+			configkit.SequenceLiteralKey("entries"),
+			configkit.SequenceLiteralKey("child"),
+			configkit.SequenceLiteralKey("collections"),
+			configkit.SequenceAnyMappingKey(),
+			configkit.SequenceLiteralKey("prompts"),
+		}, "id"),
+	}}
+	loaded, err := configkit.Load(configkit.Bytes("main", []byte(`jobs:
+entries:
+  parent:
+    collections:
+      team:
+        prompts: [{id: inherited, text: base}]
+  child:
+    extends: parent
+    collections:
+      team:
+        prompts: [{id: added, text: child}]
+`)), configkit.Options[map[string]any]{Definition: definition})
+	if err != nil {
+		t.Fatalf("load with dynamic inherited destination: %v", err)
+	}
+	child := loaded.Config["entries"].(map[string]any)["child"].(map[string]any)
+	prompts := child["collections"].(map[string]any)["team"].(map[string]any)["prompts"].([]any)
+	if len(prompts) != 2 {
+		t.Fatalf("inherited dynamic collection = %#v, want parent and child records", prompts)
+	}
+}
+
+func TestFacadeSequenceIdentityLoadsUseIndependentScopes(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{
+		configkit.SequenceIdentityMatching(configkit.SequenceSelector{
+			configkit.SequenceLiteralKey("collections"), configkit.SequenceAnyMappingKey(),
+		}, "id"),
+	}}
+	for _, source := range []string{"first", "second"} {
+		loaded, err := configkit.Load(configkit.Mapping(source, map[string]any{"collections": map[string]any{
+			source: []any{map[string]any{"id": "reused"}},
+		}}), configkit.Options[map[string]any]{Definition: definition})
+		if err != nil || len(loaded.Config["collections"].(map[string]any)[source].([]any)) != 1 {
+			t.Fatalf("independent load %q = %#v, %v", source, loaded, err)
+		}
+	}
+}
+
+func requireFacadeLoadError(t *testing.T, err error) *configkit.LoadError {
+	t.Helper()
+	var loadErr *configkit.LoadError
+	if !errors.As(err, &loadErr) {
+		t.Fatalf("error = %v, want *LoadError", err)
+	}
+	return loadErr
+}

facade_sequence_test.go

@@ -9,7 +9,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func TestFacadeNoSourcePreservesAbsenceWithSequencePolicy(t *testing.T) {
@@ -21,7 +21,7 @@ func TestFacadeNoSourcePreservesAbsenceWithSequencePolicy(t *testing.T) {
 				definition.Defaults = func() map[string]any { return map[string]any{"fallback": true} }
 			}
 			if registered {
-				definition.SequenceCompositions = []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}
+				definition.SequenceIdentities = []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")}
 			}
 			ordinary, err := configkit.Load(configkit.NoSource(), configkit.Options[map[string]any]{Definition: definition})
 			if err != nil {
@@ -51,7 +51,7 @@ func TestFacadeNoSourcePreservesAbsenceWithSequencePolicy(t *testing.T) {
 	}
 }
 
-func TestFacadeItemHelperHistoryPreservesTraversalOrder(t *testing.T) {
+func TestFacadeItemHelperHistoryPreservesScheduledPlacement(t *testing.T) {
 	t.Parallel()
 	filesystem := configkit.NewFilesystem("history", fstest.MapFS{
 		"main.yml":         {Data: []byte("records: [{id: authored}]\nconfigkit: {imports: [{path: one.yml, destination: [records], placement: sequence-item}, {path: two.yml, destination: [records], placement: sequence-item}]}\n")},
@@ -63,24 +63,22 @@ func TestFacadeItemHelperHistoryPreservesTraversalOrder(t *testing.T) {
 		"child-helper.yml": {Data: []byte("text: nested helper\n")},
 	})
 	result, err := configkit.Load(filesystem.File("main.yml"), configkit.Options[map[string]any]{
-		Imports: true, Definition: configkit.Definition[map[string]any]{SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}},
+		Imports: true, Definition: configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")}},
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
-	sourceOrder := make(map[string]int)
 	sourceFiles := make(map[string]string)
-	for index, source := range result.Sources() {
+	for _, source := range result.Sources() {
-		sourceOrder[source.ID] = index
 		sourceFiles[source.ID] = source.Path
 	}
 	for _, test := range []struct {
 		path       configkit.Path
 		file, text string
 	}{
-		{configkit.Keys("records").Index(1).Key("text"), "helper-one.yml", "first helper\n"},
+		{configkit.Keys("records").Index(0).Key("text"), "helper-one.yml", "first helper\n"},
-		{configkit.Keys("records").Index(2).Key("text"), "helper-two.yml", "second helper\n"},
+		{configkit.Keys("records").Index(1).Key("text"), "helper-two.yml", "second helper\n"},
-		{configkit.Keys("records").Index(1).Key("children").Index(0).Key("text"), "child-helper.yml", "nested helper\n"},
+		{configkit.Keys("records").Index(0).Key("children").Index(0).Key("text"), "child-helper.yml", "nested helper\n"},
 	} {
 		explanation, ok := result.Explain(test.path)
 		if !ok || explanation.Effective.YAML != test.text || len(explanation.History) != 1 {
@@ -95,20 +93,6 @@ func TestFacadeItemHelperHistoryPreservesTraversalOrder(t *testing.T) {
 			t.Fatal("metadata and explanation disagree")
 		}
 	}
-	explanation, ok := result.Explain(configkit.Keys())
-	if !ok {
-		t.Fatal("root explanation missing")
-	}
-	previous := -1
-	for _, change := range explanation.History {
-		for _, location := range change.Origin.Locations {
-			current := sourceOrder[location.SourceID]
-			if current < previous {
-				t.Fatalf("source %s replayed out of traversal order", location.SourceID)
-			}
-			previous = current
-		}
-	}
 }
 
 func TestFacadeRegisteredReplacementExplainsRemovedDescendants(t *testing.T) {
@@ -123,8 +107,14 @@ func TestFacadeRegisteredReplacementExplainsRemovedDescendants(t *testing.T) {
 		{"removed field", []any{map[string]any{"id": "main"}}, configkit.Keys("records").Index(0).Key("text")},
 	} {
 		t.Run(test.name, func(t *testing.T) {
-			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Mapping("main", map[string]any{"records": test.upper})}, configkit.LayeredOptions[map[string]any]{
+			mainYAML := "configkit:\n  sequences:\n    - destination: [records]\n      key: id\n      mode: replace\n"
-				Definition: configkit.Definition[map[string]any]{SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}},
+			if len(test.upper) == 0 {
+				mainYAML += "records: []\n"
+			} else {
+				mainYAML += "records: [{id: main}]\n"
+			}
+			result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Bytes("main", []byte(mainYAML))}, configkit.LayeredOptions[map[string]any]{
+				Definition: configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")}},
 				Underlays:  []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping("lower", map[string]any{"records": []any{map[string]any{"id": "one", "text": "old"}, map[string]any{"id": "two"}}})}}}},
 			})
 			if err != nil {
@@ -135,7 +125,7 @@ func TestFacadeRegisteredReplacementExplainsRemovedDescendants(t *testing.T) {
 				t.Fatalf("removal not explained: %#v", explanation)
 			}
 			last := explanation.History[len(explanation.History)-1]
-			if !last.Before.Present || last.After.Present || last.Origin.Layer != configkit.LayerBase || len(last.Origin.Locations) != 1 || last.Origin.Locations[0].SourceID != result.Sources()[0].ID {
+			if !last.Before.Present || last.After.Present || last.Origin.Layer != configkit.LayerMain || len(last.Origin.Locations) != 1 || last.Origin.Locations[0].SourceID != result.Sources()[0].ID {
 				t.Fatalf("wrong removal transition/origin: %#v", last)
 			}
 		})
@@ -153,14 +143,14 @@ func TestFacadeItemConflictDiagnosticsFollowEnclosingIndexes(t *testing.T) {
 		"bad.yml":    {Data: []byte("id: bad\nconfigkit: {imports: [{path: helper.yml}]}\n")},
 		"helper.yml": {Data: []byte("id: duplicate-field\n")},
 	})
-	definition := configkit.Definition[map[string]any]{SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}}
+	definition := configkit.Definition[map[string]any]{SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")}}
 	for _, test := range []struct {
 		name, file, path  string
 		grouped, itemMain bool
 	}{
-		{"preceding authored and imported items", "main.yml", "/records/2/id", false, false},
+		{"preceding authored and imported items", "main.yml", "/records/0/id", false, false},
-		{"nested item", "nested.yml", "/records/1/children/1/id", false, false},
+		{"nested item", "nested.yml", "/records/0/children/0/id", false, false},
-		{"preceding grouped input", "group.yml", "/records/2/id", true, false},
+		{"preceding grouped input", "group.yml", "/records/1/id", true, false},
 		{"item main source", "bad.yml", "/records/0/id", false, true},
 		{"grouped item source", "bad.yml", "/records/1/id", true, true},
 	} {
@@ -193,8 +183,16 @@ func TestFacadeItemConflictDiagnosticsFollowEnclosingIndexes(t *testing.T) {
 			for _, source := range loadError.Sources() {
 				files[source.ID] = source.Path
 			}
-			if diagnostic.Primary == nil || files[diagnostic.Primary.SourceID] != "bad.yml" || len(diagnostic.Related) != 1 || files[diagnostic.Related[0].SourceID] != "helper.yml" {
+			locations := append([]configkit.Location(nil), diagnostic.Related...)
-				t.Fatal("conflict lost physical source locations")
+			if diagnostic.Primary != nil {
+				locations = append(locations, *diagnostic.Primary)
+			}
+			gotFiles := make(map[string]bool, len(locations))
+			for _, location := range locations {
+				gotFiles[files[location.SourceID]] = location.Line == 1 && location.Column == 5
+			}
+			if len(locations) != 2 || !gotFiles["bad.yml"] || !gotFiles["helper.yml"] {
+				t.Fatalf("conflict lost physical source locations: diagnostic=%#v sources=%#v", diagnostic, files)
 			}
 		})
 	}
@@ -202,7 +200,7 @@ func TestFacadeItemConflictDiagnosticsFollowEnclosingIndexes(t *testing.T) {
 
 func TestFacadeSequencePlacementControlsAcrossLoadEntryPoints(t *testing.T) {
 	definition := configkit.Definition[map[string]any]{
-		SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("entries"), IdentityField: "id"}},
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("entries"), "id")},
 	}
 	ordinary, err := configkit.Load(configkit.Mapping("ordinary", map[string]any{"id": "one"}), configkit.Options[map[string]any]{
 		Definition: definition, Destination: configkit.Keys("entries"), PlacementMode: configkit.PlacementModeSequenceItem,
@@ -213,7 +211,7 @@ func TestFacadeSequencePlacementControlsAcrossLoadEntryPoints(t *testing.T) {
 	if got := ordinary.Config["entries"].([]any); len(got) != 1 || got[0].(map[string]any)["id"] != "one" {
 		t.Fatalf("ordinary item placement = %#v", ordinary.Config)
 	}
-	if sources := ordinary.Sources(); len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeSequenceItem || sources[0].Destination.String() != "/entries" || sources[0].DestinationUnresolved {
+	if sources := ordinary.Sources(); len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeSequenceItem || sources[0].Destination.String() != "/entries" || sources[0].DestinationIsFallback {
 		t.Fatalf("ordinary item source = %#v", sources)
 	}
 
@@ -232,7 +230,7 @@ func TestFacadeSequencePlacementControlsAcrossLoadEntryPoints(t *testing.T) {
 		t.Fatalf("layered item placement = %#v", layered.Config)
 	}
 	for _, source := range layered.Sources() {
-		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationUnresolved {
+		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationIsFallback {
 			t.Errorf("layered item source = %#v", source)
 		}
 	}
@@ -248,8 +246,8 @@ func TestFacadeSequencePlacementControlsAcrossLoadEntryPoints(t *testing.T) {
 	if err != nil {
 		t.Fatalf("registered sequence precedence load: %v", err)
 	}
-	if got := precedence.Config["entries"].([]any); len(got) != 1 || got[0].(map[string]any)["id"] != "main" {
+	if got := precedence.Config["entries"].([]any); len(got) != 2 || got[0].(map[string]any)["id"] != "lower" || got[1].(map[string]any)["id"] != "main" {
-		t.Fatalf("higher-priority list did not replace the lower sequence: %#v", precedence.Config)
+		t.Fatalf("registered upsert did not retain the lower sequence: %#v", precedence.Config)
 	}
 
 	for _, test := range []struct {
@@ -303,7 +301,7 @@ items:
 	result, err := configkit.Load(configkit.File(mainPath), configkit.Options[map[string]any]{
 		Imports: true,
 		Definition: configkit.Definition[map[string]any]{
-			SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("items"), IdentityField: "id"}},
+			SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
 			Resolve: func(_ *map[string]any, resolution *configkit.Resolution) error {
 				for _, id := range []string{"source-2", "source-3"} {
 					source, ok := resolution.Source(id)
@@ -326,7 +324,7 @@ items:
 		t.Fatalf("load item glob: %v", err)
 	}
 	items := result.Config["items"].([]any)
-	wantIDs := []string{"authored", "imported-a", "imported-b"}
+	wantIDs := []string{"imported-a", "imported-b", "authored"}
 	for index, item := range items {
 		if got := item.(map[string]any)["id"]; got != wantIDs[index] {
 			t.Errorf("item %d ID = %#v, want %q", index, got, wantIDs[index])
@@ -336,7 +334,7 @@ items:
 		t.Fatalf("callback snapshots = %#v, contexts %#v", callbackSources, callbackContexts)
 	}
 	for index, source := range callbackSources {
-		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/items" || source.DestinationUnresolved {
+		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/items" || source.DestinationIsFallback {
 			t.Errorf("callback source = %#v", source)
 		}
 		if callbackContexts[index].FS == nil || callbackContexts[index].BaseDir != "records" {
@@ -344,14 +342,14 @@ items:
 		}
 	}
 	metadata := result.Metadata()
-	for index := 1; index < len(wantIDs); index++ {
+	for index := 0; index < 2; index++ {
 		path := configkit.Keys("items").Index(index).Key("id")
 		info, ok := metadata.Lookup(path)
-		if !ok || !info.Explicit || len(info.Origin.Locations) != 1 || info.Origin.Locations[0].SourceID != []string{"source-2", "source-3"}[index-1] {
+		if !ok || !info.Explicit || len(info.Origin.Locations) != 1 || info.Origin.Locations[0].SourceID != []string{"source-2", "source-3"}[index] {
 			t.Errorf("shifted item origin at %s = %#v, %v", path.String(), info, ok)
 		}
 	}
-	if got := result.Sources(); len(got) != 3 || got[1].Destination.String() != "/items" || got[1].DestinationUnresolved {
+	if got := result.Sources(); len(got) != 3 || got[1].Destination.String() != "/items" || got[1].DestinationIsFallback {
 		t.Fatalf("final item sources = %#v", got)
 	}
 }
@@ -374,9 +372,9 @@ func TestFacadeItemDestinationFallbackEvidenceSurvivesFailures(t *testing.T) {
 		t.Fatalf("early failure = %v", err)
 	}
 	sources := loadError.Sources()
-	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationUnresolved ||
+	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationIsFallback ||
 		sources[0].PlacementMode != configkit.PlacementModeSequenceItem ||
-		sources[1].Destination.String() != "/items" || !sources[1].DestinationUnresolved ||
+		sources[1].Destination.String() != "/items" || !sources[1].DestinationIsFallback ||
 		sources[1].PlacementMode != configkit.PlacementModeMapping {
 		t.Fatalf("early source snapshots = %#v", sources)
 	}
@@ -401,13 +399,13 @@ func TestFacadeItemDestinationFallbackEvidenceSurvivesFailures(t *testing.T) {
 		t.Fatalf("post-placement failure = %v", err)
 	}
 	sources = loadError.Sources()
-	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationUnresolved ||
+	if len(sources) != 2 || sources[0].Destination.String() != "/items" || sources[0].DestinationIsFallback ||
-		sources[1].Destination.String() != "/items/0/metadata" || sources[1].DestinationUnresolved {
+		sources[1].Destination.String() != "/items/0/metadata" || sources[1].DestinationIsFallback {
 		t.Fatalf("post-placement source snapshots = %#v", sources)
 	}
 	firstSnapshot := sources[1]
 	sources[1].Destination = configkit.Keys("mutated")
-	if again := loadError.Sources(); len(again) != 2 || again[1].Destination.String() != firstSnapshot.Destination.String() || again[1].DestinationUnresolved {
+	if again := loadError.Sources(); len(again) != 2 || again[1].Destination.String() != firstSnapshot.Destination.String() || again[1].DestinationIsFallback {
 		t.Fatalf("failure source snapshots were aliased: %#v", again)
 	}
 
@@ -422,7 +420,7 @@ func TestFacadeItemDestinationFallbackEvidenceSurvivesFailures(t *testing.T) {
 	if err != nil {
 		t.Fatalf("successful item load: %v", err)
 	}
-	if callback.Destination.String() != "/items/0/metadata" || callback.DestinationUnresolved || callback.PlacementMode != configkit.PlacementModeMapping {
+	if callback.Destination.String() != "/items/0/metadata" || callback.DestinationIsFallback || callback.PlacementMode != configkit.PlacementModeMapping {
 		t.Fatalf("callback source snapshot = %#v", callback)
 	}
 }
@@ -452,26 +450,28 @@ func TestFacadeNestedItemFallbackUsesNearestResolvedContainer(t *testing.T) {
 	if len(sources) != 3 {
 		t.Fatalf("nested source snapshots = %#v", sources)
 	}
-	if got := sources[0]; got.Destination.String() != "/groups" || got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeSequenceItem {
+	if got := sources[0]; got.Destination.String() != "/groups" || got.DestinationIsFallback || got.PlacementMode != configkit.PlacementModeSequenceItem {
 		t.Errorf("outer item snapshot = %#v", got)
 	}
-	if got := sources[1]; got.Destination.String() != "/groups" || !got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeSequenceItem {
+	if got := sources[1]; got.Destination.String() != "/groups" || !got.DestinationIsFallback || got.PlacementMode != configkit.PlacementModeSequenceItem {
 		t.Errorf("nested item fallback = %#v", got)
 	}
-	if got := sources[2]; got.Destination.String() != "/groups" || !got.DestinationUnresolved || got.PlacementMode != configkit.PlacementModeMapping {
+	if got := sources[2]; got.Destination.String() != "/groups" || !got.DestinationIsFallback || got.PlacementMode != configkit.PlacementModeMapping {
 		t.Errorf("nested helper fallback = %#v", got)
 	}
 }
 
-func TestFacadeSequenceCompositionRegistrationPathIsDetached(t *testing.T) {
+func TestFacadeSequenceIdentityRegistrationIsDetached(t *testing.T) {
-	registrations := []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}}
+	fields := []string{"id"}
+	path := configkit.Keys("records")
+	registration := configkit.SequenceIdentityAt(path, fields...)
+	fields[0] = "changed"
 	definition := configkit.Definition[map[string]any]{
-		SequenceCompositions: registrations,
+		SequenceIdentities: []configkit.SequenceIdentity{registration},
 		Version: &configkit.VersionRule{
 			Path: configkit.Keys("version"),
 			Check: func(configkit.Version, *configkit.Validation) error {
-				registrations[0].Path = configkit.Keys("other")
+				path = configkit.Keys("other")
-				registrations[0].IdentityField = "changed"
 				return nil
 			},
 		},
@@ -496,7 +496,7 @@ func TestFacadeSequenceCompositionRegistrationPathIsDetached(t *testing.T) {
 
 func TestFacadeSourceInfoPlacementCopiesAndZeroValues(t *testing.T) {
 	zero := configkit.SourceInfo{}
-	if zero.PlacementMode != configkit.PlacementModeMapping || zero.DestinationUnresolved {
+	if zero.PlacementMode != configkit.PlacementModeMapping || zero.DestinationIsFallback {
 		t.Fatalf("zero source info = %#v", zero)
 	}
 	loaded, err := configkit.Load[map[string]any](configkit.Mapping("mapping", map[string]any{"value": true}))
@@ -504,16 +504,41 @@ func TestFacadeSourceInfoPlacementCopiesAndZeroValues(t *testing.T) {
 		t.Fatal(err)
 	}
 	sources := loaded.Sources()
-	if len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeMapping || sources[0].DestinationUnresolved {
+	if len(sources) != 1 || sources[0].PlacementMode != configkit.PlacementModeMapping || sources[0].DestinationIsFallback {
 		t.Fatalf("mapping source evidence = %#v", sources)
 	}
 	first := sources[0]
 	first.Destination = configkit.Keys("caller")
-	if again := loaded.Sources(); len(again) != 1 || again[0].Destination.String() != "" || again[0].DestinationUnresolved {
+	if again := loaded.Sources(); len(again) != 1 || again[0].Destination.String() != "" || again[0].DestinationIsFallback {
 		t.Fatalf("source evidence changed after caller mutation: %#v", again)
 	}
 }
 
+func TestLayeredSequenceUpsertHistoryRetainsLowerTierRecords(t *testing.T) {
+	definition := configkit.Definition[map[string]any]{
+		SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("entries"), "id")},
+	}
+	result, err := configkit.LoadLayered[map[string]any](configkit.Input{Source: configkit.Bytes("main", []byte("entries: [{id: main}]\n"))}, configkit.LayeredOptions[map[string]any]{
+		Definition: definition,
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{
+			Source: configkit.Bytes("lower", []byte("entries: [{id: lower}]\n")),
+		}}}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for index, id := range []string{"lower", "main"} {
+		path := configkit.Keys("entries").Index(index).Key("id")
+		explanation, ok := result.Explain(path)
+		if !ok || !explanation.Effective.Present || explanation.Effective.YAML != id+"\n" || len(explanation.History) == 0 {
+			t.Fatalf("tier history at %s = %#v, %v", path.String(), explanation, ok)
+		}
+		if explanation.History[len(explanation.History)-1].After.YAML != id+"\n" {
+			t.Fatalf("tier history at %s does not retain final record: %#v", path.String(), explanation.History)
+		}
+	}
+}
+
 func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *testing.T) {
 	type record struct {
 		ID       string  `yaml:"id"`
@@ -531,7 +556,12 @@ func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *test
 	directory := t.TempDir()
 	mainPath := filepath.Join(directory, "main.yml")
 	underlayPath := filepath.Join(directory, "underlay.yml")
-	if err := os.WriteFile(mainPath, []byte(`entries:
+	if err := os.WriteFile(mainPath, []byte(`configkit:
+  sequences:
+    - destination: [entries]
+      key: id
+      mode: replace
+entries:
   - id: current
     count: 0
     enabled: false
@@ -567,8 +597,8 @@ func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *test
 	result, err := configkit.LoadLayered(configkit.Input{Source: configkit.File(mainPath)}, configkit.LayeredOptions[configuration]{
 		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.File(underlayPath), Imports: true}}}},
 		Definition: configkit.Definition[configuration]{
-			SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("entries"), IdentityField: "id"}},
+			SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("entries"), "id")},
-			Secret: func(path configkit.Path) bool {
+			Sensitive: func(path configkit.Path) bool {
 				return path.String() == "/entries/0/token" || path.String() == "/entries/1/token"
 			},
 			Resolve: func(value *configuration, resolution *configkit.Resolution) error {
@@ -581,8 +611,8 @@ func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *test
 				if resolution.IsExplicit(configkit.Keys("entries").Index(0).Key("omitted")) {
 					t.Error("resolver treated an omitted field as explicit")
 				}
-				info, found := resolution.InputInfo(configkit.Keys("entries").Index(0).Key("count"))
+				info, found := resolution.EntryInfo(configkit.Keys("entries").Index(0).Key("count"))
-				if !found || info.Origin.Layer != configkit.LayerBase {
+				if !found || info.Origin.Layer != configkit.LayerMain {
 					t.Errorf("resolver current-record input info = %#v, %v", info, found)
 				}
 				for _, id := range []string{"source-3", "source-4"} {
@@ -616,7 +646,7 @@ func TestFacadeSequenceReplacementKeepsTypedAndHistoricalEvidenceAligned(t *test
 		t.Fatalf("callback sources = %#v; contexts = %#v", callbackItems, callbackContexts)
 	}
 	for _, source := range callbackItems {
-		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationUnresolved {
+		if source.PlacementMode != configkit.PlacementModeSequenceItem || source.Destination.String() != "/entries" || source.DestinationIsFallback {
 			t.Errorf("callback item source = %#v", source)
 		}
 	}

facade_sequence_version_test.go

@@ -0,0 +1,197 @@
+package configkit_test
+
+import (
+	"fmt"
+	"testing"
+	"testing/fstest"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+type movedVersionItem struct {
+	ID      string `yaml:"id"`
+	Version string `yaml:"version"`
+}
+
+type movedVersionCatalog struct {
+	Items []movedVersionItem `yaml:"items"`
+}
+
+func TestMainVersionDecodingFollowsSequenceMovement(t *testing.T) {
+	t.Parallel()
+	for _, mounted := range []bool{false, true} {
+		for _, matching := range []bool{false, true} {
+			for _, version := range []string{"4", "'4'"} {
+				t.Run(fmt.Sprintf("mounted=%t/matched=%t/%s", mounted, matching, version), func(t *testing.T) {
+					body := "items: [{id: main, version: " + version + "}]\n"
+					path := configkit.Keys("items").Index(0).Key("version")
+					main := configkit.Input{}
+					if mounted {
+						body, path = "id: main\nversion: "+version+"\n", configkit.Keys("version")
+						main.Destination, main.PlacementMode = configkit.Keys("items"), configkit.PlacementModeSequenceItem
+					}
+					main.Source = configkit.Bytes("main", []byte(body))
+					keep := "{id: keep}"
+					if mounted {
+						keep = "{id: keep, version: ordinary}"
+					}
+					lower := "items: [" + keep + "]\n"
+					if matching {
+						lower = "items: [" + keep + ", {id: main}]\n"
+					}
+					calls := 0
+					loaded, err := configkit.LoadLayered(main, configkit.LayeredOptions[movedVersionCatalog]{
+						SourceVersionMode: configkit.SourceVersionModeIfPresent,
+						Underlays:         []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Bytes("lower", []byte(lower))}}}},
+						Definition: configkit.Definition[movedVersionCatalog]{
+							SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+							Version: &configkit.VersionRule{Path: path, Check: func(version configkit.Version, _ *configkit.Validation) error {
+								calls++
+								if !version.Present || version.Text != "4" {
+									t.Errorf("checked version = %#v", version)
+								}
+								return nil
+							}},
+						},
+					})
+					if err != nil {
+						t.Fatal(err)
+					}
+					if calls != 1 || len(loaded.Config.Items) != 2 || loaded.Config.Items[1].ID != "main" || loaded.Config.Items[1].Version != "4" {
+						t.Fatalf("moved main = %#v, checker calls = %d", loaded.Config, calls)
+					}
+					if mounted && loaded.Config.Items[0].Version != "ordinary" {
+						t.Fatal("unrelated underlay payload was treated as the main declaration")
+					}
+					for _, source := range loaded.Sources() {
+						if source.Layer == configkit.LayerMain && source.VersionEvidence.Path.String() != path.String() {
+							t.Fatal("effective movement changed source-local version evidence")
+						}
+					}
+				})
+			}
+		}
+	}
+}
+
+func TestOverlayVersionProtectionUsesAssignedRecordPositions(t *testing.T) {
+	t.Parallel()
+	for _, test := range []struct {
+		name, payload string
+		code          configkit.Code
+	}{
+		{name: "change main header", payload: "[{id: main, version: changed}]", code: configkit.CodeOverlayVersion},
+		{name: "remove main header", payload: "[{id: main}]", code: configkit.CodeOverlayVersion},
+		{name: "other record version", payload: "[{id: keep, version: ordinary}]"},
+		{name: "new record version", payload: "[{id: new, version: ordinary}]"},
+		{name: "only main header gets integer conversion", payload: "[{id: new, version: 5}]", code: configkit.CodeDecodeType},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			files := configkit.NewFilesystem("catalog", fstest.MapFS{
+				"overlays/test.yml": {Data: []byte("items: " + test.payload + "\n")},
+			})
+			calls := 0
+			loaded, err := configkit.LoadLayered(configkit.Input{
+				Source: configkit.Bytes("main", []byte("id: main\nversion: 4\n")), Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem,
+			}, configkit.LayeredOptions[movedVersionCatalog]{
+				SourceVersionMode: configkit.SourceVersionModeIfPresent,
+				Overlay:           "test", OverlayFilesystem: &configkit.FilesystemContext{FS: &files, BaseDir: ".", Root: "."},
+				Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Bytes("lower", []byte("items: [{id: keep}]\n"))}}}},
+				Definition: configkit.Definition[movedVersionCatalog]{
+					SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+					Version:            &configkit.VersionRule{Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { calls++; return nil }},
+				},
+			})
+			if calls != 1 {
+				t.Fatalf("checker calls = %d", calls)
+			}
+			if test.code != "" {
+				loadErr := requireFacadeLoadError(t, err)
+				if loaded != nil || len(loadErr.Diagnostics()) != 1 || loadErr.Diagnostics()[0].Code != test.code {
+					t.Fatalf("version diagnostics = %#v", loadErr.Diagnostics())
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if loaded.Config.Items[1].Version != "4" {
+				t.Fatal("unrelated overlay changed main header")
+			}
+		})
+	}
+}
+
+func TestUnderlayVersionProtectionUsesMainRecordPosition(t *testing.T) {
+	t.Parallel()
+	for _, imported := range []bool{false, true} {
+		t.Run(fmt.Sprintf("imported=%t", imported), func(t *testing.T) {
+			payload := "items: [{id: keep}, {id: main, version: forbidden}]\n"
+			lower := configkit.Input{Source: configkit.Bytes("lower", []byte(payload))}
+			want := configkit.CodeUnderlayVersion
+			if imported {
+				files := configkit.NewFilesystem("lower", fstest.MapFS{
+					"main.yml":     {Data: []byte("configkit: {imports: [{path: fragment.yml}]}\n")},
+					"fragment.yml": {Data: []byte(payload)},
+				})
+				lower.Source, lower.Imports = files.File("main.yml"), true
+				want = configkit.CodeImportVersion
+			}
+			calls := 0
+			result, err := configkit.LoadLayered(configkit.Input{
+				Source:      configkit.Bytes("main", []byte("id: main\nversion: 4\n")),
+				Destination: configkit.Keys("items"), PlacementMode: configkit.PlacementModeSequenceItem,
+			}, configkit.LayeredOptions[movedVersionCatalog]{
+				SourceVersionMode: configkit.SourceVersionModeIfPresent,
+				Underlays:         []configkit.Underlay{{Inputs: []configkit.Input{lower}}},
+				Definition: configkit.Definition[movedVersionCatalog]{
+					SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("items"), "id")},
+					Version:            &configkit.VersionRule{Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { calls++; return nil }},
+				},
+			})
+			failure := requireFacadeLoadError(t, err)
+			if result != nil || calls != 1 || len(failure.Diagnostics()) != 1 || failure.Diagnostics()[0].Code != want || failure.Diagnostics()[0].Path.String() != "/items/1/version" {
+				t.Fatalf("result=%#v calls=%d diagnostics=%#v", result, calls, failure.Diagnostics())
+			}
+		})
+	}
+}
+
+func TestMainVersionFollowsInheritedSequenceMovement(t *testing.T) {
+	t.Parallel()
+	for _, parentID := range []string{"keep", "main"} {
+		t.Run(parentID, func(t *testing.T) {
+			body := "base: {items: [{id: " + parentID + ", version: ordinary}]}\nchild:\n  extends: base\n  items: [{id: main, version: 4}]\n"
+			type config struct {
+				Base, Child movedVersionCatalog
+			}
+			calls := 0
+			result, err := configkit.Load(configkit.Bytes("main", []byte(body)), configkit.Options[config]{
+				SourceVersionMode: configkit.SourceVersionModeIfPresent,
+				Definition: configkit.Definition[config]{
+					SequenceIdentities: []configkit.SequenceIdentity{
+						configkit.SequenceIdentityAt(configkit.Keys("base", "items"), "id"),
+						configkit.SequenceIdentityAt(configkit.Keys("child", "items"), "id"),
+					},
+					Version: &configkit.VersionRule{Path: configkit.Keys("child", "items").Index(0).Key("version"), Check: func(configkit.Version, *configkit.Validation) error { calls++; return nil }},
+				},
+			})
+			if calls != 1 {
+				t.Fatalf("checker calls = %d", calls)
+			}
+			if parentID == "main" {
+				failure := requireFacadeLoadError(t, err)
+				if result != nil || len(failure.Diagnostics()) != 1 || failure.Diagnostics()[0].Code != configkit.CodeInheritanceVersion {
+					t.Fatalf("diagnostics = %#v", failure.Diagnostics())
+				}
+				return
+			}
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(result.Config.Child.Items) != 2 || result.Config.Child.Items[1].Version != "4" || result.Config.Child.Items[0].Version != "ordinary" {
+				t.Fatalf("inherited items = %#v", result.Config.Child.Items)
+			}
+		})
+	}
+}

facade_source_version_mode_test.go

@@ -10,18 +10,22 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
-func TestFacadeSourceVersionEvidenceFollowsAuthoredSequenceRanges(t *testing.T) {
+func TestFacadeSourceVersionEvidenceFollowsAssembledSequenceRanges(t *testing.T) {
 	t.Parallel()
 	for _, grouped := range []bool{false, true} {
-		for _, sensitivePath := range []string{"", "/records/1/version", "/records/1"} {
+		index := 0
+		if grouped {
+			index = 1
+		}
+		for _, sensitivePath := range []string{"", fmt.Sprintf("/records/%d/version", index), fmt.Sprintf("/records/%d", index)} {
 			t.Run(fmt.Sprintf("grouped=%t/secret=%s", grouped, sensitivePath), func(t *testing.T) {
 				definition := configkit.Definition[map[string]any]{
-					SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}},
+					SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")},
-					Version:              &configkit.VersionRule{Path: configkit.Keys("records").Index(0).Key("version"), Check: func(configkit.Version, *configkit.Validation) error { return nil }},
+					Version:            &configkit.VersionRule{Path: configkit.Keys("records").Index(0).Key("version"), Check: func(configkit.Version, *configkit.Validation) error { return nil }},
-					Secret:               func(path configkit.Path) bool { return sensitivePath != "" && path.String() == sensitivePath },
+					Sensitive:          func(path configkit.Path) bool { return sensitivePath != "" && path.String() == sensitivePath },
 				}
 				first := "records: [{id: first, version: first-version}]\n"
 				child := "records: [{id: child, version: PRIVATE-VERSION-CANARY}]\n"
@@ -46,8 +50,18 @@ func TestFacadeSourceVersionEvidenceFollowsAuthoredSequenceRanges(t *testing.T)
 				if err != nil {
 					t.Fatal(err)
 				}
+				if !grouped {
+					records, ok := result.Config["records"].([]any)
+					if !ok || len(records) != 2 {
+						t.Fatalf("scheduled records = %#v", result.Config["records"])
+					}
+					firstRecord, ok := records[0].(map[string]any)
+					if !ok || firstRecord["id"] != "child" {
+						t.Fatalf("scheduled records = %#v", result.Config["records"])
+					}
+				}
 				sources := result.Sources()
-				check := sources[len(sources)-1].VersionCheck
+				check := sources[len(sources)-1].VersionEvidence
 				if check == nil || check.Path.String() != "/records/0/version" || check.Location == nil || check.Location.SourceID != sources[len(sources)-1].ID {
 					t.Fatalf("source-local evidence changed: %#v", check)
 				}
@@ -72,8 +86,8 @@ func TestFacadeSourceVersionOwnershipAcceptsContextualIndexes(t *testing.T) {
 	for _, grouped := range []bool{false, true} {
 		for _, path := range []configkit.Path{configkit.Keys("records").Index(0).Key("version"), parsed} {
 			definition := configkit.Definition[map[string]any]{
-				SequenceCompositions: []configkit.SequenceComposition{{Path: configkit.Keys("records"), IdentityField: "id"}},
+				SequenceIdentities: []configkit.SequenceIdentity{configkit.SequenceIdentityAt(configkit.Keys("records"), "id")},
-				Version:              &configkit.VersionRule{Path: path, Check: func(configkit.Version, *configkit.Validation) error { return nil }},
+				Version:            &configkit.VersionRule{Path: path, Check: func(configkit.Version, *configkit.Validation) error { return nil }},
 			}
 			first := "records: [{id: first, version: first}]\n"
 			child := "records: [{id: child, version: child}]\n"
@@ -90,11 +104,7 @@ func TestFacadeSourceVersionOwnershipAcceptsContextualIndexes(t *testing.T) {
 			if err != nil || result == nil {
 				t.Fatalf("grouped=%t path=%#v: %v", grouped, path, err)
 			}
-			want := 2
+			if len(result.Config["records"].([]any)) != 2 {
-			if grouped {
-				want = 1
-			}
-			if len(result.Config["records"].([]any)) != want {
 				t.Fatal("version path changed composition")
 			}
 		}
@@ -199,7 +209,7 @@ func TestFacadeSourceVersionEvidenceRedactsCollidingShapes(t *testing.T) {
 				continue
 			}
 			foundMapping = true
-			if check := source.VersionCheck; check == nil || !check.Version.Present || !check.Redacted || check.Version.Text != "" {
+			if check := source.VersionEvidence; check == nil || !check.Version.Present || !check.Redacted || check.Version.Text != "" {
 				t.Errorf("reverse=%v: schema-tagged header was not redacted", reverse)
 			}
 		}
@@ -255,7 +265,7 @@ func TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath(t *testing.T) {
 		{"unavailable index", "meta: [null, null, null, {version: main}]\n", "meta: []\n", configkit.Keys("meta").Index(3).Key("version")},
 	} {
 		for _, mode := range []configkit.SourceVersionMode{configkit.SourceVersionModeIfPresent, configkit.SourceVersionModeRequired} {
-			var callbackEvidence *configkit.SourceVersionCheck
+			var callbackEvidence *configkit.SourceVersionEvidence
 			loaded, err := configkit.LoadLayered(configkit.Input{Source: configkit.Bytes("main", []byte(test.main))}, configkit.LayeredOptions[map[string]any]{
 				SourceVersionMode: mode,
 				Definition: configkit.Definition[map[string]any]{
@@ -265,7 +275,7 @@ func TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath(t *testing.T) {
 						if !found {
 							t.Fatal("missing callback source")
 						}
-						callbackEvidence = source.VersionCheck
+						callbackEvidence = source.VersionEvidence
 						return nil
 					},
 				},
@@ -273,7 +283,7 @@ func TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath(t *testing.T) {
 					Source: configkit.Bytes("underlay", []byte(test.underlay)), Destination: configkit.Keys("under"),
 				}}}},
 			})
-			var evidence *configkit.SourceVersionCheck
+			var evidence *configkit.SourceVersionEvidence
 			if mode == configkit.SourceVersionModeRequired {
 				var failure *configkit.LoadError
 				if loaded != nil || !errors.As(err, &failure) {
@@ -283,12 +293,12 @@ func TestFacadeSourceVersionAbsenceKeepsCompleteEvidencePath(t *testing.T) {
 				if len(diagnostics) != 1 || diagnostics[0].Code != configkit.CodeVersionError || diagnostics[0].Path.String() != test.path.String() {
 					t.Fatalf("%s: required diagnostics=%#v", test.name, diagnostics)
 				}
-				evidence = failure.Sources()[1].VersionCheck
+				evidence = failure.Sources()[1].VersionEvidence
 			} else {
 				if err != nil {
 					t.Fatalf("%s: %v", test.name, err)
 				}
-				evidence = loaded.Sources()[1].VersionCheck
+				evidence = loaded.Sources()[1].VersionEvidence
 				if callbackEvidence == nil || callbackEvidence.Path.String() != test.path.String() {
 					t.Errorf("%s: callback path is incomplete", test.name)
 				}
@@ -355,7 +365,7 @@ func TestFacadeSourceVersionMissingHeaderDoesNotOverlapControl(t *testing.T) {
 			if child["value"] != "good" {
 				t.Fatal("valid sibling inheritance was not applied")
 			}
-			check := loaded.Sources()[1].VersionCheck
+			check := loaded.Sources()[1].VersionEvidence
 			if check == nil || check.Version.Present || check.Path.String() != path.String() {
 				t.Fatal("optional omission evidence was not retained")
 			}
@@ -534,16 +544,16 @@ func TestFacadeSourceVersionEvidenceIsSanitizedAndDetached(t *testing.T) {
 	var callbackSource configkit.SourceInfo
 	var callbackContext configkit.ResourceContext
 	definition := configkit.Definition[map[string]any]{
-		Version: &configkit.VersionRule{Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { return nil }},
+		Version:   &configkit.VersionRule{Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { return nil }},
-		Secret:  func(candidate configkit.Path) bool { return candidate.String() == "/service/version" },
+		Sensitive: func(candidate configkit.Path) bool { return candidate.String() == "/service/version" },
 		Resolve: func(_ *map[string]any, resolution *configkit.Resolution) error {
 			var found bool
 			callbackSource, found = resolution.Source("source-1")
 			if !found {
 				t.Fatal("resolution callback could not query the acquired source")
 			}
-			if callbackSource.VersionCheck == nil || !callbackSource.VersionCheck.Redacted || callbackSource.VersionCheck.Version.Text != "" {
+			if callbackSource.VersionEvidence == nil || !callbackSource.VersionEvidence.Redacted || callbackSource.VersionEvidence.Version.Text != "" {
-				t.Fatalf("callback source did not conservatively redact evidence: %#v", callbackSource.VersionCheck)
+				t.Fatalf("callback source did not conservatively redact evidence: %#v", callbackSource.VersionEvidence)
 			}
 			callbackContext, found = resolution.SourceContext("source-1")
 			if !found || callbackContext.FS == nil || callbackContext.BaseDir != "." {
@@ -558,17 +568,17 @@ func TestFacadeSourceVersionEvidenceIsSanitizedAndDetached(t *testing.T) {
 	if err != nil || loaded == nil {
 		t.Fatalf("LoadLayered = %#v, %v", loaded, err)
 	}
-	if callbackSource.VersionCheck == nil || !callbackSource.VersionCheck.Redacted || callbackSource.VersionCheck.Version.Text != "" {
+	if callbackSource.VersionEvidence == nil || !callbackSource.VersionEvidence.Redacted || callbackSource.VersionEvidence.Version.Text != "" {
-		t.Fatalf("callback evidence lost its conservative snapshot: %#v", callbackSource.VersionCheck)
+		t.Fatalf("callback evidence lost its conservative snapshot: %#v", callbackSource.VersionEvidence)
 	}
-	callbackSource.VersionCheck.Path = configkit.Keys("mutated-callback")
+	callbackSource.VersionEvidence.Path = configkit.Keys("mutated-callback")
-	callbackSource.VersionCheck.Version.Text = canary
+	callbackSource.VersionEvidence.Version.Text = canary
-	callbackSource.VersionCheck.Location.Line = 98
+	callbackSource.VersionEvidence.Location.Line = 98
 	finalSources := loaded.Sources()
-	if len(finalSources) != 1 || finalSources[0].Path != path || finalSources[0].VersionCheck == nil {
+	if len(finalSources) != 1 || finalSources[0].Path != path || finalSources[0].VersionEvidence == nil {
 		t.Fatalf("final sources = %#v", finalSources)
 	}
-	check := finalSources[0].VersionCheck
+	check := finalSources[0].VersionEvidence
 	if check.Path.String() != "/version" || check.Version != (configkit.Version{Present: true}) || !check.Redacted ||
 		check.Location == nil || check.Location.SourceID != finalSources[0].ID || check.Location.Line != 1 {
 		t.Fatalf("final classified evidence = %#v", check)
@@ -584,9 +594,9 @@ func TestFacadeSourceVersionEvidenceIsSanitizedAndDetached(t *testing.T) {
 	check.Redacted = false
 	check.Version.Text = "mutated"
 	repeated := loaded.Sources()
-	if len(repeated) != 1 || repeated[0].VersionCheck.Path.String() != "/version" ||
+	if len(repeated) != 1 || repeated[0].VersionEvidence.Path.String() != "/version" ||
-		repeated[0].VersionCheck.Location.Line != 1 || !repeated[0].VersionCheck.Redacted ||
+		repeated[0].VersionEvidence.Location.Line != 1 || !repeated[0].VersionEvidence.Redacted ||
-		repeated[0].VersionCheck.Version.Text != "" {
+		repeated[0].VersionEvidence.Version.Text != "" {
 		t.Fatalf("source evidence was aliased or re-read after source removal: %#v", repeated)
 	}
 
@@ -602,14 +612,14 @@ func TestFacadeSourceVersionEvidenceIsSanitizedAndDetached(t *testing.T) {
 			},
 		},
 	})
-	if err != nil || public == nil || len(public.Sources()) != 1 || public.Sources()[0].VersionCheck == nil {
+	if err != nil || public == nil || len(public.Sources()) != 1 || public.Sources()[0].VersionEvidence == nil {
 		t.Fatalf("unclassified source evidence = %#v, %v", public, err)
 	}
-	if got := public.Sources()[0].VersionCheck; got.Redacted || got.Version.Text != publicText || !got.Version.Present {
+	if got := public.Sources()[0].VersionEvidence; got.Redacted || got.Version.Text != publicText || !got.Version.Present {
 		t.Fatalf("unclassified evidence = %#v", got)
 	}
-	if publicCallback.VersionCheck == nil || !publicCallback.VersionCheck.Redacted || publicCallback.VersionCheck.Version.Text != "" {
+	if publicCallback.VersionEvidence == nil || !publicCallback.VersionEvidence.Redacted || publicCallback.VersionEvidence.Version.Text != "" {
-		t.Fatalf("unclassified callback evidence was not initially conservative: %#v", publicCallback.VersionCheck)
+		t.Fatalf("unclassified callback evidence was not initially conservative: %#v", publicCallback.VersionEvidence)
 	}
 }
 
@@ -626,7 +636,7 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 			Path: configkit.Keys("version"), Check: func(configkit.Version, *configkit.Validation) error { checked++; return nil },
 		}}
 		path := filepath.Join(t.TempDir(), "main.yml")
-		contents := "version: " + canary + "\nconfigkit:\n  imports:\n    - path: missing.yml\n"
+		contents := "version: " + canary + "\nconfigkit:\n  imports:\n    - path: missing.yml\n      required: true\n"
 		if err := os.WriteFile(path, []byte(contents), 0o600); err != nil {
 			t.Fatal(err)
 		}
@@ -640,7 +650,7 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 		if checked != 1 {
 			t.Fatalf("main declaration checker calls = %d; error %v", checked, err)
 		}
-		check := failure.Sources()[0].VersionCheck
+		check := failure.Sources()[0].VersionEvidence
 		if check == nil || !check.Redacted || !check.Version.Present || check.Version.Text != "" {
 			t.Fatalf("early acquisition evidence was not conservatively redacted: %#v; sources %#v", check, failure.Sources())
 		}
@@ -656,14 +666,14 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 		t.Fatalf("malformed version error = %v", err)
 	}
 	sources := loadError.Sources()
-	if len(sources) != 1 || sources[0].VersionCheck == nil || !sources[0].VersionCheck.Redacted ||
+	if len(sources) != 1 || sources[0].VersionEvidence == nil || !sources[0].VersionEvidence.Redacted ||
-		!sources[0].VersionCheck.Version.Present || sources[0].VersionCheck.Version.Text != "" || sources[0].VersionCheck.Path.String() != "/version" {
+		!sources[0].VersionEvidence.Version.Present || sources[0].VersionEvidence.Version.Text != "" || sources[0].VersionEvidence.Path.String() != "/version" {
 		t.Fatalf("failed-load source evidence = %#v", sources)
 	}
-	sources[0].VersionCheck.Path = configkit.Keys("mutated-error")
+	sources[0].VersionEvidence.Path = configkit.Keys("mutated-error")
-	sources[0].VersionCheck.Version.Text = "mutated"
+	sources[0].VersionEvidence.Version.Text = "mutated"
-	sources[0].VersionCheck.Location.Line = 99
+	sources[0].VersionEvidence.Location.Line = 99
-	if again := loadError.Sources()[0].VersionCheck; again.Path.String() != "/version" || again.Version.Text != "" || again.Location.Line == 99 {
+	if again := loadError.Sources()[0].VersionEvidence; again.Path.String() != "/version" || again.Version.Text != "" || again.Location.Line == 99 {
 		t.Fatalf("LoadError source evidence was aliased: %#v", again)
 	}
 	for _, test := range []struct {
@@ -697,7 +707,7 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 			if strings.Contains(err.Error(), test.canary) {
 				t.Fatalf("late failure disclosed source-version canary: %v", err)
 			}
-			check := failure.Sources()[0].VersionCheck
+			check := failure.Sources()[0].VersionEvidence
 			if check == nil || !check.Redacted || !check.Version.Present || check.Version.Text != "" {
 				t.Fatalf("late-failure evidence was not conservatively redacted: %#v", check)
 			}
@@ -705,7 +715,7 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 	}
 
 	defaultResult, err := configkit.Load(configkit.Bytes("default", []byte("version: 7\n")), configkit.Options[map[string]any]{})
-	if err != nil || defaultResult == nil || len(defaultResult.Sources()) != 1 || defaultResult.Sources()[0].VersionCheck != nil {
+	if err != nil || defaultResult == nil || len(defaultResult.Sources()) != 1 || defaultResult.Sources()[0].VersionEvidence != nil {
 		t.Fatalf("default source version check = %#v, %v", defaultResult, err)
 	}
 
@@ -718,7 +728,7 @@ func TestFacadeSourceVersionEvidenceOnFailedLoadsAndSyntheticSources(t *testing.
 	}
 	sawCLI := false
 	for _, source := range withCLI.Sources() {
-		if source.Kind == configkit.SourceKindCLI && source.VersionCheck != nil {
+		if source.Kind == configkit.SourceKindCLI && source.VersionEvidence != nil {
 			t.Fatalf("synthetic CLI source acquired declaration evidence: %#v", source)
 		}
 		sawCLI = sawCLI || source.Kind == configkit.SourceKindCLI
@@ -754,14 +764,14 @@ func TestFacadeSourceVersionEvidencePreservesAbsenceAndNull(t *testing.T) {
 		t.Fatalf("checker calls = %#v; absent contribution must skip while null is checked", checked)
 	}
 	sources := loaded.Sources()
-	if len(sources) != 3 || sources[1].VersionCheck == nil || sources[2].VersionCheck == nil {
+	if len(sources) != 3 || sources[1].VersionEvidence == nil || sources[2].VersionEvidence == nil {
 		t.Fatalf("source version evidence = %#v", sources)
 	}
-	absent := sources[1].VersionCheck
+	absent := sources[1].VersionEvidence
 	if absent.Version.Present || absent.Path.String() != "/version" || absent.Location == nil || absent.Redacted {
 		t.Fatalf("optional omission evidence = %#v", absent)
 	}
-	null := sources[2].VersionCheck
+	null := sources[2].VersionEvidence
 	if !null.Version.Present || !null.Version.Null || null.Version.Text != "" || null.Path.String() != "/version" {
 		t.Fatalf("null declaration evidence = %#v", null)
 	}
@@ -797,7 +807,7 @@ func TestFacadeSourceVersionLifecycleKeepsConsumedHeadersOutOfPayloadHistory(t *
 		},
 		Resolve: func(current *configuration, resolution *configkit.Resolution) error {
 			current.Service.Resolved = "resolved once"
-			resolution.Record(configkit.Keys("service", "resolved"), configkit.ChangeNormalization, "derive resolved value")
+			resolution.RecordNormalization(configkit.Keys("service", "resolved"), "derive resolved value")
 			return nil
 		},
 		Validate: func(current *configuration, validation *configkit.Validation) {
@@ -855,8 +865,8 @@ func TestFacadeSourceVersionLifecycleKeepsConsumedHeadersOutOfPayloadHistory(t *
 		t.Fatalf("consumed declarations affected effective rendering:\n%s\n%s", firstEffective.String(), secondEffective.String())
 	}
 	sourcesA, sourcesB := first.Sources(), second.Sources()
-	if len(sourcesA) != 2 || len(sourcesB) != 2 || sourcesA[1].VersionCheck == nil || sourcesB[1].VersionCheck == nil ||
+	if len(sourcesA) != 2 || len(sourcesB) != 2 || sourcesA[1].VersionEvidence == nil || sourcesB[1].VersionEvidence == nil ||
-		sourcesA[1].VersionCheck.Version.Text != "underlay-release-a" || sourcesB[1].VersionCheck.Version.Text != "underlay-release-b" {
+		sourcesA[1].VersionEvidence.Version.Text != "underlay-release-a" || sourcesB[1].VersionEvidence.Version.Text != "underlay-release-b" {
 		t.Fatalf("sanitized evidence did not retain distinct accepted declarations: %#v / %#v", sourcesA, sourcesB)
 	}
 	versionExplanation, found := first.Explain(configkit.Keys("service", "version"))

facade_tier_history_test.go

@@ -0,0 +1,50 @@
+package configkit_test
+
+import (
+	"testing"
+
+	configkit "go.maximumdirect.net/configkit"
+)
+
+func TestTierHistoryRecordsEachContributionOnce(t *testing.T) {
+	t.Parallel()
+	for _, middle := range []string{"mid", "low"} {
+		t.Run(middle, func(t *testing.T) {
+			result, err := configkit.LoadLayered[map[string]any](
+				configkit.Input{Source: configkit.Bytes("main", []byte("x: high\n"))},
+				configkit.LayeredOptions[map[string]any]{Underlays: []configkit.Underlay{
+					{Inputs: []configkit.Input{{Source: configkit.Bytes("low", []byte("x: low\n"))}}},
+					{Inputs: []configkit.Input{{Source: configkit.Bytes("middle", []byte("x: "+middle+"\n"))}}},
+				}},
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+			history := result.Metadata().History(configkit.Keys("x"))
+			if len(history) != 3 {
+				t.Fatalf("history has %d records; want the three independent contributions", len(history))
+			}
+			explanation, found := result.Explain(configkit.Keys("x"))
+			if !found || len(explanation.History) != len(history) {
+				t.Fatal("explanation lost ordered tier contributions")
+			}
+			for index, sourceID := range []string{"source-2", "source-3", "source-1"} {
+				change := history[index]
+				if len(change.Origin.Locations) != 1 || change.Origin.Locations[0].SourceID != sourceID {
+					t.Fatalf("contribution %d has origin %#v", index, change.Origin)
+				}
+				if len(explanation.History[index].Origin.Locations) != 1 || explanation.History[index].Origin.Locations[0] != change.Origin.Locations[0] {
+					t.Fatalf("explanation contribution %d has a different source origin", index)
+				}
+				if index == 0 {
+					if len(change.Previous) != 0 {
+						t.Fatal("first source contribution has a previous origin")
+					}
+				} else if len(change.Previous) != 1 || len(change.Previous[0].Locations) != 1 ||
+					change.Previous[0].Locations[0] != history[index-1].Origin.Locations[0] {
+					t.Fatalf("contribution %d has incorrect previous origin %#v", index, change.Previous)
+				}
+			}
+		})
+	}
+}

facade_underlay_origins_test.go

@@ -5,7 +5,7 @@ import (
 	"testing"
 	"testing/fstest"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 func TestUnderlaySequenceDescendantOrigins(t *testing.T) {
@@ -31,7 +31,7 @@ func TestUnderlaySequenceDescendantOrigins(t *testing.T) {
 				Definition: configkit.Definition[map[string]any]{Resolve: func(_ *map[string]any, resolution *configkit.Resolution) error {
 					for _, pointer := range paths {
 						path, _ := configkit.ParsePath(pointer)
-						info, ok := resolution.InputInfo(path)
+						info, ok := resolution.EntryInfo(path)
 						if !ok {
 							t.Errorf("missing resolver input %s", pointer)
 						}

facade_version_test.go

@@ -5,7 +5,7 @@ import (
 	"strings"
 	"testing"
 
-	configkit "gitea.maximumdirect.net/eric/ConfigKit"
+	configkit "go.maximumdirect.net/configkit"
 )
 
 type versionCountingReader struct {

go.mod

@@ -1,11 +1,11 @@
-module gitea.maximumdirect.net/eric/ConfigKit
+module go.maximumdirect.net/configkit
 
 go 1.26.0
 
 require go.yaml.in/yaml/v4 v4.0.0-rc.6
 
 require (
-	gitea.maximumdirect.net/eric/ReleaseKit v0.4.1 // indirect
+	gitea.maximumdirect.net/eric/ReleaseKit v0.4.2 // indirect
 	github.com/yuin/goldmark/v2 v2.1.6 // indirect
 	golang.org/x/mod v0.40.0 // indirect
 )

go.sum

@@ -1,5 +1,5 @@
-gitea.maximumdirect.net/eric/ReleaseKit v0.4.1 h1:Qn+mdebYOzCVCEXgCbuGSO/WHmJtItwaQ8e3XwY3qtI=
+gitea.maximumdirect.net/eric/ReleaseKit v0.4.2 h1:P2eDQ29BgyYqHnaz5MV+vzOk7r3s8py2y9k8JISFtJ0=
-gitea.maximumdirect.net/eric/ReleaseKit v0.4.1/go.mod h1:LVodqNQ3OIKv9NBq+fFeyMByd1lHY25YOmmpah/NaNI=
+gitea.maximumdirect.net/eric/ReleaseKit v0.4.2/go.mod h1:LVodqNQ3OIKv9NBq+fFeyMByd1lHY25YOmmpah/NaNI=
 github.com/yuin/goldmark/v2 v2.1.6 h1:igy0q9JcqovoFXFx/XjtU8sHVhcUHavPj2sA3EoKJUE=
 github.com/yuin/goldmark/v2 v2.1.6/go.mod h1:G6M4/qOFtfn01/o14BU1UR2Lo5N3S9Qo7xCuz/sHjGQ=
 go.yaml.in/yaml/v4 v4.0.0-rc.6 h1:1h7H1ohdUh93/FyE4YaDa1Zh64K6VVbjF4K6WUxMtH4=