Adopt ConfigKit 1.2.0

docs/consumers/pkg-promptkit.md

@@ -18,7 +18,7 @@ import "go.maximumdirect.net/promptkit"
 For migration from the former module path, see
 [Update Go Imports](configuration-migration.md#update-go-imports).
 
-Configuration APIs use `go.maximumdirect.net/configkit` v1.1.0. Its types are
+Configuration APIs use `go.maximumdirect.net/configkit` v1.2.0. Its types are
 not interchangeable with the old ConfigKit module path.
 
 The maintained [offline preparation example](../../examples/go-library/prepare/main.go)
@@ -102,6 +102,39 @@ new engine to observe configuration edits. See the [constructor GoDoc](../../eng
 for the exact public contract and the [framework format reference](../formats.md)
 for definition fields.
 
+### Load Companion Prompts Relative To The Main Configuration
+
+A non-file underlay can use the selected main configuration's directory for
+caller-declared imports. For example, this loads standalone prompt definitions
+from the adjacent `prompts/` directory into the `support` collection:
+
+```go
+main := configkit.Input{Source: configkit.File(configPath)}
+companion, err := promptkit.CollectionInput("support", configkit.Bytes("companion prompts", []byte(`
+config:
+  imports:
+    - dir: prompts
+      pattern: ["*.yaml", "*.yml"]
+      destination: [prompts]
+      placement: sequence-item
+      required: true
+`)))
+if err != nil { return err }
+companion.MainRelative = configkit.MainRelative()
+engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+	Main: &main,
+	Underlays: []configkit.Underlay{{Inputs: []configkit.Input{companion}}},
+}})
+```
+
+`CollectionInput` enables imports; for a raw `configkit.Input`, enable them with
+`Imports: true`. The binding itself does not enable imports, and an explicit
+`Input.Filesystem` takes precedence. Imported prompt `content_file` references
+keep their source-local context. See ConfigKit's
+[layered-loading contract](https://forge.maximumdirect.net/base-layer/configkit/src/tag/v1.2.0/docs/config.md#layered-loading)
+for eligible inputs, fallback contexts, and behavior when the main has no usable
+filesystem context.
+
 ### Use Scoped Engine Views
 
 Create a view when an application wants short request IDs to resolve within a
@@ -181,7 +214,9 @@ input := configkit.Input{Source: document}
 null is not needed. Prompt and backend helpers, like profiles, support sibling
 inheritance via `Extends`; partial records can be completed by other layers.
 For relative prompt `content_file` references, supply the ordinary ConfigKit
-`Input.Filesystem` context for that source. The helpers do not read files or
+`Input.Filesystem` context for that source, or use a
+[main-relative underlay](#load-companion-prompts-relative-to-the-main-configuration).
+The helpers do not read files or
 validate final definitions. Profile and backend provider maps use ConfigKit Mapping input forms: built-in
 scalars, `[]any`, and `map[string]any` recursively. Convert `json.Number` or
 typed containers explicitly to an appropriate supported value, choosing numeric
@@ -300,7 +335,7 @@ for _, difference := range differences {
 ```
 
 See the [`ConfigurationInspection.Diff` GoDoc](../../configuration_inspection.go)
-and ConfigKit's [v1.1.0 effective-configuration diff guidance](https://forge.maximumdirect.net/base-layer/configkit/src/tag/v1.1.0/docs/config.md#effective-configuration-diffs)
+and ConfigKit's [effective-configuration diff guidance](https://forge.maximumdirect.net/base-layer/configkit/src/tag/v1.2.0/docs/config.md#effective-configuration-diffs)
 for the exact comparison contract. The operation compares only frozen effective
 configuration values: it does not reread external files or compare their
 contents, resolved credential contents, later execution preparation, or