commandkit/docs/policy/architecture.md

# Architecture Policy

**Base Policy Version:** 1.3

**Last Updated**: 2026-10-08

**Upstream Source:** [architecture.md](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/docs/policy/architecture.md)

## Purpose And Ownership

CommandKit is an opinionated Go library for standard inspection commands,
consistent CLI syntax, and reduced application command infrastructure. This
policy owns normative responsibility boundaries, dependency direction, and
architectural constraints. ADRs own decision rationale; the
[implementation roadmaps](../development.md#task-specific-reading-guide) own
proposals, sequencing, and implementation status.

Architectural constraints govern future implementation. Concrete package
inventory and mechanics belong in internal documentation when implemented.
Exact exported contracts belong in Go declarations and GoDoc; implemented
operator behavior belongs in the CLI reference. Do not describe planned packages
or APIs as existing implementation.

## Success Criteria

Evaluate designs and adoption against both criteria:

1. Applications adopt consistent command vocabulary, syntax, and inspection
   behavior for the standard suite.
2. Applications remove substantial repeated CLI infrastructure while keeping
   clear ownership of domain behavior.

Existing applications supply evidence of needs, not compatibility requirements
for CommandKit. Adoption is expected to make breaking changes to divergent
consumer conventions. Once CommandKit publishes its own contracts, changes to
those contracts follow the [release policy](release.md).

Use representative simple and complex consumers to substantiate API designs.
Replacing parsing and dispatch plumbing with equally repetitive registration or
callback bookkeeping does not satisfy infrastructure reduction. Keep enough
flexibility to express genuine application requirements within one command model.

## Command And Application Ownership

[ADR 0001](../adr/0001-command-dispatch-and-inputs.md) records the selected
CommandKit-owned dispatcher, per-instance registry, and typed-input model.

CommandKit owns dispatch, common parsing, presence tracking, help, shared syntax
diagnostics, and the handlers and observable contracts of its standard families.
Applications register domain commands outside those families and own their
meaning, effects, domain validation, artifacts, and operational outcomes.
Namespaces provide the ownership boundary: standard `config` and an installed
`promptkit` family remain CommandKit-owned. CommandKit reports registration errors
for attempts to replace their handlers or add private operations beneath them.

Applications own their executable entry points, context creation, signals,
stream selection, runtime construction, and final process exit. CommandKit
returns invocation outcomes and must not terminate the process. Its common
mechanics apply to custom commands without taking ownership of their domain
semantics or success-report formats.

CommandKit's grammar applies to commands using its dispatcher and binding APIs.
Its documentation recommends the same grammar and vocabulary for application-owned
commands, including those outside its dispatcher, under
[ADR 0006](../adr/0006-command-grammar.md).

CommandKit preserves application-supplied outcome classifications and supported
error identity. It assigns responsibility for its diagnostics, avoids duplicate
presentation through its own paths, and reports write failures. Caller callbacks
retain control of their own output. [ADR 0005](../adr/0005-invocation-outcomes.md)
describes the outcome and delivery model.

Use explicit instance construction and composable command registration, not
package-global or import-time registries. One definition supplies routing,
parsing, and help metadata. Duplicate paths and attempts to replace reserved
commands report errors rather than letting registration order select a winner.

Standard families are assembled from declared provider capabilities. Each family
specifies its own resources and supported operations; shared verbs retain
consistent meanings across families. Configuration scopes describe their supported
inspection operations. CommandKit installs the supplied handlers and metadata and
reports actual availability through help and discovery. Missing upstream
capabilities leave other supported operations available.

Help and version use identity/build metadata. CommandKit's registration and
metadata paths leave acquisition callbacks uninvoked. Help and version remain
available with missing or invalid configuration. Callers retain their startup and
callback effects. Version reporting defaults to application identity; explicit
component selection reports embedded library identity.

These rules govern CommandKit's own API, dispatcher, and standard handlers.
Provider contracts define required inputs and results for enabled operations;
callback internals and application execution remain consumer choices. Shared
inspection/execution loading and focused acquisition callbacks are recommended
integration practices. Independent consumer use of other CLI frameworks remains
application-owned.

## Handler Inputs And Invocation State

Handlers receive typed input structs with explicit flag and operand bindings.
Use presence-aware fields where omission matters; preserve explicitly supplied
empty, false, and zero values independently of parser defaults. Context, streams,
and execution dependencies are separate from CLI inputs.

CommandKit keeps parsed values, collections, and presence from one invocation out
of subsequent runs. Storage allocation and safe reuse are implementation choices;
rebuilding backend state is the initial strategy under
[ADR 0002](../adr/0002-cobra-backend.md). Caller-owned closures and runtime state
retain their own lifecycle. Concurrent dispatch is a separate contract.

Applications may interpret parsed domain values and provide domain value parsers
through the binding system. Raw-argument parsing is not the primary handler model.
Keep input declarations available without application initialization.

## Public Facade And Dependency Direction

[ADR 0003](../adr/0003-public-facade.md) records the root `commandkit` facade and
internal adapter boundary. The root is the sole initial supported public package
and defines CommandKit's public named types. Additional public packages require a
deliberate decision based on a durable consumer responsibility.

Public handles retain private implementation state and expose explicitly selected
methods. Any forwarding and conversions must preserve type identity, value
ownership, callback lifetime, presence, and supported public error semantics. Do
not alias public types to internal or backend types, anonymously embed those types
to promote methods, or expose implementation bridge methods.

Straightforward implementation may live in the root package without expanding
its exports. Introduce internal packages, interfaces, and conversions where they
simplify implementation or protect the backend boundary. Package organization and
the amount of internal layering follow implementation needs.

Public signatures, fields, callbacks, constraints, and method sets must not expose
internal or Cobra/pflag types. CommandKit does not expose its internal backend
objects or backend-specific syntax errors through its public API, including
through loosely typed values or returned errors. Caller-supplied values and errors
retain their documented handling; this boundary does not require inspecting or
transforming arbitrary application objects.

Standard contracts such as `context.Context` and `io.Writer` remain appropriate.
Public types from integration libraries, such as ConfigKit and PromptKit, may be
selected as deliberate dependencies. Application-owned input types remain
application-owned. Do not expand exports merely to simplify internal assembly.

## Backend And Library Integration

[ADR 0002](../adr/0002-cobra-backend.md) selects Cobra with pflag as the sole
initial backend. Their types and operations stay inside an internal adapter that
translates CommandKit-owned definitions into backend machinery. Registry logic,
standard handlers, and shared internal representations remain independent of
backend-specific structures.

Reuse backend routing and parsing mechanisms, adapting them to selected
CommandKit semantics. Do not replicate Cobra's entire API through renamed
wrappers. Introduce narrow internal interfaces where actual interactions justify
them; a public backend selection or plugin framework is not part of the design.

ConfigKit and PromptKit own configuration composition, provenance, inspection
semantics, secret classification, and native rendering. Applications provide
schemas, acquisition, domain resolution and validation, and construction of
inspection providers. CommandKit exposes those capabilities without implementing
a parallel configuration or prompt engine. Use independently released public
contracts; do not import sibling internal packages or depend on adjacent checkouts.

Use narrow integration contracts, reusing upstream public types where useful and
introducing CommandKit-owned abstractions where they simplify integration.
Concrete integration needs guide provider representations under
[ADR 0009](../adr/0009-configuration-scopes.md).

Native report writers and safe inspection data preserve owning-library semantics.
Loading all selected views before report output is a `config show` decision under
[ADR 0007](../adr/0007-native-yaml-reports.md); other inspection operations define
their own output timing. Semantic comparison uses supported safe snapshots and
reports sensitivity gaps under [ADR 0008](../adr/0008-semantic-configuration-diff.md).

## Scope And Non-goals

Keep packages and abstractions proportionate to cohesive responsibilities. The
library is not a general application runtime, dependency-injection framework,
logging system, hosted service, or standalone application. Shared vocabulary is
recommended for application-owned commands; their names and domain behavior
remain application choices.

Accepted ADRs and current CLI/API owners define selected contracts; the
[deferred-work record](../roadmap/deferred.md) preserves remaining proposals.
Backend defaults and incidental consumer behavior do not establish new contracts.
A replacement backend must preserve published CLI behavior or follow deliberate compatibility
changes under the release policy.

Base restrictions and guarantees on selected requirements. Configuration and
prompt libraries retain their own confidentiality contracts; standard output
must use their safe inspection APIs without promising that arbitrary application
content is safe for public disclosure. New threat scope or restrictions require
a deliberate decision under the [agent policy](agents.md).