Audit the public facade boundary

docs/internal/overview.md

@@ -1,94 +1,39 @@
 # Internal Component Overview
 
-ConfigKit exposes the root `configkit` package and keeps its document and YAML
-representations private. The implemented components and their owners are:
+ConfigKit exposes one supported root `configkit` package. The root owns public
+named types, declaration comments, constructors, and explicit conversion/wrapper
+code. It delegates loading and frozen inspection to `internal/engine` through
+private state; public signatures and fields do not expose engine types.
 
-- a temporary `internal/engine` relocation candidate containing a mechanical
-  copy of the root loading, decoding, resolution, provenance, inspection, and
-  rendering mechanisms with their behavior tests; it imports no root code and
-  is not yet used by the root package or consumers;
-- immutable semantic `Path` construction and strict JSON Pointer parsing;
-- detached effective presence/origin and chronological history queries in
-  `metadata.go`, with provenance and diagnostic record types;
-- canonical, control-safe diagnostic rendering and structured `LoadError` access;
-- opaque file, byte, reader, and no-input source construction in `source.go`,
-  with shared regular-file checks and bounded read mechanics in `source_file.go`;
-- a parser-independent ordered tree in `internal/document`, with root-private
-  semantic lookup, indexing, and value traversal in `document_walk.go`;
-- the sole upstream YAML integration in `internal/yaml`, which translates validated
-  input into that owned tree and exposes no parser types outside its boundary;
-  `parse.go` owns shared translation into detached, ordered public diagnostics;
-- a private strict composer in `compose.go` that joins only disjoint document-tree
-  definitions, retains ordered claims and composite mapping origins, reports every
-  conflicting location, and never aliases an input tree;
-- fixed selected-profile loading in `profile.go` and recursive, non-aliasing overlay
-  with displacement records in `overlay.go`; overlay records retain origins,
-  while value explanation uses separate history applications;
-- CLI override validation/preparation in `override.go`, parser-neutral values in
-  `override_value.go`, and synthetic-source application in `override_apply.go`,
-  sharing overlay, source, byte, node, and depth policies;
-- a per-operation private reflection descriptor graph in `schema.go` for supported
-  types, YAML field binding, inlining, secret tags, recursion, and semantic paths;
-- descriptor-driven canonical projection in `projection.go`, detached typed
-  cloning with explicit secret-state modes in `clone.go`, shared reflection and
-  cycle/limit state in `value_operation.go`, and configuration-value comparison
-  in `document_compare.go`; validation separately audits sensitivity and secrets;
-- strict schema-driven decoding over detached defaults in `decode.go`, including
-  mapping/sequence semantics, null and numeric policy, safe codec errors, presence,
-  baseline/final trees, and initial default/input origins;
-- public lifecycle coordination in `load.go`, option selection in `options.go`,
-  input assembly in `load_input.go`, typed phases/publication in `load_result.go`,
-  bounded canonical import DFS in `imports.go`, filesystem context/containment in
-  `filesystem.go`, directive parsing/restrictions in `directives.go`,
-  pattern-directed glob expansion in `glob.go`, schema-version checking and report
-  contexts in `validation.go`, and layered metadata/history assembly in
-  `load_metadata.go`;
-- recorded application defaulting and normalization in `resolution.go`, including
-  callback-scoped fixed entry metadata/source queries, explicitness queries, helper
-  verification, structural mutation audit, coalesced intent, private before/after
-  snapshots, and resolution metadata integration;
-- post-resolution schema-aware report collection and validator mutation detection in
-  `validation.go`, completing the public callback lifecycle after composed input;
-- opaque typed environment references and per-load name resolution in
-  `secret_reference.go`, including credential-free projection/cloning and private
-  validator-state auditing;
-- explicit bounded startup environment bootstrap and safe partial reporting in
-  `secrets.go`;
-- fixed-point tag/predicate/dependency sensitivity classification in `secret.go`;
-- canonical effective output in `render.go`, using frozen-snapshot redaction
-  shared with explanation in `snapshot.go`;
-- detached public explanation records and coordination in `explain.go`, immutable
-  input applications/replay and retained-node budgeting in `history.go`, shared
-  safe snapshot projection in `snapshot.go`, and deterministic human output in
-  `explain_render.go`; the only upstream dumper integration remains isolated in
-  `internal/yaml/write.go`;
-- a separate maintained `examples/consumers` package with four sanitized consumer
-  shapes, fixtures, domain validators, and runtime-boundary functions; and
-- an everyday single-toolchain check in `scripts/check.sh` and a stricter
-  source-candidate checker in `scripts/release-check.sh`, with local
-  documentation-link and public import-boundary gates owned by root-package tests.
+Implemented component owners:
 
-Dependency direction remains inward: the public lifecycle coordinates private
-source, document, schema, and inspection helpers. Semantic paths stay in the root
-package; `internal/document` owns only representation and cloning and never imports
-the root package. Only `internal/yaml` imports the upstream YAML package. Maintained
-consumer examples use the public package and standard library.
+- `internal/engine` owns source acquisition, composition, schema inspection,
+  decoding, lifecycle coordination, callback auditing, provenance/history,
+  secret resolution and bootstrap, and safe inspection rendering. It never
+  imports the root package.
+- Root `Source`, `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
+  error boundaries. There are no public aliases, anonymous engine embeddings, or
+  public engine bridge methods.
+- `internal/document` owns the parser-independent ordered tree and cloning.
+  `internal/yaml` is the sole upstream YAML adapter and parser/dumper boundary.
+- Engine mechanism tests own source, composition, decoding, callback, provenance,
+  secret, history, rendering, and bootstrap behavior. Root tests own public API
+  compatibility, facade integration, documentation links, and dependency/public
+  boundary checks. Consumer examples remain under `examples/consumers`.
 
-The [configuration contract](../config.md) owns implemented input, schema, decoding,
-loading lifecycle, path imports, composition, profile/CLI overlay, version checking,
-recorded resolution, typed secret references/bootstrap, semantic validation,
-metadata, secret classification, redacted effective rendering, historical
-explanation, and ownership behavior.
-The [consumer adoption guide](../consumers/README.md) owns current application-fit
-and migration guidance.
+Dependency direction is root to engine to document/YAML support. The root may
+import only `internal/engine` among project internal production packages; engine
+and its supporting packages do not import root. The root boundary test enforces
+these constraints and rejects exported aliases, fields, or signatures involving
+internal types.
 
-The source-extraction inventory records the application foundations used by the
-implementation:
-
-- [Extraction inventory](extraction.md)
-
-The [architecture policy](../policy/architecture.md) owns binding boundaries and
-invariants. The [deferred scope](../roadmap/deferred.md) records deliberate
-exclusions. See the
-[development guide](../development.md) for contributor orientation and validation
-and the [release procedure](../release.md) for source-candidate gates.
+The [configuration contract](../config.md) owns implemented YAML and lifecycle
+semantics. The [consumer adoption guide](../consumers/README.md) owns application
+guidance. The [architecture policy](../policy/architecture.md) owns contributor
+boundaries, and [ADR 0006](../adr/0006-public-facade.md) records the facade
+decision. See the [development guide](../development.md) for validation commands
+and [release procedure](../release.md) for source-candidate gates.