Rename selected configuration profiles to overlays

docs/internal/extraction.md

@@ -137,9 +137,11 @@ permission failures, explicit `conf.d` use, and entry/candidate budgets. This wo
 has no Narratio production equivalent; it uses the selected standard-library
 `path.Match` and bounded `File.ReadDir` adaptation rather than its flat loader.
 
-### Profiles and overlay
+### Upstream profiles and ConfigKit selected overlays
 
-Assigned to selected-profile overlay:
+The following upstream symbols and case names retain their original profile
+terminology. ConfigKit adapts their selected-overlay behavior without renaming the
+upstream evidence:
 
 - Production: `mergeOverlayComposition`, `mergeOverlayNodes`,
   `selectPipelineProfile`, `loadPipelineProfileOverlays`, and
@@ -153,19 +155,21 @@ Assigned to selected-profile overlay:
   `TestLoadPipelineProfilePairResolvesIndependentEffectivePipelines`.
 - Preserve: recursive mapping overlay, atomic scalar/sequence replacement,
   deterministic selection failures, source ownership, and independent results.
-- Adapt: load only the selected fixed profile path; lowercase `default` means no
-  overlay. ConfigKit permits null and cross-kind replacement and does not support
-  declared defaults, inheritance, arbitrary profile paths, or validating every
+- Adapt: load only the selected fixed overlay path; lowercase `default` means no
+  selection. ConfigKit permits null and cross-kind replacement and does not support
+  declared defaults, inheritance, arbitrary overlay paths, or validating every
   unselected overlay.
 
-Implementation record (2026-09-06): `overlayDocuments`, `mergeOverlayMappings`,
-`loadProfileDocument`, and `profileDirectiveDiagnostics` adapt the assigned merge,
-selection, loading, and ownership mechanics. `TestOverlayDocumentsRecursesMappingsAndReplacesAtomicSubtrees`,
-`TestLoadAppliesSelectedProfileAfterBaseAndBeforeDefaults`, profile selection/error,
-directive/version, containment, and budget cases adapt the assigned tests. ConfigKit
+Implementation record (2026-09-06, updated 2026-09-23): `overlayDocuments`,
+`mergeOverlayMappings`, `loadSelectedOverlayDocument`, and
+`overlayDirectiveDiagnostics` adapt the assigned merge, selection, loading, and
+ownership mechanics. `TestOverlayDocumentsRecursesMappingsAndReplacesAtomicSubtrees`,
+`TestLoadAppliesSelectedOverlayAfterBaseAndBeforeDefaults`, selected-overlay
+selection/error, directive/version, containment, and budget cases adapt the assigned
+tests. ConfigKit
 uses exactly one fixed selected `.yml` source, permits null and cross-kind replacement,
-retains displaced descendant history, rejects any profile directive or version-path
-contribution, and counts the profile in aggregate budgets. Narratio's declared
+retains displaced descendant history, rejects any overlay directive or version-path
+contribution, and counts the overlay in aggregate budgets. Narratio's declared
 default, multi-overlay validation, inheritance-like application conventions, and
 null/kind restrictions were not retained.
 
@@ -196,7 +200,7 @@ previously extracted source claims, overlay displacement records, typed baseline
 and audited resolution snapshots in `load_metadata.go`. The representative
 `TestLayeredProvenanceAgreesWithResolvedSnapshot` adapts Narratio's stable ownership,
 profile ownership, deterministic effective projection, and side-effect-free
-inspection cases across one default/import/profile/resolution workflow. ConfigKit
+inspection cases across one default/import/overlay/resolution workflow. ConfigKit
 adds chronological descendant history for parent and whole-sequence operations,
 composite empty-mapping origins, canonical resolution reasons/dependencies, private
 snapshot agreement, defensive nested copies, and concurrent load isolation. Value