Record effective diff baseline evidence

docs/roadmap/implementation.md

@@ -110,7 +110,7 @@ its public contract.
 
 ## Stage 1 — Establish evidence and record the architectural decision
 
-Status: planned. Scope: orientation, baseline evidence, and one ADR; no feature
+Status: complete. Scope: orientation, baseline evidence, and one ADR; no feature
 code or current-behavior documentation changes.
 
 1. Confirm the baseline and inspect the roadmap and relevant code/test owners:
@@ -133,6 +133,27 @@ Done: baseline evidence and an accepted decision are recorded. Existing public
 behavior remains unchanged; the deferred inventory is reconciled when the API
 lands in Stage 10.
 
+### Baseline evidence
+
+- Implementation baseline: `3697a511242d60c860549f09f02b75d1eb2fe660`;
+  planning baseline: `e82b1c90543a6ab92138ee8c0c2a4cd4daea8af0`. The worktree was
+  clean before validation. The accepted architectural decision is recorded in
+  [ADR 0010](../adr/0010-effective-configuration-diff.md).
+- `GOTOOLCHAIN=local go version`: `go1.26.8 linux/amd64`.
+  `GOTOOLCHAIN=local ./scripts/check.sh`: passed formatting, whitespace,
+  `go test ./...`, `go vet ./...`, and `go build ./...`. No environmental
+  limitations were encountered.
+- Existing owners identified: canonical changed-region comparison and escaped
+  ordering in `internal/engine/document_compare.go` and
+  `TestCompareConfigurationValuesSortEscapedPointers`; snapshot presence and
+  redaction in `internal/engine/snapshot.go`, `internal/engine/render.go`, and
+  `TestWriteEffectiveRedactsTagsDynamicHistoryAndDependencyCycles`; frozen
+  inspection state and read-only lookups in `internal/engine/load_result.go`,
+  `internal/engine/document_lookup.go`, `TestFacadeInspectionUsesFrozenState`,
+  and `TestConcurrentReadOnlyInspectionQueries`; load-failure behavior in
+  `TestLoadReturnsNilForSourceSchemaAndDecodeFailures` and
+  `TestFacadeLoadReturnsFacadeLoadError`.
+
 ## Stage 2 — Prepare canonical changed regions
 
 Status: planned. Scope: a private helper and structural tests only.