docs: document direct edit solver and API contracts

.trellis/workspace/dingkang/journal-1.md

@@ -80,3 +80,63 @@ diagnostics, and wired road profiles and junction plans into geometry compilatio
 ### Next Steps
 
 - Implement exact/recheck/pending/conflicted/stale replay matching (step 4).
+
+## Session 4: Direct-edit replay matching
+
+**Date**: 2026-08-27
+**Task**: Continue `direct-edit-solver-api`, step 4
+**Git Commit**: `735ce69`
+
+### Summary
+
+Added exact-anchor replay classification, snapshot candidate fallback, stale
+lane-boundary handling, and compiler-geometry `recheck` propagation.
+
+### Testing
+
+- [OK] npm test; npm run format:check; npm run test:client; npm run test:client:unit; npm run build
+
+### Next Steps
+
+- Add the read-only edit-state and edit-preview endpoints (step 5).
+
+## Session 5: Read-only edit APIs
+
+**Date**: 2026-08-27
+**Task**: Continue `direct-edit-solver-api`, step 5
+**Git Commit**: `41c314f`
+
+### Summary
+
+Added `GET /api/edit-state` and `POST /api/edit-preview`. Preview compiles from
+the draft document without writing active files and returns sequence, degraded
+status, diagnostics, handles, and derived layers.
+
+### Testing
+
+- [OK] npm test; npm run format:check; npm run test:client; npm run test:client:unit; npm run build
+
+### Next Steps
+
+- Implement edit/revision/rebase writes with expected-version protection (step 6).
+
+## Session 6: Edit persistence and rebase APIs
+
+**Date**: 2026-08-27
+**Task**: Complete `direct-edit-solver-api`, step 6
+**Git Commit**: `f3f763f`
+
+### Summary
+
+Added atomic active-document saves with expected-version 409 protection,
+revision checkpoint creation, and read-only revision rebase status summaries.
+Existing state/session responses now expose active revision and document version.
+
+### Testing
+
+- [OK] npm test; npm run format:check; npm run test:client; npm run test:client:unit; npm run build
+
+### Next Steps
+
+- Run the solver-api quality review, then archive the child task before starting
+  the map-editor child task.