[wtj-0527]

Closes #22

Summary

• preserve the retained latest local intent on expectedRevision conflict and offer explicit local / remote / merged resolution against the newly fetched remote revision
• render saving, saved, failed, conflict, retry, and merge-saving states consistently across Steps 3/5/6 with D1.3 blue/red/amber semantics
• derive bounded per-piece Rust/WASM fields from the same canonical wall/opening spans used by selection overlays, so the minimum legal narrow opening remains visibly open on long walls while every piece retains its canonical wallId
• keep autosave serialized/latest-intent-wins after conflict resolution and reset merged canonical data to Step 3 for renewed 2D/3D review

RED → GREEN

Focused RED reproduced all three review blockers:

• project session had no local/remote/merge conflict-resolution API and discarded the retained intent on reload
• D1.3 state tests found conflict copy in red and Step 6 fixed green/purple regardless of real request state
• the legal 4000-unit wall / width 8 door probe produced a real WASM surface ray hit through the supposed doorway

GREEN regressions now prove:

• local, remote, and merged choices use the freshly fetched remote revision; local intent is retained, merged by stable IDs, persisted, and re-opened for parity review
• Step 3/5/6 display one truthful blue saving state, red failure state, or amber conflict state, including explicit retry and three conflict actions
• the same narrow-door probe produces compiled Rust/WASM geometry with no ray intersection through the doorway; resource bounds remain nx <= 97, ny = 33, nz = 9 per solid piece

Validation

Local validation on the final source candidate:

• frontend Vitest: 24 files / 146 tests passed (includes compiled real-WASM narrow-opening regression)
• frontend lint and TypeScript: passed
• frontend production build + real WASM build: passed
• Go: go test -p 1 ./... passed
• Rust/WASM: 12 tests passed
• production browser/PostgreSQL/S3/restart E2E: 15 passed
• git diff --check: passed

Exact-head CI for f5b31ecc3e82a2e1c2e3140c4a28c52c27c4679c:

• Backend tests: passed
• Frontend, WASM, and production build: passed
• Production browser persistence E2E: passed
• Socket Security checks: passed

LPK consistency

No packaging/install contract changed. package.yml, lzc-manifest.yml, lzc-build.yml, lzc-deploy-params.yml, and lzc-icon.png are unchanged from the frozen base and remain consistent with the same frontend/backend/PostgreSQL/S3 build, routing, persistence, health, and install behavior.

Candidate identity

• Base: f63f1c35bad793964165f91502aa14ae3fbb95fd
• Base Tree: a49bc7999b8af4f04812301e49daafc05769f5bd
• HEAD: f5b31ecc3e82a2e1c2e3140c4a28c52c27c4679c
• Tree: c74b4d7adf5ea871705f7ffd5874b052e90b37bc
• Patch SHA-256 (base...HEAD, binary diff): cf2fbce145eca12e7b0480f1cf132d7d9efaa9061562f549ea32a7a7243d655e