docs(M03): hand off M2 placement grouper

coordination/claims/M03-RND-M2-PLACEMENT-GROUPER-001.md

@@ -81,14 +81,29 @@ grouping from the worker callback into a scene-free service.
 
 ## Status
 
-- State: claimed
-- Done: boundary, exact preservation rules and ownership published
-- Next: implement grouper, migrate worker callback, tests and docs
+- State: handoff
+- Done: pure grouper, worker adapter, regressions and documentation verified
+- Next: M03 integrator acceptance and merge to master
 - Blocked by:
 
+<!-- OPENWC_HANDOFF:READY:M03-RND-M2-PLACEMENT-GROUPER-001:9df32d3 -->
+
 ## Handoff
 
-- Commit:
-- Results:
-- Remaining risks:
-- Documentation updated:
+- Commit: `9df32d3` (`refactor(M03): extract M2 placement grouper`)
+- Results: dedicated grouper PASS (`cases=9`, `iterations=100`,
+  `placements=256`, `elapsed_ms=67.736`); transform resolver PASS (`cases=9`,
+  `iterations=10000`, `elapsed_ms=28.571`); M2 registry/dedupe, terrain
+  cache/LOD/queue, facade, internal-access, manifest, shutdown, scheduler,
+  streaming planner/focus, terrain-query and coordinate-boundary suites PASS;
+  editor import parsed the project with only expected missing private corpus
+  diagnostics; documentation PASS (`module_specs=17`, `required_files=7`);
+  coordination PASS with 23 pre-existing expired M00/M01 warnings; checkpoint
+  dry-run planned `7/7`.
+- Remaining risks: no private asset-backed traversal/visual comparison;
+  uppercase extension preservation is historical but inconsistent with the
+  resolver's case-insensitive exception matching; grouping remains model-path
+  based rather than spatial-cell based; worker/build state and p95/p99 remain.
+- Documentation updated: inline public API; new
+  `docs/modules/m2-placement-grouper.md`; transform resolver module spec,
+  renderer module registry, `docs/modules/world-renderer.md` and `RENDER.md`.