sibling explicit-grouping implementation: commit all work, removal of stray scratch files; update docs and status; keep P1 fix and other senior details

docs/project-status.md

@@ -1,3 +1,17 @@
+## Explicit grouping extension — implementation worktree status
+
+Implemented confirmed opt-in grouping, stable existing catalog identity, immutable persisted
+decisions, and durable collision planning before no-overwrite publication with recovery and
+conservative compensation. Default legacy wiring is retained. Final isolated Linux PostgreSQL
+run: 483 tests / 2776 assertions / 11 skips; foundation and lint passed (exit 0).
+Linux SQLite: 483 tests / 2407 assertions / 44 skips. Remote RED preceded implementation.
+Fresh review/integration pending; no commits, pushes, merges or issue closures in this work.
+Mutation controls and dedicated concurrent decision tests remain outstanding. See
+`.superpowers/shared-contracts/explicit-grouping-report.md` and `docs/explicit-grouping.md`
+for exact evidence and filesystem durability limitations. Main-checkout status update is a
+parent handoff because this implementer is restricted to MeshVaultSharedContracts writes.
+
+
 # Acceptance reconciliation — 2026-10-12
 
 Baseline: `c1ef2ee`. This review compares the live Gitea acceptance criteria with