fix: address review findings — backward compat, ACP safety, result timing, security

- Fix 1: tasks_md_sync only sets MACP fields when columns exist in table headers
- Fix 2: ACP dispatch now escalates instead of falsely completing
- Fix 3: Removed premature collect_result() from dispatch_task()
- Fix 4: Yolo brief staged via temp file (0600) instead of process args
- Fix 5: cleanup_worktree validates path against configured worktree base

docs/scratchpads/macp-phase1.md

@@ -56,6 +56,32 @@ Implement MACP Phase 1 in `mosaic-bootstrap` by extending the orchestrator-matri
 - 2026-03-27: Added explicit worker escalation handling via the `MACP_ESCALATE:` stdout marker.
 - 2026-03-27: Committed and pushed branch `feat/macp-phase1` (`7ef49a3`, `fd6274f`).
 - 2026-03-27: Blocked in PR workflow when `~/.config/mosaic/tools/git/pr-create.sh` failed to resolve the remote repository from this worktree.
+- 2026-03-28: Resumed from blocked state for a review-fix pass covering 5 findings in `docs/tasks/MACP-PHASE1-fixes.md`.
+
+## Review Fix Pass
+
+### Scope
+
+1. Restore legacy `tasks_md_sync.py` behavior so rows without MACP headers do not become MACP tasks.
+2. Make ACP dispatch fail-safe via escalation instead of a no-op success path.
+3. Move MACP result writes to the controller after quality gates determine the final task status.
+4. Remove brief text from yolo command arguments by switching to file-based brief handoff.
+5. Restrict worktree cleanup to validated paths under the configured worktree base.
+
+### TDD / Test-First Decision
+
+1. This is a bug-fix and security-hardening pass, so targeted reproducer verification is required.
+2. Repo appears to use focused script-level verification rather than a Python test suite for this surface, so reproducer checks will be command-driven and recorded as evidence.
+
+### Planned Verification Additions
+
+| Finding | Verification |
+|---|---|
+| Legacy task reclassification | Sync `docs/TASKS.md` without MACP headers into `tasks.json` and confirm `dispatch` is absent so controller stays on `run_shell()` |
+| ACP no-op success | Run controller/dispatcher with `dispatch=acp` and confirm `status=escalated`, exit path is non-zero, and `task.escalated` is emitted |
+| Premature result write | Inspect result JSON after final controller state only; confirm gate results are present and no dispatcher pre-write remains |
+| Brief exposure | Build yolo command and confirm the brief body is absent from the command text |
+| Unsafe cleanup | Call cleanup against a path outside configured base and confirm it is refused |
 
 ## Tests Run