fix(gateway): unblock task claim; full Phase 0/1/2 remediation

Resolves the 100% claim-failure rate introduced by the gateway rewrite
  (commit 62bda0c plus 78 follow-ups). Live smoke runs hit
  `404 /api/v2/flow/developer/...` on every dev verb plus a manifest
  fallback that silently exposed off-role verbs to PMs — confirmed
  firing simultaneously in NAS agent logs (be-dev-1, be-pm, main-pm).

  Audit reports under docs/internal/audit_2026_05_04/ catalogue 49
  defects across gateway, services, prompts, MCP transport, substrate,
  and tests (8 detail reports + master synthesis). Six smoking guns;
  three proven in production logs.

  Phase 0 — unblock claim:
  - URL prefix /api/v2/flow/dev → /developer; slug-map board roles
    (product_owner, head_marketing) → /board (D-01)
  - _i_will_work_on AttributeError on None across pending /
    needs_revision / claimed re-entry branches (D-02)
  - Seed last_heartbeat_at in _qa_or_doc_claim (D-03)
  - Drop misleading i_have_committed verb; dev flow uses commit() (D-04)
  - Manifest mount via compose; flow_server + do_server fail loud
    instead of exposing all-verbs fallback (D-12)
  - MCP _post() surfaces envelope body on 4xx so agents see remediate
    hints (D-13)
    on git failure so retries aren't blocked by half-state (S-01)

  Phase 1 — lifecycle stability:
  - _resolve_skill falls back to AgentTable.capabilities (D-06)
  - main_pm_complete uses kwargs for escalate_to_ceo (D-07)
  - i_am_done auto-runs submit_verification when in_progress (D-08)
  - active_claimant_id wired in claim/unclaim paths — single-claimant
    invariant now functional (D-05)
  - qa_pass/qa_fail assert claimed_by parity with qa_agent_id (D-18)
  - Prompt-drift sweep: fail() shape, i_am_done(task_id, notes),
    subtask cap (12 hard / 8 soft), error-code symbology rewritten in
    base.md + per-role anti-patterns (D-10/11/29/30/31, D-37)

  Phase 2 — invariants + architecture:
  - Real-DB integration test exercising claim → in_progress → commit
    → submit_for_qa → i_am_done → awaiting_qa (P2-1)
  - choreographer.py → package; 3 of 6 role mixins extracted
    (board, doc, qa). _impl.py 2,526 → 2,080 lines (-18%). Continuation
    plan in docs/internal/audit_2026_05_04/p2_2_decompose_plan.md (P2-2)
  - Closure guards consolidated via _subtasks_not_terminal_envelope (P2-3)
  - TaskService.unclaim_for_reaper routed through canonical
    _validate_and_set_status; in_progress → pending added to
    VALID_TRANSITIONS (P2-4)
  - Dead code removed: i_am_done_with_catchup verb, _run_catch_up helper
    (P2-5)
  - 6 state-machine invariants asserted via property test (P2-6)
  - attempt_id (uuid4) stamped on every gateway.rejected audit row (P2-7)
  - _reconcile_orphan_claims_on_startup rolls back tasks left CLAIMED
    with branch_name=NULL from prior crashes (P2-8)
  - scripts/regenerate_verb_tables.py introspects Pydantic schemas +
    role_config; compose_prompt injects per-role tables as a layer.
    Eliminates the prompt-drift class structurally (P2-9)

  Other:
  - D-48: orchestrator mounts host's ~/.claude.json when present so
    agents don't boot from backup recovery on every spawn
  - D-49: dev dispatcher rejects role-mismatched spawns (e.g. doc task
    assigned to dev agent)

  Tests: 553 pass · ruff + mypy clean. Live NAS smoke verification
  pending — needs the stack brought back up.

tests/unit/services/test_task.py

@@ -442,27 +442,34 @@ async def test_doc_claim_sets_assignment_on_awaiting_documentation() -> None:
 
 @pytest.mark.asyncio
 async def test_qa_pass_delegates_to_pass_qa() -> None:
-    svc = TaskService(MagicMock())
-    pass_qa_mock = AsyncMock(return_value=MagicMock())
-    _bind(svc, "pass_qa", pass_qa_mock)
+    qa_id = uuid4()
     task_id = uuid4()
-    await svc.qa_pass(uuid4(), task_id, "looks good")
+    task = _build_task(id=task_id, claimed_by=qa_id)
+    svc = TaskService(MagicMock(flush=AsyncMock()))
+    pass_qa_mock = AsyncMock(return_value=MagicMock())
+    _bind(svc, "get", AsyncMock(return_value=task))
+    _bind(svc, "pass_qa", pass_qa_mock)
+    await svc.qa_pass(qa_id, task_id, "looks good")
     pass_qa_mock.assert_awaited_once_with(task_id, notes="looks good", agent_role="qa")
+    # active_claimant_id cleared so the documenter can claim cleanly.
+    assert task.active_claimant_id is None
 
 
 @pytest.mark.asyncio
 async def test_qa_fail_appends_issues_to_dev_notes() -> None:
-    task = _build_task(dev_notes=None)
+    qa_id = uuid4()
+    task = _build_task(dev_notes=None, claimed_by=qa_id)
     svc = TaskService(MagicMock(flush=AsyncMock()))
     fail_qa_mock = AsyncMock(return_value=task)
     _bind(svc, "get", AsyncMock(return_value=task))
     _bind(svc, "fail_qa", fail_qa_mock)
     issues = ["missing test", "no docstring"]
-    await svc.qa_fail(uuid4(), task.id, "blocking", issues)
+    await svc.qa_fail(qa_id, task.id, "blocking", issues)
     assert task.dev_notes is not None
     assert "missing test" in task.dev_notes
     assert "no docstring" in task.dev_notes
     fail_qa_mock.assert_awaited_once_with(task.id, notes="blocking", agent_role="qa")
+    assert task.active_claimant_id is None
 
 
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