fix(governance): drain km healthcheck backlog

apps/api/src/services/governance_dispatcher.py

@@ -28,11 +28,12 @@ from datetime import datetime, timezone
 from typing import Any
 
 import structlog
-from sqlalchemy import select, update
+from sqlalchemy import exists, select, update
 
 from src.db.base import get_db_context
-from src.db.models import AiGovernanceEvent
+from src.db.models import AiGovernanceEvent, GovernanceRemediationDispatch
 from src.repositories.governance_remediation_dispatch_repo import (
+    ACTIVE_STATUSES,
     DispatchAlreadyActive,
     create_dispatch,
     get_active_for_event,
@@ -136,16 +137,9 @@ async def dispatch_governance_event(event: AiGovernanceEvent) -> str | None:
     event_id = event.id
     event_type = event.event_type
 
-    # Step 0: Redis skip 冷卻檢查（防止 skip 事件每 30s 重新做 LLM 呼叫）
-    if await _is_skip_cooldown(event_id):
-        logger.debug(
-            "governance_dispatch_skip_cooldown",
-            event_id=event_id,
-            event_type=event_type,
-        )
-        return None
-
-    # Step 1: 檢查是否已有活躍 dispatch（冪等保護）
+    # Step 0: 檢查是否已有活躍 dispatch（冪等保護）。
+    # 先查 DB 再看 skip cooldown，避免曾經被 skip 的 knowledge_degradation
+    # 無法補建 Hermes KB healthcheck intake work item。
     existing = await get_active_for_event(event_id)
     if existing is not None:
         logger.debug(
@@ -162,6 +156,15 @@ async def dispatch_governance_event(event: AiGovernanceEvent) -> str | None:
     if _is_kb_growth_healthcheck_event(event):
         return await _record_kb_growth_healthcheck_dispatch(event)
 
+    # Step 1: Redis skip 冷卻檢查（防止一般 skip 事件每 30s 重新做 LLM 呼叫）。
+    if await _is_skip_cooldown(event_id):
+        logger.debug(
+            "governance_dispatch_skip_cooldown",
+            event_id=event_id,
+            event_type=event_type,
+        )
+        return None
+
     # Step 2: 決策融合（三維：LLM × Playbook × MCP）
     adapter = get_decision_fusion_adapter()
     try:
@@ -346,10 +349,15 @@ async def _poll_unresolved_events() -> list[AiGovernanceEvent]:
         最多 _MAX_EVENTS_PER_CYCLE 筆 AiGovernanceEvent ORM 物件列表
     """
     async with get_db_context() as db:
+        active_dispatch_exists = exists().where(
+            GovernanceRemediationDispatch.governance_event_id == AiGovernanceEvent.id,
+            GovernanceRemediationDispatch.dispatch_status.in_(list(ACTIVE_STATUSES)),
+        )
         result = await db.execute(
             select(AiGovernanceEvent)
             .where(AiGovernanceEvent.resolved.is_(False))
             .where(AiGovernanceEvent.event_type.in_(list(_DISPATCHABLE_EVENT_TYPES)))
+            .where(~active_dispatch_exists)
             .order_by(AiGovernanceEvent.triggered_at.asc())
             .limit(_MAX_EVENTS_PER_CYCLE)
         )

apps/api/tests/test_governance_dispatcher.py

@@ -253,6 +253,38 @@ class TestDispatchGovernanceEvent:
         assert dispatch_kwargs["decision_context"]["next_action"] == "run_kb_growth_healthcheck"
         assert dispatch_kwargs["decision_context"]["workflow"]["current_stage"] == "queued_kb_healthcheck"
 
+    @pytest.mark.asyncio
+    async def test_knowledge_degradation_intake_ignores_legacy_skip_cooldown(self):
+        """舊 skip cooldown 不可阻止 KM healthcheck 補建 work item。"""
+        event = _make_governance_event(event_type="knowledge_degradation")
+        event.details = {
+            "remediation": {"next_action": "run_kb_growth_healthcheck"},
+            "ownership": {"lead_agent": "Hermes"},
+        }
+        mock_dispatch_row = MagicMock()
+        mock_dispatch_row.id = "dispatch-kb-cooldown"
+
+        with (
+            patch(
+                "src.services.governance_dispatcher.get_active_for_event",
+                new=AsyncMock(return_value=None),
+            ),
+            patch(
+                "src.services.governance_dispatcher._is_skip_cooldown",
+                new=AsyncMock(return_value=True),
+            ) as mock_skip_cooldown,
+            patch(
+                "src.services.governance_dispatcher.create_dispatch",
+                new=AsyncMock(return_value=mock_dispatch_row),
+            ) as mock_create,
+        ):
+            from src.services.governance_dispatcher import dispatch_governance_event
+            result = await dispatch_governance_event(event)
+
+        assert result == "dispatch-kb-cooldown"
+        mock_skip_cooldown.assert_not_awaited()
+        mock_create.assert_awaited_once()
+
     @pytest.mark.asyncio
     async def test_llm_failure_fallback_to_skip(self):
         """fusion adapter 拋 Exception → fallback skip，不寫 dispatch，返回 None。"""
@@ -467,6 +499,17 @@ class TestDecisionFusionAdapterHelpers:
 class TestRunGovernanceDispatcherLoop:
     """run_governance_dispatcher_loop 排程迴圈行為測試。"""
 
+    def test_poll_unresolved_events_excludes_active_dispatch_rows(self):
+        """poll SQL 必須跳過已有 active dispatch 的事件，避免 backlog 餓死。"""
+        import inspect
+        from src.services import governance_dispatcher
+
+        source = inspect.getsource(governance_dispatcher._poll_unresolved_events)
+
+        assert "GovernanceRemediationDispatch" in source
+        assert "ACTIVE_STATUSES" in source
+        assert ".where(~active_dispatch_exists)" in source
+
     @pytest.mark.asyncio
     async def test_loop_processes_events_and_sleeps(self):
         """loop 一次 cycle 應處理 events 並 sleep。"""