fix(governance): drain km healthcheck backlog

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。"""