fix(km): bound knowledge readbacks under pool pressure

apps/api/tests/test_knowledge_service_readback_degraded.py

@@ -1,3 +1,5 @@
+import asyncio
+
 import pytest
 
 from src.models.knowledge import (
@@ -122,6 +124,30 @@ async def test_knowledge_list_entries_retries_transient_pool_timeout(monkeypatch
     assert response.operator_stage == "knowledge_readback_primary_retry_recovered"
 
 
+@pytest.mark.asyncio
+async def test_knowledge_list_entries_bounds_primary_timeout_to_source_backed(monkeypatch) -> None:
+    service = KnowledgeService.__new__(KnowledgeService)
+    calls = 0
+
+    async def never_finishes_primary(**_kwargs):
+        nonlocal calls
+        calls += 1
+        await asyncio.Event().wait()
+
+    monkeypatch.setattr(service, "_list_entries_from_primary", never_finishes_primary)
+    monkeypatch.setattr(knowledge_service_module, "_PRIMARY_KM_LIST_TIMEOUT_SECONDS", 0.01)
+    monkeypatch.setattr(knowledge_service_module, "_PRIMARY_KM_LIST_RETRY_TIMEOUT_SECONDS", 0.01)
+    monkeypatch.setattr(knowledge_service_module, "_PRIMARY_KM_RETRY_DELAY_SECONDS", 0)
+
+    response = await service.list_entries(limit=50)
+
+    assert calls == 2
+    assert response.readback_status == "source_backed_degraded"
+    assert response.primary_readback_ready is False
+    assert response.degraded_reason_code == "primary_km_db_timeout_or_pool_exhausted"
+    assert response.total == 13
+
+
 @pytest.mark.asyncio
 async def test_knowledge_list_entries_keeps_primary_items_when_taxonomy_degrades(monkeypatch) -> None:
     primary_entry = KnowledgeEntry(
@@ -247,3 +273,54 @@ async def test_knowledge_asset_taxonomy_fails_soft_when_readback_breaks(monkeypa
         "schedule",
     ]
     assert all(row.count >= 1 for row in taxonomy)
+
+
+@pytest.mark.asyncio
+async def test_knowledge_side_readbacks_bound_timeouts_to_source_backed(monkeypatch) -> None:
+    service = KnowledgeService.__new__(KnowledgeService)
+
+    async def never_finishes(*_args):
+        await asyncio.Event().wait()
+
+    monkeypatch.setattr(knowledge_service_module, "_PRIMARY_KM_SIDE_READ_TIMEOUT_SECONDS", 0.01)
+    monkeypatch.setattr(service, "_read_primary_categories", never_finishes)
+    monkeypatch.setattr(service, "_read_primary_asset_taxonomy", never_finishes)
+    monkeypatch.setattr(service, "_search_primary_entries", never_finishes)
+
+    categories = await service.get_categories()
+    taxonomy = await service.get_asset_taxonomy()
+    entries = await service.search("Telegram", limit=10)
+
+    assert [row.category for row in categories] == [
+        "project",
+        "product",
+        "website",
+        "service",
+        "package",
+        "tool",
+        "log",
+        "alert",
+        "playbook",
+        "rag",
+        "mcp",
+        "schedule",
+        "general",
+    ]
+    assert [row.key for row in taxonomy] == [
+        "project",
+        "product",
+        "website",
+        "service",
+        "package",
+        "tool",
+        "log",
+        "alert",
+        "playbook",
+        "rag",
+        "mcp",
+        "schedule",
+    ]
+    assert {entry.id for entry in entries} >= {
+        "source-backed-service-telegram-alert-receipts",
+        "source-backed-alert-telegram-monitoring-coverage",
+    }