fix(workbench): serialize events and target work order sync

tests/unit/test_workbench_event_hub.py

@@ -1,10 +1,12 @@
 import asyncio
+from types import SimpleNamespace
 from unittest.mock import AsyncMock
 from uuid import uuid4
 
 import pytest
 
 from app.infra.db.postgresql.workbench_event_hub import WorkbenchEventHub, WorkbenchEventHubManager
+from app.infra.db.postgresql import workbench_event_hub as hub_module
 
 
 @pytest.fixture
@@ -30,3 +32,60 @@ async def test_project_subscribers_share_one_hub_and_idle_close(monkeypatch):
     await asyncio.sleep(0.03)
     assert len(manager._hubs) == 0
     close.assert_awaited_once()
+
+
+@pytest.mark.anyio
+async def test_idle_subscribers_share_cursor_reads_and_notification_invalidates_the_cache(monkeypatch):
+    reads = 0
+
+    class Repository:
+        def __init__(self, *_args):
+            pass
+
+        async def read_after(self, _after):
+            nonlocal reads
+            reads += 1
+            return []
+
+    monkeypatch.setattr(hub_module, "WorkbenchEventRepository", Repository)
+    hub = WorkbenchEventHub(uuid4(), "postgresql://test/db")
+    hub._connection = SimpleNamespace(closed=False)
+    monkeypatch.setattr(hub, "start", AsyncMock())
+    await asyncio.gather(*(hub.read_after(0) for _ in range(20)))
+    assert reads == 1
+    await hub._wake()
+    await asyncio.gather(*(hub.read_after(0) for _ in range(20)))
+    assert reads == 2
+
+
+@pytest.mark.anyio
+async def test_notification_during_read_does_not_cache_stale_results(monkeypatch):
+    entered, release = asyncio.Event(), asyncio.Event()
+    reads = 0
+
+    class Repository:
+        def __init__(self, *_args):
+            pass
+
+        async def read_after(self, _after):
+            nonlocal reads
+            reads += 1
+            if reads == 1:
+                entered.set()
+                await release.wait()
+            return []
+
+    monkeypatch.setattr(hub_module, "WorkbenchEventRepository", Repository)
+    hub = WorkbenchEventHub(uuid4(), "postgresql://test/db")
+    hub._connection = SimpleNamespace(closed=False)
+    monkeypatch.setattr(hub, "start", AsyncMock())
+    first = asyncio.create_task(hub.read_after(0))
+    await entered.wait()
+    await hub._wake()
+    release.set()
+    await first
+    await hub.read_after(0)
+    assert reads == 2
+    for cursor in range(100):
+        await hub.read_after(cursor)
+    assert len(hub._reads) == 32