fix(chat): acquire dedicated session for SSE streaming log finalization

app/routes/chat.py

@@ -533,19 +533,16 @@ async def _finalize() -> None:
                 )
                 from packages.db import session as session_mod
 
-                if session_mod._session_factory is not None:
-                    try:
+                try:
+                    if session_mod._session_factory is not None:
                         async with session_mod._session_factory() as s:
                             s.add(log)
                             await s.commit()
-                    except Exception as commit_err:
-                        logger.warning("request_log_commit_failed", error=str(commit_err))
-                else:
-                    db.add(log)
-                    try:
+                    else:
+                        db.add(log)
                         await db.commit()
-                    except Exception as commit_err:
-                        logger.warning("request_log_commit_failed", error=str(commit_err))
+                except Exception as commit_err:
+                    logger.warning("request_log_commit_failed", error=str(commit_err))
 
             try:
                 async for chunk in _aiter(stream_obj):

tests/integration/test_stream_log_reliability.py

@@ -0,0 +1,137 @@
+"""Streaming chat completions log persistence and teardown resilience tests.
+
+Validates that streaming completion request logs are reliably persisted to the database
+even after the request-scoped dependency session (`get_db()`) has exited and closed.
+"""
+
+from __future__ import annotations
+
+import time
+from unittest.mock import AsyncMock
+
+import pytest
+from httpx import ASGITransport, AsyncClient
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+
+from app import router_cache
+from packages.auth.hashing import hash_api_key
+from packages.db import session as session_mod
+from packages.db.models.api_key import ApiKey
+from packages.db.models.base import Base
+from packages.db.models.request_log import RequestLog
+
+
+@pytest.mark.asyncio
+async def test_streaming_log_persistence_when_dependency_session_is_closed(monkeypatch):
+    """Verify that streaming request logs are written to the database after get_db() dependency session closes.
+
+    Root Cause (Issue #2): get_db() yields `db` and closes it when chat_completions returns
+    StreamingResponse. _finalize() runs post-return during SSE stream output. Using a dedicated
+    session from session_factory ensures the RequestLog is successfully saved despite `db` being closed.
+    """
+    engine = create_async_engine("sqlite+aiosqlite:///:memory:", future=True)
+    async with engine.begin() as conn:
+        await conn.run_sync(Base.metadata.create_all)
+
+    factory = async_sessionmaker(engine, expire_on_commit=False)
+
+    # Seed API key into isolated test database
+    raw_key = "sk-orca-test123456789012345678901234"
+    key_hash = hash_api_key(raw_key)
+    async with factory() as s:
+        s.add(
+            ApiKey(
+                id="key_streaming_test",
+                workspace_id="default",
+                name="test-key",
+                key_hash=key_hash,
+                key_prefix="sk-orca-....1234",
+                is_active=True,
+            )
+        )
+        await s.commit()
+
+    try:
+        # Set _session_factory for authentication middleware and _finalize()
+        session_mod._session_factory = factory
+
+        chunks = [
+            {
+                "id": "chatcmpl-stream-test",
+                "object": "chat.completion.chunk",
+                "model": "gpt-4o-mini",
+                "created": int(time.time()),
+                "choices": [
+                    {
+                        "index": 0,
+                        "delta": {"role": "assistant", "content": "Test stream chunk"},
+                        "finish_reason": "stop",
+                    }
+                ],
+                "usage": {"prompt_tokens": 5, "completion_tokens": 5, "total_tokens": 10},
+                "_orca_meta": {"provider": "openai", "latency_ms": 10},
+            }
+        ]
+
+        fake_client = AsyncMock()
+
+        async def _stream_iter(chunk_list):
+            for c in chunk_list:
+                yield c
+
+        fake_client.acompletion = AsyncMock(
+            return_value=_stream_iter(chunks)
+        )
+
+        async def _fake_get_router(_session):
+            return fake_client
+
+        monkeypatch.setattr(router_cache, "get_router", _fake_get_router)
+
+        from app.deps import get_db
+
+        async def _override_get_db_that_closes_on_return():
+            async with factory() as session:
+                yield session
+                # Dependency scope ends here when chat_completions returns StreamingResponse,
+                # explicitly closing session before _finalize() runs!
+                await session.close()
+
+        from app.main import create_app
+
+        app = create_app()
+        app.dependency_overrides[get_db] = _override_get_db_that_closes_on_return
+
+        async with AsyncClient(
+            transport=ASGITransport(app=app),
+            base_url="http://test",
+            headers={"Authorization": f"Bearer {raw_key}"},
+        ) as c:
+            response = await c.post(
+                "/v1/chat/completions",
+                json={
+                    "model": "gpt-4o-mini",
+                    "messages": [{"role": "user", "content": "hi"}],
+                    "stream": True,
+                },
+            )
+            assert response.status_code == 200
+            body_text = response.text
+            assert "data: [DONE]" in body_text
+
+        # Verify that the streaming request log WAS successfully written to DB via session_factory
+        async with factory() as check_session:
+            rows = (await check_session.execute(select(RequestLog))).scalars().all()
+
+        assert len(rows) == 1, (
+            f"Expected 1 RequestLog row for streaming completion, but found {len(rows)}. "
+            "Streaming log failed to persist when request-scoped db session was closed."
+        )
+        log = rows[0]
+        assert log.is_streaming is True
+        assert log.input_tokens == 5
+        assert log.output_tokens == 5
+    finally:
+        session_mod._session_factory = None
+        await engine.dispose()