feat: add queue processor with model resolution

tests/test_services.py

@@ -187,3 +187,74 @@ async def test_worker_client_health():
         client = WorkerClient()
         is_healthy = await client.health()
         assert is_healthy is True
+
+
+@pytest.mark.asyncio
+async def test_resolve_model_request_overrides():
+    from src.backend.services.queue import resolve_model
+
+    model = resolve_model(
+        request_model="claude-opus-4-7",
+        topic_model="claude-sonnet-4-6",
+    )
+    assert model == "claude-opus-4-7"
+
+
+@pytest.mark.asyncio
+async def test_resolve_model_topic_fallback():
+    from src.backend.services.queue import resolve_model
+
+    model = resolve_model(
+        request_model=None,
+        topic_model="claude-sonnet-4-6",
+    )
+    assert model == "claude-sonnet-4-6"
+
+
+@pytest.mark.asyncio
+async def test_resolve_model_global_fallback():
+    from src.backend.services.queue import resolve_model
+
+    model = resolve_model(request_model=None, topic_model=None)
+    assert model == "claude-sonnet-4-6"
+
+
+@pytest.mark.asyncio
+async def test_process_one_request():
+    from src.backend.services.queue import process_one
+    from src.backend.db.database import (
+        init_db,
+        get_db,
+        create_topic,
+        create_request,
+        get_request,
+    )
+
+    await init_db()
+    db = await get_db()
+    try:
+        topic = await create_topic(db, "test-queue", "System prompt")
+        req = await create_request(db, "Hello", topic["id"])
+    finally:
+        await db.close()
+
+    mock_worker = AsyncMock()
+    mock_worker.process.return_value = {
+        "success": True,
+        "result": "Hi there!",
+        "session_id": None,
+    }
+    mock_worker.summarize.return_value = {
+        "success": True,
+        "summary": "Greeted the user.",
+    }
+
+    await process_one(mock_worker)
+
+    db = await get_db()
+    try:
+        updated = await get_request(db, req["id"])
+        assert updated["status"] == "completed"
+        assert updated["result"] == "Hi there!"
+    finally:
+        await db.close()