런타임 계약과 학습자 흐름 보강

apps/api/engine_gateway/test_gateway_model.py

@@ -135,6 +135,7 @@ def _contract_schema_doc():
         },
         "$defs": defs,
         "x-engine-gateway-sse-events": list(contract.ENGINE_GATEWAY_SSE_EVENTS),
+        "x-engine-gateway-default-model-sentinel": contract.ENGINE_GATEWAY_DEFAULT_MODEL_SENTINEL,
     }
 
 
@@ -171,6 +172,16 @@ class _FakeStreamSession:
 
 
 class GatewayModelTest(unittest.TestCase):
+    def test_contract_owns_gateway_default_model_sentinel(self):
+        self.assertEqual(contract.ENGINE_GATEWAY_DEFAULT_MODEL_SENTINEL, "gateway-default")
+        self.assertIsNone(contract.normalize_engine_gateway_model(None))
+        self.assertIsNone(contract.normalize_engine_gateway_model(""))
+        self.assertIsNone(contract.normalize_engine_gateway_model(" gateway-default "))
+        self.assertEqual(
+            contract.normalize_engine_gateway_model("  request-model  "),
+            "request-model",
+        )
+
     def setUp(self):
         gateway.SESSIONS.clear()
 
@@ -183,6 +194,30 @@ class GatewayModelTest(unittest.TestCase):
         self.assertIs(engine_client.GenerateRequest, contract.GenerateRequest)
         self.assertEqual(contract.ENGINE_GATEWAY_SSE_EVENTS, ("token", "done", "error"))
 
+    def test_split_messages_returns_named_current_turn_prompt_parts(self):
+        parts = gateway._split_messages(
+            [
+                contract.EngineMessage(role="system", content="system one"),
+                contract.EngineMessage(role="system", content=""),
+                contract.EngineMessage(role="system", content="system two"),
+                contract.EngineMessage(role="assistant", content="previous counselor"),
+                contract.EngineMessage(role="user", content="previous client"),
+                contract.EngineMessage(role="user", content="current client"),
+            ]
+        )
+
+        self.assertIsInstance(parts, gateway.GatewayPromptParts)
+        self.assertEqual(parts.system_prompt, "system one\n\nsystem two")
+        self.assertEqual(parts.user_payload, "current client")
+
+    def test_split_messages_preserves_no_user_payload_boundary(self):
+        parts = gateway._split_messages(
+            [contract.EngineMessage(role="system", content="system only")]
+        )
+
+        self.assertEqual(parts.system_prompt, "system only")
+        self.assertEqual(parts.user_payload, "")
+
     def test_sse_frame_helper_preserves_gateway_wire_contract(self):
         self.assertEqual(
             contract.sse_frame("token", contract.StreamTokenEvent(text="hello")),
@@ -286,6 +321,46 @@ class GatewayModelTest(unittest.TestCase):
         for line in golden["compatibility_lines"]:
             self.assertIsNone(compatibility_decoder.feed_line(line))
 
+    def test_generate_response_structured_payload_prefers_structured_field(self):
+        response = contract.GenerateResponse(
+            text='{"reply":"text"}',
+            provider="test",
+            model="test-model",
+            structured={"reply": "structured"},
+        )
+
+        self.assertEqual(
+            contract.structured_payload_from_response(response),
+            {"reply": "structured"},
+        )
+
+    def test_generate_response_structured_payload_accepts_fenced_and_embedded_json(self):
+        fenced = contract.GenerateResponse(
+            text='```json\n{"reply":"fenced"}\n```',
+            provider="test",
+            model="test-model",
+        )
+        embedded = contract.GenerateResponse(
+            text='prefix {"reply":"embedded"} suffix',
+            provider="test",
+            model="test-model",
+        )
+
+        self.assertEqual(contract.structured_payload_from_response(fenced), {"reply": "fenced"})
+        self.assertEqual(
+            contract.structured_payload_from_response(embedded),
+            {"reply": "embedded"},
+        )
+
+    def test_generate_response_structured_payload_rejects_non_object_json(self):
+        response = contract.GenerateResponse(
+            text='["not", "object"]',
+            provider="test",
+            model="test-model",
+        )
+
+        self.assertIsNone(contract.structured_payload_from_response(response))
+
     def test_engine_gateway_json_schema_artifact_validates_golden_fixture(self):
         schema = _load_golden_schema()
         golden = _load_golden_contract()
@@ -321,6 +396,10 @@ class GatewayModelTest(unittest.TestCase):
         payload = json.loads(completed.stdout)
 
         self.assertTrue(payload["ok"])
+        self.assertEqual(
+            payload["defaultModelSentinel"],
+            contract.ENGINE_GATEWAY_DEFAULT_MODEL_SENTINEL,
+        )
         self.assertEqual(payload["streamEvents"], ["token", "done", "error"])
         self.assertEqual(payload["decodedPacketCount"], 4)
 
@@ -504,6 +583,21 @@ class GatewayModelTest(unittest.TestCase):
         self.assertEqual(closed, [started[0]])
         self.assertNotIn(started[0].id, gateway.SESSIONS)
 
+    def test_v1_generate_rejects_missing_user_before_session_resolution(self):
+        req = contract.GenerateRequest(
+            messages=[contract.EngineMessage(role="system", content="system only")]
+        )
+
+        with (
+            patch.object(gateway, "_resolve_session") as resolve_session,
+            self.assertRaises(gateway.HTTPException) as raised,
+        ):
+            asyncio.run(gateway.v1_generate(req))
+
+        self.assertEqual(raised.exception.status_code, 400)
+        self.assertEqual(raised.exception.detail, "no user message in payload")
+        resolve_session.assert_not_called()
+
     def test_v1_stream_frames_token_and_done_events(self):
         session = _FakeStreamSession(
             [
@@ -530,6 +624,21 @@ class GatewayModelTest(unittest.TestCase):
         self.assertEqual(session.timeout, 600.0)
         self.assertTrue(session.closed)
 
+    def test_v1_stream_rejects_missing_user_before_session_resolution(self):
+        req = contract.GenerateRequest(
+            messages=[contract.EngineMessage(role="system", content="system only")]
+        )
+
+        with (
+            patch.object(gateway, "_resolve_session") as resolve_session,
+            self.assertRaises(gateway.HTTPException) as raised,
+        ):
+            asyncio.run(gateway.v1_stream(req))
+
+        self.assertEqual(raised.exception.status_code, 400)
+        self.assertEqual(raised.exception.detail, "no user message in payload")
+        resolve_session.assert_not_called()
+
     def test_v1_stream_frames_engine_error_event(self):
         session = _FakeStreamSession(
             [