feat: stream provider responses

tests/unit/test_provider_router.py

@@ -16,6 +16,7 @@ from javis.providers.base import (
     ProviderRateLimitError,
     ProviderTimeoutError,
     ProviderUsage,
+    ResponseAbortedError,
 )
 from javis.security.privacy import CloudPolicy, PrivacyRouter
 
@@ -28,11 +29,15 @@ class _RecordingProvider:
         *,
         answer: str = "Antwort",
         error: Exception | None = None,
+        stream_chunks: tuple[str, ...] | None = None,
+        stream_error: Exception | None = None,
     ) -> None:
         self.name = name
         self.model = model
         self.answer = answer
         self.error = error
+        self.stream_chunks = stream_chunks
+        self.stream_error = stream_error
         self.calls: list[list[ChatMessage]] = []
         self.last_usage = ProviderUsage(11, 5)
 
@@ -42,6 +47,17 @@ class _RecordingProvider:
             raise self.error
         return self.answer
 
+    def stream_chat(self, messages: list[ChatMessage]):
+        self.calls.append(messages)
+        if self.stream_chunks is None:
+            if self.error:
+                raise self.error
+            yield self.answer
+        else:
+            yield from self.stream_chunks
+        if self.stream_error:
+            raise self.stream_error
+
 
 class HybridProviderTests(unittest.TestCase):
     def setUp(self) -> None:
@@ -283,6 +299,64 @@ class HybridProviderTests(unittest.TestCase):
         self.assertFalse(router.last_route.cloud_suppressed_by_local_mode)
         self.assertTrue(router.last_route.technical_fallback)
 
+    def test_allowed_cloud_response_streams_visible_chunks(self) -> None:
+        self.cloud.stream_chunks = ("Cloud ", "Stream")
+        router = self._router()
+
+        chunks = list(router.stream_chat([ChatMessage("user", "Wie funktioniert SQLite?")]))
+
+        self.assertEqual(chunks, ["Cloud ", "Stream"])
+        self.assertEqual(router.last_route.provider, "gemini")
+        self.assertFalse(router.last_route.fallback)
+
+    def test_cloud_stream_error_before_output_falls_back_locally(self) -> None:
+        self.cloud.stream_chunks = ()
+        self.cloud.stream_error = CloudNetworkError("offline")
+        self.local.stream_chunks = ("Lokaler ", "Ersatz")
+        router = self._router()
+
+        chunks = list(router.stream_chat([ChatMessage("user", "Wie funktioniert Python?")]))
+
+        self.assertEqual(chunks, ["Lokaler ", "Ersatz"])
+        self.assertTrue(router.last_route.fallback)
+        self.assertTrue(router.last_route.technical_fallback)
+        self.assertIn("lokale Antwort", self.notices[-1])
+
+    def test_cloud_stream_error_after_output_never_appends_local_answer(self) -> None:
+        self.cloud.stream_chunks = ("Teilantwort",)
+        self.cloud.stream_error = CloudNetworkError("offline")
+        self.local.stream_chunks = ("Lokaler Ersatz",)
+        router = self._router()
+        stream = router.stream_chat([ChatMessage("user", "Wie funktioniert Python?")])
+
+        self.assertEqual(next(stream), "Teilantwort")
+        with self.assertRaises(ResponseAbortedError):
+            next(stream)
+
+        self.assertFalse(self.local.calls)
+        self.assertFalse(router.last_route.fallback)
+        self.assertTrue(router.last_route.technical_fallback)
+
+    def test_medical_never_streams_locally_before_cloud_construction(self) -> None:
+        constructed = False
+        self.local.stream_chunks = ("Lokal",)
+
+        def cloud_factory() -> _RecordingProvider:
+            nonlocal constructed
+            constructed = True
+            return self.cloud
+
+        router = self._router(cloud_provider_factory=cloud_factory, mode="gemini")
+
+        chunks = list(
+            router.stream_chat([ChatMessage("user", "Welche Diagnose passt zu meinen Schmerzen?")])
+        )
+
+        self.assertEqual(chunks, ["Lokal"])
+        self.assertFalse(constructed)
+        self.assertFalse(self.approvals)
+        self.assertEqual(router.last_route.privacy_policy, CloudPolicy.NEVER)
+
 
 if __name__ == "__main__":
     unittest.main()