fix: complete streamed patch repair responses

packages/casan-harness/tests/phase3-model-router-tests.sh

@@ -159,6 +159,15 @@ class EmptyResp:
     def read(self):
         return b""
 
+class SseResp:
+    headers = {"Content-Type": "text/event-stream; charset=utf-8"}
+    def __enter__(self):
+        return self
+    def __exit__(self, exc_type, exc, tb):
+        return False
+    def read(self):
+        return b'data: {"choices":[{"delta":{"content":"CASAN"}}]}\n\ndata: {"choices":[{"delta":{"content":"_OK"}}],"usage":{"prompt_tokens":12,"completion_tokens":2}}\n\ndata: [DONE]\n'
+
 def fake_urlopen(req, timeout):
     seen.append((req.full_url, dict(req.header_items()), json.loads(req.data.decode())))
     if req.full_url.endswith("/v1/responses"):
@@ -194,6 +203,7 @@ assert seen[3][0] == "https://api.anthropic.com/v1/messages", seen[3]
 assert seen[0][2]["temperature"] == 0 and seen[0][2]["max_tokens"] == 16, seen[0][2]
 assert seen[1][2]["max_output_tokens"] == 1400 and seen[1][2]["store"] is False, seen[1][2]
 assert seen[2][2]["temperature"] == 0 and seen[2][2]["max_tokens"] == 16, seen[2][2]
+assert seen[2][2]["stream"] is False, seen[2][2]
 assert "temperature" not in seen[3][2] and seen[3][2]["max_tokens"] == 16, seen[3][2]
 
 os.environ["CASAN_OPENAI_COMPATIBLE_BASE_URL"] = "http://169.254.169.254/v1"
@@ -224,6 +234,10 @@ except SystemExit as exc:
     assert exc.code == 2, exc.code
 else:
     raise AssertionError("empty provider response was accepted")
+
+sse = mc.decode_provider_json(SseResp(), "openai-compatible")
+assert sse["choices"][0]["message"]["content"] == "CASAN_OK", sse
+assert sse["usage"] == {"prompt_tokens": 12, "completion_tokens": 2}, sse
 print("ok")
 PY
 [[ $? -eq 0 ]] && pass "cloud/gateway provider responses parse real usage and reject malformed payloads" || fail "cloud/gateway provider parser coverage failed"