Repair truncated LLM proposal JSON

tests/test_core_flow.py

@@ -317,6 +317,31 @@ class CoreFlowTests(unittest.TestCase):
             self.assertIn('"failure_reason": "engine_process_exited_before_ready exit_code=1"', prompt)
             self.assertIn('"VLLM_ATTENTION_BACKEND": "FLASHINFER"', prompt)
 
+    def test_parse_proposal_text_repairs_truncated_json(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            tmp_path = Path(tmp)
+            study = load_study_spec(_write_study_assets(tmp_path))
+            proposal = parse_proposal_text(
+                """
+                {
+                  "observation": "obs",
+                  "diagnosis": "diag",
+                  "config_patch": {
+                    "env_patch": {},
+                    "flag_patch": {
+                      "max-num-seqs": 24
+                    }
+                  },
+                  "expected_effects": [
+                    "faster batching"
+                  ],
+                  "why_not_previous_failures": "none"
+                """,
+                study,
+            )
+            self.assertEqual(proposal.diagnosis, "diag")
+            self.assertEqual(proposal.config_patch.flag_patch["max-num-seqs"], 24)
+
     def test_length_only_trace_rows_are_synthesized(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             tmp_path = Path(tmp)