fix(agent): sanitize surrogate characters from API responses and before API calls

run_agent.py

@@ -6822,9 +6822,16 @@ class AIAgent:
                 except Exception:
                     pass
 
+        # Sanitize surrogates from API response — some models (e.g. Kimi/GLM via Ollama)
+        # can return invalid surrogate code points that crash json.dumps() on persist.
+        _raw_content = assistant_message.content or ""
+        _san_content = _sanitize_surrogates(_raw_content)
+        if reasoning_text:
+            reasoning_text = _sanitize_surrogates(reasoning_text)
+
         msg = {
             "role": "assistant",
-            "content": assistant_message.content or "",
+            "content": _san_content,
             "reasoning": reasoning_text,
             "finish_reason": finish_reason,
         }
@@ -8705,6 +8712,12 @@ class AIAgent:
                     new_tcs.append(tc)
                 am["tool_calls"] = new_tcs
 
+            # Proactively strip any surrogate characters before the API call.
+            # Models served via Ollama (Kimi K2.5, GLM-5, Qwen) can return
+            # lone surrogates (U+D800-U+DFFF) that crash json.dumps() inside
+            # the OpenAI SDK. Sanitizing here prevents the 3-retry cycle.
+            _sanitize_messages_surrogates(api_messages)
+
             # Calculate approximate request size for logging
             total_chars = sum(len(str(msg)) for msg in api_messages)
             approx_tokens = estimate_messages_tokens_rough(api_messages)