Root causes of API request failures after tool calls:
1. reasoning_content (an API response field) was echoed back in assistant
messages, which could cause API format errors
2. tool_call id could be empty string when model didn't return one in a
streaming chunk, producing invalid tool_calls that caused 400 errors
3. Tool execute() could return None or non-string types; direct string
operations (len(), + "\n", [:200]) raised TypeError and produced
non-string content in tool messages, breaking JSON serialization
4. Tool output (e.g. from run_command) could contain control characters
(NULL/BEL/BS) that corrupted JSON payloads
5. When API request failed (network/4xx/5xx/parse error), messages added
in that turn (user msg, assistant msg with tool_calls, tool responses)
remained in self.messages, permanently poisoning conversation history
so all subsequent requests would also fail
Fixes:
- Stop sending reasoning_content back to API in message construction;
normalize assistant message content: null when tool_calls present, ""
when neither content nor tool_calls exist, str otherwise
- Sanitize tool messages: ensure tool_call_id is non-empty (fallback id)
and content is always a string
- Generate fallback tool_call id when model omits it; handle streaming id
delivery where id arrives in a later chunk
- Add _sanitize_tool_result(): coerce None/non-string to str, strip
control characters (preserve \n \t \r) to prevent JSON/API corruption
- Wrap execute_tool call in try/except in _handle_tool_calls for double
safety; ensure history logging never crashes
- Truncate oversized results with an explicit note instead of replacing
with a generic error that lost all useful output
- Add _rollback_messages(to_length) and record msgs_before_turn at start
of think_and_respond; on any exception (RequestException, JSONDecodeError,
or unexpected Exception), rollback self.messages to the pre-turn state
so the conversation is not left in a broken state
- In _handle_tool_calls, wrap execute_tool in try/except and always
produce a safe string result
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