Independent review of the autonomous candidate

An independent reviewer rejected your candidate pending correction. Read the current diff and BOOK_SELF_EVOLUTION_REPORT.md, then address this exact finding without expanding scope:

The real production path in agent.agent_runtime_helpers.convert_to_trajectory_format() persists tool results as one or more XML-wrapped JSON objects, for example:

<tool_response>
{"tool_call_id": "...", "name": "...", "content": {"success": false}}
</tool_response>

derive_trajectory_signals() currently attempts json.loads() on the entire wrapped value, so it reports zero tool errors for a real failed tool result. The existing synthetic test uses bare JSON and therefore misses this production/test-parity defect.

Derive conservative signals from the actual converted ShareGPT trajectory, including multiple bundled <tool_response> entries and nested content. Fail closed on malformed or unsupported shapes. Add an end-to-end behavior test that passes a production-shaped internal assistant/tool exchange through the real conversion path before saving and verifies the resulting failure signal. Preserve the original trajectory messages byte-for-byte and keep the metadata backward-compatible.

Run the focused tests, the existing trajectory-compressor tests, compilation, and git diff --check. Update the report with this review round and exact results. Do not claim downstream benefit without the separate ablation campaign, do not push or commit, and do not edit the book repository.