Covers extractToolTrace — the only untested pure function in the file.
Tests are JSON-only, no DB mocking needed:
- Happy path: result.metadata.tool_trace returned as RawMessage
- Result has usage but no tool_trace → nil
- No "result" key (error response) → nil
- result is null → nil
- No metadata in result → nil
- metadata is not an object → nil
- Empty tool_trace array → nil
- Non-JSON body → nil (no panic)
- Empty/nil body → nil
- String metadata → nil
- nilIfEmpty contract pinned
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
