fix(mistral): drop eager response serialization, use allowlist metadata pass-through

[starfolkai]

Summary

Aligns the Mistral integration with .agents/skills/sdk-integrations/SKILL.md, following the same pattern as #594 (litellm) and #583 (anthropic). Audit turned up two issues:

• Excess serialization. _normalize_mistral_multimodal_value (which recursively calls value.model_dump(mode="python", by_alias=True)) was invoked 25 times across tracing.py. Two sites did real waste:

  • Every non-streaming response finalizer (_finalize_completion_response, _finalize_conversation_response, _finalize_ocr_response, _finalize_embeddings_response) full-dumped the response just to read a handful of fields (id, model, choices/outputs/pages, usage).
  • _build_request_metadata walk-and-dumped every metadata value (temperature, top_p, tools, response_format, stop, …) — none of which carry attachments.

  Both are redundant: bt_safe_deep_copy in logger.log_internal already model_dumps pydantic values at log time. Replaced with attribute reads through the existing _get_value helper (already dict-or-pydantic aware and handles Mistral's Unset sentinel — no new helper needed).

• Aggregators. _aggregate_completion_events / _aggregate_conversation_events / _aggregate_transcription_events / _aggregate_speech_events pre-dumped usage / segments into the intermediate dict. _parse_usage_metrics already accepts pydantic, and bt_safe_deep_copy handles the output. Dropped.

• Tool-span walkers. _completion_tool_calls, _conversation_tool_outputs, _log_completion_tool_spans, _log_conversation_tool_spans switched to _get_value so they walk raw pydantic responses instead of assuming pre-dumped dict shape.

Multimodal walker retained where attachment materialization matters (_start_span input path, _append_delta_content / _merge_tool_calls streaming assembly, per-field conversation-output accumulators).

Metadata is still allowlist-per-surface — no changes to what fields we capture. Comments were not excessive; nothing to trim.

Net: −36 LOC in tracing.py, one dead helper file removed (_response_data_to_metadata, _conversation_response_data_to_metadata, _conversation_outputs_data, _ocr_output_data collapsed into the pydantic-aware equivalents).

Test plan

• No new mocks/fakes. The two existing narrow fakes (_PlainResponse for the plain-Python usage path, and lambda fail-injectors for error-propagation tests) fall under the SKILL's "narrow error injection / provider-independent helpers" carve-out. All provider-behavior coverage stays on the 30+ @pytest.mark.vcr cassette-backed tests.
• No cassette re-recording. HTTP behavior is unchanged; only in-process span shaping was touched.
• cd py && nox -s "test_mistral(latest)" — 45/45 passed.
• cd py && nox -s "test_mistral(1.12.4)" — 43/43 passed (2 pre-existing skips for speech API which doesn't exist on 1.12.4).
• ruff check + ruff format --check on touched files — clean.

Two existing unit tests were updated because their assertions hinged on the old eager-serialization behavior:

• test_wrappers_ignore_usage_when_response_normalization_fails → test_wrappers_read_usage_from_plain_python_responses. The old test asserted metrics were dropped for plain-Python responses — that only happened because .model_dump() failed on non-pydantic objects and we bailed out. The new code correctly reads usage via getattr; assertion is now positive (metrics are present).
• test_aggregate_completion_events_merges_tool_calls_and_content: aggregated["usage"] is now the raw pydantic UsageInfo (dumps at log time, not in the aggregator); switched to getattr(..., "total_tokens").

🤖 Generated with Claude Code

Created by abhijeet

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