fix(strands): allowlist metrics, add span_origin, fix agent metadata reads

[starfolkai]

Summary

Aligns the Strands integration with .agents/skills/sdk-integrations/SKILL.md, following the pattern of #606 (openai), #604 (mistral), #603 (livekit), #594 (litellm), #583 (anthropic). Audit turned up several issues:

• Missing span_origin instrumentation name. Every other integration has _INSTRUMENTATION = "<provider>-auto" + a module-level start_span wrapper; strands was the only one whose spans lacked context.span_origin.instrumentation.name. Added the standard wrapper and pass internal={"instrumentation": _INSTRUMENTATION} explicitly through the nested parent.start_span(...) path, which doesn't route through the module wrapper.

• Denylist metrics extraction (real leak vector). _end_model_invoke_span_wrapper was doing {k: v for k, v in metrics.items() if _is_supported_metric_value(v)} — every numeric key strands emits (present + future) flowed into the span's top-level metrics bag. Replaced with an explicit allowlist (latencyMs, timeToFirstByteMs). Since neither key is spec-listed, they land under metadata.strands_metrics rather than top-level metrics.

• Silently-broken agent metadata extraction. _agent_metrics_and_metadata did metrics = getattr(result, "metrics"); if not isinstance(metrics, dict): return {}, {} — but AgentResult.metrics is an EventLoopMetrics dataclass, so the guard discarded everything. Renamed to _agent_metadata_from_result and read cycle_count / accumulated_usage / accumulated_metrics off the dataclass through a single _pick_numeric(source, keys) allowlist helper. Moved cycles from metrics to metadata (not a spec metric key).

• Positional-arg reads. _start_agent_span_wrapper / _start_model_invoke_span_wrapper were kwargs.get("tools") / kwargs.get("system_prompt") etc. Strands' signatures put those at fixed positional slots — switched to _arg(args, kwargs, N, name) so positional callers work.

• Simplifications (via /simplify): collapsed twin allowlist helpers into _pick_numeric; collapsed the parent-vs-module if/else in _start_span_for_otel; replaced the _bt_parent_otel_span metadata back-channel with a direct parent_otel_span= kwarg; dropped the now-orphan metrics= parameter from _end_span_for_otel; trimmed the verbose wrap_strands_tracer and _InvalidOtelSpanKey docstrings.

Known SKILL gaps NOT fixed here

Each deserves its own PR/discussion — flagging so they don't get lost:

1. metadata.provider on LLM spans. Strands' Tracer only receives model_id, not the model class — provider inference would require brittle id-pattern matching.
2. Tokens under metadata.strands_usage rather than metrics.tokens / prompt_tokens / completion_tokens. Fixing correctly means deciding whether model-invoke should stay typed llm at all — Strands' OpenAIModel / AnthropicModel delegate to the underlying provider SDK, which per the SKILL's "framework llm-like spans that delegate" rule should NOT be typed llm.
3. No test_auto_strands.py subprocess auto-instrument test. Strands is wired into auto.py but lacks the subprocess parity test other integrations have.

Test plan

• No new mocks/fakes. Existing cassette-backed VCR test (test_strands_openai_agent_traces_native_otel_lifecycle) covers the behavior; added a span_origin.instrumentation.name == "strands-auto" assertion on every emitted span.
• No cassette re-recording. HTTP behavior is unchanged; only in-process span shaping was touched.
• cd py && nox -s "test_strands(latest)" — 2/2 pass
• cd py && nox -s "test_strands(1.20.0)" — 2/2 pass
• ruff check + ruff format --check on touched files — clean
• nox -s pylint — clean

🤖 Generated with Claude Code

Created by abhijeet

Slack thread