feat(bedrock): Add Routing Classifier Trace event

[luke-moehlenbrock]

Adds support for routingClassifierTraces and also splits out the guardrails to pre and post guardrails as separate spans.

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Note

Adds routingClassifierTrace, separates guardrails into preGuardrailTrace/postGuardrailTrace, and enhances metadata and input/output extraction across nodes and spans.

• Instrumentation (core):
  • AttributeExtractor: merge invocation/observation metadata for agent-collaborator I/O; include routingClassifierTrace event; improve agent-collaborator I/O attribute construction.
• Span assembly:
  • ResponseAccumulator:
    • Prioritize node-level chunks; special handling for agent-collaborator nodes when extracting parent input/output.
    • Parse routing-classifier outputs from rawResponse.content; fall back sensibly.
    • Name guardrail node spans as preGuardrailTrace/postGuardrailTrace; set Guardrails span kind/status (ERROR when intervened).
    • Extract and merge metadata in precedence order; use metadata times to set span start/end.
  • TraceCollector: guardrail-specific unique trace IDs; add chunks to nodes (for metadata propagation); ensure new nodes (incl. guardrail) store chunks/spans correctly.
• Tests:
  • Add cassette tests/.../cassettes/test_routing_classifier_trace.yaml and new test_routing_classifier_trace.
  • Update existing tests to assert orchestration metadata, pre/post guardrail traces, span counts/names, and metadata shapes.

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[caroger]

I'm wondering if there is a better alternatives to the hard coded expected values used in these test assertions.

In the future, when we need to update/refresh the vcr recording files, these assertions would also be manually updated again, right?

[luke-moehlenbrock]

Yeah I completely agree, it's a huge pain to get the correct hardcoded values here, it might be better just to check if there is a non-null value in these fields. We're not modifying these values after we get them from Bedrock so just checking that they've been added to the span should be good and we don't need to check the exact value.