feat: added Langchain mappers

[poshinchen]

Description

This PR adds a mapper framework for converting OpenTelemetry traces from different LangChain (with traceloop / openllmetry) into a unified Session format for evaluation

Architecture

Base Class:

• SessionMapper (abstract base class) - defines the map_to_session(data, session_id) interface and provides _normalize_to_flat_spans() helper for handling various input formats

Famework-Specific Mappers:

1. LangChainOtelSessionMapper: Maps Traceloop/OpenLLMetry LangChain traces (scope: opentelemetry.instrumentation.langchain)

2. OpenInferenceSessionMapper: Maps OpenInference LangChain traces (scope: openinference.instrumentation.langchain)

3. CloudWatchSessionMapper: Maps Strands telemetry from CloudWatch/ADOT format

4. StrandsInMemorySessionMapper: Maps Strands in-memory OTEL spans (existing, now inherits from base)

Utilities:

• detect_otel_mapper(spans) - Auto-detects appropriate mapper based on scope name
• readable_spans_to_dicts(spans) - Converts ReadableSpan objects to dict format
• get_scope_name(span) - Extracts scope from various span formats
• CloudWatchLogsParser - Normalizes raw CloudWatch logs to standard span format

---

Cleanup Opportunities for Follow-up

1. Extract Common Helper Methods to Base Class

The following methods are duplicated across all mappers:

• _get_scope_name() - identical in LangChain & OpenInference mappers
• _create_span_info() - nearly identical across all mappers
• _parse_timestamp() - identical in LangChain & OpenInference mappers
• _safe_json_parse() - identical logic (only in LangChain, but useful for others)

2. DRY Up Build Trace Logic

_build_trace() method has identical structure in LangChainOtelSessionMapper and OpenInferenceSessionMapper. This pattern could be moved to base class with abstract is*_span() methods.

3. Consolidate Message Extraction Pattern

_get_messages_from_span_events() has similar logic in both LangChain and OpenInference mappers for extracting messages from ADOT/CloudWatch format.

4. Unify Tool Extraction

_extract_tools_from_attributes() could be generalized - both mappers extract tool schemas but from different attribute keys.

Related Issues

#91

Documentation PR

N/A

Type of Change

New feature

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

• I ran hatch run prepare

Checklist

• I have read the CONTRIBUTING document
• I have added any necessary tests that prove my fix is effective or my feature works
• I have updated the documentation accordingly
• I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• My changes generate no new warnings
• Any dependent changes have been merged and published

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[afarntrog]

I would also like to see integration tests that run with langchain agent so that we can know immediately if something changes as our tests will fail.