Add langchain instrumentation

[Hector Hernandez (hectorhdzg)]

No description provided.

[Radhika Gupta (rads-1996)]

Could you add a sample app for langchain instrumentation as well, so the usage with the distro can be demonstrated? Or are you planning to add it in another PR?

[Radhika Gupta (rads-1996)]

LGTM, having a langchain sample would be quite useful.

[Radhika Gupta (rads-1996)]

A change log entry should be added

[Copilot]

Pull request overview

Adds a LangChain/LangGraph → OpenTelemetry tracing bridge under src/genai/, emitting spans annotated with GenAI semantic convention attributes and providing a CallbackManager patching instrumentor.

Changes:

• Introduces GenAI semantic convention constants and LangChain instrumentation implementation (tracer, utils, instrumentor).
• Adds extensive unit + functional tests validating span naming, attributes, filtering, parent/child relationships, and content-recording gating.
• Adds @langchain/core to dev dependencies (and lockfile updates).

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
test/internal/unit/genai/langchain/utils.test.ts	Unit tests for LangChain utils attribute extraction/mapping.
test/internal/unit/genai/langchain/tracer.test.ts	Unit tests for tracer lifecycle, filtering, parent/child, and caps.
test/internal/unit/genai/langchain/langchainTraceInstrumentor.test.ts	Unit tests for CallbackManager patching and handler injection behavior.
test/internal/functional/langchain.test.ts	End-to-end functional test using InMemorySpanExporter.
src/genai/utils.ts	Adds attribute-value truncation helper (currently unused by LangChain code).
src/genai/semconv.ts	Adds GenAI semconv constants used by instrumentation/tests.
src/genai/instrumentations/langchain/utils.ts	Extracts operation/model/provider/messages/tool/session/token attributes from LangChain runs.
src/genai/instrumentations/langchain/tracer.ts	Implements BaseTracer bridge to create/end OTel spans per LangChain run.
src/genai/instrumentations/langchain/langchainTraceInstrumentor.ts	Implements an OTel InstrumentationBase wrapper that patches LangChain CallbackManager handlers.
src/genai/instrumentations/langchain/index.ts	Re-exports LangChain tracer/instrumentor.
src/genai/index.ts	Re-exports GenAI semconv constants.
package.json	Adds @langchain/core devDependency.
package-lock.json	Lockfile updates including @langchain/core and related packages.

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