feat(langchain): emit GenAI request attributes by JacksonWeber · Pull Request #213 · microsoft/opentelemetry-distro-javascript

Jackson Weber (JacksonWeber) · 2026-08-06T17:40:52Z

Summary

emit available GenAI request parameters from LangChain extra.invocation_params on chat spans
derive gen_ai.output.type from explicit output types and structured response formats
support OpenAI-style snake_case and provider/LangChain camelCase aliases with semconv-safe type validation

Attributes

gen_ai.output.type
gen_ai.request.temperature
gen_ai.request.top_p / gen_ai.request.top_k
gen_ai.request.max_tokens
frequency/presence penalties, seed, stop sequences, and stream

Validation

LangChain unit, tracer, and functional suites pass
A365 exporter and span-processor suites pass
lint, formatting, and build pass
live Azure OpenAI invocation validated against Application Insights using @langchain/openai 1.5.5 and @langchain/core 1.2.3; the ingested span retained expected typed values for temperature, top-p, max tokens, penalties, seed, stop sequences, stream, and JSON output type

A365 compatibility

the Agent365 exporter copies span attributes into its OTLP-like payload without renaming or coercion
added a regression test proving the complete new attribute set retains its string, number, boolean, and string-array types in the A365 payload
gen_ai.request.temperature, gen_ai.request.top_p, and gen_ai.request.max_tokens are already defined by the upstream Agent365 JS constants
all added keys and types follow the current OpenTelemetry GenAI semantic conventions; A365 identity partitioning and message truncation behavior are unchanged

Upstream assessment

Current LangChain.js exposes these values as raw callback invocation_params but does not map them to OpenTelemetry gen_ai.* attributes, so the distro remains the appropriate implementation layer.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

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Adds LangChain instrumentation support for emitting GenAI request-related OpenTelemetry attributes (including output type) from extra.invocation_params, with validation/normalization and expanded unit test coverage.

Changes:

Introduces new GenAI semantic convention constants for request parameters and gen_ai.output.type.
Adds setRequestAttributes to LangChain utils and wires it into the LangChain tracer.
Expands unit tests to cover mapping/normalization and exporter payload preservation.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/internal/unit/genai/langchain/utils.test.ts	Adds focused unit tests for `setRequestAttributes` mapping/validation behavior.
test/internal/unit/genai/langchain/tracer.test.ts	Verifies tracer emits request attributes/output type onto spans.
test/internal/unit/a365/agent365Exporter.test.ts	Ensures A365 exporter payload preserves new GenAI attributes.
src/genai/semconv.ts	Defines new `gen_ai.*` attribute constants used by instrumentation.
src/genai/instrumentations/langchain/utils.ts	Implements request attribute extraction, normalization, and type validation.
src/genai/instrumentations/langchain/tracer.ts	Hooks request attribute setting into span creation flow.
CHANGELOG.md	Documents the new instrumentation feature under Unreleased.

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Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Radhika Gupta (rads-1996) · 2026-08-07T17:34:01Z

where did the other checks go? Is it a github issue?

Radhika Gupta (rads-1996) · 2026-08-07T17:35:31Z

 ## [Unreleased]

+### Features Added
+- Emit `gen_ai.output.type` and available GenAI request parameters on LangChain chat spans.


Link to the PR is missing.

Link is added and it looks like the PR change fixed the other CI jobs not running as well.

Only 4 jobs running, I don't think the entire list is being fetched.

I believe that is comperehensive from checking the pr-validation.yml We just have an ES-lint and testing the two LTS versions of Node.js (22 & 24) that we currently support. Although this might not be a bad time to add a Node 26 check as well.

Nevermind, looks like 26 is current, not LTS yet.

Jackson Weber (JacksonWeber) · 2026-08-07T17:36:42Z

where did the other checks go? Is it a github issue?

Interesting, yeah. There were issues with github actions yesterday. Let me fix this one.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Radhika Gupta (rads-1996) · 2026-08-07T19:04:16Z

+  speech: "speech",
+};
+
+function normalizeOutputType(value: unknown): string | undefined {


Are none of these helper functions available upstream which we could reuse here?

LangChain doesn’t provide public helpers for normalizing these provider-specific invocation parameters and OpenTelemetry only validates values after they’ve been normalized, so we still need the small local coercion helpers here.

So how does opentelemetry (genai js) normalize the values? When I mentioned upstream in my original comment, I was referring to the upstream langchain instrumentation, sorry for the confusion.

That makes sense. The upstream otel langchain instrumentation doesn't currently emit these attributes, so it doesn't have any normalization logic for them.

Makes sense that we can try to implement these upstream there instead of only in our vendored implementation. But we don't consume that package anywhere in this project, so is the expectation that customers just pull the upstream OTel JS langchain instrumentation to use alongside this distro?

Radhika Gupta (rads-1996) · 2026-08-07T19:11:40Z

+  return strings.length === value.length && strings.length > 0 ? strings : undefined;
+}
+
+const OUTPUT_TYPES: Readonly<Record<string, string>> = {


Per semconv, this is supported list of output types - gen_ai.output.type. Are we planning to support these extras in the distro only? Also, you are missing the image type.

I've updated the list to support the image type and unify with what's described in sem conv. Does it make sense to support these in our vendored langchain instrumentation for now and then work on supporting them upstream in the future?

I would suggest the other way around, first upstream (semconv repo) and then support them in the distro. Are there any specific scenarios where you would want to add support for the types not listed in semconv?

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Radhika Gupta (rads-1996) · 2026-08-07T20:56:46Z

+  const seed = integer(firstDefined(params, ["seed"]));
+  if (seed !== undefined) span.setAttribute(ATTR_GEN_AI_REQUEST_SEED, seed);
+
+  const topK = integer(firstDefined(params, ["top_k", "topK"]));


A little confused why are we supporting the camelCase, shouldn't the attributes satisfy the _ convention?

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

This reverts commit 0110be1.

Match upstream OpenTelemetry GenAI instrumentations by accepting typed provider parameters without coercing numeric or boolean strings. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI lite review requested due to automatic review settings August 6, 2026 17:40

Jackson Weber (JacksonWeber) requested review from Nev (MSNev), Hector Hernandez (hectorhdzg), Jeremy Voss (jeremydvoss), Leighton Chen (lzchen) and Radhika Gupta (rads-1996) as code owners August 6, 2026 17:40

feat(langchain): emit GenAI request attributes

02f1d14

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Jackson Weber (JacksonWeber) force-pushed the jacksonweber/langchain-genai-request-attributes branch from eb3eb7d to 02f1d14 Compare August 6, 2026 17:41

test(a365): cover GenAI request attributes

101be16

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI reviewed Aug 6, 2026

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Comment thread src/genai/instrumentations/langchain/utils.ts

Comment thread src/genai/instrumentations/langchain/utils.ts Outdated

Comment thread src/genai/instrumentations/langchain/utils.ts

Comment thread src/genai/instrumentations/langchain/utils.ts Outdated

fix(langchain): harden request attribute parsing

14af86a

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot started reviewing on behalf of Jackson Weber (JacksonWeber) August 6, 2026 22:54 View session

Radhika Gupta (rads-1996) reviewed Aug 7, 2026

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Add PR link to changelog

808ab34

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Jackson Weber (JacksonWeber) requested a review from Radhika Gupta (rads-1996) August 7, 2026 18:10

Radhika Gupta (rads-1996) reviewed Aug 7, 2026

View reviewed changes

Comment thread src/genai/instrumentations/langchain/utils.ts Outdated

Radhika Gupta (rads-1996) reviewed Aug 7, 2026

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fix(langchain): address request attribute review feedback

092538e

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Jackson Weber (JacksonWeber) requested a review from Radhika Gupta (rads-1996) August 7, 2026 20:04

Radhika Gupta (rads-1996) reviewed Aug 7, 2026

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Jackson Weber (JacksonWeber) and others added 3 commits August 8, 2026 11:01

ci: test Node.js 26

0110be1

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Revert "ci: test Node.js 26"

a52fd9b

This reverts commit 0110be1.

fix(langchain): preserve typed request values

ae24f29

Match upstream OpenTelemetry GenAI instrumentations by accepting typed provider parameters without coercing numeric or boolean strings. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Jackson Weber (JacksonWeber) marked this pull request as draft August 8, 2026 22:22

Jackson Weber (JacksonWeber) marked this pull request as ready for review August 8, 2026 22:30

Jackson Weber (JacksonWeber) marked this pull request as draft August 8, 2026 22:58

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Jackson Weber (JacksonWeber) commented Aug 6, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Attributes

Validation

A365 compatibility

Upstream assessment

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Radhika Gupta (rads-1996) commented Aug 7, 2026

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Jackson Weber (JacksonWeber) commented Aug 7, 2026

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Jackson Weber (JacksonWeber) Aug 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Jackson Weber (JacksonWeber) commented Aug 6, 2026 •

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