feat(ai): use tracing channels to track parent-child context by aayush-kapoor · Pull Request #15660 · vercel/ai

aayush-kapoor · 2026-05-28T00:16:53Z

Background

we introduced diagnostic channels in #14854 as a way to propagate event data.

but the problem was that there was no to establish a relation with the parent and child calls that happen when consuming information via the diagnostics channels. context propagation for subagents remained unsolved (meaning subagents will be detached from the main parent call)

Summary

use tracingChannel() instead of diagnostic channel()
model and tool execution are now wrapped with tracingChannel.tracePromise(...) via the existing executeLanguageModelCall and executeTool dispatcher paths
in unsupported/non-Node runtimes, tracing dynamically no-ops and directly runs the original callback/execution

Manual Verification

verified that event data is still transmitted at each lifecycle event by running the example examples/ai-functions/src/telemetry/tracing-channel/generate-text.ts

Checklist

All commits are signed (PRs with unsigned commits cannot be merged)
Tests have been added / updated (for bug fixes / features)
Documentation has been added / updated (for bug fixes / features)
A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
I have reviewed this pull request (self-review)

aayush-kapoor · 2026-05-28T00:25:30Z

+    expect(telemetry.executeLanguageModelCall).toBeDefined();
+    expect(telemetry.executeTool).toBeDefined();


these are now defined since before executeLanguageModelCall and executeTool only existed if a user/global telemetry integration implemented those methods. but now, we have a native reason to wrap execution so that tracing channels propagate async context across the actual model/tool

aayush-kapoor · 2026-05-28T00:25:47Z


  describe('executeTool', () => {
-    it('returns undefined when no integrations implement executeTool', () => {
+    it('passes through when no integrations implement executeTool', async () => {


changed for the reason above

aayush-kapoor · 2026-05-28T00:25:54Z


  describe('executeLanguageModelCall', () => {
-    it('returns undefined when no integrations implement executeLanguageModelCall', () => {
+    it('passes through when no integrations implement executeLanguageModelCall', async () => {


changed for the reason above

aayush-kapoor · 2026-05-28T00:28:53Z

  executeToolInTelemetryContext?: <T>(params: {
    callId: string;
    toolCallId: string;
+    event?: ToolExecutionStartEvent<TOOLS>;


this event is what the tracing channel uses as it's base context

logaretm

Just wanted to drop a couple of suggestions, second one being a nit so up to you! But thanks for doing this, this sets a great example in the ecosystem on how to do telemetry like that!

logaretm · 2026-05-28T08:59:47Z

@@ -1,6 +1,6 @@
-export const AI_SDK_TELEMETRY_DIAGNOSTIC_CHANNEL = 'aisdk:telemetry';
+export const AI_SDK_TELEMETRY_TRACING_CHANNEL = 'aisdk:telemetry';


I think this is fine, but something you may want to consider:

Right now everything goes through a single aisdk:telemetry channel with a type discriminator. The diagnostics_channel API is designed so that many purpose-focused channels with their own subscriber sets make dispatch extremely cheap.

On the other hand, filtering a "firehose" channel adds continuous overhead on every published message (this feedback came directly from @Qard, the diagnostics_channel creator on various related proposals).

Maybe something like this if you would like to consider it:

Channel Wraps

aisdk:telemetry Top-level operation (generateText, streamText, generateObject, etc.)

aisdk:telemetry:languageModelCall Individual provider call (nested)

aisdk:telemetry:toolExecution Individual tool call (nested)

But again it is up to you, I think it is fine either way. The idea is some APMs can choose which channels to care about and not incur overhead over those channels.

i guess my question would be if we do have different channels, will the context propagation still work? even if the tool execution and the model call are split?

Yep, it works cross-channel as long as the subscribers have their stores bound to the channels.

GraphQL illustrates this as they have like 5 channels that all work together, so APMs can choose the level of "granularity" of the spans/metrics they want to get out of it.

we made some changes in this PR that reduce the noise / events that are emitted through the channel.

what was before something like:

bindStart onStart asyncEnd onStart bindStart onStepStart asyncEnd onStepStart bindStart onLanguageModelCallStart asyncEnd onLanguageModelCallStart bindStart executeLanguageModelCall asyncEnd executeLanguageModelCall bindStart onLanguageModelCallEnd asyncEnd onLanguageModelCallEnd bindStart onToolExecutionStart asyncEnd onToolExecutionStart bindStart executeTool asyncEnd executeTool bindStart onToolExecutionEnd asyncEnd onToolExecutionEnd bindStart onStepFinish asyncEnd onStepFinish bindStart onStepStart asyncEnd onStepStart bindStart onLanguageModelCallStart asyncEnd onLanguageModelCallStart bindStart executeLanguageModelCall asyncEnd executeLanguageModelCall bindStart onLanguageModelCallEnd asyncEnd onLanguageModelCallEnd bindStart onStepFinish asyncEnd onStepFinish bindStart onEnd asyncEnd onEnd

is now bundled into:

bindStart generateText bindStart step bindStart languageModelCall asyncEnd languageModelCall bindStart executeTool asyncEnd executeTool asyncEnd step bindStart step bindStart languageModelCall asyncEnd languageModelCall asyncEnd step asyncEnd generateText

and so the above events are what's emitted through the channel (still only 1 ai:telemetry channel)

do you think that works @logaretm?

would appreciate any feedback you have on this! otherwise if this aligns dx wise with what you're expecting, we'll try to wrap this PR up

I think that works great! Just gave it a test round right now and looks fine DX wise

Thanks!

lgrammel · 2026-06-03T12:43:59Z

    request,
  } = await executeLanguageModelCallInTelemetryContext({
    callId: effectiveCallId,
+    event: languageModelCallStartEvent,


i find it strange to pass in an event. if we really want to do this, we may want to rename to startEvent - an alternative would be to pass the individual parts of the event. This can lead to some duplication but is semantically cleaner imo.

tracing channel depends on this event data to create the context afaik.i added this comment: https://github.com/vercel/ai/pull/15660/changes#r3314637416

sorry actually not for context, but for the tracing subscribers to see the event data

lgrammel · 2026-06-15T12:02:23Z

do we have test coverage for embed, rerank with tracing channels? the files were changed w/o test changes (also what is our test coverage for generate/streamText with tracing)? does embedMany also need adjustments?

aayush-kapoor · 2026-06-15T20:27:31Z

do we have test coverage for embed, rerank with tracing channels? the files were changed w/o test changes (also what is our test coverage for generate/streamText with tracing)? does embedMany also need adjustments?

adding now for embed and rerank.

for generateText and streamText, the test coverage is in packages/ai/src/telemetry/tracing-channel.test.ts that tests the complete flow (we import those functions specifically)

i think this is a better pattern because then all diagnostics channel imports live in packages/ai/telemetry

github-actions · 2026-06-15T21:07:21Z

🚀 Published in:

Package	Version
`ai`	7.0.0-beta.178 github npm
`@ai-sdk/angular`	3.0.0-beta.178 github npm
`@ai-sdk/gateway`	4.0.0-beta.109 github npm
`@ai-sdk/harness`	1.0.0-beta.15 github npm
`@ai-sdk/harness-claude-code`	1.0.0-beta.11 github npm
`@ai-sdk/harness-codex`	1.0.0-beta.11 github npm
`@ai-sdk/harness-pi`	1.0.0-beta.11 github npm
`@ai-sdk/langchain`	3.0.0-beta.178 github npm
`@ai-sdk/llamaindex`	3.0.0-beta.178 github npm
`@ai-sdk/otel`	1.0.0-beta.124 github npm
`@ai-sdk/policy-opa`	1.0.0-beta.15 github npm
`@ai-sdk/react`	4.0.0-beta.182 github npm
`@ai-sdk/rsc`	3.0.0-beta.179 github npm
`@ai-sdk/sandbox-just-bash`	1.0.0-beta.15 github npm
`@ai-sdk/sandbox-vercel`	1.0.0-beta.15 github npm
`@ai-sdk/svelte`	5.0.0-beta.178 github npm
`@ai-sdk/tui`	1.0.0-beta.13 github npm
`@ai-sdk/vue`	4.0.0-beta.178 github npm
`@ai-sdk/workflow`	1.0.0-beta.95 github npm

vercel/ai#15660 merged 2026-06-15 (Vercel-driven), replacing the aisdk:telemetry diagnostics_channel with the ai:telemetry TracingChannel. Shipped in pre-release v7.0.0-beta.178; stable v6 line pending, so not adoptable by most users yet (tracked like graphql's v17 rc). - TRACKER.md: Vercel AI (Node) 🟡 PR open -> ✅ Merged (prerelease); Sentry-built Merged 0->1, PR Open 1->0; Total Merged 14->15, PR Open 6->5 - data/libraries.json: ai -> shipped + prerelease, shippedVersion 7.0.0-beta.178, ai:telemetry channel chip; meta.updated 2026-06-16 - scripts/coverage.py: add ai ("7.0.0", "sentry") to COVERED; regenerate block Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

failing tests

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fix + docs

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aayush-kapoor commented May 28, 2026

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Comment thread content/docs/03-ai-sdk-core/60-telemetry.mdx Outdated

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Comment thread packages/ai/src/generate-text/stream-language-model-call.ts Outdated

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Comment thread packages/ai/src/telemetry/tracing-channel-publisher.ts

Merge branch 'main' into aayush/tracing-channel

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Merge branch 'main' into aayush/tracing-channel

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add stream step context

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rename functions and hooks

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bundle size limit increase

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test for embed and rerank

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sergical mentioned this pull request Jun 16, 2026

feat(node): Add Vercel AI v7 tracing-channel support getsentry/sentry-javascript#21584

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Notoriousbrain mentioned this pull request Jun 17, 2026

dynamic import("diagnostics_channel") breaks React Native / Hermes release builds #16191

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logaretm mentioned this pull request Jun 24, 2026

feat(server-runtimes): Add v7 support for vercelAiIntegration getsentry/sentry-javascript#21613

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aayush-kapoor mentioned this pull request Jun 29, 2026

Adopt TracingChannel for observability #14410

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gr2m mentioned this pull request Jul 6, 2026

Backport tracking: bug fixes and docs improvements from main (v7) not yet on release-v6.0 #16767

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lgrammel added the task-merge-tracking-no-issue label Jul 7, 2026

		expect(telemetry.executeLanguageModelCall).toBeDefined();
		expect(telemetry.executeTool).toBeDefined();

		@@ -1,6 +1,6 @@
		export const AI_SDK_TELEMETRY_DIAGNOSTIC_CHANNEL = 'aisdk:telemetry';
		export const AI_SDK_TELEMETRY_TRACING_CHANNEL = 'aisdk:telemetry';

Channel	Wraps
`aisdk:telemetry`	Top-level operation (`generateText`, `streamText`, `generateObject`, etc.)
`aisdk:telemetry:languageModelCall`	Individual provider call (nested)
`aisdk:telemetry:toolExecution`	Individual tool call (nested)

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aayush-kapoor commented May 28, 2026

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logaretm Jun 4, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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lgrammel commented Jun 15, 2026

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logaretm Jun 4, 2026 •

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