vercelAIIntegration: `experimental_telemetry.metadata` no longer recorded on gen_ai spans (v11 regression, `ai` <= 6)

[isaacs]

On SDK v10, vercelAIIntegration recorded experimental_telemetry.metadata as vercel.ai.telemetry.metadata.<key> span attributes. The data came from the AI SDK's own OTel spans (ai.telemetry.metadata.*), and the integration renamed every ai.* attribute to vercel.ai.*.

On v11, ai 4 to 6 go through the orchestrion subscriber (packages/server-utils/src/integrations/vercel-ai/vercel-ai-orchestrion-subscriber.ts) instead of OTel. That subscriber reads experimental_telemetry.isEnabled, functionId, recordInputs and recordOutputs, but never metadata. The channel subscriber that builds the spans (vercel-ai-dc-subscriber.ts) doesn't set any metadata attributes either. So the metadata is dropped, and apps lose request-level context (user, tenant, request id, ...) on gen_ai spans after they upgrade.

Reproduction

await generateText({
  model,
  prompt: 'Hi',
  experimental_telemetry: {
    isEnabled: true,
    functionId: 'support-chat',
    metadata: { requestId: 'req_123', tenantId: 'acme' },
  },
});

• Expected: invoke_agent support-chat and its generate_content child carry vercel.ai.telemetry.metadata.requestId and vercel.ai.telemetry.metadata.tenantId, as on v10.
• Actual (11.0.0, ai 6): neither span has any vercel.ai.telemetry.metadata.* attribute. All other attributes (function id, messages, tokens, model) are present.

A failing integration test covers this: dev-packages/node-integration-tests/suites/tracing/vercelai/span-streaming-v6/scenario-telemetry-metadata.mjs, test "records experimental_telemetry.metadata as span attributes". I only checked ai 6. ai 4 and 5 use the same subscriber, so they are probably affected too.

Proposed fix

• Pass experimental_telemetry.metadata through the orchestrion message builder.
• In the channel subscriber, set vercel.ai.telemetry.metadata.<key> on the invoke_agent span.
• Copy the same attributes to child generate_content spans through a callId map, the same way as operationIdByCallId.

Open question: v10 may also have put metadata on tool call spans. If it did, execute_tool should get it too.

Related

• vercelAIIntegration: record AI SDK v7 runtimeContext (filtered by telemetry.includeRuntimeContext) as span attributes #24706: the same gap on ai 7, where metadata moved to runtimeContext.
• test(cloudflare): Add e2e test app for @cloudflare/think #24660 notes that neither subscriber reads experimental_telemetry.metadata or runtimeContext.

[linear-code]

JS-3800