cloudflare/vinext

App Router: OTel spans during cache component fallback resume reuse the trace id

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#1,495 opened on May 22, 2026

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Description

This issue was created by an agent analysing CI failures from the Next.js Deploy Suite (vinext main vs Next.js v16.2.6, 2026-05-22).

Problem

Spans created during fallback resume inside a Cache Component should have a fresh trace id distinct from the build-time render. vinext reuses the same trace id (e.g. 11989306), implying the span context is not being re-created per request resume.

Trace id reused across build-time render and runtime resume

Estimated Impact

~1 test failures across the deploy suite.

Affected Test Suites

  • test/e2e/app-dir/cache-components-allow-otel-spans/cache-components-allow-otel-spans.test.ts

Recommendation

  1. Reproduce first in vinext's own test suite. Use the existing cache-components-allow-otel-spans fixture and assert the trace id changes between build-time prerender and runtime resume.

  2. Reset the OTel context on resume. Each cache-component resume should start a new span/trace context, not inherit the prerender's.

Contributor guide

Research direction
Inspect the cache components allow otel spans test fixture, reproduce the issue to confirm the trace id is reused, then reset the OTel span context when resuming a cache component to ensure a fresh trace id per request.
Tech stack
typescriptjavascriptnodejs
Domain
backenddeveloper experience
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
GitNode.jsTypeScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70