chore: explicitly skip the Vercel OTEL when running open-next

[dario-piotrowicz]

Description

The Vercel OTEL implementation doesn't work on the open-next build (I haven't investigated why), but it doesn't seem to cause issues either. However it produces some error in the terminal on previews.

In any case for the open-next build Vercel OTEL couldn't be used anyways (since the app wouldn't be hosted on Vercel).

In order to remove the terminal error and also to make the code more clear/explicit this PR is making the Vercel OTEL setup conditional based on whether the application is being run by Cloudflare or not.

Validation

I've validated that the open-next preview now does not present the telemetry error anymore.

Related Issues

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run pnpm format to ensure the code follows the style guide.
• I have run pnpm test to check if all tests are passing.
• I have run pnpm build to check if the website builds without errors.
• I've covered new added functionality with unit tests if necessary.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
nodejs-org	Ready	Preview	Apr 22, 2026 2:21pm

[cursor]

PR Summary

Low Risk
Small conditional/async initialization change limited to telemetry setup; low blast radius, but could affect instrumentation if environment detection is wrong.

Overview
Avoids initializing Vercel OpenTelemetry when the app runs on Cloudflare by making register() async, checking for globalThis.Cloudflare, and dynamically importing @vercel/otel only in non-Cloudflare environments. This removes Cloudflare/open-next preview errors and prevents bundling/executing Vercel OTEL in unsupported runtimes.

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[github-actions]

👋 Codeowner Review Request

The following codeowners have been identified for the changed files:

Team reviewers: @nodejs/nodejs-website

Please review the changes when you have a chance. Thank you! 🙏

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.85%. Comparing base (333d70f) to head (a284b70).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8833      +/-   ##
==========================================
- Coverage   73.88%   73.85%   -0.04%     
==========================================
  Files         105      105              
  Lines        8889     8889              
  Branches      326      327       +1     
==========================================
- Hits         6568     6565       -3     
- Misses       2320     2323       +3     
  Partials        1        1              

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[Copilot]

Pull request overview

This PR makes Vercel OpenTelemetry initialization conditional so it’s skipped when running under the Cloudflare open-next runtime, eliminating preview-time terminal telemetry errors and making the deployment intent explicit.

Changes:

• Switch instrumentation.ts to lazily import @vercel/otel only when not running on Cloudflare.
• Add a Cloudflare runtime check to bypass Vercel-specific OTEL setup.

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[ovflowd]

SGTM! Fast-tracking as a hot-fix for OpenNext.