fix(rolldown): fix CJS require handling for nodeless worker builds

[medz]

🔗 Linked issue

#4010

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This fixes the rolldown regression reported in #4010 for Cloudflare worker targets.

• Add a rolldown pre-resolver for require-call to resolve package exports with require-first conditions (instead of accidentally selecting import entries for CJS requires).
• Enable rolldown esmExternalRequirePlugin for nodeless builds so Node builtins used via CJS require() are emitted as ESM-compatible externals for worker runtimes.
• Keep Node-target behavior unchanged.
• Add unit coverage for dual export (import/require) resolution behavior.

Validated with the minimal repro:
medz/nitro-issue-4010-pg-cloudflare-repro

NITRO_BUILDER=rolldown nitro build + wrangler dev now starts successfully and serves requests (no require("events") startup failure).

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[vercel]

@medz is attempting to deploy a commit to the Nitro Team on Vercel.

A member of the Team first needs to authorize it.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR introduces require-condition resolution for Rolldown in Nitro's build system. It adds a new plugin module that conditionally resolves CommonJS require calls based on export conditions, integrates it into the Rolldown configuration, and provides comprehensive unit tests for the new functionality.

Changes

Cohort / File(s)	Summary
Config Rewiring src/build/rolldown/config.ts	Introduced dynamic plugin and externals composition: added requireConditionResolver plugin, conditionally included esmExternalRequirePlugin, precomputed builtinExternals for both standard and node:-prefixed variants, and consolidated plugins array initialization.
Require-Condition Plugin src/build/rolldown/require-condition.ts	New plugin module for conditional require() path resolution. Exports getRequireConditionNames() to compute effective condition names, resolveRequireCallPath() to resolve CommonJS imports with conditions, and requireConditionResolver() factory to integrate with Nitro's build context.
Plugin Tests test/unit/rolldown-require-condition.test.ts	Unit tests for require-condition resolution, including dual-entry package resolution preference tests and validation of builtin/relative import skipping behavior.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• feat: rolldownConfig #3887: Also modifies rolldown config construction and plugin/externals initialization patterns in the same file.
• refactor!: overhaul externals support #3799: Related changes to build external-resolution and plugin wiring with focus on condition-based module resolution.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title follows conventional commits format with 'fix' prefix and clearly describes the main change: fixing CJS require handling for nodeless worker builds.
Description check	✅ Passed	The description is directly related to the changeset, providing context about the bug fix, implementation details, and validation.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

src/build/rolldown/config.ts (1)

52-57: ⚠️ Potential issue | 🟡 Minor

Remove debug console.log — likely a leftover.

Line 54 unconditionally logs warning.code to stdout on every rolldown warning. This looks like a debug artifact. The warn(warning) call on the next line already handles emitting the warning properly. Per coding guidelines, build code should use consola or nitro.logger for logging.

Proposed fix

     onwarn(warning, warn) {
       if (!base.ignoreWarningCodes.has(warning.code || "")) {
-        console.log(warning.code);
         warn(warning);
       }
     },

As per coding guidelines, src/**/*.{js,ts}: "Use consola for logging in build/dev code; use nitro.logger when available".

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/nitrojs/nitro@4019

commit: ff04bbb