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Rolldown "Run build with devtools" produces a development build (inherits the dev server's NODE_ENV)

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Assessment

Difficulty
2/5
Estimated time
1-3 hours
Newbie friendliness
84/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
node.js, typescript, vite
Domain
build-system, devtools

Research direction

Start in packages/rolldown/src/node/rolldown/build-runner.ts, especially getBuildCommand() and its call to ctx.terminals.startChildProcess(), then reproduce the issue with a running Vite dev server and compare the generated bundle with a plain vite build. Done means Run build with devtools uses production NODE_ENV, the confirmation command reflects that environment, and the Rolldown analysis matches the plain production build.

Written by the indexing model from the issue text.

Description

Describe the bug

The Rolldown panel's Run build with devtools button (vite:rolldown:run-build) produces a development bundle, not a production one. Every size, chunk and duplicate-package figure the Rolldown panel then shows for that session describes the wrong build.

In our Vue app, the button's build ships 259.2 KB gz of first-load JS, while a plain vite build of the same commit ships 200.9 KB gz. The button's build keeps Vue's dev warnings, Pinia's devtools plugin and @vue/devtools-kit in the first-load chunk. The build log still prints building client environment for production, so nothing looks wrong from the outside.

Mechanism:

  1. The dev server sets process.env.NODE_ENV = 'development' at startup when it is unset (vite resolveConfig, isNodeEnvSet / defaultNodeEnv).
  2. getBuildCommand() spawns vite build through ctx.terminals.startChildProcess() with env: { VITE_DEVTOOLS_ROLLDOWN: 'true' } (build-runner.ts#L41-L48). The hub merges that onto the dev server's process.env, so the child inherits NODE_ENV=development.
  3. vite build keeps an already-set NODE_ENV (documented: NODE_ENV=development vite build is how you ask for a development build), and replaces process.env.NODE_ENV in library code with process.env.NODE_ENV || mode. So every if (process.env.NODE_ENV !== 'production') branch stays in the bundle.

Passing the parent env through in startChildProcess() seems right in general (PATH, proxies, the user's own variables), so the fix probably belongs here: the build runner should set NODE_ENV: 'production', which is what a plain vite build resolves to. The confirmation dialog would then also show the real command line: NODE_ENV=production VITE_DEVTOOLS_ROLLDOWN=true vite build.

Reproduction

Inline steps below; the key part needs a running Vite dev server with DevTools.

  1. Any Vite 8 app with @vitejs/devtools + @vitejs/devtools-rolldown 0.7.5 and a dependency that has process.env.NODE_ENV branches (e.g. Vue + Pinia).
  2. vite (dev), open DevTools → Rolldown → Run build with devtools.
  3. Compare the new session's first-load size and the dist/ output with a plain vite build from a fresh shell: the button's build is larger and contains dev-only code (for Vue, __VUE_DEVTOOLS_GLOBAL_HOOK__ strings appear in dist/assets/*.js).

The Vite behaviour alone, without DevTools (Vite 8.3.0):

# index.html: <script type="module" src="./main.js"></script>
# main.js:
#   if (process.env.NODE_ENV !== 'production') console.log('DEV-ONLY-BRANCH')
#   console.log('app')
vite build --outDir clean                        # what a user runs
NODE_ENV=development vite build --outDir inherited   # what the button's child effectively runs
grep -l DEV-ONLY-BRANCH clean/assets/*.js        # no match: dev branch removed
grep -l DEV-ONLY-BRANCH inherited/assets/*.js    # match: dev branch kept

Expected: the button's build matches a plain vite build (production NODE_ENV).
Actual: it is a development build, and the Rolldown panel analyses that.

System Info
OS: Windows 11 Pro 10.0.26200 (x64)
Node: 24.21.0
pnpm: 12.5.1
@vitejs/devtools / @vitejs/devtools-rolldown: 0.7.5 (also upstream main ad2d6df)
devframe / @devframes/hub: 1.0.0
vite: 8.3.0
Used Package Manager

pnpm

Validations
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  • Read the Contributing Guide.
  • Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
  • Check that this is a concrete bug. For Q&A, please open a GitHub Discussion instead.
  • The provided reproduction is a minimal reproducible of the bug.
Dominant language
TypeScript
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Merged PRs (30d)
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