fix(cli): dependency installation not including dev dependencies

[gabrielmfern]

Summary by cubic

Fixes email build installs by including dev dependencies and standardizes the build to always use npm. This resolves build failures in the generated .react-email app.

• Bug Fixes

  • Set NPM_CONFIG_INCLUDE=dev during dependency install in .react-email.
  • Use npm for both installDependencies and runScript('build') via nypm.

• Migration

  • --packageManager is deprecated and ignored; email build always uses npm. The option is hidden from --help, has no default, and shows a runtime warning if passed.

^{Written for commit 4e30e0b. Summary will update on new commits.}

[vercel]

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Project	Deployment	Actions	Updated (UTC)
react-email	Ready	Preview, Comment	May 13, 2026 3:13pm
react-email-demo	Ready	Preview, Comment	May 13, 2026 3:13pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 4e30e0b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
react-email	Patch
@react-email/editor	Patch
@react-email/ui	Patch

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[cubic-dev-ai]

No issues found across 3 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Auto-approved: These changes fix a specific bug in CLI dependency handling by including dev dependencies and standardizing the package manager to npm, with low blast radius limited to the build command and proper deprecation warnings.}

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/react-email@3499

commit: 4e30e0b

[cubic-dev-ai]

0 issues found across 1 file (changes from recent commits).

_{Requires human review: This change modifies core build logic by hardcoding npm usage and adding environment variable manipulation for dependency installation, which carries moderate risk of build failures or regressions for users relying on the now-deprecated package manager option.}