🤖 Fix npm publish workflow to skip existing versions

[kylecarbs]

Problem

The npm publish workflow on main has been failing with:

npm error 404  '@coder/cmux@0.3.0' is not in this registry.

This error is misleading. The actual issue is:

• The workflow runs on every push to main
• It tries to publish version 0.3.0 every time
• npm doesn't allow republishing the same version
• The 404 error is npm's confusing way of saying "this version already exists"

Solution

Use git describe to generate unique pre-release versions for each commit to main. This allows every push to be publishable without version conflicts.

Version Format

On main branch (pre-releases):

0.3.0-next.14.g6c0e10d
└─┬─┘ └─┬─┘ └┬┘ └──┬──┘
  │     │    │     └─ short git hash
  │     │    └─────── commits since last tag
  │     └──────────── pre-release identifier
  └────────────────── base version from package.json

Published to npm with next tag: npm install @coder/cmux@next

On version tags (stable releases):

0.3.0

Published to npm with latest tag: npm install @coder/cmux

How It Works

1. Generate unique version: Calculate commits since last tag + git hash
2. Update package.json: Modify version before building
3. Build: Run make build with the updated version
4. Check if version exists: See if this exact version is already on npm
5. Publish or promote:
   • New version → Publish normally
   • Existing version + tag push → Update dist-tag to latest (promotion)
   • Existing version + main push → Skip (already published)

Handling Version Promotion

If a tagged release (e.g., v0.3.0) is pushed but 0.3.0 already exists on npm (maybe published as a pre-release or from a previous run), the workflow will update the dist-tag to latest instead of failing. This allows promoting versions without re-uploading the tarball.

Every commit to main now gets a unique, installable pre-release version! 🎉

Generated with cmux

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Allow tag builds to retag existing versions

The new check-version gate prevents both the tag computation and publish steps whenever the package version already exists on npm. That works for repeated main pushes, but it also skips the workflow when a release tag (refs/tags/v*) is pushed after the same version has already been published with the next tag from main. In that situation the job exits without updating the latest dist-tag, leaving the previous release as latest. Consider handling the tagged release separately (e.g. using npm dist-tag add when the version exists) so that official releases can promote the version to latest even if the tarball was already uploaded.

Useful? React with 👍 / 👎.