Support OIDC authentication for NPM publishing (#52)

* Support OIDC authentication for NPM publishing

NPM has deprecated classic tokens, so this adds support for OIDC
authentication (Trusted Publishers) as an alternative to NPM_TOKEN.

- Make NPM_TOKEN optional - only configure .npmrc when provided
- For OIDC, npm handles auth automatically via GitHub's OIDC provider
- Add documentation for OIDC setup in README
- Bump version to 0.0.16

Fixes #50

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Remove NPM_TOKEN support, require OIDC authentication

- Change OIDC from "recommended" to "required"
- Add npm CLI 11.5.2+ version requirement for OIDC
- Remove NPM_TOKEN workflow example and documentation
- Remove NPM_TOKEN handling code from index.ts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Bump version to 0.1.0 for breaking changes

Minor version bump per SemVer conventions for pre-1.0.0 breaking changes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Keep NPM_TOKEN support for backwards compatibility

Mark NPM_TOKEN as deprecated but still functional for external users
who may have valid tokens.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Remove NPM_TOKEN support completely

OIDC authentication is now the only supported method for npm publishing.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: billfienberg

README.md

@@ -12,7 +12,11 @@ This GitHub action allows for automation of [Changesets Snapshot Release](https:
 
 Create a `.github/workflows/snapit.yml` file with the following contents.
 
-**Deploy to NPM**
+**Deploy to NPM (with OIDC authentication)**
+
+OIDC authentication using [NPM Trusted Publishers](https://docs.npmjs.com/trusted-publishers) is required as [NPM has deprecated classic tokens](https://github.blog/changelog/2025-09-29-strengthening-npm-security-important-changes-to-authentication-and-token-management/).
+
+> **Note:** OIDC requires npm CLI version 11.5.2 or later. Earlier versions will fail with cryptic errors.
 
 ```yml
 name: Snapit
@@ -26,15 +30,26 @@ jobs:
   snapit:
     name: Snapit
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
+      issues: write
+      pull-requests: write
     steps:
       - name: Checkout default branch
         uses: actions/checkout@v4
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          registry-url: 'https://registry.npmjs.org'
+
       - name: Create snapshot version
         uses: Shopify/snapit@main
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
+          NPM_CONFIG_PROVENANCE: true
         with:
           build_script: pnpm build # Optional
           trigger_comment: /snapit # Default value not required
@@ -75,9 +90,15 @@ jobs:
 
 The `GITHUB_TOKEN` is needed for changesets to look up the current changeset when creating a snapshot. You can use the automatically created [`${{ secrets.GITHUB_TOKEN }}` to authenticate in the workflow job](https://docs.github.com/en/actions/security-guides/automatic-token-authentication#about-the-github_token-secret).
 
-**`NPM_TOKEN`**
+**OIDC Authentication**
 
-A `NPM_TOKEN` needs to be created and added to the repository to [publish packages from GitHub actions to the npm registry](https://docs.github.com/en/actions/publishing-packages/publishing-nodejs-packages#publishing-packages-to-the-npm-registry).
+Use [NPM Trusted Publishers](https://docs.npmjs.com/trusted-publishers) with OIDC authentication. This is required as NPM has deprecated classic tokens. To use OIDC:
+
+1. Configure your npm package to trust your GitHub repository (see [NPM Trusted Publishers documentation](https://docs.npmjs.com/trusted-publishers))
+2. Ensure npm CLI version 11.5.2 or later is installed
+3. Add `id-token: write` permission to your workflow
+4. Use `actions/setup-node` with `registry-url: 'https://registry.npmjs.org'`
+5. Set `NPM_CONFIG_PROVENANCE: true` environment variable
 
 ## GitHub Action Inputs
 
@@ -107,6 +128,11 @@ To contribute a change, bug fix or feature to snapit:
 
 ## Changelog
 
+**`v0.1.0`**
+
+- **Breaking:** Require OIDC authentication (NPM Trusted Publishers). `NPM_TOKEN` is no longer supported.
+- OIDC requires npm CLI version 11.5.2 or later
+
 **`v0.0.15`**
 
 - Add `release_branch` to configure the default release branch. Default is `changeset-release/main`.

dist/index.js

@@ -188,21 +188,6 @@ try {
       await exec('git', ['checkout', '-b', branch]);
       await exec('git', ['push', '--force', 'origin', branch]);
     } else {
-      if (!process.env.NPM_TOKEN) {
-        throw new Error(
-          'Please provide the NPM_TOKEN to the snapit GitHub action',
-        );
-      }
-
-      await exec(
-        'bash',
-        [
-          '-c',
-          `echo "//registry.npmjs.org/:_authToken=${process.env.NPM_TOKEN}" > "$HOME/.npmrc"`,
-        ],
-        silentOption,
-      );
-
       await exec(changesetBinary, [
         'publish',
         '--no-git-tags',

index.ts

@@ -1,7 +1,7 @@
 {
   "name": "snapit",
   "private": true,
-  "version": "0.0.15",
+  "version": "0.1.0",
   "description": "Create a snapshot NPM release with `/snapit` comment in a PR",
   "type": "module",
   "scripts": {