ci: open release pull requests with a workflow

.github/workflows/prepare-release.yaml

@@ -0,0 +1,43 @@
+name: Prepare release
+
+on:
+    workflow_dispatch:
+        inputs:
+            bump:
+                description: Part of the version to bump
+                required: true
+                type: choice
+                options:
+                    - patch
+                    - minor
+                    - major
+
+permissions: {}
+
+jobs:
+    prepare:
+        name: Prepare release
+        runs-on: ubuntu-26.04
+        timeout-minutes: 5
+        permissions:
+            contents: read
+        concurrency:
+            group: ${{ github.workflow }}
+            cancel-in-progress: false
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+            - name: Set up Node.js and pnpm and install dependencies
+              uses: pnpm/setup@703c52620218391530e48b9e8870d5c0082e1b9b # v2.1.0
+              with:
+                  cache: true
+                  runtime: node
+                  require-lockfile: true
+
+            - name: Open the release pull request
+              uses: dnd-mapp/action-prepare-release@b316f1698ace141b667c3a6f6949937da48fbe17 # v1.1.0
+              with:
+                  bump: ${{ inputs.bump }}
+                  client-id: ${{ vars.GH_APP_CLIENT_ID }}
+                  private-key: ${{ secrets.GH_APP_PRIVATE_KEY }}

AGENTS.md

@@ -27,4 +27,4 @@ Turn on auto-merge for every pull request you open, so it merges as soon as it i
 
 - A draft cannot have auto-merge. Mark it ready with `gh pr ready <number>` first, then run the command above.
 - When the user asks to keep a pull request open, leave auto-merge off. If it is already on, turn it off with `gh pr merge <number> --disable-auto`.
-- Release pull requests (`chore: release X.Y.Z`) get auto-merge too. The release starts only when the maintainer pushes the `vX.Y.Z` tag on the merge commit by hand, as `CONTRIBUTING.md` describes.
+- Release pull requests (`chore: release X.Y.Z`) come from the Prepare release workflow, which turns on auto-merge itself. Do not prepare a release commit by hand. The release starts only when the maintainer pushes the `vX.Y.Z` tag on the merge commit by hand, as `CONTRIBUTING.md` describes.

CONTRIBUTING.md

@@ -76,8 +76,8 @@ Enabling a stricter rule or lowering a limit can make commits that passed before
 
 ## Releasing
 
-1. Open a pull request with a single `chore: release X.Y.Z` commit. It sets `version` in `package.json`, renames `[Unreleased]` to `[X.Y.Z] - YYYY-MM-DD`, adds a fresh `[Unreleased]`, and updates the link references.
-2. Merge it, then create an annotated tag `vX.Y.Z` on the merge commit and push the tag.
+1. Run the [prepare release workflow](.github/workflows/prepare-release.yaml) on `main` with the part of the version to bump, for example `gh workflow run prepare-release.yaml -f bump=minor`. It opens the `chore: release X.Y.Z` pull request with auto-merge on.
+2. Review and approve the pull request. Once it merges, create an annotated tag `vX.Y.Z` on the merge commit and push the tag.
 3. The [release workflow](.github/workflows/release.yaml) runs the CI checks, verifies the tag and the changelog, stages the package on npm, and creates the GitHub Release.
 4. Find the staged version with `pnpm stage list` and approve it with `pnpm stage approve <id>` and 2FA.