Add a workflow that generates a commit message.

.github/workflows/detect-gutenberg-sha-change.yml

@@ -0,0 +1,59 @@
+# Generates a list of changes and a commit message when the pinned gutenberg repository hash changes.
+name: Draft commit message
+
+on:
+  # This workflow was introduced in WordPress 7.0.
+  pull_request:
+    branches:
+      - trunk
+      - '[7-9].[0-9]'
+    paths:
+      - 'package.json'
+
+# Cancels all previous workflow runs for pull requests that have not completed.
+concurrency:
+  # The concurrency group contains the workflow name and the branch name for pull requests
+  # or the commit hash for any other events.
+  group: ${{ github.workflow }}-${{ github.event_name == 'pull_request' && github.head_ref || github.sha }}
+  cancel-in-progress: true
+
+# Disable permissions for all available scopes by default.
+# Any needed permissions should be configured at the job level.
+permissions: {}
+
+jobs:
+  # Detects whether the gutenberg.sha value in the package.json file has changed.
+  detect-hash-change:
+    name: Detect Gutenberg SHA change
+    uses: ./.github/workflows/reusable-detect-gutenberg-hash-change-v1.yml
+    permissions:
+      contents: read
+
+  # Generates a list of changes between two specified hashes.
+  generate-changelog:
+    name: Generate a list of changes between the hashes
+    uses: ./.github/workflows/reusable-generate-gutenberg-changelog-v1.yml
+    needs: [ 'detect-hash-change' ]
+    if: ${{ needs.detect-hash-change.outputs.sha_changed == 'true' }}
+    permissions:
+      contents: read
+    with:
+      base-sha: ${{ needs.detect-hash-change.outputs.base_sha }}
+      head-sha: ${{ needs.detect-hash-change.outputs.head_sha }}
+
+  # Drafts a commit message containing a detailed list of changes being merged.
+  #
+  # Performs the following steps:
+  # - Downloads the changelog artifact.
+  # - Builds a commit message.
+  # - Uploads the commit message as an artifact.
+  generate-commit-message:
+    name: Generate commit message
+    uses: ./.github/workflows/reusable-generate-commit-message-v1.yml
+    needs: [ 'detect-hash-change', 'generate-changelog' ]
+    if: ${{ needs.generate-changelog.outputs.has_changes == 'true' }}
+    permissions:
+      contents: read
+    with:
+      previous-hash: ${{ needs.detect-hash-change.outputs.base_sha }}
+      new-hash: ${{ needs.detect-hash-change.outputs.head_sha }}

.github/workflows/pull-request-comments.yml

@@ -5,7 +5,7 @@ on:
   pull_request_target:
     types: [ 'opened', 'synchronize', 'reopened', 'edited' ]
   workflow_run:
-    workflows: [ 'Test Build Processes' ]
+    workflows: [ 'Test Build Processes', 'Draft commit message' ]
     types:
       - completed
 
@@ -228,3 +228,120 @@ jobs:
             `,
               } );
             }
+
+  # Adds a comment with a drafted commit message.
+  drafted-commit-message:
+    name: Manage commit message draft
+    runs-on: ubuntu-24.04
+    permissions:
+      issues: write
+      pull-requests: write
+    if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event_name == 'pull_request_target' && ! github.event.pull_request.draft && github.event.pull_request.state == 'open' }}
+
+    steps:
+      - name: Download artifact
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        with:
+          script: |
+            const fs = require( 'fs' );
+
+            const artifacts = await github.rest.actions.listWorkflowRunArtifacts( {
+               owner: context.repo.owner,
+               repo: context.repo.repo,
+               run_id: process.env.RUN_ID,
+            } );
+
+            const matchPrNumberArtifact = artifacts.data.artifacts.filter( ( artifact ) => {
+              return artifact.name === 'pr-number'
+            } )[0];
+
+            if ( ! matchPrNumberArtifact ) {
+              core.setFailed( 'No PR number artifact found!' );
+              return;
+            }
+
+            const downloadPrNumber = await github.rest.actions.downloadArtifact( {
+               owner: context.repo.owner,
+               repo: context.repo.repo,
+               artifact_id: matchPrNumberArtifact.id,
+               archive_format: 'zip',
+            } );
+
+            fs.writeFileSync( '${{github.workspace}}/pr-number.zip', Buffer.from( downloadPrNumber.data ) )
+
+            const matchMessageArtifact = artifacts.data.artifacts.filter( ( artifact ) => {
+              return artifact.name === 'commit-message.md'
+            } )[0];
+
+            if ( ! matchMessageArtifact ) {
+              core.setFailed( 'No commit message artifact found!' );
+              return;
+            }
+
+            const downloadCommitMessage = await github.rest.actions.downloadArtifact( {
+               owner: context.repo.owner,
+               repo: context.repo.repo,
+               artifact_id: matchMessageArtifact.id,
+               archive_format: 'zip',
+            } );
+
+            fs.writeFileSync( '${{github.workspace}}/commit-message.zip', Buffer.from( downloadCommitMessage.data ) )
+        env:
+          RUN_ID: ${{ github.event.workflow_run.id }}
+
+      - name: Unzip the artifact containing the PR number
+        run: unzip pr-number.zip
+
+      - name: Unzip the artifact containing the commit mesage
+        run: unzip commit-message.zip
+
+      - name: Leave or update a comment with the commit message draft
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        with:
+          script: |
+            const fs = require( 'fs' );
+            const issue_number = Number( fs.readFileSync( './NR' ) );
+
+            core.info( `Checking pull request #${issue_number}.` );
+
+            // Confirm that the pull request is still open before leaving a comment.
+            const pr = await github.rest.pulls.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: issue_number,
+            });
+
+            if ( pr.data.state !== 'open' ) {
+              core.info( 'The pull request has been closed. No comment will be left.' );
+              return;
+            }
+
+            // Comments are only added once and then updated on future commits.
+            const commentInfo = {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number,
+            };
+
+            const comments = ( await github.rest.issues.listComments( commentInfo ) ).data;
+            const hasCommitMessageDraft = comments.find( comment => comment.user.type === 'Bot' && comment.body.includes( 'Editor: Bump pinned hash' ) );
+
+            // Construct comment
+            commentInfo.body = '## Commit Message Draft\n' +
+            'This pull request changes the pinned hash for the Gutenberg repository. Here is a commit message draft containing a compiled list of changes included with additional required information:\n\n' +
+            ```\n' +
+            commitMessageContents +
+            '\n```\n' +
+            '**Always verify these commit message drafts before using. And don't forget to include props!**';
+
+            // Only update the comment when there are changes.
+            if ( hasCommitMessageDraft ) {
+              if ( hasCommitMessageDraft.body != commentInfo.body ) {
+                commentInfo.comment_id = hasCommitMessageDraft.id;
+
+                github.rest.issues.updateComment( commentInfo );
+              }
+              return;
+            }
+
+            github.rest.issues.createComment( commentInfo );

.github/workflows/reusable-detect-gutenberg-hash-change-v1.yml

@@ -0,0 +1,64 @@
+##
+# A reusable workflow that detects when the `gutenberg.sha` value changes in the `package.json` file.
+##
+name: Detect hash change (reusable)
+
+on:
+  workflow_call:
+    outputs:
+      sha_changed:
+        description: 'Whether the pinned Gutenberg hash has changed.'
+        value: ${{ jobs.detect-hash-change.outputs.sha_changed }}
+      base_sha:
+        description: 'The previous pinned Gutenberg hash.'
+        value: ${{ jobs.detect-hash-change.outputs.base_sha }}
+      head_sha:
+        description: 'The new pinned Gutenberg hash.'
+        value: ${{ jobs.detect-hash-change.outputs.head_sha }}
+
+# Disable permissions for all available scopes by default.
+# Any needed permissions should be configured at the job level.
+permissions: {}
+
+jobs:
+  # Detects whether the gutenberg.sha value in the package.json file has changed.
+  #
+  # Performs the following steps:
+  # - Checks out the repository.
+  # - Check if the pinned hash has changed.
+  detect-hash-change:
+    name: Detect Gutenberg SHA change
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+    timeout-minutes: 5
+    outputs:
+      sha_changed: ${{ steps.check-sha.outputs.sha_changed }}
+      base_sha: ${{ steps.check-sha.outputs.base_sha }}
+      head_sha: ${{ steps.check-sha.outputs.head_sha }}
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          fetch-depth: 0
+          persist-credentials: false
+
+      - name: Check if the pinned Gutenberg hash has changed
+        id: check-sha
+        run: |
+          BASE_GUTENBERG_SHA=$(git show ${{ github.event.pull_request.base.sha }}:package.json | jq -r '.gutenberg.sha // empty')
+          HEAD_GUTENBERG_SHA=$(git show ${{ github.event.pull_request.head.sha }}:package.json | jq -r '.gutenberg.sha // empty')
+
+          echo "base_sha=$BASE_GUTENBERG_SHA" >> "$GITHUB_OUTPUT"
+          echo "head_sha=$HEAD_GUTENBERG_SHA" >> "$GITHUB_OUTPUT"
+
+          if [ "$BASE_GUTENBERG_SHA" != "$HEAD_GUTENBERG_SHA" ]; then
+            echo "sha_changed=true" >> "$GITHUB_OUTPUT"
+            echo "The pinned Gutenberg Repository hash has changed."
+            echo "  Previous SHA (base branch): $BASE_GUTENBERG_SHA"
+            echo "  New SHA (head branch): $HEAD_GUTENBERG_SHA"
+          else
+            echo "sha_changed=false" >> "$GITHUB_OUTPUT"
+            echo "The pinned Gutenberg repository hash has not changed: $HEAD_GUTENBERG_SHA"
+          fi

.github/workflows/reusable-generate-commit-message-v1.yml

@@ -0,0 +1,85 @@
+##
+# A reusable workflow that detects when the `gutenberg.sha` value changes in the `package.json` file.
+##
+name: Detect hash change (reusable)
+
+on:
+  workflow_call:
+    inputs:
+      previous-hash:
+        description: 'The previous commit SHA value.'
+        required: true
+        type: 'string'
+      new-hash:
+        description: 'The new commit hash value.'
+        required: true
+        type: 'string'
+
+# Disable permissions for all available scopes by default.
+# Any needed permissions should be configured at the job level.
+permissions: {}
+
+jobs:
+  # Drafts a commit message containing a detailed list of changes being merged.
+  #
+  # Performs the following steps:
+  # - Downloads the changelog artifact.
+  # - Builds a commit message.
+  # - Uploads the commit message as an artifact.
+  # - Saves the pull request number to a text file.
+  # - Uploads the pull request number as an artifact.
+  generate-commit-message:
+    name: Generate commit message
+    runs-on: ubuntu-24.04
+    permissions:
+      contents: read
+
+    steps:
+      - name: Download changelog artifact
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
+        with:
+          name: changelog.txt
+          skip-decompress: true
+
+      - name: Build commit message
+        env:
+          BASE_SHA: ${{ inputs.previous-hash }}
+          HEAD_SHA: ${{ inputs.new-hash }}
+        run: |
+          {
+            printf 'Editor: Bump pinned hash for the Gutenberg repository.\n\n'
+            printf "This updates the pinned hash from the gutenberg from \`%s\` to \`%s\`.\n\n" "$BASE_SHA" "$HEAD_SHA"
+
+            if [ "$HAS_CHANGES" = "false" ]; then
+              printf '> [!WARNING]\n'
+              printf '> No pull request references were found in the commits between the two hashes. Please verify the hash range is correct.\n\n'
+            else
+              printf 'The following changes are included:\n\n'
+              cat changelog.txt
+              printf '\n'
+            fi
+
+            printf 'A full list of changes can be found on GitHub: https://github.com/WordPress/gutenberg/compare/%s...%s.\n\n' "$BASE_SHA" "$HEAD_SHA"
+            printf 'See #64595, #64393.\n'
+          } > commit-message.md
+
+      - name: Upload commit message as an artifact
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
+        with:
+          name: commit-message
+          path: commit-message.md
+
+      - name: Save PR number
+        run: |
+          mkdir -p ./pr-number
+          echo "${EVENT_NUMBER}" > ./pr-number/NR
+        env:
+          EVENT_NUMBER: ${{ github.event.number }}
+
+      # Uploads the PR number as an artifact for the Pull Request Commenting workflow to download and then
+      # leave a comment detailing how to test the PR within WordPress Playground.
+      - name: Upload PR number as artifact
+        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        with:
+          name: pr-number
+          path: pr-number/