feat(ci): auto-generate PR titles from added file paths (#4790)

* feat(ci): auto-generate PR titles from added file paths

* refactor(ci): single source of truth for conventional commit types

* ci: skip PR title generation when "Keep PR title" label is present

Co-authored-by: ericfennis <11825403+ericfennis@users.noreply.github.com>

* refactor(ci): align package path scopes with package.json names

* Apply changes to generated pr titles

* Add .github/conventional-commit-types.json to gitignore

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: ericfennis <11825403+ericfennis@users.noreply.github.com>
Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

.github/conventional-commit-types.json

@@ -0,0 +1,12 @@
+[
+  "fix",
+  "feat",
+  "perf",
+  "refactor",
+  "test",
+  "style",
+  "docs",
+  "ci",
+  "build",
+  "chore"
+]

.github/workflows/generate-pr-title.yml

@@ -0,0 +1,100 @@
+name: PR title
+
+on:
+  pull_request_target:
+    types:
+      - opened
+      - reopened
+      - synchronize
+      - edited
+
+permissions: {}
+
+concurrency:
+  group: pr-title-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  generate-pr-title:
+    name: Generate PR Title
+    # Skip when a maintainer has opted out by adding the "Keep PR title" label,
+    # and on manual edits so they are not reverted straight away.
+    if: github.repository == 'lucide-icons/lucide' &&
+      github.event.action != 'edited' &&
+      !contains(github.event.pull_request.labels.*.name, 'Keep PR title')
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write # Required to edit the PR title
+
+    steps:
+      #  We check out the main branch of the main repository for security reasons.
+      #  The script only reads its input from the environment, so it never runs
+      #  any code from the (untrusted) pull request.
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          repository: lucide-icons/lucide
+          fetch-depth: 0
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version-file: 'package.json'
+
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@9426d40962ed5378910ee2e21d5f8c6fcbf2dd96 # v47.0.6
+
+      - name: Generate PR title
+        id: generate
+        run: |
+          NEW_TITLE="$(node ./scripts/generatePullRequestTitle.mts)"
+          {
+            echo "new_title<<PR_TITLE_EOF"
+            echo "$NEW_TITLE"
+            echo "PR_TITLE_EOF"
+          } >> "$GITHUB_OUTPUT"
+        env:
+          ADDED_FILES: ${{ steps.changed-files.outputs.added_files }}
+          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_and_modified_files }}
+          CURRENT_TITLE: ${{ github.event.pull_request.title }}
+
+      - name: Update PR title
+        if: steps.generate.outputs.new_title != ''
+        run: gh pr edit "$PR_NUMBER" --title "$NEW_TITLE"
+        env:
+          GH_TOKEN: ${{ github.token }}
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+          NEW_TITLE: ${{ steps.generate.outputs.new_title }}
+
+  # Runs after the title is generated: an edit made with `GITHUB_TOKEN` does not
+  # trigger new workflow runs, so a separate workflow would lint the old title.
+  # The lint action fetches the current title through the API.
+  lint-pr-title:
+    name: PR Title Lint
+    needs: generate-pr-title
+    if: ${{ !cancelled() }}
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: read # Required to read the PR title
+
+    steps:
+      # Checks out the base branch, so the allowed types can't be changed by the PR.
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Read conventional commit types
+        id: commit-types
+        run: |
+          {
+            echo "types<<TYPES_EOF"
+            jq -r '.[]' .github/conventional-commit-types.json
+            echo "TYPES_EOF"
+          } >> "$GITHUB_OUTPUT"
+
+      - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          types: ${{ steps.commit-types.outputs.types }}
+          requireScope: true
+          ignoreLabels: |
+            bot

.github/workflows/lint-pr-title.yml

@@ -1,36 +0,0 @@
-name: Linting PR title
-
-on:
-  pull_request:
-    types:
-      - opened
-      - edited
-      - reopened
-
-permissions:
-  contents: read
-  pull-requests: read # Required to read the PR title
-
-jobs:
-  lint-pr-title:
-    name: PR Title Lint
-    runs-on: ubuntu-latest
-    steps:
-      - uses: amannn/action-semantic-pull-request@48f256284bd46cdaab1048c3721360e808335d50 # v6.1.1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          types: |
-            fix
-            feat
-            perf
-            refactor
-            test
-            style
-            docs
-            ci
-            build
-            chore
-          requireScope: true
-          ignoreLabels: |
-            bot