chore: automatically label pull requests

.github/workflows/auto-label.yml

@@ -0,0 +1,59 @@
+# This code has been fully generated by an AI.
+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: 2026 The semrel Authors
+name: Automatically label pull requests
+
+on:
+  pull_request_target:
+    types: [opened, reopened, synchronize, edited]
+
+permissions:
+  issues: write
+  pull-requests: read
+
+concurrency:
+  group: auto-label-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+jobs:
+  label:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Apply labels based on the title and changed files
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const pullRequest = context.payload.pull_request;
+            const titleMatch = pullRequest.title.match(/^\s*(fix|bugfix|bug|feat|feature|enhancement|docs?|ci|deps?)(?:\([^)]*\))?!?:/i);
+            const titleLabels = {
+              fix: "bug", bugfix: "bug", bug: "bug",
+              feat: "enhancement", feature: "enhancement", enhancement: "enhancement",
+              doc: "documentation", docs: "documentation",
+              ci: "github_actions", dep: "dependencies", deps: "dependencies",
+            };
+            const labels = new Set();
+            if (titleMatch) labels.add(titleLabels[titleMatch[1].toLowerCase()]);
+
+            const files = await github.paginate(github.rest.pulls.listFiles, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: pullRequest.number,
+              per_page: 100,
+            });
+            const dependencyFile = /(^|\/)(go\.(mod|sum|work|work\.sum)|package\.json|package-lock\.json|npm-shrinkwrap\.json|pnpm-lock\.yaml|yarn\.lock|Cargo\.(toml|lock)|pyproject\.toml|poetry\.lock|uv\.lock|requirements[^/]*\.txt|Pipfile(\.lock)?|composer\.(json|lock)|Gemfile(\.lock)?|pom\.xml|build\.gradle(\.kts)?|gradle\.properties|packages\.lock\.json|dependabot\.yml|renovate\.json|\.semrel\.lock)$/i;
+            for (const file of files) {
+              if (/(^|\/)(docs?|documentation)(\/|$)/i.test(file.filename) || /\.mdx?$/i.test(file.filename)) labels.add("documentation");
+              if (/^\.github\/workflows\//i.test(file.filename)) labels.add("github_actions");
+              if (dependencyFile.test(file.filename)) labels.add("dependencies");
+            }
+
+            const existing = new Set(pullRequest.labels.map((label) => label.name));
+            const missing = [...labels].filter((label) => label && !existing.has(label));
+            if (missing.length > 0) {
+              await github.rest.issues.addLabels({
+                owner: context.repo.owner,
+                repo: context.repo.repo,
+                issue_number: pullRequest.number,
+                labels: missing,
+              });
+            }