Add GitHub Pages PR previews

.github/scripts/publish-pages.sh

@@ -0,0 +1,65 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+mode=${1:?Usage: publish-pages.sh <production|preview|delete> [source-directory] [pr-number]}
+source_directory=${2:-}
+pr_number=${3:-}
+repository_root=$(git rev-parse --show-toplevel)
+pages_directory=$(mktemp -d "${RUNNER_TEMP:-/tmp}/rifm-pages.XXXXXX")
+
+cleanup() {
+  git -C "$repository_root" worktree remove --force "$pages_directory" >/dev/null 2>&1 || true
+  rm -rf "$pages_directory"
+}
+trap cleanup EXIT
+
+if git ls-remote --exit-code --heads origin gh-pages >/dev/null 2>&1; then
+  git -C "$repository_root" fetch origin gh-pages:refs/remotes/origin/gh-pages
+  git -C "$repository_root" worktree add --detach "$pages_directory" origin/gh-pages
+else
+  git -C "$repository_root" worktree add --detach "$pages_directory" HEAD
+  git -C "$pages_directory" checkout --orphan gh-pages
+  git -C "$pages_directory" rm -rf .
+fi
+
+case "$mode" in
+  production)
+    test -d "$source_directory"
+    # Replace production while preserving all pr-* preview directories.
+    find "$pages_directory" -mindepth 1 -maxdepth 1 \
+      ! -name .git ! -name .nojekyll ! -name 'pr-*' -exec rm -rf {} +
+    cp -a "$source_directory"/. "$pages_directory"/
+    commit_message="Deploy production site"
+    ;;
+  preview)
+    test -d "$source_directory"
+    test -n "$pr_number"
+    rm -rf "$pages_directory/pr-$pr_number"
+    mkdir -p "$pages_directory/pr-$pr_number"
+    cp -a "$source_directory"/. "$pages_directory/pr-$pr_number/"
+    commit_message="Deploy preview for PR #$pr_number"
+    ;;
+  delete)
+    test -n "$pr_number"
+    rm -rf "$pages_directory/pr-$pr_number"
+    commit_message="Remove preview for PR #$pr_number"
+    ;;
+  *)
+    echo "Unknown publishing mode: $mode" >&2
+    exit 1
+    ;;
+esac
+
+touch "$pages_directory/.nojekyll"
+git -C "$pages_directory" add -A
+
+if git -C "$pages_directory" diff --cached --quiet; then
+  echo "Pages content is already up to date."
+  exit 0
+fi
+
+git -C "$pages_directory" config user.name github-actions\[bot\]
+git -C "$pages_directory" config user.email 41898282+github-actions\[bot\]@users.noreply.github.com
+# This generated branch has no package.json, so repository hooks cannot run here.
+git -C "$pages_directory" commit --no-verify -m "$commit_message"
+git -C "$pages_directory" push origin HEAD:gh-pages

.github/workflows/pages-preview.yml

@@ -0,0 +1,86 @@
+name: Deploy PR preview
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, closed]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+# Prevent lost updates when multiple previews or production deploy together.
+concurrency:
+  group: pages-publish
+  cancel-in-progress: false
+
+jobs:
+  deploy:
+    if: >-
+      github.event.action != 'closed' &&
+      github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+
+      - uses: pnpm/action-setup@f40ffcd9367d9f12939873eb1018b921a783ffaa # v4
+
+      - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
+        with:
+          node-version: 22
+          cache: pnpm
+
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm run build
+      - run: pnpm --dir website run build
+        env:
+          BASE_PATH: /rifm/pr-${{ github.event.pull_request.number }}/
+
+      - name: Publish preview
+        run: >-
+          bash .github/scripts/publish-pages.sh preview website/dist
+          "${{ github.event.pull_request.number }}"
+
+      - name: Add preview link to PR
+        uses: actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea # v7
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        with:
+          script: |
+            const marker = '<!-- gh-pages-preview -->';
+            const owner = context.repo.owner.toLowerCase();
+            const repo = context.repo.repo;
+            const url = `https://${owner}.github.io/${repo}/pr-${process.env.PR_NUMBER}/`;
+            const body = `${marker}\n🚀 PR preview: ${url}`;
+            const comments = await github.paginate(github.rest.issues.listComments, {
+              ...context.repo,
+              issue_number: context.issue.number,
+            });
+            const existing = comments.find(comment =>
+              comment.user?.type === 'Bot' && comment.body?.includes(marker)
+            );
+            if (existing) {
+              await github.rest.issues.updateComment({
+                ...context.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                ...context.repo,
+                issue_number: context.issue.number,
+                body,
+              });
+            }
+
+  cleanup:
+    if: >-
+      github.event.action == 'closed' &&
+      github.event.pull_request.head.repo.full_name == github.repository
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
+
+      - name: Remove preview
+        run: >-
+          bash .github/scripts/publish-pages.sh delete ""
+          "${{ github.event.pull_request.number }}"

.github/workflows/pages.yml

@@ -7,21 +7,19 @@ on:
   workflow_dispatch:
 
 permissions:
-  contents: read
+  contents: write
 
+# Preview and production jobs both mutate the same gh-pages branch.
 concurrency:
-  group: pages
+  group: pages-publish
   cancel-in-progress: false
 
 jobs:
-  build:
-    if: github.ref == 'refs/heads/main'
-    name: Build
+  deploy:
+    name: Deploy
     runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
-        with:
-          persist-credentials: false
       - name: Install pnpm
         uses: pnpm/action-setup@f40ffcd9367d9f12939873eb1018b921a783ffaa # v4
       - uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4
@@ -30,30 +28,11 @@ jobs:
           cache: pnpm
       - name: Install dependencies
         run: pnpm install --frozen-lockfile
-      - name: Configure Pages
-        id: pages
-        uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5
       - name: Build package
         run: pnpm run build
       - name: Build website
-        run: pnpm --dir website build --base "${{ steps.pages.outputs.base_path }}/"
-      - name: Upload Pages artifact
-        uses: actions/upload-pages-artifact@7b1f4a764d45c48632c6b24a0339c27f5614fb0b # v4
-        with:
-          path: website/dist
-
-  deploy:
-    if: github.ref == 'refs/heads/main'
-    name: Deploy
-    permissions:
-      pages: write
-      id-token: write
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    runs-on: ubuntu-22.04
-    needs: build
-    steps:
-      - name: Deploy to Pages
-        id: deployment
-        uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4
+        run: pnpm --dir website run build
+        env:
+          BASE_PATH: /rifm/
+      - name: Publish production site
+        run: bash .github/scripts/publish-pages.sh production website/dist

website/vite.config.ts

@@ -1,6 +1,7 @@
 import { defineConfig } from "vite";
 
 export default defineConfig({
+  base: process.env.BASE_PATH || "/",
   optimizeDeps: {
     rolldownOptions: {
       transform: {