chore(pages): deploy the demo from CI instead of by hand

.github/workflows/pages.yml

@@ -0,0 +1,61 @@
+name: Deploy demo site
+
+# Publishes demo/ to GitHub Pages on every push to main that touches it.
+#
+# This replaces `npm run publish:demo` (the gh-pages package), which pushed
+# the working directory to a gh-pages branch by hand. That made merging and
+# deploying two separate events — a merged PR left the live site stale until
+# someone remembered to run it — and published whatever happened to be on
+# disk rather than a specific commit.
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "demo/**"
+      - ".github/workflows/pages.yml"
+  workflow_dispatch:
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+# The site is only ever the newest commit, so a queued run can be dropped —
+# but never one that is mid-deploy.
+concurrency:
+  group: pages
+  cancel-in-progress: false
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Stage the publishable demo files
+        run: |
+          mkdir -p _site
+          # index-local.html points at a local dist/ build and is a dev-only
+          # harness; the old publish script excluded it and so does this.
+          rsync -a --exclude 'index-local.html' demo/ _site/
+          # Without .nojekyll, Pages runs Jekyll and drops files starting "_".
+          touch _site/.nojekyll
+          echo "Publishing:"
+          ls -A _site
+
+      - name: Configure Pages
+        uses: actions/configure-pages@v5
+
+      - name: Upload site
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: _site
+
+      - name: Deploy
+        id: deployment
+        uses: actions/deploy-pages@v4

CONTRIBUTING.md

@@ -46,34 +46,42 @@ visual-image-tool/
 
 ## Available scripts
 
-| Script                 | Purpose                                                      |
-| ---------------------- | ------------------------------------------------------------ |
-| `npm run build`        | Generate the distribution files in `dist/`                   |
-| `npm run dev`          | Run the build in watch mode                                  |
-| `npm test`             | Run the unit tests once                                      |
-| `npm run test:watch`   | Run the tests in watch mode                                  |
-| `npm run lint:check`   | Check linting and formatting of JS/JSON with Biome           |
-| `npm run lint:fix`     | Apply Biome fixes                                            |
-| `npm run format:check` | Check formatting of other file types with Prettier           |
-| `npm run format:fix`   | Apply Prettier formatting                                    |
-| `npm run demo`         | Serve `demo/` locally                                        |
-| `npm run publish:demo` | Publish `demo/` to GitHub Pages (all but `index-local.html`) |
+| Script                 | Purpose                                            |
+| ---------------------- | -------------------------------------------------- |
+| `npm run build`        | Generate the distribution files in `dist/`         |
+| `npm run dev`          | Run the build in watch mode                        |
+| `npm test`             | Run the unit tests once                            |
+| `npm run test:watch`   | Run the tests in watch mode                        |
+| `npm run lint:check`   | Check linting and formatting of JS/JSON with Biome |
+| `npm run lint:fix`     | Apply Biome fixes                                  |
+| `npm run format:check` | Check formatting of other file types with Prettier |
+| `npm run format:fix`   | Apply Prettier formatting                          |
+| `npm run demo`         | Serve `demo/` locally                              |
 
 Linting and formatting are enforced in CI, so run `npm run lint:check` and `npm run format:check` before pushing.
 
 ### Publishing the demos
 
-`npm run publish:demo` pushes `demo/` to the `gh-pages` branch, which is served
-at <https://h4md1.fr/visual-image-tool/>.
+There is nothing to run. `.github/workflows/pages.yml` deploys `demo/` to
+<https://h4md1.fr/visual-image-tool/> on every push to `main` that touches it,
+so merging a change to the demo publishes it.
 
-The `--src "**/!(index-local).*"` pattern excludes `index-local.html`. That page
-loads `../dist/visual-image-tool.umd.js`, which resolves above the site root
-once published and 404s, so the page is only meaningful when served locally.
-Everything else in `demo/` loads the published package from the CDN.
+The workflow excludes `index-local.html`. That page loads
+`../dist/visual-image-tool.umd.js`, which resolves above the site root once
+published and 404s, so it is only meaningful when served locally with
+`npm run demo`. Everything else in `demo/` loads the published package from
+the CDN.
 
-Note that `gh-pages` removes the branch's existing files before copying, but the
-pattern it uses for that never matches dotfiles — anything like `.github/` that
-lands on `gh-pages` stays there until it is removed by hand.
+It also writes `.nojekyll`, without which Pages runs Jekyll and drops any file
+whose name starts with an underscore.
+
+To publish without a code change — or to re-deploy — run the workflow manually
+from the Actions tab (`workflow_dispatch`).
+
+This replaced `npm run publish:demo`, which pushed the working directory to a
+`gh-pages` branch by hand. That made merging and deploying two separate events,
+so a merged PR left the live site stale until someone remembered to run it, and
+it published whatever was on disk rather than a specific commit.
 
 ## Build process