Self-host pinned WASM demo from dasher-web releases

.gitignore

@@ -33,3 +33,7 @@ public/legacy/
 
 # Logs
 *.log
+
+# fetched dasher demo release artifact
+public/demo/
+.cache/

package.json

@@ -4,7 +4,8 @@
   "description": "Dasher - An information-efficient text-entry interface",
   "type": "module",
   "scripts": {
-    "prebuild": "node scripts/sync-related-research.mjs",
+    "prebuild": "node scripts/fetch-demo.mjs && node scripts/sync-related-research.mjs",
+    "demo:fetch": "node scripts/fetch-demo.mjs",
     "dev": "astro dev",
     "build": "astro check && astro build && pagefind --site dist",
     "research:sync": "node scripts/sync-related-research.mjs",

scripts/fetch-demo.mjs

@@ -0,0 +1,58 @@
+// Fetches a pinned dasher-web WASM demo release artifact and unpacks it
+// into public/demo/, so the site self-hosts a known-good demo instead of
+// iframing the always-moving GitHub Pages deployment.
+//
+// Pin the version with DASHER_DEMO_VERSION (default below). The artifact
+// is produced by dasher-web's wasm-release workflow on v* tags.
+
+import { createWriteStream, existsSync, mkdirSync, statSync } from 'node:fs';
+import { spawnSync } from 'node:child_process';
+import process from 'node:process';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+
+const root = path.dirname(path.dirname(fileURLToPath(import.meta.url)));
+const version = process.env.DASHER_DEMO_VERSION || 'v0.2.8';
+const outDir = path.join(root, 'public', 'demo');
+const marker = path.join(outDir, 'VERSION');
+
+const assetName = `dasher-wasm-demo-${version}.zip`;
+const url = `https://github.com/dasher-project/dasher-web/releases/download/${version}/${assetName}`;
+const zipPath = path.join(root, '.cache', assetName);
+
+// Skip if the pinned version is already unpacked.
+if (existsSync(marker) && existsSync(path.join(outDir, 'index.html'))) {
+  const installed =
+    statSync(marker).size > 0 ? (await import('node:fs')).readFileSync(marker, 'utf8').trim() : '';
+  if (installed === version) {
+    console.log(`demo ${version} already installed at public/demo/`);
+    process.exit(0);
+  }
+}
+
+mkdirSync(path.dirname(zipPath), { recursive: true });
+mkdirSync(outDir, { recursive: true });
+
+console.log(`downloading ${url}`);
+const response = await fetch(url);
+if (!response.ok) {
+  console.error(
+    `failed: HTTP ${response.status} — is dasher-web release ${version} published with asset ${assetName}?`
+  );
+  process.exit(1);
+}
+await (await import('node:stream')).promises.pipeline(response.body, createWriteStream(zipPath));
+
+console.log('unpacking');
+const unzip = spawnSync('unzip', ['-oq', zipPath, '-d', root], { stdio: 'inherit' });
+if (unzip.status !== 0) {
+  console.error('unzip failed');
+  process.exit(1);
+}
+const staged = path.join(root, 'dasher-wasm-demo');
+for (const entry of ['index.html', 'dasher-wasm-wrapper.js', 'wasm', 'BUILD']) {
+  spawnSync('mv', [path.join(staged, entry), path.join(outDir, entry)], { stdio: 'inherit' });
+}
+spawnSync('rm', ['-rf', staged]);
+(await import('node:fs')).writeFileSync(marker, version);
+console.log(`demo ${version} installed at public/demo/`);