Add 'Reset demos' button to refresh canonical demo files

Existing accounts (including admin) seeded before new demos shipped
had no easy way to pull in the latest copies — the registration-time
seeder is intentionally non-destructive. The new badge action fetches
src/static/bundled-demos/manifest.json, confirms the overwrite, and
re-copies each canonical demo into code/. Open tabs of those files are
refreshed in place so the user sees the new content immediately.

src/static/bundled-demos/ ships the six canonical files plus the
manifest so this works in local mode and on a static-only host. The
Dockerfile now mirrors workspace/code/<demo>.py into bundled-demos/
during the image build, keeping the two locations in sync.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/static/script.js

@@ -192,6 +192,14 @@ class TextEditor {
       importBtn.addEventListener('click', () => this.importWorkspaceZip());
       badge.appendChild(importBtn);
 
+      const resetBtn = document.createElement('button');
+      resetBtn.type = 'button';
+      resetBtn.className = 'workspace-badge-action';
+      resetBtn.textContent = 'Reset demos';
+      resetBtn.title = 'Re-copy the bundled demos into code/ (overwrites your edits to those files)';
+      resetBtn.addEventListener('click', () => this.resetDemoFiles());
+      badge.appendChild(resetBtn);
+
       const exit = document.createElement('button');
       exit.type = 'button';
       exit.className = 'workspace-badge-exit';
@@ -259,9 +267,107 @@ class TextEditor {
     importBtn.addEventListener('click', () => this.importWorkspaceZip());
     badge.appendChild(importBtn);
 
+    const resetBtn = document.createElement('button');
+    resetBtn.type = 'button';
+    resetBtn.className = 'workspace-badge-action';
+    resetBtn.textContent = 'Reset demos';
+    resetBtn.title = 'Re-copy the bundled demos into code/ (overwrites your edits to those files)';
+    resetBtn.addEventListener('click', () => this.resetDemoFiles());
+    badge.appendChild(resetBtn);
+
     badge.classList.remove('hidden');
   }
 
+  async resetDemoFiles() {
+    let manifest;
+    try {
+      const r = await fetch('/static/bundled-demos/manifest.json', { cache: 'no-store' });
+      if (!r.ok) throw new Error(`manifest fetch ${r.status}`);
+      manifest = await r.json();
+    } catch (err) {
+      this.showError(
+        `Could not load demo manifest: ${err && err.message ? err.message : err}`
+      );
+      return;
+    }
+    const names = Array.isArray(manifest && manifest.files) ? manifest.files.slice() : [];
+    if (!names.length) {
+      this.showError('No demos in bundle');
+      return;
+    }
+    if (!confirm(
+      `Reset ${names.length} demo file${names.length === 1 ? '' : 's'}?\n\n` +
+        names.map((n) => `  • code/${n}`).join('\n') +
+        '\n\nAny edits you made to these files will be overwritten. Other ' +
+        'files (main.py, your own scripts) are not touched.'
+    )) return;
+
+    let written = 0;
+    let failed = 0;
+    for (const name of names) {
+      try {
+        const r = await fetch(`/static/bundled-demos/${encodeURIComponent(name)}`, {
+          cache: 'no-store',
+        });
+        if (!r.ok) {
+          failed += 1;
+          continue;
+        }
+        const content = await r.text();
+        const w = await this.apiFetch(`/api/file/code/${encodeURIComponent(name)}`, {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ content }),
+        });
+        if (w && w.ok) {
+          written += 1;
+        } else {
+          failed += 1;
+        }
+      } catch (_err) {
+        failed += 1;
+      }
+    }
+    this.workspaceSourcesCache = null;
+    this.directoryCache.clear();
+    /* If a stale demo is currently open in a tab, refresh the editor
+       contents from disk so the user sees the new version. */
+    for (const name of names) {
+      const path = `code/${name}`;
+      if (this.findTab(path)) {
+        try {
+          const fr = await this.apiFetch(`/api/file/${encodeURIComponent(path)}`);
+          if (fr && fr.ok) {
+            const fd = await fr.json();
+            const tab = this.findTab(path);
+            if (tab) {
+              tab.content = typeof fd.content === 'string' ? fd.content : '';
+              tab.savedContent = tab.content;
+              if (this.activeTabPath === path) {
+                this.ignoreNextChange = true;
+                this.editor.dispatch({
+                  changes: {
+                    from: 0,
+                    to: this.editor.state.doc.length,
+                    insert: tab.content,
+                  },
+                });
+              }
+            }
+          }
+        } catch (_err) {
+          // Skip refresh failure; user can re-open manually.
+        }
+      }
+    }
+    await this.loadInitialDirectoryState();
+    if (failed) {
+      this.showError(`Reset ${written} demo${written === 1 ? '' : 's'} (${failed} failed)`);
+    } else {
+      this.showSuccess(`Reset ${written} demo${written === 1 ? '' : 's'}`);
+    }
+  }
+
   async pickLocalFolder() {
     if (!this.localWorkspace) return;
     try {