diff --git a/scripts/build_release.py b/scripts/build_release.py
index f6f77f4..e2dfdfa 100755
--- a/scripts/build_release.py
+++ b/scripts/build_release.py
@@ -164,7 +164,13 @@ def main() -> int:
         if len(video_streams) != 1 or video_streams[0].get("codec_name") != "h264" or video_streams[0].get("pix_fmt") != "yuv420p" or video_streams[0].get("width") != 720 or video_streams[0].get("height") != 1280:
             raise SystemExit("Release demo media probe failed")
         contact_sheet = release_dir / f"timmy-talking-turd-{version}-demo-contact-sheet.jpg"
-        run(["ffmpeg", "-y", "-v", "error", "-i", str(demo), "-vf", "fps=1/2,scale=180:-1,tile=4x3:padding=4:margin=4", "-frames:v", "1", str(contact_sheet)], tree)
+        # Span the whole recording: a fixed 1/2 fps sheet only covered the first 24s of a longer demo.
+        demo_duration = float(run(["ffprobe", "-v", "error", "-show_entries", "format=duration", "-of", "csv=p=0", str(demo)], tree, capture=True))
+        if demo_duration <= 0:
+            raise SystemExit("Release demo has no measurable duration")
+        run(["ffmpeg", "-y", "-v", "error", "-i", str(demo), "-vf", f"fps={12 / demo_duration:.6f},scale=180:-1,tile=4x3:padding=4:margin=4", "-frames:v", "1", str(contact_sheet)], tree)
+        if not contact_sheet.exists() or contact_sheet.stat().st_size == 0:
+            raise SystemExit("Release demo contact sheet was not produced")
         run(["npm", "audit", "--audit-level=high"], tree)
         for file in ("app.js", "server.mjs", "service-worker.js", "src/analysis.js", "src/domain.js", "src/draft.js", "src/suggestion.js", "src/followup.js", "src/vision-readiness.js", "src/hermes-agent-service.js", "src/vision-config.js", "src/vision-service.js", "tests/staging.acceptance.mjs"):
             run(["node", "--check", file], tree)
diff --git a/scripts/record_release_demo.mjs b/scripts/record_release_demo.mjs
index ba4e010..b0fb5bd 100644
--- a/scripts/record_release_demo.mjs
+++ b/scripts/record_release_demo.mjs
@@ -87,6 +87,16 @@ async function caption(text, duration = 1400) {
     node.animate([{ opacity: 0, transform: 'translateY(-8px)' }, { opacity: 1, transform: 'translateY(0)' }], { duration: 260, fill: 'forwards' });
   }, text);
   await sleep(duration);
+  // A caption must not outlive its stated duration. It used to stay on screen until the next one
+  // replaced it, so a view change left the previous screen's claim hanging over a different screen —
+  // e.g. a delete-data caption sitting on top of the home view.
+  await page.evaluate(() => {
+    const node = document.querySelector('#demo-caption');
+    if (!node) return;
+    node.animate([{ opacity: 1 }, { opacity: 0 }], { duration: 180, fill: 'forwards' });
+    setTimeout(() => node.remove(), 220);
+  });
+  await sleep(220);
 }
 
 async function tap(selector, after = 650) {
diff --git a/tests/release-demo.test.js b/tests/release-demo.test.js
index 529562b..e09f694 100644
--- a/tests/release-demo.test.js
+++ b/tests/release-demo.test.js
@@ -136,3 +136,15 @@ test('release builder refuses to publish without the on-camera delta receipt', a
   assert.match(builder, /"release_delta_visible_on_camera": "passed"/);
   assert.match(builder, /"release_delta": release_delta/);
 });
+
+test('release demo captions expire and the contact sheet spans the whole recording', async () => {
+  const demo = await readFile(demoPath, 'utf8');
+  const builder = await readFile(builderPath, 'utf8');
+
+  // A caption that outlives its stated duration hangs the previous view's claim over the next screen.
+  assert.match(demo, /creates via removal after duration|A caption must not outlive its stated duration/);
+  assert.match(demo, /setTimeout\(\(\) => node\.remove\(\), 220\)/);
+  // The sheet must cover the entire demo, not just its opening.
+  assert.match(builder, /12 \/ demo_duration/);
+  assert.match(builder, /Release demo contact sheet was not produced/);
+});