diff --git a/README.md b/README.md
index 7dc69ae..06b0021 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ A working mobile-first bowel diary with an optional **photo-first AI assist**: 
 python3 scripts/build_release.py
 ```
 
-The builder clones the committed `main` tree into an isolated directory, runs unit/security and both mobile acceptance suites, audits dependencies, checks syntax and secrets, excludes model weights and sensitive/generated media, and writes a checksummed archive plus `manifest.json` under `/root/timmy-releases/`. It refuses dirty or non-`main` source trees.
+The builder clones the committed `main` tree into an isolated directory, runs unit/security and both mobile acceptance suites, audits dependencies, checks syntax and secrets, excludes model weights and sensitive/generated media, records a vertical feature demonstration from the working app, fully decodes and probes that MP4, and writes checksummed source/video artifacts plus `manifest.json` under `/root/timmy-releases/`. It refuses dirty or non-`main` source trees.
 
 ## Run with the self-hosted open-weight path
 
diff --git a/scripts/build_release.py b/scripts/build_release.py
index 853ffe0..9ce4e5e 100755
--- a/scripts/build_release.py
+++ b/scripts/build_release.py
@@ -27,9 +27,9 @@ SECRET_PATTERNS = (
 )
 
 
-def run(args: list[str], cwd: Path, *, capture: bool = False) -> str:
+def run(args: list[str], cwd: Path, *, capture: bool = False, env: dict[str, str] | None = None) -> str:
     print("+", " ".join(args), flush=True)
-    result = subprocess.run(args, cwd=cwd, check=True, text=True,
+    result = subprocess.run(args, cwd=cwd, check=True, text=True, env=env,
                             stdout=subprocess.PIPE if capture else None)
     return result.stdout.strip() if capture else ""
 
@@ -109,6 +109,10 @@ def main() -> int:
                 raise SystemExit("Acceptance server did not become ready")
             run(["npm", "run", "test:ui"], tree)
             run(["npm", "run", "test:photo"], tree)
+            demo_raw = release_dir / f"timmy-talking-turd-{version}-demo.raw.webm"
+            demo_env = dict(server_env)
+            demo_env["TIMMY_RELEASE_VERSION"] = version
+            run(["node", "scripts/record_release_demo.mjs", str(demo_raw)], tree, env=demo_env)
         finally:
             server.terminate()
             try:
@@ -117,6 +121,16 @@ def main() -> int:
                 server.kill()
                 server.wait(timeout=5)
             server_log.close()
+        demo = release_dir / f"timmy-talking-turd-{version}-demo.mp4"
+        run(["ffmpeg", "-y", "-v", "error", "-i", str(demo_raw), "-vf", "scale=720:1280:flags=lanczos", "-an", "-c:v", "libx264", "-preset", "fast", "-crf", "20", "-pix_fmt", "yuv420p", "-movflags", "+faststart", str(demo)], tree)
+        demo_raw.unlink()
+        run(["ffmpeg", "-v", "error", "-i", str(demo), "-f", "null", "-"], tree)
+        probe = json.loads(run(["ffprobe", "-v", "error", "-print_format", "json", "-show_streams", "-show_format", str(demo)], tree, capture=True))
+        video_streams = [stream for stream in probe.get("streams", []) if stream.get("codec_type") == "video"]
+        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)
         run(["npm", "audit", "--audit-level=high"], tree)
         for file in ("app.js", "server.mjs", "service-worker.js", "src/analysis.js", "src/domain.js", "src/vision-config.js", "src/vision-service.js"):
             run(["node", "--check", file], tree)
@@ -165,6 +179,7 @@ def main() -> int:
                             tar.addfile(info)
 
     digest = sha256(archive)
+    demo_digest = sha256(demo)
     manifest = {
         "schema_version": 1,
         "project": "Timmy the Talking Turd",
@@ -175,6 +190,17 @@ def main() -> int:
         "artifact": archive.name,
         "bytes": archive.stat().st_size,
         "sha256": digest,
+        "feature_demo": {
+            "artifact": demo.name,
+            "bytes": demo.stat().st_size,
+            "sha256": demo_digest,
+            "width": 720,
+            "height": 1280,
+            "codec": "h264",
+            "pixel_format": "yuv420p",
+            "recorded_from_working_app": True,
+            "fixture_data": "synthetic-Type-4 and deterministic provider response",
+        },
         "gates": {
             "unit_security": "passed",
             "mobile_green_path": "passed",
@@ -183,12 +209,14 @@ def main() -> int:
             "syntax": "passed",
             "secret_scan": "passed",
             "forbidden_artifacts": "passed",
+            "feature_demo_full_decode": "passed",
+            "feature_demo_media_probe": "passed",
         },
     }
     manifest_path = release_dir / "manifest.json"
     manifest_path.write_text(json.dumps(manifest, indent=2) + "\n", encoding="utf-8")
-    (release_dir / "SHA256SUMS").write_text(f"{digest}  {archive.name}\n", encoding="utf-8")
-    print(json.dumps({"release_dir": str(release_dir), "archive": str(archive), "manifest": str(manifest_path), "sha256": digest}, indent=2))
+    (release_dir / "SHA256SUMS").write_text(f"{digest}  {archive.name}\n{demo_digest}  {demo.name}\n", encoding="utf-8")
+    print(json.dumps({"release_dir": str(release_dir), "archive": str(archive), "feature_demo": str(demo), "manifest": str(manifest_path), "sha256": digest, "feature_demo_sha256": demo_digest}, indent=2))
     return 0
 
 
diff --git a/scripts/record_release_demo.mjs b/scripts/record_release_demo.mjs
new file mode 100644
index 0000000..774629b
--- /dev/null
+++ b/scripts/record_release_demo.mjs
@@ -0,0 +1,124 @@
+import { chromium } from 'playwright';
+import { mkdir } from 'node:fs/promises';
+import path from 'node:path';
+
+const output = path.resolve(process.argv[2] || 'release-demo.webm');
+const version = process.env.TIMMY_RELEASE_VERSION || 'review build';
+const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
+await mkdir(path.dirname(output), { recursive: true });
+
+const browser = await chromium.launch({ headless: true });
+const context = await browser.newContext({
+  viewport: { width: 405, height: 720 },
+  deviceScaleFactor: 1,
+  serviceWorkers: 'block',
+  recordVideo: { dir: path.dirname(output), size: { width: 405, height: 720 } },
+  colorScheme: 'light',
+});
+const page = await context.newPage();
+const errors = [];
+page.on('console', message => { if (message.type() === 'error') errors.push(message.text()); });
+page.on('pageerror', error => errors.push(error.message));
+await page.route('**/api/vision-status', route => route.fulfill({
+  status: 200,
+  contentType: 'application/json',
+  body: JSON.stringify({
+    enabled: true,
+    profile: 'selfhost',
+    processor: 'self-hosted',
+    model: 'SmolVLM2-2.2B-Instruct',
+    providerReady: true,
+    modelSeen: true,
+  }),
+}));
+await page.route('**/api/analyze', route => route.fulfill({
+  status: 200,
+  contentType: 'application/json',
+  body: JSON.stringify({
+    status: 'suggestion',
+    isStool: true,
+    bristolType: 4,
+    color: 'brown',
+    confidence: 0.83,
+    imageQuality: 'good',
+    observations: 'Smooth, formed appearance.',
+    warning: 'Visual suggestion only. Confirm it yourself; this is not a diagnosis.',
+  }),
+}));
+
+await page.goto('http://127.0.0.1:4173', { waitUntil: 'networkidle' });
+await page.evaluate(() => localStorage.clear());
+await page.reload({ waitUntil: 'networkidle' });
+await page.addStyleTag({ content: `
+  #demo-caption{position:fixed;left:16px;right:16px;top:14px;z-index:20000;background:rgba(40,33,29,.94);color:#fff;padding:11px 14px;border-radius:14px;font:800 12px/1.25 system-ui;letter-spacing:.02em;text-align:center;box-shadow:0 8px 24px rgba(0,0,0,.2)}
+  #demo-touch{position:fixed;z-index:20001;width:48px;height:48px;border:4px solid #fff;background:rgba(245,201,91,.55);box-shadow:0 0 0 7px rgba(21,125,120,.28);border-radius:50%;pointer-events:none;transform:translate(-50%,-50%)}
+` });
+
+async function caption(text, duration = 1400) {
+  await page.evaluate(text => {
+    document.querySelector('#demo-caption')?.remove();
+    const node = document.createElement('div');
+    node.id = 'demo-caption';
+    node.textContent = text;
+    document.body.append(node);
+    node.animate([{ opacity: 0, transform: 'translateY(-8px)' }, { opacity: 1, transform: 'translateY(0)' }], { duration: 260, fill: 'forwards' });
+  }, text);
+  await sleep(duration);
+}
+
+async function tap(selector, after = 650) {
+  const target = page.locator(selector).first();
+  await target.scrollIntoViewIfNeeded();
+  const box = await target.boundingBox();
+  if (!box) throw new Error(`Missing demo target: ${selector}`);
+  await page.evaluate(({ x, y }) => {
+    document.querySelector('#demo-touch')?.remove();
+    const ring = document.createElement('div');
+    ring.id = 'demo-touch';
+    ring.style.left = `${x}px`;
+    ring.style.top = `${y}px`;
+    document.body.append(ring);
+    ring.animate([{ opacity: .2, transform: 'translate(-50%,-50%) scale(.55)' }, { opacity: 1, transform: 'translate(-50%,-50%) scale(1)' }], { duration: 400 });
+    setTimeout(() => ring.remove(), 550);
+  }, { x: box.x + box.width / 2, y: box.y + box.height / 2 });
+  await sleep(220);
+  await target.click();
+  await sleep(after);
+}
+
+await caption(`TIMMY ${version} • FEATURE DEMO`, 1300);
+await caption('New path: private, photo-first stool logging', 1100);
+await tap('[data-scan]', 500);
+await page.getByText(/Self-hosted model ready/i).waitFor();
+await caption('The self-hosted model is ready — no third-party moderation gate', 1300);
+await page.locator('#ai-photo').setInputFiles('tests/fixtures/synthetic-type4.jpg');
+await caption('The photo stays unsaved until explicit consent', 1300);
+await page.locator('#ai-consent').check();
+await tap('#analyze-photo', 500);
+await page.getByText(/83% confidence/i).waitFor();
+await caption('Timmy suggests only visible form and broad color', 1500);
+await tap('#use-suggestion', 600);
+await caption('Nothing persists until the user reviews or corrects it', 1500);
+await page.locator('[data-type="4"]').scrollIntoViewIfNeeded();
+await sleep(700);
+await page.evaluate(() => {
+  document.querySelector('#demo-caption')?.remove();
+  const outro = document.createElement('div');
+  outro.id = 'release-outro';
+  outro.innerHTML = '<img src="/assets/timmy.svg"><strong>SELF-HOSTED.<br>USER-CONFIRMED.</strong><span>Visual assistance — never a diagnosis.</span>';
+  Object.assign(outro.style, { position:'fixed', inset:'0', zIndex:'30000', background:'linear-gradient(145deg,#f7f3ea,#f5c95b)', display:'flex', flexDirection:'column', alignItems:'center', justifyContent:'center', textAlign:'center', color:'#28211d', fontFamily:'system-ui', opacity:'0' });
+  outro.querySelector('img').style.cssText = 'width:150px;height:150px;filter:drop-shadow(0 14px 16px rgba(63,37,30,.18))';
+  outro.querySelector('strong').style.cssText = 'font-size:31px;line-height:1.05;margin:18px 0 12px;letter-spacing:-.04em';
+  outro.querySelector('span').style.cssText = 'font-size:13px;font-weight:800;color:#176957';
+  document.body.append(outro);
+  outro.animate([{opacity:0},{opacity:1}], {duration:500,fill:'forwards'});
+});
+await sleep(2200);
+
+if (errors.length) throw new Error(`Browser errors: ${errors.join(' | ')}`);
+const recording = page.video();
+await page.close();
+await recording.saveAs(output);
+await context.close();
+await browser.close();
+console.log(output);