diff --git a/.gitignore b/.gitignore
index 2385ede..2ae8ed9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@ test-results/
 playwright-report/
 blob-report/
 playwright/.cache/
+demo-assets/
diff --git a/apps/api/src/local/server.ts b/apps/api/src/local/server.ts
index 9669f84..a541826 100644
--- a/apps/api/src/local/server.ts
+++ b/apps/api/src/local/server.ts
@@ -216,7 +216,7 @@ async function main(): Promise<void> {
   app.use(express.json());
   app.use((_req, res, next) => {
     res.header("Access-Control-Allow-Origin", "*");
-    res.header("Access-Control-Allow-Headers", "content-type, x-api-key");
+    res.header("Access-Control-Allow-Headers", "content-type, x-api-key, authorization");
     next();
   });
 
diff --git a/apps/web/src/lib/cognito.ts b/apps/web/src/lib/cognito.ts
index afaf5e4..0edac0a 100644
--- a/apps/web/src/lib/cognito.ts
+++ b/apps/web/src/lib/cognito.ts
@@ -40,7 +40,17 @@ export interface IdTokenClaims {
 export function decodeIdToken(idToken: string): IdTokenClaims {
   const [, payloadB64] = idToken.split(".");
   const payload = JSON.parse(atob(payloadB64.replace(/-/g, "+").replace(/_/g, "/"))) as Record<string, unknown>;
-  const groups = typeof payload["cognito:groups"] === "string" ? (payload["cognito:groups"] as string) : "";
+  // A real Cognito ID token encodes `cognito:groups` as a genuine JSON
+  // array (e.g. ["owner"]); API Gateway's HTTP API JWT authorizer is the
+  // only place that ever flattens it to a comma-separated string (see
+  // authContext.ts) — this decodes the token directly, so both shapes
+  // need handling here.
+  const rawGroups = payload["cognito:groups"];
+  const groups = Array.isArray(rawGroups)
+    ? rawGroups.map(String)
+    : typeof rawGroups === "string"
+      ? rawGroups.split(",").map((group) => group.trim())
+      : [];
   const role = (["owner", "manager", "counter_staff"] as const).find((candidate) => groups.includes(candidate));
   return {
     sub: payload.sub as string,
diff --git a/apps/web/test/lib/cognito.test.ts b/apps/web/test/lib/cognito.test.ts
index 59b490c..0c464ce 100644
--- a/apps/web/test/lib/cognito.test.ts
+++ b/apps/web/test/lib/cognito.test.ts
@@ -37,11 +37,16 @@ describe("decodeIdToken", () => {
     expect(decodeIdToken(token)).toEqual({ sub: "abc", email: "a@b.com", shopId: "shop-123", role: undefined });
   });
 
-  it("resolves the role from a comma-flattened cognito:groups claim", () => {
+  it("resolves the role from a comma-flattened cognito:groups claim (API Gateway JWT authorizer shape)", () => {
     const token = fakeIdToken({ sub: "abc", "cognito:groups": "owner" });
     expect(decodeIdToken(token).role).toBe("owner");
   });
 
+  it("resolves the role from a real Cognito ID token's array-shaped cognito:groups claim", () => {
+    const token = fakeIdToken({ sub: "abc", "cognito:groups": ["owner"] });
+    expect(decodeIdToken(token).role).toBe("owner");
+  });
+
   it("returns undefined role when no known group is present", () => {
     const token = fakeIdToken({ sub: "abc" });
     expect(decodeIdToken(token).role).toBeUndefined();
diff --git a/docs/VIDEO-SCRIPT.md b/docs/VIDEO-SCRIPT.md
new file mode 100644
index 0000000..6efe0d0
--- /dev/null
+++ b/docs/VIDEO-SCRIPT.md
@@ -0,0 +1,191 @@
+# StockSync — 3-Minute Demo Video Script
+
+The video is done: **`demo-assets/stocksync-full-tour.mp4`** (also
+`.webm`), at the repo root, gitignored. It's a real, automated 2:59
+recording — dark mode throughout, an animated visible cursor for every
+click and hover, and genuine data at every step (real stock arithmetic,
+a real price conflict, a real completed checkout). Nothing here is
+freeze-framed or stretched — the full 3 minutes is real screen time, in
+the order below. You just need to add your voice.
+
+**Timestamp precision:** four points are exact, read directly off the
+file: **0:00**, **0:42** (end of the intro), **2:04** (end of the
+two-counter demo), and **3:00** (end). Everything in between is
+sequenced correctly (I wrote the automation, so the order is certain)
+but the seconds are reasonable estimates, not frame-measured — page
+loads and network calls don't take identical time on every run. Watch
+the video once with this script open and nudge your narration to match
+what you actually see; don't read it as a stopwatch drill.
+
+---
+
+## Segment 1 — Hero, dark mode, sign-in, counter picker (0:00–0:42)
+
+**0:00–0:08 — Hook + dark mode**
+Hero page loads in light mode, headline animates in, then the cursor
+moves to the theme toggle (top right) and clicks it — the whole page
+switches to dark.
+
+> "This is StockSync — an offline-first inventory sync engine for shops
+> running more than one billing counter. And yes, it supports dark
+> mode."
+
+**0:08–0:20 — Design tour**
+Cursor scrolls down through the "How it works" steps and the feature
+grid (offline-first, conflict-free merge, real-time sync, AI-assisted
+review, real multi-tenant auth, barcode quick-entry).
+
+> "Two counters can go offline, sell the same item, restock it, change
+> its price — in any order, for any duration — and when they reconnect,
+> the stock always converges to one correct number. Every one of these
+> pieces is real: real auth, real AI review, real barcode scanning."
+
+**0:20–0:38 — Sign in + counter picker**
+Cursor clicks the email field, types it out; clicks the password field,
+types it out; clicks "Sign in." The counter picker appears; the cursor
+hovers "Counter B" briefly, then clicks "Counter A."
+
+> "Signing in is real Cognito authentication — this account owns a real
+> shop. Once you're in, you pick which physical counter this browser
+> session is."
+
+**0:38–0:42 — Counter A glance**
+The item grid loads — Bread, Milk, Parle-G, Rice — cursor glances over
+a couple of cards and the barcode-scan button.
+
+> "Four items, seeded with real stock and prices. Let's break it."
+
+---
+
+## Segment 2 — The two-counter conflict demo, side by side (0:42–2:04)
+
+**0:42–1:00 — Both counters sign in, side by side**
+Two windows, side by side: the left signs in and picks Counter A, the
+right signs in and picks Counter B — same shop account, two sessions,
+both switch to dark mode independently.
+
+> "Here's the real test: two windows, same shop, different counters.
+> Counter A on the left, Counter B on the right."
+
+**1:00–1:05 — Both go offline**
+Both connectivity toggles get clicked — both badges flip from green
+"Online" to red "Offline."
+
+> "Both go offline — right now, live. Neither can see the other."
+
+**1:05–1:15 — Selling while offline**
+Counter A's "Sell 1" gets clicked five times, pauses, then two more.
+Counter B's "Sell 1" gets clicked three times. Stock numbers drop
+independently on each side.
+
+> "Counter A sells 5, then 2 more. Counter B sells 3. Both counting down
+> from the same starting stock, with zero visibility into each other."
+
+**1:15–1:20 — Reconnect**
+Both toggles get clicked back to "Online"; both pages refresh.
+
+> "Reconnect both — right now."
+
+**1:20–1:26 — Arithmetic proof**
+The stock number settles at **40** on both screens simultaneously.
+
+> "Fifty, minus five, minus two, minus three — forty. On both screens.
+> Every sale counted, nothing silently overwritten."
+
+**1:26–1:32 — Audit trail**
+Cursor clicks "parle-g" under the audit trail section on Counter A —
+the sale history expands, showing each transaction attributed to the
+right counter.
+
+> "And the audit log proves it — every sale, correctly attributed, in
+> the order it actually happened."
+
+**1:32–1:38 — Setting up the hard case**
+Both counters toggle offline again.
+
+> "Now the case that can't be auto-merged."
+
+**1:38–1:45 — Concurrent price edits**
+Counter A's price field gets clicked and set to **₹15**; Counter B's
+price field gets clicked and set to **₹18**.
+
+> "Both counters set a different price for the same item, while both are
+> offline."
+
+**1:45–1:50 — Reconnect**
+Both toggles click back online.
+
+> "Reconnect."
+
+**1:50–2:04 — The conflict banner**
+An amber "Needs your review" banner appears on Counter A, showing both
+candidate values — ₹15 from counter_a, ₹18 from counter_b — with a
+"Generating explanation…" line where Amazon Bedrock's plain-language
+summary would appear.
+
+> "StockSync never guesses on a genuine conflict. It flags it for a
+> human, shows both real values, and calls Amazon Bedrock to explain the
+> disagreement in plain language — advisory only, it never decides for
+> you."
+
+_If Bedrock's explanation has actually rendered by the time you record
+this (it depends on account access clearing), read the generated text
+instead of "calls Bedrock to explain" — say what's actually on screen._
+
+---
+
+## Segment 3 — Products, Checkout, Dashboard, Staff (2:04–3:00)
+
+**2:04–2:12 — Back in, single window**
+A fresh sign-in as Counter A, straight to the item grid, dark mode.
+
+> "That's the core engine. Everything past here is the product built on
+> top of it."
+
+**2:12–2:20 — Products**
+Cursor clicks "Products" in the nav; the catalog table appears — name,
+SKU, category, supplier, price.
+
+> "A real product catalog — categories, suppliers, pricing — all backed
+> by the same DynamoDB tables."
+
+**2:20–2:32 — Checkout**
+Cursor clicks "Checkout"; two product cards get clicked to add them to
+the cart; "Complete checkout" gets clicked; a real order confirmation
+and toast notification appear.
+
+> "Checkout builds a real cart and submits it — and it goes through the
+> exact same write pipeline as a manual sale. Same guarantees, same
+> conflict resolution, zero special-casing."
+
+**2:32–2:42 — Dashboard**
+Cursor clicks "Dashboard"; the trust-score, revenue, and low-stock cards
+are visible — the trust score reflects the real conflict from Segment 2.
+
+> "The owner's dashboard — daily revenue, and a trust score that
+> reframes the conflict rate as a business signal, not just an internal
+> correctness number. Right now it's showing the exact conflict we just
+> caused."
+
+**2:42–2:49 — Staff**
+Cursor clicks "Staff"; an email gets typed into the invite field; the
+role dropdown gets set to "Manager."
+
+> "And owners can invite real staff accounts — managers, counter staff —
+> each with their own scoped permissions, enforced server-side, not just
+> hidden in the UI."
+
+**2:49–3:00 — Close**
+Held on the Staff page as the final frame.
+
+> "That's StockSync — offline-first, mathematically correct, and a
+> complete product around it. Live on AWS today."
+
+---
+
+## If you want a shorter cut
+
+The single most important 45 seconds, if you ever need a trimmed version:
+**1:00–1:26** (offline → sell → reconnect → arithmetic) plus **1:50–2:04**
+(the conflict banner). That's the whole correctness claim proven twice,
+back to back.