diff --git a/tests/uat/harness.test.ts b/tests/uat/harness.test.ts
index 309cd25..fea57e1 100644
--- a/tests/uat/harness.test.ts
+++ b/tests/uat/harness.test.ts
@@ -263,7 +263,7 @@ async function main(): Promise<number> {
     // ─── Setup: launch browser, attach to SW + open popup bridge ───
     process.stdout.write('\nLaunching Chrome + opening popup bridge...\n');
     handles = await launchHarnessBrowser();
-    const { browser, sw, page, popup, extensionId, downloadsDir } = handles;
+    const { browser, sw, page, popup, extension, extensionId, downloadsDir } = handles;
     process.stdout.write(`  extensionId: ${extensionId}\n`);
     process.stdout.write(`  downloadsDir: ${downloadsDir}\n`);
     process.stdout.write(`  popup: chrome-extension://${extensionId}/src/popup/index.html\n\n`);
@@ -283,16 +283,134 @@ async function main(): Promise<number> {
     const manifest = await getManifest(popupPage);
     const expectedVersion = manifest.version;
 
-    // ─── Wave 3 stubbed assertions (Tasks 4-7 will wire these) ──────
+    // ─── Assertion 1: SW bootstrap → setIdleMode ───────────────────
+    const a1 = await runAssertion(
+      1,
+      'SW bootstrap → setIdleMode (badge="" + popup="" + isRecording=false)',
+      buffers,
+      async () => {
+        // Wake the SW via the keepalive ping first — this ensures the
+        // SW's initialize() has been observed before we sample state.
+        // In MV3, the SW may have suspended between launch and now;
+        // sendMessage wakes it for 30s.
+        await keepalivePing(popupPage);
+        // After SW init (production initialize() calls setIdleMode()),
+        // badge becomes empty + popup becomes empty + isRecording is false.
+        // Poll for the popup transition because setIdleMode's setPopup
+        // call is async-propagated through the action API; the popup
+        // page may briefly observe the manifest default before the
+        // override lands.
+        const popupUrl = await waitFor(
+          () => getPopup(popupPage),
+          (v) => v === '',
+          3_000,
+          'popup should become empty after SW initialize() runs setIdleMode',
+          100,
+        );
+        assertEqual(popupUrl, '', 'popup expected empty in idle mode');
+        const badge = await getBadgeText(popupPage);
+        assertEqual(badge, '', 'badge expected empty after SW bootstrap');
+        const recording = await getIsRecording(popupPage);
+        assertEqual(recording, false, 'isRecording expected false at bootstrap');
+      },
+    );
+    results.push(a1);
+
+    // ─── Assertion 2: Toolbar onClicked-idle → REC + popup ─────────
+    const a2 = await runAssertion(
+      2,
+      'toolbar onClicked-idle → badge "REC" + popup set + isRecording=true',
+      buffers,
+      async () => {
+        // Trigger the toolbar action — the production code's
+        // chrome.action.onClicked listener calls startVideoCapture(),
+        // which creates the offscreen + starts recording + transitions
+        // the badge to REC + sets the popup to popup/index.html.
+        await page.bringToFront();
+        await page.triggerExtensionAction(extension);
+        // Badge transition is async (offscreen create + handshake +
+        // getDisplayMedia picker + post-grant validation + setBadgeText).
+        // Poll up to 8s; the auto-select picker shaves most of the time.
+        const badge = await waitFor(
+          () => getBadgeText(popupPage),
+          (v) => v === 'REC',
+          8_000,
+          'badge should become REC after toolbar click',
+          200,
+        );
+        assertEqual(badge, 'REC', 'badge after toolbar click');
+        const popupUrl = await getPopup(popupPage);
+        assertMatch(
+          popupUrl,
+          /src\/popup\/index\.html$/,
+          'popup should be set to popup/index.html during recording',
+        );
+        const recording = await getIsRecording(popupPage);
+        assertEqual(recording, true, 'isRecording expected true after click');
+      },
+    );
+    results.push(a2);
+
+    // ─── Assertion 3: offscreen displaySurface === 'monitor' ───────
+    const a3 = await runAssertion(
+      3,
+      'offscreen getCurrentStream displaySurface === "monitor"',
+      buffers,
+      async () => {
+        // A2 left recording active. The offscreen document was created
+        // by startVideoCapture; wait for the target + attach.
+        const offTarget = await waitForOffscreenTarget(browser, extensionId);
+        const offPage = await attachToOffscreen(offTarget);
+        offPage.on('console', (msg) => {
+          buffers.offscreenLines.push(`[OS:${msg.type()}] ${msg.text()}`);
+        });
+        const ds = await getDisplaySurface(offPage);
+        assertEqual(
+          ds,
+          'monitor',
+          'displaySurface expected "monitor" per post-grant validation (D-15)',
+        );
+      },
+    );
+    results.push(a3);
+
+    // ─── Assertion 4: onClicked-recording → popup, no new offscreen
+    const a4 = await runAssertion(
+      4,
+      'toolbar onClicked while recording → popup opens, no new offscreen target',
+      buffers,
+      async () => {
+        const offscreenCountBefore = countOffscreenTargets(browser, extensionId);
+        // Triggering the action during recording opens the popup
+        // (production code keeps popup set in REC mode); the click
+        // does NOT spawn a second offscreen.
+        await page.bringToFront();
+        await page.triggerExtensionAction(extension);
+        // Give the popup a moment to open + Chrome to settle.
+        await new Promise((r) => setTimeout(r, 500));
+        const offscreenCountAfter = countOffscreenTargets(browser, extensionId);
+        assertEqual(
+          offscreenCountAfter,
+          offscreenCountBefore,
+          'offscreen target count must not increase on second click during recording',
+        );
+        // popup must still be set (recording is ongoing).
+        const popupUrl = await getPopup(popupPage);
+        assertMatch(
+          popupUrl,
+          /src\/popup\/index\.html$/,
+          'popup must remain set while recording',
+        );
+      },
+    );
+    results.push(a4);
+
+    // ─── Wave 3 STUBBED assertions (Tasks 5-7 will wire these) ─────
     const stubs: Array<{
       index: number;
       name: string;
       taskNumber: number;
     }> = [
-      { index: 1, name: 'SW bootstrap → setIdleMode', taskNumber: 4 },
-      { index: 2, name: 'toolbar onClicked-idle → badge REC + popup', taskNumber: 4 },
-      { index: 3, name: 'offscreen displaySurface === monitor', taskNumber: 4 },
-      { index: 4, name: 'toolbar onClicked-recording → popup, no new offscreen', taskNumber: 4 },
       { index: 5, name: 'SAVE_ARCHIVE → download fires + zip appears', taskNumber: 5 },
       { index: 6, name: 'BUG B canonical: simulateUserStop → badge OFF + no recovery notif', taskNumber: 5 },
       { index: 7, name: 'RECORDING_ERROR codec-unsupported → badge ERR + recovery notif', taskNumber: 5 },
@@ -314,30 +432,17 @@ async function main(): Promise<number> {
       results.push(rec);
     }
 
-    // Suppress unused-warning placeholders — Tasks 4-7 will use these
-    // imports + handles directly. Reference them here for type-clean.
-    void browser;
-    void page;
-    void popupPage;
+    // Suppress unused-warning placeholders for Tasks 5-7 helpers.
     void expectedVersion;
-    void waitForOffscreenTarget;
-    void attachToOffscreen;
-    void countOffscreenTargets;
-    void waitFor;
-    void getBadgeText;
-    void getPopup;
-    void getIsRecording;
     void getIconSize;
     void fireOnStartup;
     void sendSyntheticRecordingError;
     void getNotificationSnapshot;
     void keepalivePing;
-    void getDisplaySurface;
     void simulateUserStop;
     void getSegmentCount;
     void assertArchiveShape;
     void extractEntryToFile;
-    void assertMatch;
     void assertTrue;
     void assertGte;
     void waitForDownloadedZip;
diff --git a/tests/uat/lib/sw.ts b/tests/uat/lib/sw.ts
index 18c3ecc..bebe4ca 100644
--- a/tests/uat/lib/sw.ts
+++ b/tests/uat/lib/sw.ts
@@ -245,15 +245,21 @@ export async function getNotificationSnapshot(
 /**
  * Send a no-op keepalive ping to the SW so Chrome's ~30s idle timer
  * does not evict the worker during long waits (assertion 11's 35s
- * recording window). Uses chrome.runtime.sendMessage as the cheapest
- * wake-up signal; the SW's onMessage handler treats unknown messages
- * as a warning-log no-op.
+ * recording window). Uses a __mokoshTestQuery 'snapshot' op as the
+ * cheapest round-trip with a guaranteed response — the bridge handler
+ * answers synchronously with the current notification state.
  *
  * @param popup - The extension popup page handle.
  */
 export async function keepalivePing(popup: Page): Promise<void> {
   await popup.evaluate(async () => {
-    await chrome.runtime.sendMessage({ type: '__mokoshKeepalive' });
+    const msg = { type: '__mokoshTestQuery', op: 'snapshot' };
+    return new Promise<void>((resolve) => {
+      chrome.runtime.sendMessage(msg, () => resolve());
+      // Cap at 2s — if the bridge is gone (SW reload race etc.) we
+      // still continue (the assertion may catch downstream issues).
+      setTimeout(() => resolve(), 2_000);
+    });
   });
 }