fix: clear stale preview URL from SQLite and prevent stale white screen on preview clear (#2358)

* fix: remove auto-switch-to-summary effect, keep browser tab on clear

* fix: clear browser preview when session is terminated

backend/internal/preview/poller.go

@@ -44,6 +44,10 @@ type entryState struct {
 	path    string
 	modUnix int64
 	size    int64
+	// cleared is set when the poller itself cleared the preview URL because the
+	// workspace entry was missing. When the file reappears, shouldRefresh uses
+	// this to re-discover even though the revision was bumped by the clear.
+	cleared bool
 }
 
 // NewPoller constructs a preview poller over the supplied session source and setter.
@@ -112,6 +116,13 @@ func (p *Poller) Poll(ctx context.Context) error {
 		}
 		entry, ok := DiscoverEntry(sess.Metadata.WorkspacePath)
 		if !ok {
+			if isWorkspacePreviewURL(sess.Metadata.PreviewURL, sess.ID) {
+				if _, err := p.setter.SetPreview(ctx, sess.ID, ""); err != nil {
+					p.logger.Error("preview poller: failed to clear stale preview",
+						"session", sess.ID, "err", err)
+				}
+				p.seen[sess.ID] = entryState{cleared: true}
+			}
 			continue
 		}
 		state := stateFor(entry)
@@ -140,7 +151,11 @@ func (p *Poller) Poll(ctx context.Context) error {
 func (p *Poller) shouldRefresh(sess domain.SessionRecord, target string, seenBefore bool) bool {
 	current := strings.TrimSpace(sess.Metadata.PreviewURL)
 	if current == "" {
-		return !seenBefore && sess.Metadata.PreviewRevision == 0
+		if !seenBefore {
+			return sess.Metadata.PreviewRevision == 0
+		}
+		previous := p.seen[sess.ID]
+		return previous.cleared
 	}
 	if current == target || isWorkspacePreviewURL(current, sess.ID) {
 		return true

backend/internal/preview/poller_test.go

@@ -118,6 +118,47 @@ func TestPollerRefreshesOnlyWhenEntrypointChanges(t *testing.T) {
 	}
 }
 
+func TestPollerRediscoverEntryAfterDeleteAndRecreate(t *testing.T) {
+	workspace := t.TempDir()
+	entry := filepath.Join(workspace, "index.html")
+	writeFile(t, entry, "<main>v1</main>")
+	svc := &fakePreviewSessions{sessions: []domain.SessionRecord{workerSession("ao-1", workspace, "")}}
+	poller := NewPoller(svc, svc, "http://127.0.0.1:3001", PollerConfig{Logger: discardLogger()})
+
+	// First poll discovers the entry and sets the preview.
+	if err := poller.Poll(context.Background()); err != nil {
+		t.Fatalf("first Poll: %v", err)
+	}
+	wantURL := "http://127.0.0.1:3001/api/v1/sessions/ao-1/preview/files/index.html"
+	assertSets(t, svc.sets, previewSet{id: "ao-1", url: wantURL})
+
+	// Delete the entry — poller must clear the preview and mark the session cleared.
+	if err := os.Remove(entry); err != nil {
+		t.Fatalf("remove index.html: %v", err)
+	}
+	if err := poller.Poll(context.Background()); err != nil {
+		t.Fatalf("second Poll (delete): %v", err)
+	}
+	if len(svc.sets) != 2 {
+		t.Fatalf("sets after delete = %#v, want clear + set", svc.sets)
+	}
+	if svc.sets[1].url != "" {
+		t.Fatalf("second set.url = %q, want empty (clear)", svc.sets[1].url)
+	}
+
+	// Recreate the entry — poller must re-discover.
+	writeFile(t, entry, "<main>v2</main>")
+	if err := poller.Poll(context.Background()); err != nil {
+		t.Fatalf("third Poll (recreate): %v", err)
+	}
+	if len(svc.sets) != 3 {
+		t.Fatalf("sets after recreate = %#v, want 3 sets (discover + clear + rediscover)", svc.sets)
+	}
+	if svc.sets[2].url != wantURL {
+		t.Fatalf("third set.url = %q, want %q", svc.sets[2].url, wantURL)
+	}
+}
+
 func TestPollerDoesNotRestoreClearedPreviewAfterRestart(t *testing.T) {
 	workspace := t.TempDir()
 	writeFile(t, filepath.Join(workspace, "index.html"), "<main>hello</main>")

frontend/src/main/browser-view-host.test.ts

@@ -14,6 +14,7 @@ function setupHost() {
 	const webContents = {
 		canGoBack: () => false,
 		canGoForward: () => false,
+		clearHistory: () => undefined,
 		getTitle: () => "",
 		getURL: () => currentURL,
 		goBack: () => undefined,
@@ -120,6 +121,7 @@ describe("dispose after the window is destroyed", () => {
 			webContents: {
 				canGoBack: () => false,
 				canGoForward: () => false,
+				clearHistory: () => undefined,
 				getTitle: () => "",
 				getURL: () => "",
 				goBack: () => undefined,

frontend/src/main/browser-view-host.ts

@@ -27,6 +27,7 @@ type BrowserWebContents = Pick<
 	WebContents,
 	| "canGoBack"
 	| "canGoForward"
+	| "clearHistory"
 	| "getTitle"
 	| "getURL"
 	| "goBack"
@@ -190,7 +191,10 @@ export function createBrowserViewHost(options: BrowserViewHostOptions): BrowserV
 	// empty state.
 	const clear = async (viewId: string): Promise<BrowserNavState> => {
 		const entry = ensure(viewId);
+		entry.view.setVisible?.(false);
+		entry.view.setBounds(OFFSCREEN_BOUNDS);
 		await entry.view.webContents.loadURL("about:blank");
+		entry.view.webContents.clearHistory();
 		return pushNavState(options, entry);
 	};
 

frontend/src/renderer/components/SessionView.tsx

@@ -60,6 +60,7 @@ export function SessionView({ sessionId }: SessionViewProps) {
 		sessionId,
 		active: Boolean(session && hasInspector && (browserPoppedOut || isInspectorOpen)),
 		poppedOut: browserPoppedOut,
+		terminated: session?.status === "terminated",
 		previewUrl,
 		previewRevision,
 	});

frontend/src/renderer/hooks/useBrowserView.test.tsx

@@ -75,6 +75,18 @@ describe("useBrowserView", () => {
 		const { result } = renderHook(() => useBrowserView({ sessionId: "sess-1", active: true, poppedOut: false }));
 
 		await waitFor(() => expect(bridge.ensure).toHaveBeenCalledWith("sess-1"));
+		// Simulate the real IPC flow: after ensure, a navigate call sends a nav
+		// state with a URL so the positioning effect considers the view visible.
+		act(() =>
+			bridge.emit({
+				viewId: "42:sess-1",
+				url: "http://localhost:3000/",
+				title: "",
+				canGoBack: false,
+				canGoForward: false,
+				isLoading: false,
+			}),
+		);
 		act(() => result.current.slotRef(slot));
 
 		await waitFor(() =>
@@ -111,6 +123,16 @@ describe("useBrowserView", () => {
 
 		const { result } = renderHook(() => useBrowserView({ sessionId: "sess-1", active: true, poppedOut: false }));
 		await waitFor(() => expect(bridge.ensure).toHaveBeenCalledWith("sess-1"));
+		act(() =>
+			bridge.emit({
+				viewId: "42:sess-1",
+				url: "http://localhost:3000/",
+				title: "",
+				canGoBack: false,
+				canGoForward: false,
+				isLoading: false,
+			}),
+		);
 		act(() => result.current.slotRef(slot));
 
 		await waitFor(() =>
@@ -140,6 +162,17 @@ describe("useBrowserView", () => {
 			await act(async () => {
 				await Promise.resolve();
 			});
+			// Simulate a real nav state with URL so the positioning effect shows the view.
+			act(() =>
+				bridge.emit({
+					viewId: "42:sess-1",
+					url: "http://localhost:3000/",
+					title: "",
+					canGoBack: false,
+					canGoForward: false,
+					isLoading: false,
+				}),
+			);
 			act(() => result.current.slotRef(slot));
 			// Flush the mount measure (immediate frame + settle timer).
 			await act(async () => {
@@ -316,4 +349,27 @@ describe("useBrowserView", () => {
 		expect(bridge.navigate).not.toHaveBeenCalled();
 		expect(bridge.clear).not.toHaveBeenCalled();
 	});
+
+	it("clears the view when the session is terminated, even with an active preview URL", async () => {
+		const bridge = setupBridge();
+		const { rerender } = renderHook(
+			({ terminated }) =>
+				useBrowserView({
+					sessionId: "sess-1",
+					active: true,
+					poppedOut: false,
+					terminated,
+					previewUrl: "http://localhost:5173/",
+					previewRevision: 1,
+				}),
+			{ initialProps: { terminated: false } },
+		);
+		// The preview drives a navigate on mount.
+		await waitFor(() => expect(bridge.navigate).toHaveBeenCalledTimes(1));
+
+		// Terminate the session – the view must be cleared and no re-navigate.
+		rerender({ terminated: true });
+		await waitFor(() => expect(bridge.clear).toHaveBeenCalledWith("42:sess-1"));
+		expect(bridge.navigate).toHaveBeenCalledTimes(1);
+	});
 });

frontend/src/renderer/hooks/useBrowserView.ts

@@ -7,6 +7,12 @@ type UseBrowserViewOptions = {
 	sessionId: string;
 	active: boolean;
 	poppedOut: boolean;
+	/**
+	 * When true, the view is cleared and the daemon-driven preview is suppressed.
+	 * Use when the session is terminated: the old preview content should not
+	 * remain visible even if the DB still carries a preview_url.
+	 */
+	terminated?: boolean;
 	/**
 	 * Preview target driven by the daemon (via `ao preview`, streamed over CDC).
 	 * When set, the view navigates here automatically; an empty value clears it.
@@ -68,6 +74,7 @@ export function useBrowserView({
 	sessionId,
 	active,
 	poppedOut,
+	terminated,
 	previewUrl,
 	previewRevision,
 }: UseBrowserViewOptions): BrowserViewModel {
@@ -80,11 +87,16 @@ export function useBrowserView({
 	const settleTimerRef = useRef<number | null>(null);
 	const observerRef = useRef<ResizeObserver | null>(null);
 	const previewTriggerRef = useRef<{ revision: number | null; target: string } | null>(null);
+	const hasUrlRef = useRef(false);
 
 	useEffect(() => {
 		activeRef.current = active;
 	}, [active]);
 
+	useEffect(() => {
+		hasUrlRef.current = Boolean(navState.url);
+	}, [navState.url]);
+
 	const sendHiddenBounds = useCallback((id = viewIdRef.current) => {
 		if (!id) return;
 		window.ao?.browser.setBounds({ viewId: id, rect: HIDDEN_RECT, visible: false });
@@ -95,7 +107,7 @@ export function useBrowserView({
 		const id = viewIdRef.current;
 		const node = slotNodeRef.current;
 		if (!id) return;
-		if (!activeRef.current || !node || !node.isConnected) {
+		if (!activeRef.current || !node || !node.isConnected || !hasUrlRef.current) {
 			sendHiddenBounds(id);
 			return;
 		}
@@ -189,12 +201,12 @@ export function useBrowserView({
 	}, []);
 
 	useEffect(() => {
-		if (active) {
+		if (navState.url && active) {
 			scheduleSettleMeasure();
 		} else {
 			sendHiddenBounds();
 		}
-	}, [active, poppedOut, scheduleSettleMeasure, sendHiddenBounds]);
+	}, [active, navState.url, poppedOut, scheduleSettleMeasure, sendHiddenBounds]);
 
 	useEffect(() => {
 		const handle = () => scheduleMeasure();
@@ -223,11 +235,18 @@ export function useBrowserView({
 
 	const clear = useCallback(() => withView((id) => window.ao!.browser.clear(id)), [withView]);
 
+	// When the session is terminated, clear the view and stop reacting to
+	// daemon-driven preview changes so stale content does not remain visible.
+	useEffect(() => {
+		if (!terminated) return;
+		void clear();
+	}, [clear, terminated]);
+
 	// Drive the view from the daemon-set preview target. Current daemons key
 	// this on previewRevision (bumped on every `ao preview` call); older daemons
 	// did not send it, so fall back to URL changes for compatibility.
 	useEffect(() => {
-		if (!viewId) return;
+		if (!viewId || terminated) return;
 		const target = previewUrl?.trim() ?? "";
 		const revision = typeof previewRevision === "number" ? previewRevision : null;
 		const previous = previewTriggerRef.current;