fix(desktop): browser tab fixes for fullscreen, shortcuts, links, reload and hidden tabs (#16961)

Co-authored-by: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Author: juliusmarminge

apps/desktop/package.json

@@ -24,7 +24,7 @@
     "@t3tools/tailscale": "workspace:*",
     "dbus-next": "0.10.2",
     "effect": "catalog:",
-    "electron": "44.4.2",
+    "electron": "44.4.5",
     "electron-store": "^8.2.0",
     "electron-updater": "^6.8.9",
     "ffi-rs": "1.3.2",

apps/desktop/src/app/DesktopLifecycle.test.ts

@@ -96,6 +96,7 @@ function layerDesktopWindow(
     dispatchMenuAction: () => Effect.void,
     dispatchSnapShotEvent: () => Effect.void,
     zoomMain: () => Effect.void,
+    runMainContentsCommand: () => Effect.void,
     syncAppearance: Effect.void,
   });
 }

apps/desktop/src/backend/DesktopBackendPool.test.ts

@@ -100,6 +100,7 @@ function layerPool(labelRef: Ref.Ref<string>): Layer.Layer<DesktopBackendPool.De
           dispatchMenuAction: () => Effect.die("unexpected menu action"),
           dispatchSnapShotEvent: () => Effect.void,
           zoomMain: () => Effect.die("unexpected zoom"),
+          runMainContentsCommand: () => Effect.die("unexpected main contents command"),
           syncAppearance: Effect.void,
         } satisfies DesktopWindow.DesktopWindow["Service"]),
       ),

apps/desktop/src/electron/ElectronDialog.ts

@@ -95,8 +95,10 @@ export class ElectronDialog extends Context.Service<
     readonly pickFiles: (
       input: ElectronDialogPickFilesInput,
     ) => Effect.Effect<readonly string[], ElectronDialogPickFilesError>;
+    /** Pass `owner` to attach the box to that window so it cannot fall behind it. */
     readonly showMessageBox: (
       options: Electron.MessageBoxOptions,
+      owner?: Electron.BrowserWindow,
     ) => Effect.Effect<Electron.MessageBoxReturnValue, ElectronDialogShowMessageBoxError>;
     readonly showErrorBox: (title: string, content: string) => Effect.Effect<void>;
   }
@@ -164,9 +166,12 @@ export const make = ElectronDialog.of({
     });
     return result.canceled ? [] : result.filePaths;
   }),
-  showMessageBox: (options) =>
+  showMessageBox: (options, owner) =>
     Effect.tryPromise({
-      try: () => Electron.dialog.showMessageBox(options),
+      try: () =>
+        owner === undefined
+          ? Electron.dialog.showMessageBox(options)
+          : Electron.dialog.showMessageBox(owner, options),
       catch: (cause) =>
         new ElectronDialogShowMessageBoxError({
           type: options.type ?? null,

apps/desktop/src/ipc/channels.ts

@@ -109,6 +109,7 @@ export const PREVIEW_RECORDING_SAVE_CHANNEL = "desktop:preview-recording-save";
 export const PREVIEW_RECORDING_FRAME_CHANNEL = "desktop:preview-recording-frame";
 export const PREVIEW_STATE_CHANGE_CHANNEL = "desktop:preview-state-change";
 export const PREVIEW_POINTER_EVENT_CHANNEL = "desktop:preview-pointer-event";
+export const PREVIEW_OPEN_LINK_CHANNEL = "desktop:preview-open-link";
 
 export const MAC_PERMISSION_HELPER_CHANNEL = "desktop:mac-permission-helper";
 

apps/desktop/src/ipc/methods/preview.ts

@@ -54,6 +54,9 @@ export const installPreviewEventForwarding = Effect.fn(
   yield* manager.subscribePointerEvents((event) =>
     electronWindow.sendAll(IpcChannels.PREVIEW_POINTER_EVENT_CHANNEL, event),
   );
+  yield* manager.subscribeOpenLinks((event) =>
+    electronWindow.sendAll(IpcChannels.PREVIEW_OPEN_LINK_CHANNEL, event),
+  );
 });
 
 export const setForwardedShortcuts = DesktopIpc.makeIpcMethod({

apps/desktop/src/preload.ts

@@ -1,5 +1,6 @@
 import type {
   DesktopBridge,
+  DesktopPreviewOpenLinkEvent,
   DesktopPreviewPointerEvent,
   DesktopPreviewRecordingInputEvent,
   DesktopPreviewRecordingFrame,
@@ -416,5 +417,14 @@ contextBridge.exposeInMainWorld("desktopBridge", {
       return () =>
         ipcRenderer.removeListener(IpcChannels.PREVIEW_POINTER_EVENT_CHANNEL, wrappedListener);
     },
+    onOpenLink: (listener) => {
+      const wrappedListener = (_event: Electron.IpcRendererEvent, linkEvent: unknown) => {
+        if (typeof linkEvent !== "object" || linkEvent === null) return;
+        listener(linkEvent as DesktopPreviewOpenLinkEvent);
+      };
+      ipcRenderer.on(IpcChannels.PREVIEW_OPEN_LINK_CHANNEL, wrappedListener);
+      return () =>
+        ipcRenderer.removeListener(IpcChannels.PREVIEW_OPEN_LINK_CHANNEL, wrappedListener);
+    },
   },
 } satisfies DesktopBridge);

apps/desktop/src/preview/BrowserSession.test.ts

@@ -21,15 +21,35 @@ const { fromPartition, sessions } = vi.hoisted(() => ({
   >(),
 }));
 
+const { fromWebContents } = vi.hoisted(() => ({
+  fromWebContents: vi.fn<(webContents: unknown) => unknown>(() => null),
+}));
+
 vi.mock("electron", () => ({
+  BrowserWindow: { fromWebContents },
   session: {
     fromPartition,
   },
 }));
 
+import * as ElectronDialog from "../electron/ElectronDialog.ts";
 import * as BrowserSession from "./BrowserSession.ts";
 
-const layer = BrowserSession.layer.pipe(Layer.provide(NodeServices.layer));
+const { showMessageBox } = vi.hoisted(() => ({
+  showMessageBox: vi.fn<
+    (options: Electron.MessageBoxOptions, owner?: Electron.BrowserWindow) => number
+  >(() => 1),
+}));
+const layerDialog = Layer.succeed(ElectronDialog.ElectronDialog, {
+  pickFolder: () => Effect.die("unused"),
+  pickFiles: () => Effect.die("unused"),
+  showMessageBox: (options, owner) =>
+    Effect.sync(() => ({ response: showMessageBox(options, owner), checkboxChecked: false })),
+  showErrorBox: () => Effect.void,
+});
+const layer = BrowserSession.layer.pipe(
+  Layer.provide(Layer.merge(NodeServices.layer, layerDialog)),
+);
 
 describe("BrowserSession", () => {
   beforeEach(() => {
@@ -168,6 +188,7 @@ describe("BrowserSession", () => {
         "clipboard-sanitized-write",
         "notifications",
         "geolocation",
+        "fullscreen",
       ]) {
         assert.isTrue(requestAllows(permission), `request handler should allow ${permission}`);
         assert.isTrue(
@@ -189,6 +210,73 @@ describe("BrowserSession", () => {
     }).pipe(Effect.provide(layer)),
   );
 
+  it.effect("opens custom-scheme links externally only after the user confirms", () =>
+    Effect.gen(function* () {
+      const browserSessions = yield* BrowserSession.BrowserSession;
+      const partition = yield* browserSessions.getPartition("scope-a");
+      yield* browserSessions.getSession("scope-a");
+      const requestHandler =
+        sessions.get(partition)?.setPermissionRequestHandler.mock.calls[0]?.[0];
+      assert.isFunction(requestHandler);
+
+      const request = (externalURL: string) =>
+        Effect.callback<boolean>((resume) => {
+          requestHandler(
+            null,
+            "openExternal",
+            (granted: boolean) => resume(Effect.succeed(granted)),
+            { externalURL },
+          );
+        });
+
+      showMessageBox.mockReset();
+      showMessageBox.mockReturnValueOnce(0).mockReturnValueOnce(1);
+      assert.isTrue(yield* request("slack://open?team=T1"));
+      assert.isFalse(yield* request("zoommtg://zoom.us/join"));
+      assert.strictEqual(showMessageBox.mock.calls.length, 2);
+
+      for (const url of ["file:///etc/passwd", "javascript:alert(1)", "data:text/html,x"]) {
+        assert.isFalse(yield* request(url), `${url} must never open externally`);
+      }
+      assert.strictEqual(showMessageBox.mock.calls.length, 2);
+    }).pipe(Effect.provide(layer)),
+  );
+
+  // A prompt without an owner can open behind the app window, leaving the one
+  // prompt slot taken and every later link silently denied.
+  it.effect("attaches the open-externally prompt to the window hosting the preview", () =>
+    Effect.gen(function* () {
+      const browserSessions = yield* BrowserSession.BrowserSession;
+      const partition = yield* browserSessions.getPartition("scope-a");
+      yield* browserSessions.getSession("scope-a");
+      const requestHandler =
+        sessions.get(partition)?.setPermissionRequestHandler.mock.calls[0]?.[0];
+      assert.isFunction(requestHandler);
+
+      const hostWindow = { id: 7 } as unknown as Electron.BrowserWindow;
+      const host = { isDestroyed: () => false };
+      const guest = { isDestroyed: () => false, hostWebContents: host };
+      fromWebContents.mockImplementation((webContents) =>
+        webContents === host ? hostWindow : null,
+      );
+      showMessageBox.mockReset();
+      showMessageBox.mockReturnValueOnce(1);
+
+      yield* Effect.callback<boolean>((resume) => {
+        requestHandler(
+          guest,
+          "openExternal",
+          (granted: boolean) => resume(Effect.succeed(granted)),
+          {
+            externalURL: "slack://open?team=T1",
+          },
+        );
+      });
+
+      assert.strictEqual(showMessageBox.mock.calls[0]?.[1], hostWindow);
+    }).pipe(Effect.provide(layer)),
+  );
+
   it.effect("preserves partition scope and the platform failure chain", () => {
     const nativeCause = new Error("native digest failed");
     const platformCause = PlatformError.systemError({
@@ -218,7 +306,11 @@ describe("BrowserSession", () => {
         "Failed to derive a desktop preview browser partition for scope environment-a.",
       );
       assert.notInclude(error.message, nativeCause.message);
-    }).pipe(Effect.provide(BrowserSession.layer.pipe(Layer.provide(layerFailingCrypto))));
+    }).pipe(
+      Effect.provide(
+        BrowserSession.layer.pipe(Layer.provide(Layer.merge(layerFailingCrypto, layerDialog))),
+      ),
+    );
   });
 
   it.effect("preserves session scope, partition, and the Electron failure", () =>

apps/desktop/src/preview/BrowserSession.ts

@@ -1,5 +1,5 @@
-import type { Session } from "electron";
-import { session } from "electron";
+import type { Session, WebContents } from "electron";
+import { BrowserWindow, session } from "electron";
 import * as Context from "effect/Context";
 import * as Crypto from "effect/Crypto";
 import * as Effect from "effect/Effect";
@@ -9,6 +9,8 @@ import * as PlatformError from "effect/PlatformError";
 import * as Schema from "effect/Schema";
 import * as SynchronizedRef from "effect/SynchronizedRef";
 
+import * as ElectronDialog from "../electron/ElectronDialog.ts";
+
 const PREVIEW_PARTITION_PREFIX = "persist:t3code-preview-";
 /**
  * Incognito partitions deliberately omit the `persist:` prefix, which is what
@@ -33,12 +35,51 @@ const ALLOWED_PREVIEW_PERMISSIONS: ReadonlySet<string> = new Set([
   "clipboard-sanitized-write",
   "notifications",
   "geolocation",
+  // The Fullscreen API. `DesktopWindow` disables HTML fullscreen window resizing
+  // for the app window and every preview guest, so a page that goes fullscreen
+  // fills its own webview instead of taking over the whole T3 window.
+  "fullscreen",
   // Deliberately NOT local-fonts: preview sessions run untrusted web content,
   // and silently granting it would hand every page the user's installed-font
   // fingerprint (and font file bytes via FontData.blob()). The app's own font
   // picker runs in the main window session, which is unaffected by this list.
 ]);
 
+/**
+ * Schemes a preview page may never hand to the OS, even with the user's
+ * consent: they read local files, run script, or are web pages that belong in
+ * the preview itself.
+ */
+const NEVER_EXTERNAL_PROTOCOLS: ReadonlySet<string> = new Set([
+  "about:",
+  "blob:",
+  "chrome:",
+  "data:",
+  "devtools:",
+  "file:",
+  "filesystem:",
+  "http:",
+  "https:",
+  "javascript:",
+  "view-source:",
+]);
+
+/**
+ * The URL to offer the user when a preview page navigates to a custom scheme
+ * such as `slack://` or `zoom://`, or `null` when it must stay denied.
+ */
+const externalProtocolPromptUrl = (rawUrl: string | undefined): string | null => {
+  if (!rawUrl) return null;
+  try {
+    const url = new URL(rawUrl);
+    return NEVER_EXTERNAL_PROTOCOLS.has(url.protocol) ? null : url.href;
+  } catch {
+    return null;
+  }
+};
+
+const MAX_PROMPT_URL_LENGTH = 300;
+
 export class BrowserSessionPartitionDerivationError extends Schema.TaggedError<BrowserSessionPartitionDerivationError>()(
   "BrowserSessionPartitionDerivationError",
   {
@@ -159,9 +200,68 @@ const encodeScopeForDigest = (scope: string): Uint8Array =>
       ),
   );
 
+/**
+ * The window showing a preview guest. A `<webview>` guest has no window of its
+ * own, so look it up through the page that embeds it.
+ */
+const previewHostWindow = (guest: WebContents | null): BrowserWindow | undefined => {
+  if (guest === null || guest.isDestroyed()) return undefined;
+  const host = guest.hostWebContents ?? guest;
+  if (host.isDestroyed()) return undefined;
+  return BrowserWindow.fromWebContents(host) ?? undefined;
+};
+
 /** @public Service construction is part of the canonical Effect module API. */
 export const make = Effect.gen(function* BrowserSessionMake() {
   const crypto = yield* Crypto.Crypto;
+  const electronDialog = yield* ElectronDialog.ElectronDialog;
+  const runFork = Effect.runForkWith(yield* Effect.context<never>());
+  // One prompt at a time, so a page cannot stack dialogs by looping a deep link.
+  let externalPromptOpen = false;
+  /**
+   * Electron grants an external-protocol navigation through the `openExternal`
+   * permission and then launches the OS handler itself. Ask first: previews run
+   * untrusted pages, and a silent grant would let any of them launch apps.
+   */
+  const confirmOpenExternal = (
+    requester: WebContents | null,
+    rawUrl: string | undefined,
+    callback: (granted: boolean) => void,
+  ): void => {
+    const url = externalProtocolPromptUrl(rawUrl);
+    if (url === null || externalPromptOpen) {
+      callback(false);
+      return;
+    }
+    externalPromptOpen = true;
+    const settle = (granted: boolean) =>
+      Effect.sync(() => {
+        externalPromptOpen = false;
+        callback(granted);
+      });
+    const shownUrl =
+      url.length > MAX_PROMPT_URL_LENGTH ? `${url.slice(0, MAX_PROMPT_URL_LENGTH)}…` : url;
+    runFork(
+      electronDialog
+        .showMessageBox(
+          {
+            type: "question",
+            buttons: ["Open", "Cancel"],
+            defaultId: 0,
+            cancelId: 1,
+            message: `Open this ${new URL(url).protocol.slice(0, -1)} link?`,
+            detail: `A page in the browser wants to open another application:\n\n${shownUrl}`,
+          },
+          previewHostWindow(requester),
+        )
+        .pipe(
+          Effect.map(({ response }) => response === 0),
+          Effect.orElseSucceed(() => false),
+          Effect.flatMap(settle),
+          Effect.onInterrupt(() => settle(false)),
+        ),
+    );
+  };
   const sessionsRef = yield* SynchronizedRef.make<ReadonlyMap<string, Session>>(new Map());
 
   const getPartition = Effect.fn("BrowserSession.getPartition")(function* (
@@ -203,9 +303,19 @@ export const make = Effect.gen(function* BrowserSessionMake() {
           // the challenge every few seconds, so logins behind it never complete
           // (#5002). Re-setting the unchanged native string is harmless, so it
           // is the rewritten string itself that trips the check.
-          browserSession.setPermissionRequestHandler((_webContents, permission, callback) => {
-            callback(ALLOWED_PREVIEW_PERMISSIONS.has(permission));
-          });
+          browserSession.setPermissionRequestHandler(
+            (webContents, permission, callback, details) => {
+              if (permission === "openExternal") {
+                confirmOpenExternal(
+                  webContents,
+                  "externalURL" in details ? details.externalURL : undefined,
+                  callback,
+                );
+                return;
+              }
+              callback(ALLOWED_PREVIEW_PERMISSIONS.has(permission));
+            },
+          );
           browserSession.setPermissionCheckHandler((_webContents, permission) =>
             ALLOWED_PREVIEW_PERMISSIONS.has(permission),
           );