fix(desktop): repair the Windows notification shim's false denial on read

desktop/src/features/notifications/lib/desktop.test.mjs

@@ -23,7 +23,55 @@ class ThrowingNotification {
 
 globalThis.window = { Notification: ThrowingNotification };
 
-const { sendDesktopNotification } = await import("./desktop.ts");
+const { sendDesktopNotification, getDesktopNotificationPermissionState } =
+  await import("./desktop.ts");
+
+// Stands in for the plugin's injected shim: `permission` is a cached value and
+// only `requestPermission()` reaches the backend and rewrites it.
+function shimNotification(initialPermission, grantedPermission = "granted") {
+  class ShimNotification {
+    static permission = initialPermission;
+    static requestCount = 0;
+
+    static async requestPermission() {
+      ShimNotification.requestCount += 1;
+      ShimNotification.permission = grantedPermission;
+      return grantedPermission;
+    }
+
+    close() {}
+  }
+
+  return ShimNotification;
+}
+
+async function withEnvironment({ platform, isTauri, notification }, callback) {
+  const originalNavigator = Object.getOwnPropertyDescriptor(
+    globalThis,
+    "navigator",
+  );
+  const originalNotification = window.Notification;
+  const originalIsTauri = globalThis.isTauri;
+
+  Object.defineProperty(globalThis, "navigator", {
+    configurable: true,
+    value: { platform, userAgent: "" },
+  });
+  window.Notification = notification;
+  globalThis.isTauri = isTauri;
+
+  try {
+    return await callback();
+  } finally {
+    if (originalNavigator) {
+      Object.defineProperty(globalThis, "navigator", originalNavigator);
+    } else {
+      delete globalThis.navigator;
+    }
+    window.Notification = originalNotification;
+    globalThis.isTauri = originalIsTauri;
+  }
+}
 
 test("constructor failure is a delivery miss and does not prevent a later notification", async (t) => {
   const warnings = [];
@@ -50,3 +98,72 @@ test("constructor failure is a delivery miss and does not prevent a later notifi
     },
   ]);
 });
+
+test("Windows Tauri repairs the shim's false denied state on read", async () => {
+  const Notification = shimNotification("denied");
+
+  const permission = await withEnvironment(
+    { platform: "Win32", isTauri: true, notification: Notification },
+    () => getDesktopNotificationPermissionState(),
+  );
+
+  assert.equal(permission, "granted");
+  assert.equal(Notification.requestCount, 1);
+});
+
+test("the repaired state is cached, so later reads do not request again", async () => {
+  const Notification = shimNotification("denied");
+
+  await withEnvironment(
+    { platform: "Win32", isTauri: true, notification: Notification },
+    async () => {
+      await getDesktopNotificationPermissionState();
+      const second = await getDesktopNotificationPermissionState();
+      assert.equal(second, "granted");
+    },
+  );
+
+  assert.equal(Notification.requestCount, 1);
+});
+
+test("a denial that survives the request is reported as denied", async () => {
+  const Notification = shimNotification("denied", "denied");
+
+  const permission = await withEnvironment(
+    { platform: "Win32", isTauri: true, notification: Notification },
+    () => getDesktopNotificationPermissionState(),
+  );
+
+  assert.equal(permission, "denied");
+  assert.equal(Notification.requestCount, 1);
+});
+
+test("denied stays terminal outside the Windows Tauri app", async () => {
+  for (const environment of [
+    { label: "Windows web", platform: "Win32", isTauri: false },
+    { label: "Linux Tauri", platform: "Linux x86_64", isTauri: true },
+    { label: "Linux web", platform: "Linux x86_64", isTauri: false },
+  ]) {
+    const Notification = shimNotification("denied");
+
+    const permission = await withEnvironment(
+      { ...environment, notification: Notification },
+      () => getDesktopNotificationPermissionState(),
+    );
+
+    assert.equal(permission, "denied", environment.label);
+    assert.equal(Notification.requestCount, 0, environment.label);
+  }
+});
+
+test("granted is returned untouched and never triggers a request", async () => {
+  const Notification = shimNotification("granted");
+
+  const permission = await withEnvironment(
+    { platform: "Win32", isTauri: true, notification: Notification },
+    () => getDesktopNotificationPermissionState(),
+  );
+
+  assert.equal(permission, "granted");
+  assert.equal(Notification.requestCount, 0);
+});

desktop/src/features/notifications/lib/desktop.ts

@@ -6,7 +6,11 @@ import {
   onAction,
   requestPermission,
 } from "@tauri-apps/plugin-notification";
-import { isLinuxPlatform, isMacPlatform } from "@/shared/lib/platform";
+import {
+  isLinuxPlatform,
+  isMacPlatform,
+  isWindowsPlatform,
+} from "@/shared/lib/platform";
 
 // Backend event emitted when a native Linux notification is clicked or a
 // queued macOS activation becomes available. See src-tauri notification code.
@@ -147,6 +151,25 @@ export async function getDesktopNotificationPermissionState(): Promise<DesktopNo
   }
 
   if (window.Notification.permission !== "default") {
+    // On Windows the notification plugin's injected shim stamps `denied` at
+    // startup without ever consulting the backend — `permission_state()`
+    // returns `Granted` unconditionally on desktop — so a `denied` reading
+    // inside the Windows Tauri app is never a real denial. Repair it by
+    // requesting once: on Windows `request_permission()` raises no prompt,
+    // returns `Granted`, and rewrites the shim's cached value, so subsequent
+    // reads short-circuit here as `granted`.
+    if (
+      window.Notification.permission === "denied" &&
+      isTauri() &&
+      isWindowsPlatform()
+    ) {
+      try {
+        return await requestDesktopNotificationAccess();
+      } catch {
+        return window.Notification.permission;
+      }
+    }
+
     return window.Notification.permission;
   }
 

desktop/src/shared/lib/platform.test.mjs

@@ -0,0 +1,38 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { isWindowsPlatform } from "./platform.ts";
+
+function withNavigator(navigator, callback) {
+  const original = Object.getOwnPropertyDescriptor(globalThis, "navigator");
+  Object.defineProperty(globalThis, "navigator", {
+    configurable: true,
+    value: navigator,
+  });
+
+  try {
+    callback();
+  } finally {
+    if (original) {
+      Object.defineProperty(globalThis, "navigator", original);
+    } else {
+      delete globalThis.navigator;
+    }
+  }
+}
+
+test("Windows detection accepts the platform strings WebView2 reports", () => {
+  for (const platform of ["Win32", "Win64", "Windows"]) {
+    withNavigator({ platform, userAgent: "" }, () => {
+      assert.equal(isWindowsPlatform(), true, platform);
+    });
+  }
+});
+
+test("Windows detection rejects the other desktop platforms", () => {
+  for (const platform of ["MacIntel", "Darwin", "Linux x86_64"]) {
+    withNavigator({ platform, userAgent: "" }, () => {
+      assert.equal(isWindowsPlatform(), false, platform);
+    });
+  }
+});

desktop/src/shared/lib/platform.ts

@@ -23,6 +23,15 @@ export function isLinuxPlatform(): boolean {
   );
 }
 
+/** Returns true on Windows desktops. */
+export function isWindowsPlatform(): boolean {
+  if (typeof navigator === "undefined") {
+    return false;
+  }
+
+  return /^win/i.test(navigator.platform);
+}
+
 /**
  * The platform's normal application-shortcut modifier:
  * - macOS: Command (Meta)