test(e2e): desktop browser-tabs hides developer toasts on its attached page

The locator handler that dismissed #error-toast could match a toast that closed before its
click; dispatchEvent then waited for the gone button until the test timed out. Hiding the toast
with CSS keeps it off app actions with no race.

packages/app/e2e/support/developer-ui.mjs

@@ -1,10 +1,15 @@
+const HIDE_DEVELOPER_TOASTS = "#error-toast { display: none !important; }";
+
 /** @param {import('@playwright/test').Page} page */
-export async function installDeveloperToastDismissal(page) {
+export async function hideDeveloperToasts(page) {
   // Developer chrome must not cover app actions or move the test's pointer/focus.
-  // Console errors remain in the runner's logs.
-  const dismiss = page.locator("#error-toast").getByRole("button", { name: "", exact: true });
-  await page.addLocatorHandler(dismiss, () => dismiss.dispatchEvent("click"), {
-    // A new logged error can replace the toast before the old one disappears.
-    noWaitAfter: true,
-  });
+  // Console errors remain in the runner's logs. Hiding the toast, instead of clicking it away,
+  // leaves no race with a toast that closes or is replaced between matching and clicking.
+  await page.addInitScript((css) => {
+    const style = document.createElement("style");
+    style.textContent = css;
+    document.addEventListener("DOMContentLoaded", () => document.head.append(style));
+  }, HIDE_DEVELOPER_TOASTS);
+  // A page attached after it loaded (Electron over CDP) runs no init script until it navigates.
+  await page.addStyleTag({ content: HIDE_DEVELOPER_TOASTS });
 }

packages/app/e2e/support/fixtures.ts

@@ -1,5 +1,5 @@
 import { test as base, expect, type Page } from "@playwright/test";
-import { installDeveloperToastDismissal } from "./developer-ui.mjs";
+import { hideDeveloperToasts } from "./developer-ui.mjs";
 import { startOutdatedDaemon, type OutdatedDaemon } from "./helpers/daemon-update";
 import { startE2EWorker } from "./helpers/e2e-worker";
 import { getE2EDaemonPort } from "./helpers/daemon-port";
@@ -131,7 +131,7 @@ const test = daemonTest.extend<{
         await ws.close({ code: 1008, reason: "Blocked connection to localhost:6767 during e2e." });
       });
 
-      await installDeveloperToastDismissal(page);
+      await hideDeveloperToasts(page);
 
       const entries: string[] = [];
 

packages/desktop/e2e/browser-tabs.e2e.mjs

@@ -12,7 +12,7 @@ import { fileURLToPath } from "node:url";
 import { experimental_createMCPClient } from "ai";
 import { StreamableHTTPClientTransport } from "@modelcontextprotocol/sdk/client/streamableHttp.js";
 import { chromium } from "playwright";
-import { installDeveloperToastDismissal } from "../../app/e2e/support/developer-ui.mjs";
+import { hideDeveloperToasts } from "../../app/e2e/support/developer-ui.mjs";
 import { runAppearanceFontSizeRegression } from "./appearance-font-size.electron.mjs";
 import { runSettingsMemoryRegression } from "./settings-memory.electron.mjs";
 
@@ -1189,7 +1189,7 @@ async function main() {
 
     browser = await chromium.connectOverCDP(`http://127.0.0.1:${cdpPort}`);
     const page = await waitForAppPage(browser, expoPort);
-    await installDeveloperToastDismissal(page);
+    await hideDeveloperToasts(page);
     const status = await waitForDesktopStatus(page);
 
     const checkPluginLinks = () =>