Windows: /browse daemon spawns bun without windowsHide → console window flashes and steals focus

[abolrous]

Summary

On Windows, the /browse daemon repeatedly pops a console window that steals foreground focus (interrupting typing and voice dictation). The window shows the path of the WinGet bun.exe shim, e.g. ...\WinGet\Links\bun.exe.

Environment

• Windows 11
• gstack 1.51.0.0
• bun installed via WinGet (a console-subsystem exe on PATH as ...\Microsoft\WinGet\Links\bun.exe)
• Browse daemon running under the Node fallback (browse/dist/server-node.mjs + browse/dist/bun-polyfill.cjs), which is the Windows path since Bun can't drive Playwright's Chromium on Windows.

Root cause

On Windows the browse server runs under Node with browse/src/bun-polyfill.cjs shimming the Bun API. Its Bun.spawn / Bun.spawnSync implementations call Node's child_process.spawn / spawnSync without windowsHide: true:

spawn(cmd, options = {}) {
  const [command, ...args] = cmd;
  const proc = spawn(command, args, {
    stdio,
    env: options.env,
    cwd: options.cwd,
    // no windowsHide  <-- here
  });
  ...
}

spawnTerminalAgent (browse/src/terminal-agent-control.ts) launches bun run terminal-agent.ts through this shim. Because bun resolves to a console executable, Windows allocates a fresh console window (conhost) for every spawn, which pops up and grabs foreground.

It recurs continuously because the agent-health watchdog in browse/src/server.ts (~line 1481, 60s tick) respawns the terminal-agent whenever its recorded PID dies. A daemon left over from an earlier /browse keeps flashing even with no browse session open.

Impact

Constant focus theft breaks typing and speech-to-text on Windows. HKCU\Control Panel\Desktop\ForegroundLockTimeout only softens the focus grab; the window still pops and flickers over the terminal.

Fix

Pass windowsHide: true in the options for both spawn and spawnSync in browse/src/bun-polyfill.cjs (then rebuild the dist bundle):

   const proc = spawn(command, args, {
     stdio,
     env: options.env,
     cwd: options.cwd,
+    windowsHide: true,
   });

   const result = spawnSync(command, args, {
     stdio: [ ... ],
     timeout: options.timeout,
     env: options.env,
     cwd: options.cwd,
+    windowsHide: true,
   });

windowsHide: true sets CREATE_NO_WINDOW, so no console is ever allocated. This also silences the version-probe spawnSync calls (e.g. chrome --version). Verified locally: after the patch, restarting the browse daemon eliminates the flashing entirely with no functional change.

Repro

1. On Windows, install bun via WinGet.
2. Run any /browse-backed skill (or just leave a browse daemon running).
3. Observe console windows citing ...\WinGet\Links\bun.exe popping up and stealing focus, especially on the 60s watchdog respawn.

[abolrous]

Follow-up: on Windows 11 there is a second, bigger spawn site than the bun-polyfill.cjs one, and it is the main cause of a focus-stealing window.

The /browse daemon itself is launched detached, stdio: ['ignore','ignore','ignore'], without windowsHide in browse/src/cli.ts (the Windows node -e launcherCode, ~line 239), and again in browse/src/security.ts (~line 494, the telemetry spawn).

On Windows 11 a detached spawn without windowsHide gets a new console, and since the default terminal application is now Windows Terminal, that console materialises as a visible Windows Terminal window that steals foreground focus. chrome-headless-shell.exe and bun run terminal-agent.ts are children that inherit that console, so the WT tab title shows their path (which is what a confused user sees).

Suggested fix, same as the polyfill one, add windowsHide: true to both detached spawns:

// cli.ts launcherCode
-      `{detached:true,stdio:['ignore','ignore','ignore'],env:Object.assign({},process.env,` +
+      `{detached:true,windowsHide:true,stdio:['ignore','ignore','ignore'],env:Object.assign({},process.env,` +

// security.ts
     const child = spawn(result.cmd, result.cmdArgs, {
       stdio: 'ignore',
       detached: true,
+      windowsHide: true,
     });

Workaround for users until this ships: set the Windows default terminal application to "Windows Console Host" (Terminal Settings -> Startup), which runs detached background consoles invisibly.