Environment

• OS: Windows 11 Pro 10.0.26100
• Bun: 1.3.5
• gstack: invoked via ~/.claude/skills/gstack/browse/dist/browse.exe
• claude CLI: 2.1.119

Symptom

After $B connect, sidebar Terminal pane shows:

Cannot start: 503 {"error":"terminal-agent not ready"}

Even after manually starting terminal-agent.ts and confirming it listens + writes ~/.gstack/terminal-port + ~/.gstack/terminal-internal-token, pressing Start in the sidebar still fails.

Two stacked Windows-only issues

1. cli.ts doesn't reliably auto-spawn terminal-agent on Windows

browse/src/cli.ts:891-915:

spawnSync('pkill', ['-f', 'terminal-agent\.ts'], { stdio: 'ignore', timeout: 3000 });
// ...
const termProc = Bun.spawn(['bun', 'run', termAgentScript], { ... });
termProc.unref();

• pkill doesn't exist on Windows (try/catch swallows ENOENT, harmless).
• Bun.spawn(['bun', ...]) from inside the compiled browse.exe produces a child that dies before writing its state files. Manual bun run terminal-agent.ts from a normal shell works fine — port listens, files appear.

2. terminal-agent.ts PTY spawn unconditionally fails on Windows

browse/src/terminal-agent.ts:170-177:

const proc = (Bun as any).spawn([claudePath, '--append-system-prompt', tabHint], {
  terminal: { rows, cols, data(_t, chunk) { onData(chunk); } },
  env,
});

Bun's terminal: option is Linux/macOS only. Verified:

$ bun -e 'Bun.spawn(["claude","--version"], { terminal: { rows:24, cols:80, data(){} } })'
ERR: terminal option is not supported on this platform

Repro

1. On Windows, ~/.claude/skills/gstack/browse/dist/browse.exe connect
2. Open sidebar in launched Chromium → Terminal pane
3. Press Start → 503 (or after manual terminal-agent restart, connection drops on first input)

Suggested fix

Replace terminal: spawn option with a cross-platform PTY library on Windows:

• @lydell/node-pty (maintained fork, ConPTY support)
• or node-pty directly
• Platform detect: keep Bun.spawn({terminal}) on Linux/macOS, node-pty on win32.

Side issue: cli.ts:901 pkill should be platform-gated (taskkill /F /IM or process-registry on Windows), and the Bun.spawn(['bun', ...]) reliability from inside the compiled exe on Windows needs investigation separately.

Workaround

Run browse connect from WSL Ubuntu — Linux PTY path works. Trade-off: separate Chromium profile, requires bun + Playwright deps installed in WSL.

Impact

Per docs/designs/SIDEBAR_MESSAGE_FLOW.md, the Terminal pane (live claude PTY) is the primary sidebar surface. Browser control + Activity feed still work on Windows. But the headline "AI in your sidebar" experience is unavailable to Windows-native users.