[Bug]: Launch signed-in agy when Antigravity is closed

[iiiMohammed]

Existing issues

• I searched existing issues and did not find a duplicate.

What happened?

When the Antigravity desktop app and agy are both closed, the Antigravity provider falls back to an informational Offline · N conversations snapshot even if the signed-in agy CLI is installed.

The macOS CodexBar provider already covers this case by launching a short-lived agy session, waiting for its loopback quota service, reading usage, and stopping only the process it owns. Win-CodexBar should offer the same fallback so Gemini usage remains available without keeping Antigravity open.

Affected area

• CLI
• Provider-specific behavior
• Startup / background behavior

Steps to reproduce

1. Install and sign in to agy.
2. Enable the Antigravity provider in Win-CodexBar.
3. Close Antigravity and ensure no agy process is running.
4. Refresh Antigravity usage or run codexbar usage --provider antigravity --source auto --brief.
5. Observe an offline conversation count instead of live quota usage.
6. Start agy manually and refresh again; live Session/Weekly quota usage appears.

Logs, screenshots, or recordings

Before: Antigravity  Offline · 37 conversations
After manually starting agy: live Session and Weekly quota windows

No credentials, account identifiers, or terminal output are required to reproduce the issue.

App version

v0.56.8

Windows version

Windows 11

Additional context

Upstream behavior is documented in docs/antigravity.md: CodexBar launches agy in a PTY when the desktop app is closed, waits for API/keyring readiness, and tears down only its owned child for a one-shot fetch.

A Windows implementation can reuse the existing portable-pty dependency and should:

• prefer an existing Antigravity or user-owned agy process;
• launch agy in a hidden ConPTY only when no runtime exists;
• bound readiness polling and never scrape or log TUI output;
• stop and reap only the task-owned child;
• preserve the current offline-history fallback when neither runtime nor CLI is installed.