support Antigravity CLI migration and deprecate Gemini CLI

[sechanchoi]

Summary

Update the plugin to support the new Antigravity CLI (agy) and deprecate Gemini CLI before its service termination on June 18th.

Motivation

• Breaking Disruption: Existing workflows utilizing this plugin will break after June 18th, 2026, as Google One and unpaid tier users will no longer be able to use the Gemini CLI backend.
• Seamless Migration: Users are already migrating to Antigravity CLI (using the agy command). The plugin should natively recognize the new CLI path and commands to ensure a seamless transition without forcing users to rely on manual aliases or symbolic links.
• Future-Proofing: Aligning with Google’s new unified multi-agent platform architecture keeps this plugin up-to-date with official individual-tier toolchains.

Proposed solution

1. CLI Auto-Detection Update: Update the plugin's executable look-up logic to scan for agy in the system path (PATH) alongside or prior to gemini.
2. Configuration Fallback: Allow users to explicitly configure the CLI binary path (e.g., executable_path: "/Users/user/.local/bin/agy").
3. Graceful Warning: If only gemini is detected, display a deprecation warning notice reminding the user to migrate before June 18th.

Alternatives considered

• Manual Symbolic Links / Aliasing: Users can manually create a symlink (ln -s .../agy .../gemini) as a temporary workaround. However, this is a brittle fix because:
  1. Some plugin execution environments or security policies strictly resolve canonical paths, failing to follow or recognize symlinks.
  2. If the plugin relies on checking specific CLI version strings (e.g., parsing gemini --version output), the new agy output format will cause parsing errors.
     Therefore, this doesn't solve the plugin's long-term technical debt regarding the official tool rename.

Additional context

Google's official migration announcement notice:
"Gemini CLI is transitioning to the new Antigravity CLI for Google One and unpaid tier (Gemini Code Assist for individuals) users. ... Gemini CLI will stop serving requests for Google One and unpaid tiers starting June 18th. Please migrate to Antigravity CLI before this date to avoid disruption to your workflow."

[razvanantonescu]

I second this

[RAIT-09]

Thanks for the report!

I'm aware of the upcoming Gemini CLI service termination as well, and I'd like to notify users in some way before the June 18th cutoff.

A quick note on the technical side: agents used through this plugin need to support the Agent Client Protocol (ACP). Gemini CLI provided the --experimental-acp option to launch in ACP mode, but unfortunately, from my own investigation and testing so far, Antigravity CLI does not appear to support ACP. Because of this, simply swapping the binary (e.g., auto-detecting agy in place of gemini) wouldn't be enough — the plugin wouldn't be able to communicate with it.

Given that, my current plan is:

1. Add a deprecation notice for Gemini CLI users ahead of the June 18th cutoff, as you suggested.
2. Keep monitoring Antigravity CLI for ACP support and add it as a built-in agent as soon as that lands.
3. In the meantime, point users to other ACP-compatible agents (e.g., Claude Code, Codex CLI) as alternatives.

If anyone has information showing that Antigravity CLI supports ACP — or a public roadmap for it — please share. I'd be happy to revisit this once that's confirmed.

[v1adicke]

found this repo (https://github.com/openabdev/openab/tree/main/agy-acp), in theory you could use it as a bridge since it translates acp requests to agy commands

[RAIT-09]

@v1adicke
Thanks for sharing the agy-acp bridge!

I built it locally and tried it through the plugin. It does work — but only as a minimal text chat. Streaming isn't supported, tool calls aren't shown, and so on. This is likely a structural limitation of wrapping Antigravity CLI's -p mode: the bridge parses the CLI's text output rather than consuming structured agent events, so most of what this plugin offers (diffs, tool calls, permission prompts, streaming) can't come through.

So for now, I'm planning to document this as a Custom Agent workaround rather than ship it as a built-in agent the way Gemini CLI was. It's a useful escape hatch, but not yet the same experience.

The ideal outcome is Google officially supporting ACP. If they don't, an adapter built on the Antigravity SDK could still emerge — much like claude-agent-acp is built on the Claude Agent SDK rather than wrapping the CLI. I'll keep watching for that and revisit built-in support once something at that level exists.

In the meantime, I'll move ahead with the Gemini CLI deprecation notice separately, ahead of the June 18th cutoff.