agy-acp

agy-acp is an Agent Client Protocol (ACP) stdio adapter for Google Antigravity CLI (agy).

It lets an ACP-compatible host, such as Paseo or Zed, talk to agy over JSON-RPC. The adapter starts agy as a subprocess, reads Antigravity's local conversation database, and turns the result into ACP session/update notifications.

How It Works

ACP host  <--stdin/stdout JSON-RPC-->  agy-acp  <--subprocess-->  agy  <--API-->  Gemini

agy-acp is intentionally a thin compatibility layer. It does not change agy itself into a native ACP server; it bridges the current CLI behavior and Antigravity's local conversation data into the ACP shape expected by the host.

Current Features

• ACP initialize, session/new, session/load, session/resume, and session/prompt support.
• Incremental session/update notifications while agy is running.
• Session persistence in ~/.openab/agy-acp/sessions.json.
• Conversation replay from ~/.gemini/antigravity-cli/conversations/*.db.
• Model listing via agy models and ACP model/config option responses.
• Generated image artifacts are emitted as Markdown image links when local file paths or inline data URIs can be extracted from Antigravity conversation data.

Prerequisites

• Rust with Cargo.
• agy installed and available in PATH.
• Antigravity/Gemini authentication configured for agy, for example with GEMINI_API_KEY or ~/.gemini/antigravity-cli/settings.json.

Build

cargo build --release

The binary is created at target/release/agy-acp. You can reference that path directly from your ACP host, or copy it somewhere in your PATH.

cp target/release/agy-acp /usr/local/bin/

Host Configuration

Configure your ACP host to spawn the agy-acp binary over stdio. The exact settings format depends on the host.

Paseo

Example custom provider configuration:

{
  "antigravity-acp": {
    "extends": "acp",
    "label": "Antigravity",
    "command": ["/absolute/path/to/agy-acp"],
    "params": {
      "supportsMcpServers": false
    }
  }
}

Use the absolute path to the built binary, such as /Users/you/path/to/agy-acp/target/release/agy-acp, or a path in your PATH.

Zed

Example custom agent server configuration:

{
  "agent_servers": {
    "agy": {
      "type": "custom",
      "command": "agy-acp",
      "args": [],
      "env": {}
    }
  }
}

Options

Extra agy Arguments

Set AGY_EXTRA_ARGS to pass additional space-separated arguments to every agy invocation:

{
  "AGY_EXTRA_ARGS": "--some-flag value"
}

Skip Narration

Run the adapter with --skip-naration to drop leading narration-only assistant chunks such as "I will ...".

agy-acp --skip-naration

The option name keeps the current historical spelling.

Generated Images

When Antigravity records a generated image artifact, agy-acp tries to extract the local image reference from the conversation payload.

• file://... image URIs are converted to absolute local paths.
• Bare absolute image paths are used as-is.
• data:image/...;base64,... payloads are materialized under ~/.openab/agy-acp/images.

The adapter sends the image back as assistant text containing Markdown:

![Generated image](/absolute/path/to/generated.png)

Whether the image renders inline depends on the ACP host's Markdown/media support.

This path has been verified end-to-end with Paseo: an image-generation prompt sent through a custom ACP provider can invoke Antigravity and render the generated local image inline in Paseo.

Data Locations

Path	Purpose
~/.openab/agy-acp/sessions.json	Persisted ACP session to Antigravity conversation mapping
~/.openab/agy-acp/images/	Materialized inline image data
~/.gemini/antigravity-cli/conversations/*.db	Antigravity conversation SQLite databases read by the adapter

Development

cargo build
cargo test
cargo test -- --include-ignored
cargo test e2e -- --ignored --nocapture

The e2e tests require a release build, an agy binary, and valid Antigravity/Gemini authentication.

Notes

agy-acp depends on Antigravity CLI's current local conversation storage format. If agy gains native ACP support or changes its internal SQLite/protobuf layout, this adapter may need to be updated.

License

MIT