Antigravity Agent

Antigravity Agent connects Syrus workflows and chats to Google's agy CLI. It provides the provider adapter used for implementation, review, repair, coding handoff, and interactive chat sessions, while feeding provider availability and failure classification back into Syrus' admission and retry systems.

Enable this plugin when a Syrus instance should offer Antigravity-backed automation. It can run alongside the Claude and Codex plugins so jobs and chats choose the appropriate provider per workflow or conversation.

What It Adds

• A workflow agent provider with provider key agy and display name Antigravity.
• A chat provider for Antigravity-backed chat turns.
• Provider readiness evidence through the shared Gemini API key credential.
• Transcript capture and session resume for Antigravity conversation JSONL.

Requirements

• The agy CLI must be installed on worker hosts and available on PATH. The Docker worker image includes the pinned Antigravity CLI; Docker Compose operators should rebuild or pull an image that contains it before enabling this plugin.
• Each user who selects Antigravity needs a saved Gemini API key. Syrus stores that key in User#gemini_api_key and passes it to agy as GEMINI_API_KEY and GOOGLE_API_KEY.
• Optional model and effort defaults can be set with SYRUS_AGY_MODEL and SYRUS_AGY_EFFORT. Syrus also forwards them to the child process as AGY_MODEL and AGY_EFFORT.

Invocation Contract

Syrus runs agy with stream JSON input and output:

agy --input-format stream-json --output-format stream-json --print= --dangerously-skip-permissions --disable-slash-commands --print-timeout 90m

Prompts are written to stdin as one NDJSON event:

{"event":"user","message":{"content":"..."}}

This avoids putting large prompts or secrets on argv. Syrus keeps AgentInvocation as the outer timeout/aliveness supervisor and passes Antigravity's print timeout as 90m.

MCP And Resume

Antigravity reads MCP servers from ~/.gemini/config/mcp_config.json. Syrus writes that config inside an isolated per-run or per-chat Antigravity home and currently uses stdio sidecars only; persistent HTTP MCP routing downgrades to stdio for this provider.

The init.conversation_id value is stored as the provider session id. On resume, Syrus restores the captured JSONL transcript into Antigravity's expected session path and invokes agy --conversation <conversation_id>. Invalid conversation ids are ignored and the turn starts fresh rather than placing unsafe values on argv.

Smoke Test

Use the repository helper for local verification:

bin/smoke-agy

The helper verifies agy --version. If neither GEMINI_API_KEY nor GOOGLE_API_KEY is set, it exits successfully after reporting that the authenticated --print probe was skipped, keeping CI deterministic. When a key is present it sends a tiny stream-json prompt through stdin and requires a result event.

Operational Notes

The Antigravity card in Credentials shares the Gemini API key card intentionally: the key remains the durable credential, while the Antigravity card probes whether that key and the local agy CLI can run provider turns.

See also docs/syrus_docs/antigravity.md for the operator-facing setup reference indexed by Syrus docs search.