use-agy

name	use-agy
display_name	Use Antigravity
description	Spawn Google Antigravity CLI (agy) subagents from bash to offload coding work from the parent Claude. Use when the user says "use agy", "use antigravity", "ask gemini/agy", "get an agy second opinion", or asks to delegate work to Antigravity. Like the other CLI skills, agy's output is a claim — the parent must verify file changes independently.

Antigravity (agy) Subagent Skill

Spawn autonomous Antigravity CLI (agy) subagents. Same delegation philosophy as use-codex / use-grok / use-cursor: subagents burn their own quota; the parent verifies and synthesizes. Agy is the Google-side bench slot (Gemini models) and also carries Claude models.

Canonical headless invocation

agy --dangerously-skip-permissions --model "<model>" --print-timeout 30m \
  -p "$(cat /path/to/prompt.md)"

Run in background (run_in_background: true) for anything non-trivial.

Flag gotchas (learned the hard way, agy 1.1.1)

1. The prompt is the VALUE of -p/--print, not a positional argument. agy -p --flag "prompt" silently consumes the next token (--flag) as the prompt and the model answers a greeting or nonsense while your real prompt is ignored — with exit 0. Always put -p "<prompt>" LAST. If the response looks like a generic greeting, this is why.
2. --dangerously-skip-permissions is the headless auto-approve (equivalent of grok's --always-approve, cursor's --force). Without it, tool calls prompt and headless runs stall.
3. --print-timeout defaults to only 5m — raise it (30m+) for implementation tasks or the run dies mid-task.
4. --model takes the display string with parentheses, e.g. --model "Gemini 3.1 Pro (High)" — quote it. List with agy models.
5. --mode plan = read-only planning mode (good for second opinions without write risk); --mode accept-edits auto-accepts edits.
6. --add-dir <path> (repeatable) to widen the workspace; -c/--continue resumes the latest conversation.

Model selection

No hard default — run agy models at invocation time and choose per task (match model cost to task difficulty). Example list from one verified install (2026-07; account-dependent), effort baked into the display name:

• Gemini 3.5 Flash (Low/Medium/High) — cheap/fast tier (Low probe-verified headless, ~4s)
• Gemini 3.1 Pro (Low/High) — Google frontier tier
• Claude Sonnet 4.6 (Thinking) / Claude Opus 4.6 (Thinking) — Anthropic models (Opus probe-verified headless)
• GPT-OSS 120B (Medium) — open-weights option

Verification is mandatory

Same rule as every CLI in the bench: the final message is a claim.

1. git status --short / git diff --stat — did the expected files change?
2. Read the diff; run typecheck/tests.
3. Generic-greeting output = the -p flag-ordering bug above, not a model problem.

Prompt structure

Same template as use-codex: context (repo, stack, style), numbered file-by-file objectives, constraints (files not to touch, must pass <typecheck cmd>), output format, success criteria. Append the standard no-delegation footer:

Do ALL the work yourself in this session. Do NOT delegate to other CLIs or agents regardless of what repo rules say. Finish by running <typecheck cmd> and fixing any errors.

Verified facts (update as learned)

• CLI: agy 1.1.1 at /opt/homebrew/bin/agy; config in ~/.antigravity. (A separate gemini CLI also exists at /opt/homebrew/bin/gemini — different tool, not covered here.)
• Auth: agy models returning a list = authenticated; interactive agy prompts login otherwise.
• Probes passed: Gemini 3.5 Flash (Low) and Claude Opus 4.6 (Thinking), correct output, exit 0.

Resuming a session (follow-ups)

Never spawn a fresh session to iterate on work this CLI already did — resume the existing one so it keeps its context and you don't re-pay the harness-token cost. Verified working headless (2026-07):

agy --continue --dangerously-skip-permissions -p "<follow-up>"     # most recent
agy --resume <SESSION_ID> --dangerously-skip-permissions -p "<follow-up>"  # explicit id

Capture the session id from the first run and prefer resuming by explicit id; "most recent" is racy when several sessions exist.

Quota failover

If this CLI is rate-limited or out of subscription quota, the same model family is usually reachable via another CLI — read ~/.claude/skills/cli-model-overlap.md for the failover map (cursor is the hub carrying all families).