antigravity-python-prompt - SKILL.md Agent Skill

name: antigravity-python-prompt description: Send prompts directly to Google Antigravity (Gemini + Claude) via Python using OAuth refresh tokens, without OpenCode; includes correct headers, model ID normalization, endpoint selection, SSE streaming, and 429 backoff.

Antigravity Python Prompt

[Created by Codex: 019ba92d-c995-77c0-b090-e9109492f53b]

Overview

Send prompts directly to Antigravity using Python (no OpenCode), with correct request envelope, headers, model naming, and streaming SSE parsing.

Quick Start

Run the bundled script: scripts/antigravity_prompt.py.
Prefer --quota gemini-cli for Gemini if Antigravity is 429, but Claude only works on Antigravity.

Copy/paste:

python ~/.codex/skills/antigravity-python-prompt/scripts/antigravity_prompt.py \
  "Write a short story about programmers (~500 words)" \
  --model gemini-3-pro --thinking high --quota gemini-cli

Workflow

1) Load credentials

Read refresh tokens from ~/.config/opencode/antigravity-accounts.json (default), or pass --accounts-file.
Select account with --account-index (default 0).

2) Normalize model IDs

Strip prefixes (google/…, antigravity-…).
Map common versioned Claude names (e.g. claude-opus-4-20250514) to Antigravity model IDs.

3) Choose quota bucket + endpoints

For Gemini:
- --quota antigravity uses Antigravity header style and sandbox endpoints (may 429).
- --quota gemini-cli uses Gemini CLI header style and production endpoint (often a separate quota pool).
- --quota auto tries Antigravity first, then Gemini CLI.
For Claude/GPT: only --quota antigravity is valid.

4) Send request

Build Antigravity request envelope:
- Top-level: { project, model, request, requestType, userAgent, requestId }
- request.contents uses Gemini-style {role: "user"|"model", parts:[{text:"…"}]}.
Inject request.systemInstruction with Antigravity system instruction when using Antigravity header style (this matches OpenCode plugin behavior and avoids flaky Claude throttling).

5) Stream SSE

Parse data: {json} lines and print text deltas from candidates[].content.parts[].text.

6) Handle throttling

On HTTP 429, apply exponential backoff (script supports --retry-on-429 and --max-backoff-seconds).
No reliable “remaining quota” header exists; treat 429 as the signal.

Examples

Gemini 3 Pro (streaming, use Gemini CLI quota)

python ~/.codex/skills/antigravity-python-prompt/scripts/antigravity_prompt.py \
  "Summarize this repo's purpose in 3 bullets." \
  --model gemini-3-pro --thinking high --quota gemini-cli

Claude Opus (streaming, Antigravity only)

python ~/.codex/skills/antigravity-python-prompt/scripts/antigravity_prompt.py \
  "Explain the difference between rate limit and capacity." \
  --model claude-opus-4-20250514 --retry-on-429 12

Notes

Avoid asking the model to run tools: this script is a raw LLM call, not an agent runtime.
Prefer --quota gemini-cli for Gemini workloads when Antigravity sandbox returns 429.