OpenCode + opencode-antigravity-auth setup (Pro/Opus primary, Flash/Sonnet budget subagents; no effort pins)

A developer shared a portable setup for OpenCode using the opencode-antigravity-auth plugin, which enables Google OAuth-based access to Antigravity quota for Gemini and Claude models. The configuration assigns primary models (Gemini 3.1 Pro and Claude Opus 4-6 Thinking) for coding and planning, with budget subagents (Gemini 3.5 Flash and Claude Sonnet 4-6) for lighter tasks, and includes installation instructions via a public gist.

Portable setup for OpenCode with opencode-antigravity-auth Google OAuth → Antigravity quota for Gemini + Claude . Notthe Antigravity IDE. This is OpenCode’s Google/Gemini auth path only. Gist: https://gist.github.com/saadev0/0e3f43d24c3f05903f9c4bd732e961d0 https://gist.github.com/saadev0/0e3f43d24c3f05903f9c4bd732e961d0 | Role | Model id | Notes | |---|---|---| Primary default / build | google/antigravity-gemini-3.1-pro | Main coding | Primary plan | google/antigravity-claude-opus-4-6-thinking | Planning / deep work | Budget subagent explore , titles, summary, compaction, small model | google/antigravity-gemini-3.5-flash | Search / light utility | Budget subagent general | google/antigravity-claude-sonnet-4-6 | Tool-call / general subagent | Effort/variants are not pinned. Variants low / high / max / … stay available so you or the agent can choose per task. Subagents use budget model families , not primary Pro/Opus. | File | Install path | |---|---| opencode.jsonc | ~/.config/opencode/opencode.jsonc | antigravity.json | ~/.config/opencode/antigravity.json | package.json | ~/.config/opencode/package.json optional deps pin | README.md | this doc | Do not copy OAuth secrets or antigravity-accounts.json into a public gist. 1 Install OpenCode if needed — https://opencode.ai/docs 2 Config dir mkdir -p ~/.config/opencode cd ~/.config/opencode 3 Pull this gist BASE="https://gist.githubusercontent.com/saadev0/0e3f43d24c3f05903f9c4bd732e961d0/raw" curl -fsSL "$BASE/opencode.jsonc" -o opencode.jsonc curl -fsSL "$BASE/antigravity.json" -o antigravity.json curl -fsSL "$BASE/package.json" -o package.json 4 Install plugin dependency npm install 5 Google OAuth login Antigravity accounts opencode auth login Select Google / Antigravity provider, complete browser OAuth. Re-run to add more accounts for rotation. 6 Verify models opencode models | grep antigravity Expect: google/antigravity-gemini-3.1-pro google/antigravity-claude-opus-4-6-thinking google/antigravity-gemini-3.5-flash google/antigravity-claude-sonnet-4-6 7 Smoke test opencode run "Hello" --model=google/antigravity-gemini-3.1-pro opencode run "Hello" --model=google/antigravity-claude-opus-4-6-thinking opencode run "Hello" --model=google/antigravity-gemini-3.5-flash BASE="https://gist.githubusercontent.com/saadev0/0e3f43d24c3f05903f9c4bd732e961d0/raw" mkdir -p ~/.config/opencode && cd ~/.config/opencode curl -fsSL "$BASE/opencode.jsonc" -o opencode.jsonc curl -fsSL "$BASE/antigravity.json" -o antigravity.json curl -fsSL "$BASE/package.json" -o package.json npm install - Loads plugin: opencode-antigravity-auth@latest - Whitelists only the four Antigravity models above - Declares model limits, modalities, and optional variants not forced - Agent model family map:- primary → Pro / Opus - subagent / utility → Flash / Sonnet - No variant: "high" / variant: "low" on agents | Key | Value | Why | |---|---|---| account selection strategy | hybrid | Good multi-account default | auto update | false | Avoid silent plugin overwrites of local patches | debug | true | Logs under ~/.config/opencode/antigravity-logs/ | quota fallback | false | No silent Gemini CLI / alternate routing | cli first | false | Prefer Antigravity quota first | Optional later: { "pid offset enabled": true // parallel subagents across accounts } - Credentials: ~/.config/opencode/antigravity-accounts.json local only, never gist - Add accounts: opencode auth login again - Reset auth: delete antigravity-accounts.json , re-login - ToS risk: unofficial Google OAuth path — use an established account; see upstream README Upstream plugin: opencode-antigravity-auth https://github.com/NoeFabris/opencode-antigravity-auth opencode.jsonc alone is enough for model registration whitelist + agent map . These optional patches live under: ~/.config/opencode/node modules/opencode-antigravity-auth/ They are wiped on npm reinstall/update hence auto update: false . | Change | Purpose | |---|---| Register antigravity-gemini-3.5-flash in plugin models.js | Official plugin list may lag 3.5 Flash | Aliases gemini-3.5-flash-{minimal,low,medium,high} in model-resolver.js | Tier suffixes resolve cleanly | SEARCH MODEL = "gemini-3.5-flash" in constants.js | Search tool uses budget Flash | No silent default -low / -high on bare models | Effort only when you pick a variant | Opus variant high = max budget 32768 | Friendly label alongside max | After npm install , re-apply patches if you rely on them, or keep a local fork. Only when you want an explicit effort tier opencode run "..." --model=google/antigravity-gemini-3.1-pro --variant=high opencode run "..." --model=google/antigravity-claude-opus-4-6-thinking --variant=high opencode run "..." --model=google/antigravity-gemini-3.5-flash --variant=medium Without --variant , the plugin does not invent low/high for you. | Symptom | Fix | |---|---| | Model missing from list | Ensure opencode.jsonc whitelist + models block; restart OpenCode | | 403 / project denied | Set projectId on each account in antigravity-accounts.json ; enable Cloud Code Assist API | | OAuth callback fails Safari | Use Chrome/Firefox or disable Safari HTTPS-Only for localhost | | Rate limited | Add more Google accounts; wait; check quotas via auth menu | | Plugin update wiped 3.5 Flash | Re-install configs from this gist; re-apply local patches; keep auto update: false | Source of truth for a new machine: this gist Live machine config: ~/.config/opencode/opencode.jsonc + antigravity.json - After changing live config, push updates back into this gist same files Maintained for saadev0 https://gist.github.com/saadev0 · OpenCode Google auth via Antigravity OAuth