Provider: Google Antigravity CLI

Process guidance for keeping the gateway's Gemini-compatible provider key (gemini) aligned with Google Antigravity CLI (agy). This skill does not define argv/env behaviour; the single mechanical source of truth is UPSTREAM_CLI_CONTRACTS.gemini in src/upstream-contracts.ts, enforced by validateUpstreamCliArgs / validateUpstreamCliEnv. Never re-encode flags, permission modes, output formats, or resume rules here or in TOML.

Identity

These values mirror UPSTREAM_CLI_CONTRACTS.gemini.upstreamMetadata and docs/upstream/provider-sources.dag.toml ([providers.gemini]). The TypeScript metadata is authoritative; the TOML is scanner input only.

When to use

• A Google Antigravity CLI release lands and you need to check for contract drift.
• A gemini request fails the upstream contract check before spawn.
• npm run upstream:scan -- --live reports a change on either Antigravity source.

How LLM agents should use Gemini/Antigravity through the gateway

1. Discover the live gateway/provider surface before relying on Antigravity-specific controls:

   provider_tool_capabilities({cli:"gemini"})

   For a cached read-only resource, use provider-tools://gemini.
2. Use gemini_request for normal turns and gemini_request_async for long-running review or analysis. Sync calls may auto-defer; poll llm_job_status and fetch with llm_job_result when that happens.
3. Omit model unless the caller explicitly asked for a specific variant; the gateway resolves the configured Gemini/Antigravity default.
4. Do not pass non-empty allowedTools to the current Antigravity request path; the gateway rejects them. Antigravity owns its MCP configuration, and mcpServers is descriptive metadata rather than an enforceable gateway allowlist. Do not assume old Gemini CLI allowlist semantics apply to agy.
5. Use approvalStrategy:"legacy" for every Gemini/Antigravity request. mcp_managed is Claude-only and is rejected before the Antigravity CLI launches because ambient MCP configuration cannot be isolated. approvalPolicy has no effect for Gemini.
6. sandbox, includeDirs, sessionId, resumeLatest, createNewSession, project, and newProject are the relevant request controls. workspace and worktree are gateway routing selections, not Antigravity-native flags. includeDirs is an additional read path and does not select cwd. Use workingDir to select the process cwd, or a verified registered workspace for remote HTTP/OAuth callers. An unscoped child uses a fresh neutral temporary cwd, not the gateway repository. JSON and stream-json output are supported. Attachments, policy files, admin policy files, and skipTrust remain unsupported or rejected in the current Antigravity path.
7. For continuity, use a verified caller-owned Antigravity conversation ID or resumeLatest:true. Gateway-generated gw-* IDs are bookkeeping IDs and are rejected if replayed as Gemini session IDs; check the response resumable field. resumeLatest:true requires workingDir, workspace, or a configured default workspace so --continue remains bound to a stable cwd.
8. Antigravity's current print contract carries the prompt in argv. Oversized UTF-8 input fails before spawn as non-retryable input_too_large; the gateway never truncates instructions. All other caller-controlled argv values are admitted in their final encoded form before spawn. Embedded NUL bytes return non-retryable invalid_input without exposing the rejected value.

Full-access review handoff

For a user-authorized exhaustive review that needs full provider permissions and native MCP access, do not infer the launch controls from this maintenance guide. Follow multi-llm-review's full-access protocol, inspect the current request schema and live capability response, and use a fresh target-checkout node dist/index.js --transport=stdio gateway rather than a global process. Reapply the grant on every new job, preserve native MCP configuration without a pretend gateway allowlist, send the corrective-program report and exact diff/file identity, set no caller caps, and honor a user-required 90-second progress cadence. The reviewer must independently inspect code, docs, tests, and commands before it can approve.

Scan for upstream change

npm run upstream:scan -- --provider gemini
npm run upstream:scan -- --live --provider gemini --fail-on-critical
npm run upstream:scan -- --live --provider gemini --write-snapshot --write-report

Antigravity has two tracked sources (docs site + GitHub releases); both are fetched under --live. A failed fetch is advisory unless --fail-on-critical is set.

Update procedure when the upstream CLI changes

1. Edit the contract in src/upstream-contracts.ts (UPSTREAM_CLI_CONTRACTS.gemini): flag arities, permission bypasses, output-format support, and session flags live here.
2. Add a conformance fixture proving the new accept/reject behaviour (mirror the existing gemini-* fixtures).
3. If a source URL or watch category changed, update upstreamMetadata and mirror it into docs/upstream/provider-sources.dag.toml.
4. Verify: npm run build && npm run upstream:contracts and npm test.

Antigravity-specific notes (see the contract for exact rules)

• Tested against agy 1.1.25. Antigravity (agy) has no native ACP entrypoint; legacy Gemini CLI ACP evidence does not transfer, so provider-acp://gemini reports native:false (no methods, no adapter-as-native masquerade) and gemini_request exposes no transport:"acp" selector.
• The public MCP tool names stay gemini_request / gemini_request_async, but the spawned executable is agy.
• Antigravity 1.1.25 consumes the token after bare --print as its prompt, so gateway requests attach the value as --print=<prompt>. This keeps later gateway flags from being mistaken for prompt text.
• agy 1.1.25 retains root --agent plus agent and agents commands. Track and acknowledge those upstream-only controls before exposing them through a request schema; custom agent selection can change tool and permission posture.
• approvalMode:"auto_edit" maps to --mode accept-edits, approvalMode:"plan" maps to --mode plan, and yolo maps to --dangerously-skip-permissions. Unsupported Gemini-only knobs such as --approval-mode, -o, policy files, MCP allowlists, and attachment tokens must fail before spawn unless Antigravity adds an equivalent.
• Continuity is real via --conversation <id> or --continue; gateway-generated gw-* IDs are bookkeeping only and rejected if replayed as sessionId. Continuation remains provider-native under legacy.
• Check the resumable response field to know whether a session can continue.