Antigravity Subscription DirectSDK Provider for Hermes Agent

Hermes Agent model provider that routes inference through an active Google Antigravity account using the local agy binary.

This plugin lets Hermes use Gemini and Claude models through your existing Antigravity quota.

How It Works

Token streaming: Reads stdout chunks from agy --output-format stream-json and yields standard completion deltas.
Tool call routing: The model emits <tool_call> tags in text. The plugin parses these into OpenAI function call deltas, so Hermes executes tools on the host instead of agy.
Tool execution guard: agy registers local system tools by default. This plugin runs agy in headless mode without permissions skip flags. If agy attempts to execute an internal tool step, the stream closes and terminates the child process.
Thinking effort mapping: Maps Hermes reasoning effort settings (low, medium, high) directly to backend model variants (gemini-3.8-flash-low, gemini-3.8-flash-high).
Subagent concurrency: Each completion turn runs in its own process group (start_new_session=True). Multiple Hermes subagents can request completions concurrently without shared state.
Filesystem isolation: Subprocesses run in an isolated, private temporary working directory per client and slash commands are disabled. Local GEMINI.md and AGENTS.md project files are not read.

Models

Model	Suffix	Context	Supported Efforts
`gemini-3.8-flash`	`-low`, `-medium`, `-high`	1M tokens	`low`, `medium`, `high`
`gemini-3.7-flash`	`-low`, `-medium`, `-high`	1M tokens	`low`, `medium`, `high`
`gemini-3.6-flash`	`-low`, `-medium`, `-high`	1M tokens	`low`, `medium`, `high`
`gemini-3.1-pro`	`-low`, `-high`	2M tokens	`low`, `high`
`claude-sonnet-4-6`	None	200k tokens	Default
`claude-opus-4-6-thinking`	None	200k tokens	Extended thinking
`gpt-oss-120b-medium`	None	128k tokens	Default

Security Model

┌─────────────────────────────────────────────────────────────┐
│                        Hermes Agent                         │
│  - Prompts and system instructions                          │
│  - Tool definitions and approvals                           │
│  - Host execution                                           │
└──────────────┬───────────────────────────────▲──────────────┘
               │ Prompt + tool schemas         │ Text with <tool_call> tags
               │                               │ parsed into completion chunks
┌──────────────▼───────────────────────────────┴──────────────┐
│       Antigravity Subscription DirectSDK Plugin             │
│                                                             │
│  1. Preamble tells the model to emit tool tags in text.     │
│  2. Omits --dangerously-skip-permissions to deny agy tools. │
│  3. Stream watcher kills agy if it emits a tool step.       │
│  4. Runs in private temp dir to ignore rules files.         │
└──────────────────────────────┬──────────────────────────────┘
                               │ Stdin / stdout (NDJSON pipes)
┌──────────────────────────────▼──────────────────────────────┐
│               Local `agy` CLI binary (Go)                   │
└─────────────────────────────────────────────────────────────┘

Requirements

Antigravity CLI: agy must be installed and authenticated on the system.
```
agy --version
```
Hermes Agent: Version 0.21.0 or higher.
```
hermes --version
```

Installation

Install directly through the Hermes plugin manager:

hermes plugins install https://github.com/soyelmismo/hermes-antigravity-subscription
hermes plugins enable antigravity-subscription-directsdk

Or clone into the local plugins folder:

git clone https://github.com/soyelmismo/hermes-antigravity-subscription.git \
  ~/.hermes/plugins/antigravity-subscription-directsdk

hermes plugins enable antigravity-subscription-directsdk

Usage

Interactive model picker

Open the model picker inside Hermes:

/model

Select Antigravity Subscription DirectSDK, then pick a model and effort level.

Command line flag

hermes --provider antigravity-subscription-directsdk --model gemini-3.8-flash

Configuration file

Add to ~/.hermes/config.yaml:

agent:
  provider: antigravity-subscription-directsdk
  model: gemini-3.8-flash
  reasoning_effort: high

Tests

Run the test suite:

PYTHONPATH=/usr/local/lib/hermes-agent:. python3 tests/test_antigravity_plugin.py

License

MIT