# How to Install Ponytail for Gemini CLI or Antigravity CLI > Learn to install Ponytail for Gemini CLI or Antigravity CLI. Effortlessly add powerful slash commands and rulesets to your LLM context for enhanced functionality. - Repository: [DietrichGebert/ponytail](https://github.com/DietrichGebert/ponytail) - Tags: getting-started - Published: 2026-09-09 --- **Install Ponytail as a Gemini CLI extension using `gemini extensions install https://github.com/DietrichGebert/ponytail`, or use `agy plugin install https://github.com/DietrichGebert/ponytail` for Antigravity CLI; the [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json) manifest automatically registers six slash commands and injects the [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) ruleset into every LLM context window.** Ponytail is an always-on coding assistant distributed as a native extension for Google's Gemini CLI and its successor, Antigravity CLI. According to the DietrichGebert/ponytail repository source code, the extension leverages a declarative manifest system to inject behavioral rules and register slash commands without requiring manual file copying or hook configuration. ## How the Ponytail Extension Works The installation process relies on [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json), the manifest file located in the repository root that tells the CLI how to load Ponytail. When you install the extension, the CLI performs three actions automatically: - **Ruleset injection** – The guidance defined in [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) is injected as context for every LLM turn, making Ponytail’s coding standards always active. - **Skill registration** – The TypeScript files under the `skills/` directory are discovered and compiled into the six `/ponytail*` commands. - **Zero-hook loading** – Gemini auto-loads the extension’s manifest directly; Ponytail does **not** ship a root [`hooks/hooks.json`](https://github.com/DietrichGebert/ponytail/blob/main/hooks/hooks.json) because the CLI already knows where to look based on the manifest declaration. ## Installing Ponytail in Gemini CLI To install Ponytail for Gemini CLI, run the following command in your terminal: ```bash gemini extensions install https://github.com/DietrichGebert/ponytail ``` This command downloads the repository, parses [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json), and registers the extension. Once complete, the `skills/` directory is mounted and the commands become available immediately in new Gemini sessions. ## Installing Ponytail in Antigravity CLI For Antigravity CLI (the successor to Gemini CLI), use the `agy` command with the plugin subcommand: ```bash agy plugin install https://github.com/DietrichGebert/ponytail ``` Antigravity reads the same [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json) manifest structure, ensuring compatibility across both CLI versions without modification to the extension source code. ## Available Ponytail Commands After installation, the following slash commands are registered from the `skills/` directory: - **`/ponytail`** – Toggles the assistant mode or displays current configuration status. - **`/ponytail-review`** – Runs the review skill on the current git diff. - **`/ponytail-audit`** – Performs a comprehensive codebase audit against Ponytail's ruleset. - **`/ponytail-debt`** – Identifies and categorizes technical debt in the current project. - **`/ponytail-gain`** – Suggests performance or architectural improvements. - **`/ponytail-help`** – Displays help documentation for Ponytail commands. ## Manual Ruleset Installation (Optional) If you prefer not to install the full extension but want the always-on behavior, you can manually copy the ruleset to your agents configuration directory: ```bash cp AGENTS.md ~/.agents/rules/ponytail.md ``` This method injects the [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) content into every LLM turn without registering the `/ponytail*` commands, useful for lightweight setups where you only need the behavioral guardrails. ## Summary - Ponytail installs as a native extension via `gemini extensions install` or `agy plugin install`. - The [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json) manifest drives automatic loading of rules from [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) and commands from the `skills/` directory. - Six slash commands (`/ponytail`, `/ponytail-review`, `/ponytail-audit`, `/ponytail-debt`, `/ponytail-gain`, `/ponytail-help`) become available immediately after installation. - No manual hook configuration is required; Gemini and Antigravity parse the manifest automatically. - Alternatively, copy [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) to `~/.agents/rules/ponytail.md` for rules-only operation without command registration. ## Frequently Asked Questions ### Do I need to manually copy files to install Ponytail for Gemini CLI? No manual file copying is necessary. The `gemini extensions install` command handles the entire installation by reading the [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json) manifest, which specifies the location of the [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) ruleset and the `skills/` directory. ### What is the difference between installing Ponytail in Gemini CLI versus Antigravity CLI? There is no functional difference in the extension behavior. Both CLIs consume the same [`gemini-extension.json`](https://github.com/DietrichGebert/ponytail/blob/main/gemini-extension.json) manifest and load identical rulesets and commands. The only variation is the installation command: `gemini extensions install` versus `agy plugin install`. ### Where does Ponytail store its always-on ruleset? The canonical ruleset lives in the repository's [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) file. When you install the extension, the CLI reads this file and injects its contents into the system prompt for every LLM interaction. You can also manually place this file in `~/.agents/rules/ponytail.md` to achieve similar behavior without the full extension. ### Can I use Ponytail commands without installing the full extension? No. The six `/ponytail*` commands are implemented as skills within the `skills/` directory and require the extension installation to register with the CLI's command parser. However, you can use the [`AGENTS.md`](https://github.com/DietrichGebert/ponytail/blob/main/AGENTS.md) ruleset independently by copying it to your agents rules directory, though this only provides the behavioral guidance, not the interactive commands.