How to Use Ponytail with Cursor: Complete Setup Guide

Copy the ponytail.mdc rule file to your project's .cursor/rules directory and Cursor automatically loads Ponytail's instructions on startup—no runtime activation required.

Ponytail provides an "always‑on" integration for the Cursor editor through a simple rule file mechanism. This lets you invoke Ponytail commands with @ prefixes or benefit from context‑aware suggestions transparently within your workflow. According to the DietrichGebert/ponytail source code, the integration requires only a file copy operation with no additional configuration.

How the Cursor Integration Works

Cursor recognizes .mdc files placed in the .cursor/rules directory as permanent project rules. When you open a project, Cursor automatically loads every *.mdc file it finds there and applies those instructions to all AI interactions.

The Ponytail repository provides a pre‑configured rule file at .cursor/rules/ponytail.mdc that encodes the complete instruction set. This file implements what the repository calls "instruction‑only" mode—functionality that works without a separate skill host.

Step‑by‑Step Setup

1. Copy the Rule File

Create the rules directory in your project and copy the ponytail.mdc file from the Ponytail repository:

mkdir -p .cursor/rules
cp path/to/ponytail/.cursor/rules/ponytail.mdc .cursor/rules/

The source path depends on where you cloned or extracted the Ponytail repository. The repository structure places the file at .cursor/rules/ponytail.mdc relative to the project root.

2. Verify Cursor Loaded the Rules

Open your project in Cursor and inspect the Rules view. You should see ponytail.mdc listed among the active project rules. Cursor reads these files on startup, so a restart may be needed if the file was added while Cursor was already running.

3. Use Ponytail Features

Once loaded, Ponytail operates in one of two modes depending on your environment:

• With a skill‑capable host (Claude Code, Codex, OpenCode, Gemini, π, etc.): Invoke commands directly using @ prefixes:

@ponytail-review   # reviews the current file or selection

• Cursor‑only mode: The rule file provides the instruction set automatically. Write prompts normally and Ponytail's context‑aware suggestions apply transparently.

Key Files in the Ponytail Repository

File	Purpose
.cursor/rules/ponytail.mdc	Core rule set that Cursor loads on project start
README.md (Cursor section)	Documents the copy‑and‑paste workflow
AGENTS.md	Lists supported agents and explains the "always‑on" rule concept
hooks/ponytail-instructions.js	Implementation of instruction loading logic used by adapters

The ponytail.mdc file is version‑controlled alongside Ponytail itself. Keep it current by pulling the latest changes from the repository and re‑copying when updates are released.

Why This Approach Works

The integration leverages Cursor's native rule system rather than requiring a plugin or extension. As implemented in DietrichGebert/ponytail, the hooks/ponytail-instructions.js module provides the underlying instruction loading logic that adapters like Cursor consume. The .mdc file format is Cursor's standard for persistent, project‑scoped AI instructions.

This architecture separates concerns: the repository maintains the instruction logic, while Cursor handles the runtime integration. You benefit from updates to Ponytail by refreshing a single file rather than managing complex package dependencies.

Summary

• Primary requirement: Copy .cursor/rules/ponytail.mdc from the Ponytail repository to your project's .cursor/rules directory
• Activation: Automatic on Cursor startup—no commands or runtime steps needed
• Usage modes: @ command prefixes with skill hosts, or transparent "instruction‑only" mode in Cursor alone
• Maintenance: Update by re‑copying the file when the repository changes

Frequently Asked Questions

Where does the ponytail.mdc file come from?

The file is located in the Ponytail repository at .cursor/rules/ponytail.mdc. Clone or download the DietrichGebert/ponytail repository, then copy this file into your own project's .cursor/rules directory.

Do I need to install anything else for Ponytail to work in Cursor?

No additional installation is required. Cursor's native rule system loads .mdc files automatically. The only dependency is the rule file itself, which contains all necessary instructions.

Can I use Ponytail commands without a skill host like Claude Code?

Yes. While @ commands require a skill‑capable host, the rule file activates Ponytail's "instruction‑only" mode automatically. This provides context‑aware suggestions within Cursor's normal chat interface without special command syntax.

How do I update Ponytail when the repository changes?

Pull the latest changes from the DietrichGebert/ponytail repository, then replace your local copy of .cursor/rules/ponytail.mdc with the updated version. Restart Cursor to load the new rules.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}