# How Ponytail Integrates with Instruction‑Tier Hosts like Cursor: Rule‑Based Setup Guide

> Learn how Ponytail integrates with instruction-tier hosts like Cursor using a simple rule file for automatic, always-on project rules. Set up easily with this guide.

- Repository: [DietrichGebert/ponytail](https://github.com/DietrichGebert/ponytail)
- Tags: how-to-guide
- Published: 2026-08-28

---

**Ponytail integrates with instruction‑tier hosts like Cursor through a single rule file located at** `.cursor/rules/ponytail.mdc`**, which the host automatically loads as an always‑on project rule without requiring additional commands or skill invocations.**

The **DietrichGebert/ponytail** repository provides a lightweight integration mechanism for AI coding assistants that operate in instruction‑only mode. By placing a dedicated rule file in your project, you can make Ponytail’s guidelines automatically available to hosts like **Cursor**, Windsurf, and Cline every time they generate code.

## Understanding Instruction‑Tier Hosts

Instruction‑tier hosts represent a class of AI assistants that process natural language prompts without supporting executable "skills" or command prefixes. These environments, which include **Cursor**, Windsurf, Cline, GitHub Copilot Chat, and Kiro, cannot invoke tools like `@ponytail-review` or other command‑level capabilities.

Instead, these hosts rely entirely on static rule files to shape model behavior. This contrasts with **skill‑capable hosts** such as Claude Code, Codex, and OpenCode, which expose commands via `@` prefixes and dynamic skill invocation.

## The Rule File Architecture

### Core File Location

Ponytail’s integration centers on a single markdown rule file stored at `/.cursor/rules/ponytail.mdc` in the repository. This file contains the complete instruction set that defines Ponytail’s coding standards, safety guidelines, and style conventions.

### Automatic Discovery Mechanism

When Cursor detects a project‑local `.cursor/rules/ponytail.mdc` file, it automatically treats the contents as a permanent **project rule**. According to the source code in [`scripts/check-rule-copies.js`](https://github.com/DietrichGebert/ponytail/blob/main/scripts/check-rule-copies.js) (line 20), the system validates this specific path: `['.cursor/rules/ponytail.mdc', stripFrontmatter]`. The host reads these directives on every generation request and merges them with your natural language prompts.

## Step‑by‑Step Integration Process

### Step 1 — Copy the Rule File

Users must manually copy the rule file from the Ponytail repository into their own project structure. The file must reside at exactly `.cursor/rules/ponytail.mdc` relative to your project root.

### Step 2 — Host Activation

Once the file is present, Cursor loads it as an **always‑on** rule set. As documented in [`docs/agent-portability.md`](https://github.com/DietrichGebert/ponytail/blob/main/docs/agent-portability.md), Cursor specifically looks for `.cursor/rules/ponytail.mdc` to establish "always‑on project rule" behavior. No additional configuration or restart is required.

### Step 3 — Generation with Merged Context

During code generation, the LLM receives a merged prompt containing both your specific request and the Ponytail rules. This ensures output respects Ponytail’s guidance regarding style conventions and command patterns without requiring explicit mentions in your prompts.

## Practical Setup Commands

To integrate Ponytail with Cursor, execute the following commands in your project root:

```bash

# Create the required directory structure

mkdir -p .cursor/rules

# Download the latest rule file from the Ponytail repository

curl -L https://raw.githubusercontent.com/DietrichGebert/ponytail/main/.cursor/rules/ponytail.mdc \
     -o .cursor/rules/ponytail.mdc

```

After copying the file, Cursor automatically applies the rules to all subsequent generation requests. To remove Ponytail’s influence, simply delete the file:

```bash
rm .cursor/rules/ponytail.mdc

```

## Validation and Maintenance

The repository includes [`scripts/check-rule-copies.js`](https://github.com/DietrichGebert/ponytail/blob/main/scripts/check-rule-copies.js) to validate that rule files exist in host‑specific directories. This script references the exact path `['.cursor/rules/ponytail.mdc', stripFrontmatter]` (line 20), ensuring the integration remains intact across project updates.

## Instruction‑Tier vs. Skill‑Capable Hosts

The key distinction lies in command invocation capabilities:

- **Instruction‑tier hosts**: Rely solely on the `ponytail.mdc` rule file. They cannot execute `@ponytail-review` or similar commands. The rule file represents the only integration point.
- **Skill‑capable hosts** (Claude Code, Codex, OpenCode): Support dynamic skill invocation through `@` prefixes and can execute Ponytail commands beyond static rules.

This design makes Ponytail portable across development assistants without requiring host‑specific code implementations.

## Summary

- Ponytail integrates with instruction‑tier hosts through a single rule file at `.cursor/rules/ponytail.mdc`.
- Cursor, Windsurf, and Cline automatically load this file as an always‑on project rule.
- The [`scripts/check-rule-copies.js`](https://github.com/DietrichGebert/ponytail/blob/main/scripts/check-rule-copies.js) utility validates the presence of rule files in host‑specific paths.
- Unlike skill‑capable hosts, instruction‑tier assistants cannot invoke `@ponytail-review` commands and rely entirely on static rules.
- No additional configuration is required after copying the rule file into the correct directory.

## Frequently Asked Questions

### Which hosts support Ponytail’s rule file integration?

Cursor, Windsurf, Cline, GitHub Copilot Chat, and Kiro all support the `.cursor/rules/ponytail.mdc` placement. According to the [`docs/agent-portability.md`](https://github.com/DietrichGebert/ponytail/blob/main/docs/agent-portability.md) documentation, these instruction‑tier hosts treat the file as an always‑on project rule, automatically applying it to every generation request.

### Can I use Ponytail commands like @ponytail-review in Cursor?

No. Instruction‑tier hosts like Cursor lack "skill" support and cannot execute command‑level capabilities. As implemented in the DietrichGebert/ponytail source, these hosts rely exclusively on the static rule file content to shape model behavior, unlike skill‑capable hosts such as Claude Code or Codex.

### Do I need to restart Cursor after copying the rule file?

No restart is required. Cursor detects the `.cursor/rules/ponytail.mdc` file automatically on the next generation request. The host reads the rules and merges them with your prompt immediately upon detection.

### How do I verify that Ponytail rules are active in my project?

You can verify installation by running the [`scripts/check-rule-copies.js`](https://github.com/DietrichGebert/ponytail/blob/main/scripts/check-rule-copies.js) validation script, which checks for the presence of `['.cursor/rules/ponytail.mdc', stripFrontmatter]` in your project structure. Alternatively, observe whether generated code follows Ponytail’s documented style conventions and safety guidelines.