---
title: Prompts
description: Write prompts for Claude Code, Codex, and Pi, and know what they reference.
sidebar:
  label: Introduction
---

**`@foundry/prompts` reads a prompt the way a coding harness reads it.**

Each harness has its own notation. Claude Code invokes a skill as `/name`,
Codex mentions one as `$name`, and Pi loads one as `/skill:name`. All three
mention a file as `@path`; Claude Code mentions an agent as
`@"name (agent)"`. The package knows these notations. It lists what a prompt
references, checks each reference against the skills, agents, and files you
have, and writes a reference in the notation each harness expects.

```typescript
import { prompts, ref } from "@foundry/prompts";

const reviewer = ref.agent("reviewer");
const review = prompts.claude`/code-review @src/auth, then ask ${reviewer}.`;

review.text;
// '/code-review @src/auth, then ask @"reviewer (agent)".'
review.references;
// the skill, the file, and the agent, each with its position
review.diagnostics;
// empty, or findings such as 'Unknown agent "reviewer".'
```

`prompts.codex` and `prompts.pi` work the same way. A reference interpolated
with `ref` is written in the notation of the tag it lands in, so the same
skill reads as `/code-review`, `$code-review`, or `/skill:code-review`.

Diagnostics are read against what exists each time you ask, so a skill
defined after the prompt was written still resolves. With `strict` on, a tag
throws instead of returning a prompt with errors.

The package is internal to Foundry for now. Its README covers the full API:
sources, custom dialects, and the parser that editor tooling builds on.

## In the editor

[Editor support](/prompts/editor) covers a VS Code extension that highlights
these references as you write them, in TypeScript and in skill, agent, and
rule files. [Linting](/prompts/lint) covers the ESLint and Oxlint rules that
check them.

![One review written for Claude Code, Codex, and Pi, each reference highlighted in VS Code](/foundry/blume-assets/content/prompts/images/harnesses-dark.png)