System Prompt

edge-pi includes a system prompt builder that generates instructions tailored to the enabled tools. You can use it as-is, extend it, or replace it entirely.

Default Behavior

When you create a CodingAgent without specifying a system prompt, it automatically builds one based on the selected tool set. The prompt includes:

A description of each enabled tool
Guidelines for tool usage (e.g., prefer grep over bash for search)
Instructions to read files before editing
Working directory context

buildSystemPrompt()

Use buildSystemPrompt() directly to generate or inspect the prompt.

import { buildSystemPrompt } from "edge-pi";

const prompt = buildSystemPrompt({
}, {
  selectedTools: ["read", "bash", "edit", "write"],
  cwd: process.cwd(),
});

console.log(prompt);

Options

Option	Type	Description
`customPrompt`	`string`	Replace the entire generated prompt with a custom one.
`appendSystemPrompt`	`string`	Text to append to the end of the generated prompt.
`contextFiles`	`Array<{ path: string; content: string }>`	Pre-loaded file contents to include in the prompt context.
`skills`	`Record<string, Skill>`	Pre-loaded skills to include in the model-visible skills section. The map key is the skill name shown to the model.

Call options

Pass runtime values like selected tools and cwd in the second argument of buildSystemPrompt().

Option	Type	Description
`selectedTools`	`string[]`	Which tools to include descriptions for. Defaults to read, bash, edit, write.
`cwd`	`string`	Working directory to include in the prompt footer.

Tool Descriptions

The prompt builder includes short descriptions for each tool that guide the model on when and how to use them:

Tool	Description
`read`	Read file contents
`bash`	Execute bash commands
`edit`	Make surgical edits
`write`	Create or overwrite files
`grep`	Search file contents
`find`	Find files by glob
`ls`	List directory contents

Customization Examples

Append instructions

const agent = new CodingAgent({
  model,
  systemPromptOptions: {
    appendSystemPrompt: `
Always write tests for new code.
Follow the project's existing code style.
Use TypeScript strict mode.
`,
  },
});

Include context files

import fs from "fs";

const agent = new CodingAgent({
  model,
  systemPromptOptions: {
    contextFiles: [
      {
        path: "CONVENTIONS.md",
        content: fs.readFileSync("CONVENTIONS.md", "utf-8"),
      },
    ],
  },
});

Include skills

import type { Skill } from "edge-pi";

const skills = {
  codeReview: {
    description: "Perform detailed code reviews",
    filePath: "/tmp/skills/code-review/SKILL.md",
  },
};

const agent = new CodingAgent({
  model,
  systemPromptOptions: {
    skills,
  },
});

Replace the prompt entirely

const agent = new CodingAgent({
  model,
  systemPromptOptions: {
    customPrompt: `You are a code review assistant.
Only analyze code - never modify files.
Focus on security issues and performance.`,
  },
});