/**
* Prompt Customizer Extension
*
* Demonstrates using systemPromptOptions to make informed, context-aware
* modifications to the system prompt without re-discovering resources.
*
* This extension adds tool-specific guidance based on what tools and skills
* are currently active, respecting whatever the user has configured.
*
* Usage:
* 1. Copy this file to ~/.pi/agent/extensions/ or your project's .pi/extensions/
* 2. Use the extension — it automatically adapts to your active tools and skills
*/
import type { BuildSystemPromptOptions, ExtensionAPI } from "@earendil-works/pi-coding-agent";
/**
* Adds tool-specific guidance that adapts to the active tool set.
* Instead of appending one-size-fits-all instructions, this reads what's
* actually loaded and tailors the guidance accordingly.
*/
function addToolGuidance(options: BuildSystemPromptOptions, basePrompt: string): string {
const hasTool = (name: string) => options.selectedTools?.includes(name) ?? false;
const parts: string[] = [];
if (hasTool("ipython")) {
parts.push(
"• Use the `ipython` tool for Python execution, file access, data inspection, and shell subprocesses.",
);
}
if (hasTool("bash")) {
parts.push("• Execute shell commands with the `bash` tool when it is explicitly enabled.");
}
if (hasTool("edit")) {
parts.push(
"• Use the `edit` tool for precise text replacements in files. Match exact content including whitespace.",
);
}
if (options.skills && options.skills.length > 0) {
const skillNames = options.skills.map((s) => s.name).join(", ");
parts.push(`\nAvailable skills: ${skillNames}`, "Use skill documentation for best practices on specific tools.");
}
if (parts.length === 0) {
return basePrompt;
}
return `${basePrompt}
## Tool Guidance
${parts.join("\n")}
`;
}
/**
* Merges extension instructions with user-provided append prompts.
* This respects whatever the user configured via --append-system-prompt
* flags or files, rather than duplicating that work.
*/
function mergeWithUserAppend(options: BuildSystemPromptOptions): string {
const userAppend = options.appendSystemPrompt;
const extensionSpecific = `
## Extension-Added Context
This prompt includes tool guidance and skill information loaded dynamically.
If you have additional requirements, configure them via --append-system-prompt or project context files.
`;
if (userAppend) {
return `${userAppend}\n\n${extensionSpecific}`;
}
return extensionSpecific;
}
export default function promptCustomizer(pi: ExtensionAPI) {
pi.on("before_agent_start", async (event) => {
const { systemPrompt, systemPromptOptions } = event;
const customPrompt = addToolGuidance(systemPromptOptions, systemPrompt);
const appendSection = mergeWithUserAppend(systemPromptOptions);
return {
systemPrompt: `${customPrompt}${appendSection}`,
};
});
}