/**
* @file MCP Prompt request handlers
* @module handlers/prompt-handlers
*
* @remarks
* This module implements handlers for MCP prompt operations. Prompts are
* pre-defined templates that can be used with the sampling feature to
* generate Reddit content with AI assistance.
*
* @see {@link https://modelcontextprotocol.io/specification/2025-06-18/core/prompts | MCP Prompts}
* @see {@link https://modelcontextprotocol.io/specification/2025-06-18/client/sampling | MCP Sampling}
*/
import { logger } from '@/utils/logger';
import type { AuthInfo } from '@modelcontextprotocol/sdk/server/auth/types.js';
import type {
ListPromptsRequest,
ListPromptsResult,
GetPromptRequest,
GetPromptResult,
PromptMessage,
} from '@modelcontextprotocol/sdk/types.js';
import { PROMPTS } from '@reddit/constants/sampling/index';
/**
* Handles MCP prompt listing requests.
*
* @remarks
* Returns all available prompts that can be used for Reddit content generation.
* These prompts are templates for creating posts, comments, and messages with
* AI assistance through the sampling feature.
*
* @param request - The prompt listing request
* @param extra - Optional extra context (currently unused)
* @returns Promise resolving to the list of available prompts
*
* @see {@link https://modelcontextprotocol.io/specification/2025-06-18/core/prompts#listing-prompts | Listing Prompts}
*/
export async function handleListPrompts(
request: ListPromptsRequest,
extra?: { authInfo?: AuthInfo },
): Promise<ListPromptsResult> {
return { prompts: PROMPTS };
}
/**
* Handles MCP prompt retrieval requests.
*
* @remarks
* Retrieves a specific prompt by name and replaces template variables
* with provided arguments. Template variables use the {{variable}} syntax
* and are replaced with values from the request arguments.
*
* For example, if a prompt contains "{{subreddit}}" and the request
* includes {subreddit: "typescript"}, the text will be updated accordingly.
*
* @param request - The prompt retrieval request with name and arguments
* @param extra - Optional extra context (currently unused)
* @returns Promise resolving to the prompt with variables replaced
* @throws Error if the requested prompt is not found
*
* @see {@link https://modelcontextprotocol.io/specification/2025-06-18/core/prompts#getting-prompts | Getting Prompts}
*/
export async function handleGetPrompt(
request: GetPromptRequest,
extra?: { authInfo?: AuthInfo },
): Promise<GetPromptResult> {
const prompt = PROMPTS.find((p: any) => p.name === request.params.name);
if (!prompt) {
throw new Error(`Prompt not found: ${request.params.name}`);
}
// Replace variables in the prompt messages
const messages = prompt.messages.map((message: PromptMessage) => {
if (message.content.type !== 'text') {
return message; // Return non-text content as-is
}
let text = String(message.content.text);
// Replace variables with provided arguments
if (request.params.arguments) {
Object.entries(request.params.arguments).forEach(([key, value]) => {
const placeholder = `{{${key}}}`;
text = text.replace(new RegExp(placeholder, 'g'), String(value));
});
}
logger.info('Prompt messages sccuessfuly replaced');
return {
role: message.role,
content: {
type: 'text' as const,
text: text,
},
};
});
return {
description: prompt.description,
messages: messages,
_meta: prompt._meta,
};
}
