import {
completable,
ProtocolError,
ProtocolErrorCode,
type McpServer,
} from '@modelcontextprotocol/server';
import * as z from 'zod/v4';
const implementationStyles = ['minimal', 'production', 'experimental'] as const;
const implementationStyleSet = new Set(implementationStyles);
export function register(server: McpServer): void {
server.registerPrompt(
'scaffold-plan',
{
title: 'Scaffold Plan',
description: 'Generate a practical implementation plan for a new MCP capability.',
argsSchema: z.object({
feature: z.string().describe('Capability you want to add.'),
style: completable(z.string().describe('Implementation style').optional(), async (value) =>
implementationStyles.filter((item) => item.startsWith((value ?? '').toLowerCase())),
),
}),
},
({ feature, style }) => {
if (style && !implementationStyleSet.has(style as (typeof implementationStyles)[number])) {
throw new ProtocolError(
ProtocolErrorCode.InvalidParams,
`Invalid style '${style}'. Expected one of: ${implementationStyles.join(', ')}`,
);
}
const selectedStyle = style ?? 'production';
return {
messages: [
{
role: 'user',
content: {
type: 'text',
text: [
`Create a ${selectedStyle} implementation plan for: ${feature}.`,
'Return: goal, schema design, error handling, and rollout checklist.',
'Keep the plan specific to MCP v2 stdio server constraints.',
].join('\n'),
},
},
],
};
},
);
}
