Hevy MCP

/** * Type-safe utilities for MCP tool handlers */ import { z } from "zod"; import type { McpToolResponse } from "./response-formatter.js"; /** * Infer TypeScript types from Zod schema objects * * @example * ```typescript * const schema = { * page: z.number(), * pageSize: z.number(), * } as const; * * type Params = InferToolParams<typeof schema>; // { page: number; pageSize: number } * ``` */ export type InferToolParams<T extends Record<string, z.ZodTypeAny>> = z.infer< z.ZodObject<T> >; /** * Create a type-safe tool handler that validates and narrows args to inferred types * * This function wraps a handler with automatic Zod validation, ensuring runtime * type safety while maintaining compile-time type inference. * * @param schema - Zod schema object (e.g., { page: z.number(), ... }) * @param handler - Handler function that receives validated, typed parameters * @returns A handler function that accepts Record<string, unknown> and validates it * * @example * ```typescript * const schema = { * page: z.coerce.number().int().gte(1).default(1), * pageSize: z.coerce.number().int().gte(1).lte(10).default(5), * } as const; * * const handler = createTypedToolHandler(schema, async (args) => { * // args is fully typed as { page: number; pageSize: number } * const { page, pageSize } = args; * // ... * }); * ``` */ export function createTypedToolHandler<T extends Record<string, z.ZodTypeAny>>( schema: T, handler: (args: InferToolParams<T>) => Promise<McpToolResponse>, ): (args: Record<string, unknown>) => Promise<McpToolResponse> { const zodSchema = z.object(schema); return async (args: Record<string, unknown>) => { const validated = zodSchema.parse(args); return handler(validated); }; }