output-error-missing-schemas

Fix Missing Schema Definitions

Overview

This skill helps diagnose and fix issues caused by steps that lack explicit inputSchema or outputSchema definitions. Schemas are essential for type safety, validation, and proper data serialization between steps.

When to Use This Skill

You're seeing:

• Type errors at step boundaries
• Undefined properties in step inputs/outputs
• Validation failures when passing data between steps
• TypeScript errors about incompatible types
• Runtime errors about unexpected data shapes

Root Cause

Steps without explicit schemas:

• Don't validate input data at runtime
• Don't provide TypeScript type inference
• May serialize/deserialize data incorrectly
• Can pass undefined or malformed data silently

Symptoms

Missing Input Schema

// WRONG: No input validation
export const processData = step( {
  name: 'processData',
  // inputSchema: missing!
  outputSchema: z.object( { result: z.string() } ),
  fn: async input => {
    return { result: input.value };  // input.value might be undefined!
  }
} );

Missing Output Schema

// WRONG: No output validation
export const fetchData = step( {
  name: 'fetchData',
  inputSchema: z.object( { id: z.string() } ),
  // outputSchema: missing!
  fn: async input => {
    return { data: await getFromApi( input.id ) };  // Output shape not validated
  }
} );

Both Schemas Missing

// WRONG: No validation at all
export const transformData = step( {
  name: 'transformData',
  // No schemas!
  fn: async input => {
    return transform( input );
  }
} );

Solution

Always define both inputSchema and outputSchema for every step:

Complete Step Definition

import { z, step } from '@outputai/core';

export const processData = step( {
  name: 'processData',
  inputSchema: z.object( {
    id: z.string(),
    value: z.number(),
    optional: z.string().optional()
  } ),
  outputSchema: z.object( {
    result: z.string(),
    processedAt: z.number()
  } ),
  fn: async input => {
    // input is fully typed: { id: string, value: number, optional?: string }
    return {
      result: `Processed ${input.id}`,
      processedAt: Date.now()
    };
    // output is validated against outputSchema
  }
} );