Fix Direct I/O in Workflow Functions

Fix Direct I/O in Workflow Functions

Overview

This skill helps diagnose and fix a critical error pattern where I/O operations (HTTP calls, database queries, file operations) are performed directly in workflow functions instead of in steps. This violates Temporal's determinism requirements.

When to Use This Skill

You're seeing:

• Workflow hangs indefinitely
• Undefined or empty responses
• "workflow must be deterministic" errors
• Network operations failing silently
• Timeouts without clear cause

Root Cause

Workflow functions must be deterministic - they should only orchestrate steps, not perform I/O directly. When you make HTTP calls, database queries, or any external operations directly in a workflow function:

1. Hangs: The workflow may hang because I/O isn't properly handled
2. Determinism violations: Temporal replays workflows, and I/O results differ
3. No retry logic: Direct calls bypass Output SDK's retry mechanisms
4. No tracing: Operations aren't recorded in the workflow trace

Symptoms

Direct fetch/axios in Workflow

// WRONG: I/O directly in workflow
export default workflow( {
  fn: async input => {
    const response = await fetch( 'https://api.example.com/data' );  // BAD!
    const data = await response.json();
    return { data };
  }
} );

Direct Database Calls