AI

TypeScript performance issues with Zod and AI SDK 5

Issue

When using the AI SDK 5 with Zod, you may experience:

  • TypeScript server crashes or hangs
  • Extremely slow type checking in files that import AI SDK functions
  • Error messages like "Type instantiation is excessively deep and possibly infinite"
  • IDE becoming unresponsive when working with AI SDK code

Background

The AI SDK 5 has specific compatibility requirements with Zod versions. When importing Zod using the standard import path (import { z } from 'zod'), TypeScript's type inference can become excessively complex, leading to performance degradation or crashes.

Solution

Use the Zod Version-Specific Import Path

The recommended solution is to import Zod using a version-specific import path:

// ❌ Avoid: Standard import causes TypeScript issues
import { z } from 'zod';


// ✅ Use: version-specific import for AI SDK 5 compatibility
import { z } from 'zod/v3';
// or
import { z } from 'zod/v4';

After making this change, restart your TypeScript server (in VS Code: Cmd/Ctrl + Shift + P → "TypeScript: Restart TS Server").