Docs: “no shared discriminator key → init error” statement is inaccurate in v4 beta

[bufferings]

Hi 👋

While trying the v4 beta I noticed that the docs for z.discriminatedUnion() don’t match the current behavior.

https://v4.zod.dev/v4#upgraded-zdiscriminatedunion

If no shared discriminator key is found, Zod will throw an error at schema initialization time.

What actually happens

• Each option only needs at least one discriminator field.
• The discriminator keys do not have to be shared across options.
• Zod throws at init time only when an option has zero discriminator fields, not when keys differ.

import { z } from 'zod';

// ✅ Works – different keys but each option has a literal
z.discriminatedUnion([
  z.object({ kind: z.literal('square'), size: z.number() }),
  z.object({ name: z.literal('rectangle'), width: z.number(), height: z.number() }),
]);

// ❌ Fails – second option lacks any literal / enum field
z.discriminatedUnion([
  z.object({ kind: z.literal('square'), size: z.number() }),
  z.object({ name: z.string(), width: z.number(), height: z.number() }), // ← error
]);
// Error: Invalid discriminated union option at index "1"

Checked with [email protected].

Suggested wording

If any option lacks a discriminator key, Zod will throw an error at schema initialization time.

Thanks,