Nextjs Forms And Mutations

Make mutations resilient, typed, and user-readable.

Preferred Mutation Surface

• Default to server actions for same-app mutations.
• Use route handlers when the mutation must be called over HTTP by non-UI clients or third parties.
• Keep mutation transport separate from domain logic; both may call the same use-case.

Validation Layers

• Validate raw form input at the boundary.
• Validate business invariants in the use-case.
• Return field-level errors in a typed action/result shape.
• Keep client-side validation additive, not authoritative.

UX Rules

• Always show pending, success, and failure states.
• Disable duplicate submits or make commands idempotent.
• Preserve user input on recoverable failures.
• Use optimistic updates only when rollback is clear and low-risk.
• Revalidate or refresh the smallest affected surface after success.