Modals have clear states: closed, opening, open, closing. A state machine prevents double-opens, ensures proper cleanup on close, and coordinates nested dialogs.

• States: closed → opening → open → closing → closed

• Guard conditions for conditional closes (unsaved changes)

• Nested dialog stacks

• Esc key handling and backdrop clicks

• Modals → Forms — Modals containing forms

• Modals → Animations — Enter/exit transitions

• Case Study: Onboarding — Modal-based onboarding

• Add modal stack machine

• Add keyboard event handling

• Add accessibility state management