TypeScript satisfies

Goal

Validate that a value matches a type without replacing the value's inferred type.

Rules

• Use satisfies when value specificity should win.
• Use : Type when the variable should have the wider type.
• Use as const satisfies for readonly literal config.
• Avoid as Type unless it is a deliberate escape hatch.
• Use Record<Union, Value> with satisfies for exhaustive maps.

Mental Model