Angular Child-to-Parent Error Propagation via Output

Each child component exposes form errors via an @Output() EventEmitter. The parent binds a handler per child in the template and aggregates the results to control UI state (e.g. disabling a save button).

Limitation — N handlers: the parent must declare a distinct handler for every child that can emit errors. As the number of children grows, the parent accumulates unrelated error-handling logic.

Limitation — stepper cost: in a stepper layout, the parent must additionally track the active step to know which child's errors are currently relevant. This means the parent holds both per-child handlers and step-awareness logic, coupling it tightly to the structure of its children.

Use when: there are 1–2 child components with simple, independent error surfaces and no step context.