# Objective
- Improve robustness of state transitions. Currently events that should
be scoped to a specific state can leak between state scopes since events
live for two ticks.
- See https://github.com/bevyengine/bevy/issues/15072
## Solution
- Allow registering state scoped events that will be automatically
cleared when exiting a state. This is *most of the time* not obviously
useful, but enables users to write correct code that will avoid/reduce
edge conditions (such as systems that aren't state scoped polling for a
state scoped event and having unintended side effects outside a specific
state instance).
## Testing
Did not test.
---
## Showcase
Added state scoped events that will be automatically cleared when
exiting a state. Useful when you want to guarantee clean state
transitions.
Normal way to add an event:
```rust
fn setup(app: &mut App) {
app.add_event::<MyGameEvent>();
}
```
Add a state-scoped event (**NEW**):
```rust
fn setup(app: &mut App) {
app.add_state_scoped_event::<MyGameEvent>(GameState::Play);
}
```
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