# modules/vista/ — Deck horizontal swipe (PageView)

**Propósito.** Carousel/PageView estilo Flutter: gesto horizontal con
snap a página, distinción horizontal vs vertical, soporte mouse +
touch + pointer events. Lógica separada del binding DOM.

## Crates

| crate         | tipo | rol                                                       |
| ------------- | ---- | --------------------------------------------------------- |
| `vista-core`  | lib  | `DeckState` agnóstico: pointer_down/move/end → outcomes   |
| `vista-web`   | lib  | Binding DOM sobre `<strip>`: traduce eventos + aplica CSS |

## Dependencias

- `vista-core`: sin deps externas. Pura state machine.
- `vista-web` ← `vista-core`, `wasm-bindgen`, `web-sys` (PointerEvent).

## API agnóstica (vista-core)

```rust
let mut deck = DeckState::new();
deck.pointer_down(x, y, pointer_id, viewport_width);
match deck.pointer_move(x, y) {
    DragOutcome::StartHorizontal { pointer_id } => capture_pointer(),
    DragOutcome::DragOffset(px) => apply_translate(px),
    DragOutcome::CancelVertical => yield_to_scroll(),
    DragOutcome::Idle => {}
}
if let Some(r) = deck.pointer_end(offset, width, n_pages) {
    apply_translate(r.offset_px);
    if r.changed { notify(r.target_index); }
}
```

## Estado

vista-core: 5 tests verdes (drag decision + snap + clamp + goto).
vista-web: binding DOM intacto, ahora delega toda la lógica a core.
LOC core 177 + web ~355. Reutilizable en backends no-web.