# Pinning and Visible Context

## Pinning

Pressing `P` toggles the selected entity through
`Canvas_Scene_Toggle_Selected_Pin()`.

When pinning starts, `Canvas_Entity_Capture_Pin()` records:

- the entity's current screen-space origin;
- its current screen-space size.

After camera input, `Canvas_Scene_Sync_Pinned()` clamps that screen rectangle to
the viewport, converts its origin back into world coordinates, and divides its
screen size by the current zoom. The entity therefore still participates in the
world renderer and picking system, but appears fixed in the camera view while
the camera pans or zooms. Pinned entities are marked with the generated Lucide
`pin` vector, drawn through the same Raylib icon path as the gallery.

Dragging or activating a pinned entity recaptures its screen-space state.
Notifications are the exception: they use the dedicated animated stack in
`Canvas_Scene_Update_Notification_Stack()` and cannot be toggled with `P`.

## Visible context

`Canvas_Scene_Build_Visible_Context()` treats the camera viewport as the context
boundary:

1. Convert the screen viewport to world bounds.
2. Intersect each entity's semantic bounds with that viewport.
3. Skip dismissed notifications.
4. Append identity, type, position, size, pin state, and type-specific state.
5. Report visible count, bytes written, and truncation.

Zooming out expands the world-space viewport, so more entities become context.
Panning removes entities that no longer intersect it. The serializer preserves
scene order and concatenates all visible entries into one provisional text
snapshot.

Examples of semantic state include text-area content/editing, dropdown
selection/open state, switch value, selected calendar date or table row, scroll
offset, image source, browser URL, and Lucide gallery scroll/renderer metadata.

When adding an entity, never leave it on the generic `value=%d` fallback if an
agent would need richer meaning. Update the serializer and the viewport/context
tests together.