Stack → Spatial

Purpose

Use when a familiar stack should open into an authored X/Y/Z arrangement without changing the collection identity.

Use when

• An album, project set or document group benefits from one reveal of relationships.
• The collapsed state is already useful on its own.

Avoid when

• The collection needs immediate comparison or contains many items.
• The expansion would explode into an uncontrolled decorative animation.

Interaction

Use one pressed toggle. The same keyed items remain present; focus and labels survive the transition. Spatial hover may lift one item, but never hides its neighbours.

Mobile and reduced motion

Flatten the expanded state into a responsive grid and switch immediately under reduced motion. CSS transforms are enough; do not add a canvas.