Explain Figma Smart Animate's core principle and layer matching requirements

WHAT THIS TESTS: Whether you understand the algorithm Figma uses to pair layers across prototype frames for interpolation. Interviewers want to see that you know it is a name-driven system, not a visual or pixel-based one, and that you can list the practical requirements for a successful morph.

A GOOD ANSWER COVERS: First, state the core principle: Smart Animate matches layers by their exact layer names across the source and destination frames. When Figma finds two layers with identical names, it treats them as the same object and interpolates animatable properties between the two states. Second, list the key requirements: the layers must share the exact same name, they must be compatible types (for example, a rectangle can morph into another rectangle, and text can morph into text, but mismatched types may fail), and the properties being changed must be interpolatable. Third, enumerate the properties Figma can tween: position, dimensions, rotation, opacity, corner radius, and fill colors. Fourth, explain the fallback behavior: layers that do not find a name match dissolve out in the source frame and dissolve in at the destination rather than morphing.

COMMON WRONG ANSWERS: Claiming that Figma compares pixels, bounding boxes, or visual appearance to decide what animates. Saying the layers must live in identical group hierarchies or have the same nesting path, which is stricter than reality; while matching hierarchy helps, Smart Animate primarily keys off the layer name. Asserting that auto layout is required, or that Smart Animate works between any two arbitrary layer types such as a boolean operation and a raster image.

LIKELY FOLLOW-UPS: How does Smart Animate behave with components and instances? What happens if duplicate layer names exist in the same frame? How do you troubleshoot a transition that dissolves when you expected a morph? Does Smart Animate support easing curves and spring animations? Can it animate layout changes inside auto layout frames?

ONE CONCRETE EXAMPLE: Imagine a source frame with a button layer named PrimaryButton at width 120, height 40, and corner radius 4. In the destination frame, the layer is also named PrimaryButton but has width 200, height 56, and corner radius 16. During the Smart Animate transition, Figma tweens all three properties over the chosen duration. If the destination frame renames that layer to PrimaryButtonLarge, Figma finds no match; the original button fades out and the new one fades in instead of smoothly expanding.