Compose Animation — M3 Expressive Motion System

M3 Expressive (2025) replaced fixed-duration easing with physics-based springs. These rules cover the complete animation toolkit — from micro-interactions to screen transitions.

The M3 Expressive motion philosophy

// M3 Expressive motion tokens — import from design-system skill's DesignTokens.kt

// Physics-based springs for SPATIAL motion (position, size, scale)
// → Never use tween() for elements that move — spring feels natural
val spatialEnter = spring<Float>(
    dampingRatio = Spring.DampingRatioLowBouncy,   // slight bounce
    stiffness    = Spring.StiffnessMediumLow        // smooth, not jerky
)