06 — Motion System
Duration Scale
IDL defines five named duration steps that govern all animation timing in an IDL-governed system. All animation durations MUST reference one of these named steps. Absolute numeric durations in motion declarations are Transform-phase errors. Custom durations outside the five named steps require a formal RFC and governance approval before they may be used in IDL source.
Duration Scale Reference
| Step | Value | Purpose |
|---|---|---|
| motion.duration.instant | 0ms | State changes that require no perceptible transition — toggling visibility, swapping icons. |
| motion.duration.fast | 100ms | Micro-interactions: hover states, focus rings, toggle switches. |
| motion.duration.base | 200ms | Standard transitions: opening dropdowns, expanding accordions. |
| motion.duration.slow | 300ms | Larger layout changes: sidebar expansion, modal entry. |
| motion.duration.deliberate | 500ms | Complex orchestrated sequences: page transitions, multi-step onboarding. |
Duration Selection Guidelines
Duration selection is informed by the perceptual scale of the motion and its relationship to user expectation. Micro-interactions that provide immediate feedback use fast or instant. Transitions that move content between spatial contexts use base or slow. Deliberate is reserved for intentional, orchestrated sequences where the animation itself communicates importance or completion. Using deliberate for routine interactions is an antipattern.