m3e-animation-standards

name	m3e-animation-standards
description	Material 3 Expressive (M3E) animation, transition, and touch-physics standards for Hora-family Android apps — duration tokens, cascading list entrances, shared-axis transitions, scroll/FAB behaviour.

Material 3 Expressive (M3E) animation standards

M3E is more dramatic than baseline M3: pronounced scale depth, fast entrances with long "emphasized" easing tails, heavy touch physics. These are the family-wide rules; each app implements them with its own helper/constants (don't hardcode the numbers inline).

Duration tokens

Define three named duration constants app-wide and reference them everywhere — never hardcode milliseconds in views or XML:

• short ~100–200ms — rapid snaps, interactive-press recovery bounce.
• medium ~300–400ms — standard layout/state changes.
• long ~500ms — activity/fragment shared-axis transitions and large list entrances (the signature "fast entrance, long emphasized tail").

Cascading list entrances

List items must not merely slide up — they cascade from a deeper Z scale:

• Start at scaleX/scaleY ≈ 0.85, animate to 1.0 while translating up ~50px.
• Run over the long (~500ms) emphasized curve, staggered by item position.

Cinematic screen transitions

Use MaterialSharedAxis(MaterialSharedAxis.Z) for primary activity-to-activity navigation. The default window-animation duration is too short for M3E — override .duration to the long token (~500ms) on both the enter/return and exit/reenter definitions.

Scroll harmony, FAB, insets

• Attach scroll haptics to lists carrying core data (a mechanical tick on scroll milestones); always gate them behind the user's haptics preference (see m3e-haptic-standards).
• FAB rule: a FloatingActionButton over a scrollable list must fully hide() on scroll-down and show() on scroll-up. Don't use an Extended FAB for the main feed — it permanently obstructs too much vertical space.
• Edge-to-edge padding: give lists bottom padding ≈ inset.bottom + FAB height + margin (~88dp) so the last item can scroll above the resting FAB.

Checklist

• No hardcoded animation durations — only the three named tokens.
• List entrances scale 0.85→1.0 + translate, on the long curve.
• Shared-axis Z transitions with .duration overridden to the long token.
• FAB hides on scroll-down; lists padded for the resting FAB.