fusengine/design-android

Design Android — Mockup and Handoff, Not Code

When

After design-system tokens exist. This skill never writes Jetpack Compose — it produces a static HTML mockup at exact device dimensions plus a spec an Android developer implements.

Input

• design-system.md — OKLCH palette, typography direction, motion personality.
• The screen/flow to mock up and the target window size class.

Steps

1. Map tokens to Material 3 type roles. references/type-scale.md gives the 15-role baseline scale (displayLarge 57/64sp … labelSmall 11/16sp, Roboto). Material 3 Expressive adds a parallel 15-role Emphasized set on top (30 roles total) for stronger visual rhythm — use baseline by default, reach for Emphasized when the tone from design-method calls for it. Source: m3.material.io/styles/typography/type-scale-tokens.
2. Map tokens to Material 3 color roles. references/color-roles.md documents the core role families (primary/secondary/tertiary + surface/onSurface) derived from a seed color. Material 3's full role system is larger — 45 color roles, including a surface-container ramp (lowest → highest: surfaceContainerLowest, surfaceContainerLow, surfaceContainer, surfaceContainerHigh, surfaceContainerHighest — 5 levels for layering surfaces without shadow), error/ onError/errorContainer (kept static, never derived from the dynamic seed, so error states stay legible regardless of theme), and dynamic color: on Android 12+ all roles can be generated tonally from a user's wallpaper/seed, not just the design seed. Source: m3.material.io/styles/color/roles, m3.material.io/styles/color/system/how-the-system-works. Gap: color-roles.md documents the core families, not the full 45-role/surface-container enumeration — use the fact above until that reference is expanded (out of this pass's exclusive scope).
3. Map tokens to shapes. references/shape-scale.md (never an arbitrary border-radius). Material 3's full shape scale extends to 32dp, 48dp, and Full (pill) beyond what's currently listed — Expressive defaults buttons to pill (Full) shape unless a product reason calls for a smaller radius. Source: m3.material.io/styles/shape/shape-scale-tokens. Gap: shape-scale.md stops at 28dp (Extra Large); reconfirm 32/48/Full on the m3.material.io page above until expanded.
4. Apply elevation as tokens, not ad-hoc shadow. 6 levels, 0 → 5, mapping to 0 / 1 / 3 / 6 / 8 / 12dp. Elevation is expressed via shadow at each level — the older surfaceTint-only approach is deprecated; don't rely on tint alone to convey elevation. Source: m3.material.io/styles/elevation/overview. Gap: no references/elevation.md exists yet — these token values are grounded but inlined here pending a dedicated reference file (out of this pass's exclusive scope).
5. Pick the window size class from references/window-size-classes.md — mock up at the dp width that matches the target device class (phone/foldable/tablet/desktop).
6. Build the HTML mockup: a device-frame <div> sized in dp-equivalent px, following the 4dp base / 8dp grid throughout.
7. Verify touch targets and spacing: 48×48dp minimum touch target, ≥ 8dp spacing between adjacent targets — see references/touch-targets.md.
8. FAB: pick one of 3 tiers, sized to the screen's primary-action weight — small FAB is deprecated in Material 3 Expressive, don't use it. Source: m3.material.io/components/floating-action-button/overview. Gap: no dedicated FAB reference file yet; the 3 surviving tiers and their exact dp sizes should be reconfirmed on the page above before finalizing a mockup.
9. Motion: Material 3 Expressive uses spring-physics-based motion (not fixed duration/easing curves) for its signature feel; the legacy duration/easing-curve tokens still apply where spring motion isn't specified. Source: m3.material.io/styles/motion/overview. Gap: no references/motion.md exists yet — note spring vs legacy-easing choice explicitly in the handoff spec until one exists.
10. Write the handoff spec per references/handoff-compose.md: colors → MaterialTheme.colorScheme.*, typography → MaterialTheme.typography.*, shapes → MaterialTheme.shapes.*, custom spacing scale in dp, explicit sizing, states + tonal elevation (name the elevation level, 0–5, not just "raised"/"flat"), and start/end (never left/right) for RTL correctness.

Failure Handling

• Screenshot/preview tooling unavailable → describe the mockup in the handoff spec with exact dp values instead of blocking on a visual.
• A fact needed isn't in the references below → mark it "to reconfirm on developer.android.com / m3.material.io" in the output; never invent a number. This applies especially to the gaps flagged in Steps 2–4, 8, 9 above (full 45-role color system, 32/48dp/Full shapes, FAB tier dp sizes, motion spring parameters) — the reference files for these are not yet expanded/created; do not backfill invented numbers to close that gap silently.

Output

• Device-framed HTML mockup at the target window size class.
• handoff.md (or equivalent) with Compose theme mappings, spacing, sizing, states, tonal elevation (level 0–5) — ready for an Android developer.

Next → design-review (mockup-scoped: screenshot the mockup, verify contrast, no

full site audit loop).

References

| File | Purpose | |------|---------| | references/type-scale.md | Canonical Material 3 baseline type scale — verified material-components-android (Expressive Emphasized set: see Step 1 above, not yet a separate file) | | references/shape-scale.md | Canonical shape/corner-radius scale — verified m3.material.io (stops at 28dp — 32/48/Full gap, see Step 3) | | references/color-roles.md | Canonical Material 3 core color-role families — verified m3.material.io (45-role/surface-container/dynamic-color gap, see Step 2) | | references/window-size-classes.md | Canonical window size classes — verified developer.android.com | | references/touch-targets.md | 48×48dp target + 8dp spacing — verified | | references/handoff-compose.md | Compose-ready handoff spec format |

Gaps (grounded facts, no reference file yet — inlined in Steps above, flagged for future references/elevation.md, references/motion.md, FAB-tier detail; out of this pass's exclusive scope to create): elevation tokens 0–5, FAB tiers, spring motion.