Ferrous-Solitaire/docs/android/PLAYABILITY_TODO.md

Android Playability TODO

Started: 2026-05-10 — first hardware screenshot of v0.22.3 APK running on a real device showed the desktop HUD projected onto a 360 dp portrait viewport with no mobile adaptation. This list tracks the work needed to make the APK genuinely playable, not just "boots without crashing."

Context: v0.22.3 (signed release APK) builds and launches. JNI bridges (clipboard, keystore) compile but are untested on hardware. The work below is UI/UX port work — no architectural rewrites required.

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Reading from the v0.22.3 screenshot

Region	Observation
Top ~5 %	System bar (clock, signal, battery) overlapped by game HUD — no safe-area inset
HUD text row	Score:0 Pause Esc Help A Modes [] New_Game N Moves:0 0:08 all overlapping — desktop layout crammed into 360 dp
Keyboard hints	Esc, A, [], N shown next to buttons — meaningless on touch
Foundations row	Leftmost foundation (♥) clipped left; rightmost tableau column (♠ 4) clipped right
Card backs	Face-down cards render as solid red squares, not back-art texture
Vertical use	Cards occupy top ~30 % only; bottom 70 % empty black — no portrait-aware layout
Bottom edge	No accommodation for Android gesture / home-indicator area

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P0 — Blocking playability

• Safe-area insets (top + bottom). Closed 2026-05-10 by b9aa262. SafeAreaInsets resource + SafeAreaInsetsPlugin query WindowInsets.getInsets(systemBars()) via JNI on Android; HUD anchors carry SafeAreaAnchoredTop { base_top } and the change-detection fix-up system re-applies base_top + insets.top whenever the resource updates. Bottom inset is captured but not yet consumed (waits for bottom-anchored UI).
• Mobile HUD layout. Closed 2026-05-10. Both the left HUD column and the right action button row are now capped at max_width: 50 % and the button row + tier-row child Nodes carry flex_wrap: Wrap. On a 360 dp viewport the 6-button row breaks to multiple lines (right-justified) and the tier rows wrap individually instead of overflowing into the action column. On desktop (≥ 1280 px) the 50 % cap is wider than any natural row width so the existing single-line layout is unchanged.
• Card-back asset not rendering. Closed 2026-05-10 by fcc7337. AssetPlugin::file_path = "../assets" was set unconditionally to fix the desktop cargo run -p solitaire_app CWD relativity, but on Android cargo-apk packages the same directory into the APK at assets/ and Bevy's AndroidAssetReader is already rooted there — prepending ../ walked the reader out of the APK assets root and every load failed silently. The face-down branch then fell through to the card_back_colour(0) solid-red brick fallback. Gated the override behind #[cfg(not(target_os = "android"))].
• Viewport overflow. Closed 2026-05-10. compute_layout was clamping the input window up to MIN_WINDOW = 800 × 600, so a 360 dp phone got laid out as if it were 800-wide and the outer piles fell outside the actual viewport. Lowered the floor to 320 × 400 (below the smallest reasonable phone) so real Android resolutions flow through without clamping, while keeping a sentinel to guard against degenerate / startup-zero windows. New regression test phone_portrait_layout_fits_horizontally asserts all 13 piles fit a 360 × 800 viewport.

P1 — Touch UX

• Suppress keyboard-hint labels on Android. Closed 2026-05-10. spawn_action_button now nulls the hotkey argument on Android via a #[cfg(target_os = "android")] rebind, so the U / Esc / F1 / N chips next to the action row labels disappear on touch builds. Other hint sites (onboarding panel, pause-modal Esc hint, mode-card hotkey chips on the home screen, replay overlay footer, modal toggle hints in profile/stats/leaderboard/settings, help screen) survive — they live behind navigation and a touch user reaches them less often. Track as a P3 sweep when more screens are audited on hardware.
• Thumb-sized hit targets. Closed 2026-05-10. Action button Node carries min_width: Val::Px(48.0), min_height: Val::Px(48.0) — meets Material's 48 dp baseline on touch and is a no-op for buttons whose content already exceeds 48 px in either axis. Applied universally rather than cfg-gated since Material's guideline applies to all input modes. Cards, pile markers, modal close buttons not yet audited — track as P3 if they fall below threshold on hardware.
• Portrait-first card spacing. Closed 2026-05-11. compute_layout now derives an adaptive tableau_fan_frac from the available vertical space below the tableau row. On height-limited (desktop) windows the formula returns ≈ 0.25 and the clamp keeps the existing behaviour. On width-limited (portrait phone) windows — where card size is constrained by the 9-column horizontal packing — the fan fraction expands to fill the viewport (≈ 0.84 at 360 × 800 dp). tableau_facedown_fan_frac scales proportionally. Both values live in the Layout struct; card_plugin::card_positions and input_plugin::card_position / pile_drop_rect read from the struct so rendering and hit-testing stay in sync across viewport sizes.
• Double-tap auto-move visible feedback. Closed 2026-05-11. On a recognised double-tap (priority 1 single-card or priority 2 stack move), the moved card(s) receive a 0.35 s lime flash (STATE_SUCCESS tint + HintHighlight { remaining: 0.35 }) before the move request is written. The flash persists through the card animation and is cleaned up by the existing tick_hint_highlight system. Hardware trigger-verification remains a manual step — connect AVD or device and confirm two rapid TouchPhase::Ended events within 0.5 s produce the lime flash.

P2 — Polish

• Drag responsiveness on touch. Bevy default touch-to-mouse mapping can lag; confirm drag start threshold isn't too high for a finger.
• Long-press menu. Alternative to right-click (which doesn't exist on touch). Wire to the existing right-click-highlight system.
• HUD typography. Reduce text sizes for Score:, Moves:, timer so they fit cleanly in one row.
• Orientation lock. Set android:screenOrientation="portrait" in cargo-apk manifest (or design a landscape layout).

P3 — Asset density

• Density-aware card scaling. Currently single texture size; on a high-DPI phone the cards look small. Scale by Window::scale_factor() or ship multiple PNG sizes.
• App-icon density buckets. Nine sizes already exist in assets/icon/; verify the manifest references them so Android's launcher picks the right one.

P4 — Stability / runtime

• B0004 ECS hierarchy warnings. Flagged in SESSION_HANDOFF.md after APK launch verification — investigate whether they cause gameplay bugs on hardware vs. AVD.
• AVD functional tests for JNI bridges. Clipboard (2c822ba) and Keystore (f281425) shipped but never tested on real device or AVD.

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Notes / decisions

• This list is screenshot-driven; expect more items to surface once P0 unblocks actually moving cards on hardware.
• The pattern across all the bugs is "no one ran the relevant code path on Android yet." The hard work — Bevy 0.18 on Android, JNI bridges, signed CI builds — is done. What's left is a coordinated pass of #[cfg(target_os = "android")] gates plus making LayoutResource query the real surface size.
• Where possible, prefer responsive layout (query window size) over branching #[cfg] blocks. Branches are fine for input methods (touch vs. mouse) but not for screen geometry — a foldable or desktop window of equivalent size should look the same.