fix(layout): reserve action-bar height so tableau never hides behind buttons

compute_layout only subtracted safe_area_bottom (OS gesture/nav bar) from
the vertical budget, but the app's own action bar (≡ ← || ? ! M +) sits
*above* that zone — invisible to safe_area_bottom. On Android the bar is
60 px tall (44 px min-height buttons + 8 px top + 8 px bottom bar padding),
so deep tableau columns scrolled 60 px behind the button row.

Fix: add BOTTOM_BAR_HEIGHT (60 px Android, 0 desktop) to safe_area_bottom
before both affected calculations:
  • card_width_height_based — height-based card sizing
  • avail — budget fed to update_tableau_fan_frac for adaptive fan spacing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/hud_plugin.rs

@@ -140,6 +140,12 @@ pub struct HudColumn;
 #[derive(Component, Debug)]
 pub struct HudActionBar;
 
+/// Marker on the text node inside each action-bar button (Android only).
+/// Used by `resize_action_bar_labels` to update font size on window resize.
+#[cfg(target_os = "android")]
+#[derive(Component, Debug)]
+struct ActionButtonLabel;
+
 /// Marker on the circular profile-picture button anchored to the
 /// top-right of the HUD band. Pressing it opens the Profile overlay.
 /// Shows the server avatar image when loaded; falls back to the player's
@@ -489,6 +495,11 @@ impl Plugin for HudPlugin {
                         .after(TouchDragSet::AfterStartDrag)
                         .in_set(TouchDragSet::BeforeEndDrag),
                 );
+            app.add_systems(
+                Update,
+                resize_action_bar_labels
+                    .run_if(resource_exists_and_changed::<crate::layout::LayoutResource>),
+            );
         }
     }
 }
@@ -843,11 +854,25 @@ fn handle_avatar_button(
 /// on its own visual edge.
 fn spawn_action_buttons(
     font_res: Option<Res<FontResource>>,
+    windows: Query<&Window>,
     mut commands: Commands,
 ) {
+    // On Android the glyph labels must scale with the viewport so they remain
+    // legible on any screen density. Use the window width at startup; the
+    // resize_action_bar_labels system keeps this current on window changes.
+    #[cfg(target_os = "android")]
+    let action_font_size = {
+        let w = windows.iter().next().map_or(900.0, |win| win.width());
+        action_bar_font_size(w)
+    };
+    #[cfg(not(target_os = "android"))]
+    let action_font_size = TYPE_BODY;
+    #[cfg(not(target_os = "android"))]
+    let _windows = windows;
+
     let font = TextFont {
         font: font_res.as_ref().map(|f| f.0.clone()).unwrap_or_default(),
-        font_size: TYPE_BODY,
+        font_size: action_font_size,
         ..default()
     };
 
@@ -992,6 +1017,9 @@ fn spawn_action_button<M: Component>(
         HighContrastBorder::with_default(BORDER_SUBTLE),
     ))
     .with_children(|b| {
+        #[cfg(target_os = "android")]
+        b.spawn((ActionButtonLabel, Text::new(label), font.clone(), TextColor(text_color)));
+        #[cfg(not(target_os = "android"))]
         b.spawn((Text::new(label), font.clone(), TextColor(text_color)));
         if let Some(key) = hotkey {
             // Hotkey hint rendered as a dim caption next to the label —
@@ -2483,6 +2511,32 @@ fn restore_hud_on_modal(
     }
 }
 
+/// Returns the action-bar glyph font size for a given logical window width.
+/// Scales linearly so glyphs remain legible at any phone density.
+#[cfg(target_os = "android")]
+fn action_bar_font_size(window_width: f32) -> f32 {
+    // ~1/40 of the window width gives ~22 px on a 900 logical-px phone.
+    // Clamped so it never goes too tiny on narrow viewports or too large
+    // on landscape tablets.
+    (window_width / 40.0).clamp(16.0, 30.0)
+}
+
+/// Resizes the glyph text inside every [`ActionButtonLabel`] to match the
+/// current viewport width whenever [`LayoutResource`] changes (orientation
+/// change or window resize).
+#[cfg(target_os = "android")]
+fn resize_action_bar_labels(
+    layout: Res<crate::layout::LayoutResource>,
+    windows: Query<&Window>,
+    mut labels: Query<&mut TextFont, With<ActionButtonLabel>>,
+) {
+    let w = windows.iter().next().map_or(layout.0.card_size.x * 7.25, |win| win.width());
+    let new_size = action_bar_font_size(w);
+    for mut font in &mut labels {
+        font.font_size = new_size;
+    }
+}
+
 #[cfg(target_os = "android")]
 fn toggle_hud_on_tap(
     mut touch_events: MessageReader<bevy::input::touch::TouchInput>,

solitaire_engine/src/layout.rs

@@ -107,6 +107,22 @@ pub const HUD_BAND_HEIGHT: f32 = 64.0;
 #[cfg(target_os = "android")]
 pub const HUD_BAND_HEIGHT: f32 = 112.0;
 
+/// Height of the bottom action-bar (the row of ≡ ← || ? ! M + buttons).
+///
+/// The action bar sits *above* the OS gesture/navigation zone, so it is NOT
+/// covered by `safe_area_bottom`. `compute_layout` adds this constant to
+/// `safe_area_bottom` before computing the height-based card-size candidate
+/// and the available tableau height, ensuring the deepest fanned column
+/// never scrolls behind the button row.
+///
+/// Derivation (Android): `min_height 44 px` buttons
+///   + `padding.top 8 px` + `padding.bottom 8 px` outer bar padding = **60 px**.
+/// Desktop: no persistent bottom bar, so 0.
+#[cfg(not(target_os = "android"))]
+const BOTTOM_BAR_HEIGHT: f32 = 0.0;
+#[cfg(target_os = "android")]
+const BOTTOM_BAR_HEIGHT: f32 = 60.0;
+
 /// Table background colour (dark green felt).
 pub const TABLE_COLOUR: [f32; 3] = [0.059, 0.322, 0.196];
 
@@ -190,9 +206,13 @@ pub fn compute_layout(window: Vec2, safe_area_top: f32, safe_area_bottom: f32, h
     // Substituting h_gap = w/4 and h = CARD_ASPECT * w and solving for the
     // largest w that fits gives:
     //   (window.y - HUD_BAND_HEIGHT) = w * (0.5 + (1 + fan_factor + VERTICAL_GAP_FRAC) * CARD_ASPECT)
+    // Reserve space for both the OS gesture/nav bar and the app's own action
+    // bar, which sits above it and is invisible to safe_area_bottom.
+    let effective_safe_bottom = safe_area_bottom + BOTTOM_BAR_HEIGHT;
+
     let fan_factor = 1.0 + (MAX_TABLEAU_CARDS - 1.0) * TABLEAU_FAN_FRAC;
     let height_denom = 0.5 + (1.0 + fan_factor + VERTICAL_GAP_FRAC) * CARD_ASPECT;
-    let card_width_height_based = (window.y - safe_area_top - safe_area_bottom - band_h).max(0.0) / height_denom;
+    let card_width_height_based = (window.y - safe_area_top - effective_safe_bottom - band_h).max(0.0) / height_denom;
 
     let card_width = card_width_width_based.min(card_width_height_based);
     let card_height = card_width * CARD_ASPECT;
@@ -241,7 +261,7 @@ pub fn compute_layout(window: Vec2, safe_area_top: f32, safe_area_bottom: f32, h
     //
     // avail = distance from the top of the first tableau card to the bottom
     //         margin — i.e. the space available for 12 fan steps.
-    let avail = (tableau_y - (-window.y / 2.0 + safe_area_bottom + h_gap) - card_height / 2.0).max(0.0);
+    let avail = (tableau_y - (-window.y / 2.0 + effective_safe_bottom + h_gap) - card_height / 2.0).max(0.0);
     let ideal_fan_frac = if card_height > 0.0 {
         avail / ((MAX_TABLEAU_CARDS - 1.0) * card_height)
     } else {