feat(engine): Phase F touch action bar — thumb-reach Undo/Draw/Hint + hold-to-repeat undo

Touch layout (USE_TOUCH_UI_LAYOUT) restructures the bottom action bar
to five buttons: an enlarged Undo / Draw / Hint trio (96x64px targets,
1.35x labels) between compact Menu and Pause. Draw is new — it fires
the same DrawRequestEvent as tapping the stock, so the most frequent
action no longer needs a reach to the top of a tall folded screen.
Help, Modes, and New Game leave the touch bar (they live in Menu ->
System, the Home grid, and Home's hero respectively). Desktop keeps
the seven-button bar unchanged (decision 5: touch-only).

Holding Undo now steps back repeatedly after a 0.45s delay (5.5/s),
each step through the normal request path so the scoring penalty
applies. New self-ambiguous DrawRequestWriters set keeps the ambiguity
gate at zero with the fourth DrawRequestEvent writer.

6 new hud_plugin tests; workspace suite + clippy green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

solitaire_engine/src/game_plugin/mod.rs

@@ -86,6 +86,14 @@ pub struct NewGameRequestWriters;
 #[derive(SystemSet, Debug, Clone, PartialEq, Eq, Hash)]
 pub struct UndoRequestWriters;
 
+/// Self-ambiguous set for writers of `DrawRequestEvent` — same rationale as
+/// [`NewGameRequestWriters`]: consumers drain the queue, append order is
+/// meaningless (#143). Members: keyboard `D`/`Space`, stock click, touch
+/// stock tap (input_plugin), and the touch action bar's Draw button
+/// (hud_plugin, Phase F).
+#[derive(SystemSet, Debug, Clone, PartialEq, Eq, Hash)]
+pub struct DrawRequestWriters;
+
 /// Self-ambiguous set for writers of `InfoToastEvent` — toasts queue in
 /// arrival order and any same-frame order is fine (#143).
 #[derive(SystemSet, Debug, Clone, PartialEq, Eq, Hash)]

solitaire_engine/src/hud_plugin/interaction.rs

@@ -30,6 +30,86 @@ pub(super) fn handle_undo_button(
     }
 }
 
+/// Seconds the Undo button must be continuously held before hold-to-repeat
+/// kicks in. Long enough that a normal tap (press + release inside one or
+/// two frames) never triggers a second undo.
+const UNDO_HOLD_INITIAL_DELAY_SECS: f32 = 0.45;
+
+/// Interval between repeated undos while the hold continues. ~5.5 undos/s —
+/// fast enough to unwind a long line, slow enough to release in time when
+/// the board reaches the state the player wants.
+const UNDO_HOLD_REPEAT_INTERVAL_SECS: f32 = 0.18;
+
+/// Hold-to-repeat undo (Phase F): while the Undo button stays pressed,
+/// fire additional [`UndoRequestEvent`]s after an initial delay, one per
+/// repeat interval. The plain tap path stays in [`handle_undo_button`]
+/// (its `Changed<Interaction>` filter fires exactly once per press);
+/// this system only adds events once the hold outlives the delay, so a
+/// tap never double-undoes.
+///
+/// Each repeat goes through the normal request queue — the scoring
+/// penalty and No-Undo-mode gating in the consumer apply to every step.
+pub(super) fn repeat_undo_on_hold(
+    time: Res<Time>,
+    buttons: Query<&Interaction, With<UndoButton>>,
+    mut state: ResMut<UndoHoldState>,
+    mut undo: MessageWriter<UndoRequestEvent>,
+) {
+    let held = buttons.iter().any(|i| *i == Interaction::Pressed);
+    if !held {
+        if state.held_secs != 0.0 {
+            state.held_secs = 0.0;
+        }
+        return;
+    }
+
+    let before = state.held_secs;
+    state.held_secs += time.delta_secs();
+    if undo_hold_crossed_fire_boundary(before, state.held_secs) {
+        undo.write(UndoRequestEvent);
+    }
+}
+
+/// `true` when a hold that lasted `before` seconds at the previous frame
+/// and `now` seconds this frame should fire a repeat undo: once when the
+/// hold first outlives the initial delay, then once per repeat-interval
+/// boundary. Pure so the timing contract is unit-testable without
+/// fighting `Time`.
+pub(super) fn undo_hold_crossed_fire_boundary(before: f32, now: f32) -> bool {
+    if now < UNDO_HOLD_INITIAL_DELAY_SECS {
+        return false;
+    }
+    if before < UNDO_HOLD_INITIAL_DELAY_SECS {
+        // Crossed the initial-delay threshold this frame — first repeat.
+        return true;
+    }
+    // Fire once each time the hold crosses another repeat-interval boundary.
+    let intervals_before =
+        ((before - UNDO_HOLD_INITIAL_DELAY_SECS) / UNDO_HOLD_REPEAT_INTERVAL_SECS).floor();
+    let intervals_now =
+        ((now - UNDO_HOLD_INITIAL_DELAY_SECS) / UNDO_HOLD_REPEAT_INTERVAL_SECS).floor();
+    intervals_now > intervals_before
+}
+
+/// Click on the touch action bar's Draw button — same
+/// [`DrawRequestEvent`] the stock-pile tap writes, so the consumer's
+/// rules (recycle, won-game rejection) apply identically. Skipped while
+/// paused, mirroring `handle_stock_click`'s guard.
+pub(super) fn handle_draw_button(
+    interaction_query: Query<&Interaction, (With<DrawButton>, Changed<Interaction>)>,
+    paused: Option<Res<PausedResource>>,
+    mut draw: MessageWriter<DrawRequestEvent>,
+) {
+    if paused.is_some_and(|p| p.0) {
+        return;
+    }
+    for interaction in &interaction_query {
+        if *interaction == Interaction::Pressed {
+            draw.write(DrawRequestEvent);
+        }
+    }
+}
+
 pub(super) fn handle_pause_button(
     interaction_query: Query<&Interaction, (With<PauseButton>, Changed<Interaction>)>,
     mut pause: MessageWriter<PauseRequestEvent>,

solitaire_engine/src/hud_plugin/mod.rs

@@ -28,7 +28,7 @@ struct AvatarResource(Option<bevy::prelude::Handle<bevy::prelude::Image>>);
 use crate::challenge_plugin::CHALLENGE_UNLOCK_LEVEL;
 use crate::daily_challenge_plugin::DailyChallengeResource;
 use crate::events::{
-    HelpRequestEvent, InfoToastEvent, NewGameRequestEvent, PauseRequestEvent,
+    DrawRequestEvent, HelpRequestEvent, InfoToastEvent, NewGameRequestEvent, PauseRequestEvent,
     StartChallengeRequestEvent, StartDailyChallengeRequestEvent, StartTimeAttackRequestEvent,
     StartZenRequestEvent, ToggleAchievementsRequestEvent, ToggleHomeRequestEvent,
     ToggleLeaderboardRequestEvent, ToggleProfileRequestEvent, ToggleSettingsRequestEvent,
@@ -313,6 +313,18 @@ pub struct UndoButton;
 #[derive(Component, Debug)]
 pub struct PauseButton;
 
+/// Accumulated hold time on the Undo button, driving hold-to-repeat undo
+/// (Phase F). `handle_undo_button` owns the instant first undo on press;
+/// `repeat_undo_on_hold` starts firing additional [`UndoRequestEvent`]s
+/// once the hold passes `UNDO_HOLD_INITIAL_DELAY_SECS` and then every
+/// `UNDO_HOLD_REPEAT_INTERVAL_SECS`. Each repeated undo goes through the
+/// normal request path, so the existing scoring penalty applies per step.
+#[derive(Resource, Debug, Default)]
+pub struct UndoHoldState {
+    /// Seconds the Undo button has been continuously held.
+    held_secs: f32,
+}
+
 /// Marker on the "Help" action button. Click fires [`HelpRequestEvent`],
 /// mirroring the `F1` keyboard accelerator.
 #[derive(Component, Debug)]
@@ -323,31 +335,27 @@ pub struct HelpButton;
 #[derive(Component, Debug)]
 pub struct HintButton;
 
+/// Marker on the touch action bar's "Draw" button (Phase F). Click fires
+/// [`DrawRequestEvent`] — same queue as tapping the stock pile — so the
+/// draw action is within thumb reach without stretching to the top of a
+/// tall folded screen. Touch layout only; desktop draws via stock
+/// click / `D` / `Space`.
+#[derive(Component, Debug)]
+pub struct DrawButton;
+
 /// Android HUD label for the Hint button — shared with the help screen's
 /// controls reference so both always agree.
 #[cfg(target_os = "android")]
 pub(crate) const ANDROID_HINT_LABEL: &str = "Hint";
 
+/// Hint label used by the touch action bar. Aliases [`ANDROID_HINT_LABEL`]
+/// on Android so the bar and the help screen's controls reference can
+/// never drift; the non-Android value only exists so the touch spawn
+/// path stays host-compilable for tests.
 #[cfg(target_os = "android")]
-const ACTION_BAR_LABELS: [&str; 7] = [
-    "Menu",
-    "Undo",
-    "Pause",
-    "Help",
-    ANDROID_HINT_LABEL,
-    "Mode",
-    "New",
-];
+const TOUCH_HINT_LABEL: &str = ANDROID_HINT_LABEL;
 #[cfg(not(target_os = "android"))]
-const ACTION_BAR_LABELS: [&str; 7] = [
-    "Menu \u{2193}",
-    "Undo",
-    "Pause",
-    "Help",
-    "Hint",
-    "Modes \u{2193}",
-    "New Game",
-];
+const TOUCH_HINT_LABEL: &str = "Hint";
 #[cfg(target_os = "android")]
 const ACTION_BAR_COLUMN_GAP: Val = Val::Px(4.0);
 #[cfg(not(target_os = "android"))]
@@ -455,6 +463,7 @@ impl Plugin for HudPlugin {
         // idempotent.
         app.add_message::<NewGameRequestEvent>()
             .add_message::<UndoRequestEvent>()
+            .add_message::<DrawRequestEvent>()
             .add_message::<PauseRequestEvent>()
             .add_message::<HelpRequestEvent>()
             .add_message::<StartZenRequestEvent>()
@@ -471,6 +480,7 @@ impl Plugin for HudPlugin {
             .init_resource::<PreviousScore>()
             .init_resource::<HudActionFade>()
             .init_resource::<HudVisibility>()
+            .init_resource::<UndoHoldState>()
             // Escape-close handlers for popovers read this; init defensively
             // so HudPlugin works under MinimalPlugins in tests.
             .init_resource::<ButtonInput<KeyCode>>()
@@ -560,6 +570,14 @@ impl Plugin for HudPlugin {
                         .in_set(crate::game_plugin::UndoRequestWriters)
                         .ambiguous_with(crate::game_plugin::UndoRequestWriters)
                         .before(GameMutation),
+                    repeat_undo_on_hold
+                        .in_set(crate::game_plugin::UndoRequestWriters)
+                        .ambiguous_with(crate::game_plugin::UndoRequestWriters)
+                        .before(GameMutation),
+                    handle_draw_button
+                        .in_set(crate::game_plugin::DrawRequestWriters)
+                        .ambiguous_with(crate::game_plugin::DrawRequestWriters)
+                        .before(GameMutation),
                     handle_pause_button,
                     handle_help_button,
                     handle_hint_button

solitaire_engine/src/hud_plugin/spawn.rs

@@ -400,83 +400,152 @@ pub(super) fn spawn_action_buttons(
             HudActionBar,
         ))
         .with_children(|row| {
-            // The trailing `order` argument feeds `Focusable { group: Hud, order }`
-            // so Tab cycles the action bar in visual reading order.
-            // Undo and Pause are the primary gameplay actions — full brightness.
-            // Menu, Help, Hint, Modes, New are navigation/utility — dimmed.
-            spawn_action_button(
-                row,
-                MenuButton,
-                ACTION_BAR_LABELS[0],
-                None,
-                "Open Stats, Achievements, Profile, Settings, or Leaderboard.",
-                &font,
-                0,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                UndoButton,
-                ACTION_BAR_LABELS[1],
-                Some("U"),
-                "Take back your last move. Costs points and blocks No Undo.",
-                &font,
-                1,
-                TEXT_PRIMARY,
-            );
-            spawn_action_button(
-                row,
-                PauseButton,
-                ACTION_BAR_LABELS[2],
-                Some("Esc"),
-                "Pause the game and freeze the timer.",
-                &font,
-                2,
-                TEXT_PRIMARY,
-            );
-            spawn_action_button(
-                row,
-                HelpButton,
-                ACTION_BAR_LABELS[3],
-                Some("F1"),
-                "Show controls, rules, and keyboard shortcuts.",
-                &font,
-                3,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                HintButton,
-                ACTION_BAR_LABELS[4],
-                Some("H"),
-                "Highlight a suggested move. Cycles through alternatives on repeat taps.",
-                &font,
-                4,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                ModesButton,
-                ACTION_BAR_LABELS[5],
-                None,
-                "Switch modes: Classic, Daily, Zen, Challenge, Time Attack.",
-                &font,
-                5,
-                TEXT_SECONDARY,
-            );
-            spawn_action_button(
-                row,
-                NewGameButton,
-                ACTION_BAR_LABELS[6],
-                Some("N"),
-                "Start a fresh deal. Confirms first if a game is in progress.",
-                &font,
-                6,
-                TEXT_SECONDARY,
-            );
+            if USE_TOUCH_UI_LAYOUT {
+                spawn_touch_action_bar(row, &font);
+            } else {
+                spawn_desktop_action_bar(row, &font);
+            }
         });
 }
 
+/// Phase F touch action bar — five buttons, three of them big.
+///
+/// The core gameplay trio (**Undo · Draw · Hint**) gets enlarged
+/// thumb-reach targets; Menu and Pause stay compact at the edges. The
+/// utility actions the desktop bar carries are reachable elsewhere on
+/// touch and are deliberately absent here: Help lives in Menu → System,
+/// mode switching lives on the Home screen (Phase B), and New Game is
+/// Home's hero button. Draw duplicates the stock-pile tap so the most
+/// frequent action of all no longer requires reaching the top half of a
+/// tall folded screen.
+pub(super) fn spawn_touch_action_bar(row: &mut ChildSpawnerCommands, font: &TextFont) {
+    // The trailing `order` argument feeds `Focusable { group: Hud, order }`
+    // so Tab (external keyboard) cycles the bar in visual reading order.
+    spawn_action_button(
+        row,
+        MenuButton,
+        "Menu",
+        None,
+        "Open Home, Stats, Achievements, Profile, Settings, or Leaderboard.",
+        font,
+        0,
+        TEXT_SECONDARY,
+    );
+    spawn_primary_action_button(
+        row,
+        UndoButton,
+        "Undo",
+        "Take back your last move. Hold to keep undoing. Costs points and blocks No Undo.",
+        font,
+        1,
+    );
+    spawn_primary_action_button(
+        row,
+        DrawButton,
+        "Draw",
+        "Draw from the stock — same as tapping the deck.",
+        font,
+        2,
+    );
+    spawn_primary_action_button(
+        row,
+        HintButton,
+        TOUCH_HINT_LABEL,
+        "Highlight a suggested move. Cycles through alternatives on repeat taps.",
+        font,
+        3,
+    );
+    spawn_action_button(
+        row,
+        PauseButton,
+        "Pause",
+        None,
+        "Pause the game and freeze the timer.",
+        font,
+        4,
+        TEXT_SECONDARY,
+    );
+}
+
+/// Desktop action bar — unchanged by Phase F (decision 5: the touch bar
+/// is touch-only). All seven actions, uniform sizing.
+pub(super) fn spawn_desktop_action_bar(row: &mut ChildSpawnerCommands, font: &TextFont) {
+    // The trailing `order` argument feeds `Focusable { group: Hud, order }`
+    // so Tab cycles the action bar in visual reading order.
+    // Undo and Pause are the primary gameplay actions — full brightness.
+    // Menu, Help, Hint, Modes, New are navigation/utility — dimmed.
+    spawn_action_button(
+        row,
+        MenuButton,
+        "Menu \u{2193}",
+        None,
+        "Open Stats, Achievements, Profile, Settings, or Leaderboard.",
+        font,
+        0,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        UndoButton,
+        "Undo",
+        Some("U"),
+        "Take back your last move. Hold to keep undoing. Costs points and blocks No Undo.",
+        font,
+        1,
+        TEXT_PRIMARY,
+    );
+    spawn_action_button(
+        row,
+        PauseButton,
+        "Pause",
+        Some("Esc"),
+        "Pause the game and freeze the timer.",
+        font,
+        2,
+        TEXT_PRIMARY,
+    );
+    spawn_action_button(
+        row,
+        HelpButton,
+        "Help",
+        Some("F1"),
+        "Show controls, rules, and keyboard shortcuts.",
+        font,
+        3,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        HintButton,
+        "Hint",
+        Some("H"),
+        "Highlight a suggested move. Cycles through alternatives on repeat taps.",
+        font,
+        4,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        ModesButton,
+        "Modes \u{2193}",
+        None,
+        "Switch modes: Classic, Daily, Zen, Challenge, Time Attack.",
+        font,
+        5,
+        TEXT_SECONDARY,
+    );
+    spawn_action_button(
+        row,
+        NewGameButton,
+        "New Game",
+        Some("N"),
+        "Start a fresh deal. Confirms first if a game is in progress.",
+        font,
+        6,
+        TEXT_SECONDARY,
+    );
+}
+
 /// Spawns a single action button as a child of `row`. Each button shares
 /// the same node geometry, idle colour, and `ActionButton` marker so
 /// `paint_action_buttons` can recolour all of them with one query.
@@ -510,13 +579,69 @@ pub(super) fn spawn_action_button<M: Component>(
         None
     };
 
+    let (pad, min_w, min_h) = action_button_metrics();
+    spawn_action_button_sized(
+        row, marker, label, hotkey, tooltip, font, order, text_color, pad, min_w, min_h,
+    );
+}
+
+/// Enlarged variant for the touch bar's core gameplay trio (Phase F):
+/// bigger padding / minimum target and a scaled-up label so Undo, Draw,
+/// and Hint read (and hit) as the primary actions. Hotkey chips are
+/// irrelevant on touch, so the variant takes none.
+pub(super) fn spawn_primary_action_button<M: Component>(
+    row: &mut ChildSpawnerCommands,
+    marker: M,
+    label: &str,
+    tooltip: &'static str,
+    font: &TextFont,
+    order: i32,
+) {
+    let (pad, min_w, min_h) = primary_action_button_metrics();
+    let primary_font = TextFont {
+        font: font.font.clone(),
+        // 1.35× the bar's responsive size, capped so landscape tablets
+        // don't blow the row height out.
+        font_size: (font.font_size * 1.35).min(24.0),
+        ..default()
+    };
+    spawn_action_button_sized(
+        row,
+        marker,
+        label,
+        None,
+        tooltip,
+        &primary_font,
+        order,
+        TEXT_PRIMARY,
+        pad,
+        min_w,
+        min_h,
+    );
+}
+
+/// Shared body of [`spawn_action_button`] / [`spawn_primary_action_button`]
+/// — one place owns the component set so `paint_action_buttons`, tooltips,
+/// and the focus ring treat every bar button identically.
+#[allow(clippy::too_many_arguments)]
+fn spawn_action_button_sized<M: Component>(
+    row: &mut ChildSpawnerCommands,
+    marker: M,
+    label: &str,
+    hotkey: Option<&'static str>,
+    tooltip: &'static str,
+    font: &TextFont,
+    order: i32,
+    text_color: Color,
+    pad: UiRect,
+    min_w: Val,
+    min_h: Val,
+) {
     let hotkey_font = TextFont {
         font: font.font.clone(),
         font_size: TYPE_CAPTION,
         ..default()
     };
-    let (pad, min_w, min_h) = action_button_metrics();
-
     row.spawn((
         marker,
         ActionButton,

solitaire_engine/src/hud_plugin/tests.rs

@@ -670,7 +670,7 @@ fn hud_elements_carry_expected_tooltip_strings() {
     );
     assert_eq!(
         tooltip_for::<UndoButton>(&mut app),
-        "Take back your last move. Costs points and blocks No Undo."
+        "Take back your last move. Hold to keep undoing. Costs points and blocks No Undo."
     );
     assert_eq!(
         tooltip_for::<PauseButton>(&mut app),
@@ -899,3 +899,157 @@ fn hud_focus_only_engages_when_button_hovered() {
         "Hud-engaged Tab must focus a Hud-grouped entity"
     );
 }
+
+// ---------------------------------------------------------------------------
+// Phase F: touch action bar + hold-to-repeat undo
+// ---------------------------------------------------------------------------
+
+/// Bare app (no `HudPlugin`) so bar-content assertions count only the
+/// buttons the tested spawn function creates — `headless_app` would
+/// pre-spawn the platform-default bar and pollute the counts.
+fn bar_only_app(touch: bool) -> App {
+    let mut app = App::new();
+    app.add_plugins(MinimalPlugins);
+    app.update();
+    let font = TextFont::default();
+    let world = app.world_mut();
+    let mut commands = world.commands();
+    commands.spawn(Node::default()).with_children(|row| {
+        if touch {
+            spawn_touch_action_bar(row, &font);
+        } else {
+            spawn_desktop_action_bar(row, &font);
+        }
+    });
+    app.update();
+    app
+}
+
+fn count_buttons<C: Component>(app: &mut App) -> usize {
+    app.world_mut()
+        .query_filtered::<(), With<C>>()
+        .iter(app.world())
+        .count()
+}
+
+#[test]
+fn touch_action_bar_has_thumb_trio_plus_menu_and_pause() {
+    let mut app = bar_only_app(true);
+
+    assert_eq!(count_buttons::<UndoButton>(&mut app), 1);
+    assert_eq!(count_buttons::<DrawButton>(&mut app), 1);
+    assert_eq!(count_buttons::<HintButton>(&mut app), 1);
+    assert_eq!(count_buttons::<MenuButton>(&mut app), 1);
+    assert_eq!(count_buttons::<PauseButton>(&mut app), 1);
+
+    // Utility actions live elsewhere on touch: Help in Menu → System,
+    // modes on the Home screen, New Game on Home's hero button.
+    assert_eq!(count_buttons::<HelpButton>(&mut app), 0);
+    assert_eq!(count_buttons::<ModesButton>(&mut app), 0);
+    assert_eq!(count_buttons::<NewGameButton>(&mut app), 0);
+}
+
+#[test]
+fn desktop_action_bar_keeps_all_seven_and_no_draw() {
+    let mut app = bar_only_app(false);
+
+    for (count, name) in [
+        (count_buttons::<MenuButton>(&mut app), "Menu"),
+        (count_buttons::<UndoButton>(&mut app), "Undo"),
+        (count_buttons::<PauseButton>(&mut app), "Pause"),
+        (count_buttons::<HelpButton>(&mut app), "Help"),
+        (count_buttons::<HintButton>(&mut app), "Hint"),
+        (count_buttons::<ModesButton>(&mut app), "Modes"),
+        (count_buttons::<NewGameButton>(&mut app), "New Game"),
+    ] {
+        assert_eq!(count, 1, "desktop bar must keep its {name} button");
+    }
+    assert_eq!(
+        count_buttons::<DrawButton>(&mut app),
+        0,
+        "Draw is touch-only (decision 5); desktop draws via stock click / D / Space"
+    );
+}
+
+#[test]
+fn draw_button_press_fires_draw_request() {
+    let mut app = headless_app();
+    app.world_mut()
+        .resource_mut::<Messages<DrawRequestEvent>>()
+        .clear();
+
+    app.world_mut().spawn((DrawButton, Interaction::Pressed));
+    app.update();
+
+    let events = app.world().resource::<Messages<DrawRequestEvent>>();
+    let mut cursor = events.get_cursor();
+    assert_eq!(
+        cursor.read(events).count(),
+        1,
+        "pressing the Draw button must fire exactly one DrawRequestEvent"
+    );
+}
+
+#[test]
+fn draw_button_press_is_noop_while_paused() {
+    let mut app = headless_app();
+    app.insert_resource(PausedResource(true));
+    app.world_mut()
+        .resource_mut::<Messages<DrawRequestEvent>>()
+        .clear();
+
+    app.world_mut().spawn((DrawButton, Interaction::Pressed));
+    app.update();
+
+    let events = app.world().resource::<Messages<DrawRequestEvent>>();
+    let mut cursor = events.get_cursor();
+    assert_eq!(
+        cursor.read(events).count(),
+        0,
+        "the Draw button must be inert while paused (mirrors the stock-click guard)"
+    );
+}
+
+/// The timing contract for hold-to-repeat undo, exercised through the
+/// pure boundary function so no wall-clock is involved. Delay = 0.45 s,
+/// interval = 0.18 s → boundaries at 0.45, 0.63, 0.81, …
+#[test]
+fn undo_hold_boundary_math() {
+    // A tap never repeats.
+    assert!(!undo_hold_crossed_fire_boundary(0.0, 0.05));
+    assert!(!undo_hold_crossed_fire_boundary(0.2, 0.44));
+    // Crossing the initial delay fires the first repeat.
+    assert!(undo_hold_crossed_fire_boundary(0.44, 0.46));
+    // Inside the first repeat interval: quiet.
+    assert!(!undo_hold_crossed_fire_boundary(0.46, 0.62));
+    // Each interval boundary fires exactly once.
+    assert!(undo_hold_crossed_fire_boundary(0.62, 0.64));
+    assert!(!undo_hold_crossed_fire_boundary(0.64, 0.80));
+    assert!(undo_hold_crossed_fire_boundary(0.80, 0.82));
+}
+
+#[test]
+fn undo_hold_state_accumulates_and_resets_on_release() {
+    let mut app = headless_app();
+    let button = app
+        .world_mut()
+        .spawn((UndoButton, Interaction::Pressed))
+        .id();
+    app.update();
+    app.update();
+    app.update();
+
+    assert!(
+        app.world().resource::<UndoHoldState>().held_secs > 0.0,
+        "held time must accumulate while the Undo button stays pressed"
+    );
+
+    app.world_mut().entity_mut(button).insert(Interaction::None);
+    app.update();
+
+    assert_eq!(
+        app.world().resource::<UndoHoldState>().held_secs,
+        0.0,
+        "releasing the Undo button must reset the hold state"
+    );
+}

solitaire_engine/src/hud_plugin/updates.rs

@@ -554,11 +554,11 @@ pub(super) fn action_bar_font_size(window_width: f32) -> f32 {
 
 pub(super) fn action_button_metrics() -> (UiRect, Val, Val) {
     if USE_TOUCH_UI_LAYOUT {
-        // Tight 3 px horizontal padding (down from 4) trims 14 px off the row
-        // total across 7 buttons, and a 44 px min_width (down from 52) lets the
-        // shortest labels ("New", "Help") shrink to their text rather than
-        // padding the row out past the 900 logical-px viewport. min_height
-        // stays at 44 px to preserve the comfortable touch target.
+        // Tight 3 px horizontal padding keeps the compact buttons narrow;
+        // Phase F trimmed the touch bar to 5 buttons (2 compact + 3
+        // primary), so width pressure is lower than the old 7-button row.
+        // min_height stays at 44 px to preserve the comfortable touch
+        // target on the compact buttons.
         (
             UiRect::axes(Val::Px(3.0), Val::Px(4.0)),
             Val::Px(44.0),
@@ -573,6 +573,20 @@ pub(super) fn action_button_metrics() -> (UiRect, Val, Val) {
     }
 }
 
+/// Metrics for the touch bar's enlarged Undo / Draw / Hint trio (Phase F).
+/// 96×64 px targets — comfortably past the 44 px accessibility floor and
+/// big enough to hit one-handed without looking. Only the touch layout
+/// spawns primary buttons, so no desktop branch is needed; the desktop
+/// values exist purely so host-side tests can exercise the touch spawn
+/// path with sensible numbers.
+pub(super) fn primary_action_button_metrics() -> (UiRect, Val, Val) {
+    (
+        UiRect::axes(Val::Px(10.0), Val::Px(8.0)),
+        Val::Px(96.0),
+        Val::Px(64.0),
+    )
+}
+
 pub(super) fn spawn_action_button_label(
     parent: &mut ChildSpawnerCommands,
     label: &str,

solitaire_engine/src/input_plugin/mod.rs

@@ -136,11 +136,22 @@ impl Plugin for InputPlugin {
             .add_systems(
                 Update,
                 (
-                    handle_keyboard_core,
+                    // The three `DrawRequestEvent` writers join the
+                    // self-ambiguous `DrawRequestWriters` set so the HUD's
+                    // touch Draw button (hud_plugin, Phase F) can write the
+                    // same queue without tripping the ambiguity gate. The
+                    // `.chain()` still orders them relative to each other.
+                    handle_keyboard_core
+                        .in_set(crate::game_plugin::DrawRequestWriters)
+                        .ambiguous_with(crate::game_plugin::DrawRequestWriters),
                     handle_keyboard_hint,
                     handle_keyboard_forfeit,
-                    handle_stock_click,
-                    handle_touch_stock_tap,
+                    handle_stock_click
+                        .in_set(crate::game_plugin::DrawRequestWriters)
+                        .ambiguous_with(crate::game_plugin::DrawRequestWriters),
+                    handle_touch_stock_tap
+                        .in_set(crate::game_plugin::DrawRequestWriters)
+                        .ambiguous_with(crate::game_plugin::DrawRequestWriters),
                     handle_double_click,
                     // Mouse drag pipeline.
                     start_drag,