feat(client_web): checkers slide animation

Cargo.lock

@@ -1397,6 +1397,7 @@ dependencies = [
  "futures",
  "getrandom 0.3.4",
  "gloo-storage",
+ "gloo-timers",
  "leptos",
  "leptos_i18n",
  "rand 0.9.2",
@@ -1404,6 +1405,7 @@ dependencies = [
  "serde_json",
  "trictrac-store",
  "wasm-bindgen-futures",
+ "web-sys",
 ]
 
 [[package]]

client_web/Cargo.toml

@@ -17,9 +17,17 @@ serde_json      = "1"
 futures         = "0.3"
 rand            = "0.9"
 gloo-storage    = "0.3"
+gloo-timers     = "0.3"
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 wasm-bindgen-futures = "0.4"
 # getrandom 0.3 requires an explicit WASM backend; "wasm_js" uses window.crypto.getRandomValues.
 # Must be a direct dependency (not just transitive) for the feature to take effect.
 getrandom = { version = "0.3", features = ["wasm_js"] }
+web-sys = { version = "0.3", features = [
+    "Document",
+    "Element",
+    "HtmlElement",
+    "CssStyleDeclaration",
+    "DomTokenList",
+] }

client_web/assets/style.css

@@ -999,6 +999,24 @@ body {
     letter-spacing: 0.14em;
 }
 
+/* ── §4a — Checker slide animation ─────────────────────────────────── */
+@keyframes checker-slide-in {
+    from { transform: translate(var(--slide-dx, 0px), var(--slide-dy, 0px)); }
+    to   { transform: none; }
+}
+.checker-stack.sliding {
+    animation: checker-slide-in 0.28s cubic-bezier(0.25, 0.46, 0.45, 0.94);
+}
+/* Lift the field that owns a sliding stack above its siblings so the
+   checker doesn't slide under adjacent fields (isolation:isolate traps
+   z-index within each field's stacking context, so we must elevate the
+   field itself). */
+.field:has(.checker-stack.sliding) {
+    isolation: auto;
+    z-index: 10;
+    position: relative;
+}
+
 /* ── Checker lift on selected field (§4b) ───────────────────────────── */
 .field.selected .checker-stack {
     transform: translateY(-5px);

client_web/src/app.rs

@@ -13,6 +13,7 @@ use crate::i18n::I18nContextProvider;
 use crate::trictrac::backend::TrictracBackend;
 use crate::trictrac::bot_local::bot_decide;
 use crate::trictrac::types::{GameDelta, JanEntry, PlayerAction, ScoredEvent, SerTurnStage, ViewState};
+use trictrac_store::CheckerMove;
 
 use std::collections::VecDeque;
 
@@ -35,6 +36,8 @@ pub struct GameUiState {
     /// Points scored by this player in the transition to this state (if any).
     pub my_scored_event: Option<ScoredEvent>,
     pub opp_scored_event: Option<ScoredEvent>,
+    /// Checker moves to animate on this render. None when board is unchanged.
+    pub last_moves: Option<(CheckerMove, CheckerMove)>,
 }
 
 /// Reason the UI is paused waiting for the player to click Continue.
@@ -272,6 +275,7 @@ pub fn App() -> impl IntoView {
                                     pause_reason: None,
                                     my_scored_event: None,
                                     opp_scored_event: None,
+                                    last_moves: compute_last_moves(&prev_vs, &vs),
                                 },
                                 pending,
                                 screen,
@@ -338,6 +342,7 @@ async fn run_local_bot_game(
         pause_reason: None,
         my_scored_event: None,
         opp_scored_event: None,
+        last_moves: None,
     }));
 
     loop {
@@ -361,6 +366,7 @@ async fn run_local_bot_game(
                     pause_reason: None,
                     my_scored_event: scored,
                     opp_scored_event: opp_scored,
+                    last_moves: compute_last_moves(&prev_vs, &vs),
                 }));
             }
             Some(NetCommand::PlayVsBot) => return true,
@@ -389,6 +395,7 @@ async fn run_local_bot_game(
                             pause_reason: None,
                             my_scored_event: None,
                             opp_scored_event: None,
+                            last_moves: compute_last_moves(&prev_vs, &vs),
                         },
                         pending,
                         screen,
@@ -399,6 +406,22 @@ async fn run_local_bot_game(
     }
 }
 
+/// Returns the checker moves to animate when the board changed between two ViewStates.
+/// Returns `None` when the board is unchanged or no real moves were recorded.
+fn compute_last_moves(prev: &ViewState, next: &ViewState) -> Option<(CheckerMove, CheckerMove)> {
+    if prev.board == next.board {
+        return None;
+    }
+    let (m1, m2) = next.dice_moves;
+    if m1 == CheckerMove::default() && m2 == CheckerMove::default() {
+        // Relies on the engine invariant: dice_moves is updated atomically with the board
+        // change in the Move event handler. Any future engine path that mutates the board
+        // without setting dice_moves would bypass this guard and replay stale animation.
+        return None;
+    }
+    Some((m1, m2))
+}
+
 /// Computes a scoring event for `player_id` by comparing the previous and next
 /// ViewState. Returns `None` when no points changed for that player.
 fn compute_scored_event(prev: &ViewState, next: &ViewState, player_id: u16) -> Option<ScoredEvent> {
@@ -471,7 +494,9 @@ fn push_or_show(
                 ..new_state.clone()
             });
         });
-        screen.set(Screen::Playing(new_state));
+        // Animation belongs to the buffered confirmation step; clear it on the
+        // fallback live state so it doesn't fire again after the queue drains.
+        screen.set(Screen::Playing(GameUiState { last_moves: None, ..new_state }));
     } else {
         // No pause: show scoring directly on the live state.
         screen.set(Screen::Playing(GameUiState {
@@ -528,6 +553,7 @@ mod tests {
             scores: [score(), score()],
             dice,
             dice_jans: Vec::new(),
+            dice_moves: (CheckerMove::default(), CheckerMove::default()),
         }
     }
 

client_web/src/components/board.rs

@@ -1,8 +1,8 @@
 use leptos::prelude::*;
 use trictrac_store::CheckerMove;
 
-use crate::trictrac::types::{SerTurnStage, ViewState};
 use super::die::Die;
+use crate::trictrac::types::{SerTurnStage, ViewState};
 
 /// Field numbers in visual display order (left-to-right for each quarter), white's perspective.
 const TOP_LEFT_W: [u8; 6] = [13, 14, 15, 16, 17, 18];
@@ -20,17 +20,21 @@ const BOT_RIGHT_B: [u8; 6] = [18, 17, 16, 15, 14, 13];
 /// Returns true when `field_num` is the rest corner for this perspective.
 #[allow(dead_code)]
 fn is_rest_corner(field_num: u8, is_white: bool) -> bool {
-    if is_white { field_num == 12 } else { field_num == 13 }
+    if is_white {
+        field_num == 12
+    } else {
+        field_num == 13
+    }
 }
 
 /// Zone CSS class for a field number (field coordinates are always White's 1-24).
 fn field_zone_class(field_num: u8) -> &'static str {
     match field_num {
-        1..=6   => "zone-petit",
+        1..=6 => "zone-petit",
-        7..=12  => "zone-grand",
+        7..=12 => "zone-grand",
         13..=18 => "zone-retour",
         19..=24 => "zone-dernier",
-        _       => "",
+        _ => "",
     }
 }
 
@@ -39,11 +43,20 @@ fn bar_matched_dice_used(staged: &[(u8, u8)], dice: (u8, u8)) -> (bool, bool) {
     let mut d0 = false;
     let mut d1 = false;
     for &(from, to) in staged {
-        let dist = if from < to { to.saturating_sub(from) } else { from.saturating_sub(to) };
+        let dist = if from < to {
-        if !d0 && dist == dice.0 { d0 = true; }
+            to.saturating_sub(from)
-        else if !d1 && dist == dice.1 { d1 = true; }
+        } else {
-        else if !d0 { d0 = true; }
+            from.saturating_sub(to)
-        else { d1 = true; }
+        };
+        if !d0 && dist == dice.0 {
+            d0 = true;
+        } else if !d1 && dist == dice.1 {
+            d1 = true;
+        } else if !d0 {
+            d0 = true;
+        } else {
+            d1 = true;
+        }
     }
     (d0, d1)
 }
@@ -72,7 +85,8 @@ fn displayed_value(
 /// Fields whose checkers may be selected as the next origin given already-staged moves.
 fn valid_origins_for(seqs: &[(CheckerMove, CheckerMove)], staged: &[(u8, u8)]) -> Vec<u8> {
     let mut v: Vec<u8> = match staged.len() {
-        0 => seqs.iter()
+        0 => seqs
+            .iter()
             .map(|(m1, _)| m1.get_from() as u8)
             .filter(|&f| f != 0)
             .collect(),
@@ -103,28 +117,46 @@ fn field_center(f: usize, is_white: bool) -> Option<(f32, f32)> {
         match f {
             13..=18 => (f - 13, false, true),
             19..=24 => (f - 19, true, true),
-            7..=12  => (12 - f, false, false),
+            7..=12 => (12 - f, false, false),
-            1..=6   => (6 - f, true, false),
+            1..=6 => (6 - f, true, false),
-            _       => return None,
+            _ => return None,
         }
     } else {
         match f {
-            1..=6   => (f - 1, false, true),
+            1..=6 => (f - 1, false, true),
-            7..=12  => (f - 7, true, true),
+            7..=12 => (f - 7, true, true),
             19..=24 => (24 - f, false, false),
             13..=18 => (18 - f, true, false),
-            _       => return None,
+            _ => return None,
         }
     };
     // Left-quarter field i center x:  4(pad) + i*62 + 30(half field) = 34 + 62i
     // Right-quarter:  4 + 370(quarter) + 4(gap) + 68(bar) + 4(gap) + i*62 + 30 = 480 + 62i
-    let x = if right { 480.0 + qi as f32 * 62.0 } else { 34.0 + qi as f32 * 62.0 };
+    let x = if right {
+        480.0 + qi as f32 * 62.0
+    } else {
+        34.0 + qi as f32 * 62.0
+    };
     // Top row triangle base (wide end) ≈ y=30; bot row triangle base ≈ y=358.
     // (Top base: 4pad + 4field-pad + 20half-checker ≈ 28; Bot base: 388 − 4pad − 4field-pad − 20 ≈ 360)
     let y = if top { 30.0 } else { 358.0 };
     Some((x, y))
 }
 
+#[cfg(target_arch = "wasm32")]
+fn apply_slide_animation(to_field: usize, dx: f32, dy: f32) {
+    use web_sys::wasm_bindgen::JsCast;
+    let Some(doc) = web_sys::window().and_then(|w| w.document()) else { return };
+    let selector = format!("#field-{} .checker-stack", to_field);
+    let Ok(Some(el)) = doc.query_selector(&selector) else { return };
+    let Ok(html) = el.dyn_into::<web_sys::HtmlElement>() else { return };
+    let style = html.style();
+    style.set_property("--slide-dx", &format!("{:.1}px", dx)).ok();
+    style.set_property("--slide-dy", &format!("{:.1}px", dy)).ok();
+    html.class_list().add_1("sliding").ok();
+}
+
+
 /// SVG `<g>` element drawing one arrow (shadow + gold) from `fp` to `tp`.
 fn arrow_svg(fp: (f32, f32), tp: (f32, f32)) -> AnyView {
     let (x1, y1) = fp;
@@ -153,15 +185,21 @@ fn arrow_svg(fp: (f32, f32), tp: (f32, f32)) -> AnyView {
     let bary = y2 - ny * ah;
     let pts = format!(
         "{:.1},{:.1} {:.1},{:.1} {:.1},{:.1}",
-        x2, y2,
+        x2,
-        bx + px * aw, bary + py * aw,
+        y2,
-        bx - px * aw, bary - py * aw,
+        bx + px * aw,
+        bary + py * aw,
+        bx - px * aw,
+        bary - py * aw,
     );
     let shadow_pts = format!(
         "{:.1},{:.1} {:.1},{:.1} {:.1},{:.1}",
-        x2, y2,
+        x2,
-        bx + px * (aw + 1.5), bary + py * (aw + 1.5),
+        y2,
-        bx - px * (aw + 1.5), bary - py * (aw + 1.5),
+        bx + px * (aw + 1.5),
+        bary + py * (aw + 1.5),
+        bx - px * (aw + 1.5),
+        bary - py * (aw + 1.5),
     );
 
     view! {
@@ -187,9 +225,14 @@ fn arrow_svg(fp: (f32, f32), tp: (f32, f32)) -> AnyView {
 
 /// Valid destinations for a selected origin given already-staged moves.
 /// May include 0 (exit); callers handle that case.
-fn valid_dests_for(seqs: &[(CheckerMove, CheckerMove)], staged: &[(u8, u8)], origin: u8) -> Vec<u8> {
+fn valid_dests_for(
+    seqs: &[(CheckerMove, CheckerMove)],
+    staged: &[(u8, u8)],
+    origin: u8,
+) -> Vec<u8> {
     let mut v: Vec<u8> = match staged.len() {
-        0 => seqs.iter()
+        0 => seqs
+            .iter()
             .filter(|(m1, _)| m1.get_from() as u8 == origin)
             .map(|(m1, _)| m1.get_to() as u8)
             .collect(),
@@ -222,11 +265,17 @@ pub fn Board(
     /// All valid two-move sequences for this turn (empty when not in move stage).
     valid_sequences: Vec<(CheckerMove, CheckerMove)>,
     /// Dice to display in the center bars; None means dice not yet rolled (cups shown upright).
-    #[prop(default = None)] bar_dice: Option<(u8, u8)>,
+    #[prop(default = None)]
+    bar_dice: Option<(u8, u8)>,
     /// Whether we're in the move stage (determines used/unused die appearance).
-    #[prop(default = false)] bar_is_move: bool,
+    #[prop(default = false)]
+    bar_is_move: bool,
     /// Whether the dice are a double (golden glow).
-    #[prop(default = false)] bar_is_double: bool,
+    #[prop(default = false)]
+    bar_is_double: bool,
+    /// Checker moves to animate on mount (None when board unchanged).
+    #[prop(default = None)]
+    last_moves: Option<(CheckerMove, CheckerMove)>,
 ) -> impl IntoView {
     let board = view_state.board;
     let is_move_stage = view_state.active_mp_player == Some(player_id)
@@ -245,12 +294,12 @@ pub fn Board(
     let exit_field_test: fn(u8) -> bool;
     if is_white {
         let in_exit: i8 = board_snapshot[18..24].iter().map(|&v| v.max(0)).sum();
-        let total:   i8 = board_snapshot.iter().map(|&v| v.max(0)).sum();
+        let total: i8 = board_snapshot.iter().map(|&v| v.max(0)).sum();
         all_in_exit = total > 0 && in_exit == total;
         exit_field_test = |f| matches!(f, 19..=24);
     } else {
         let in_exit: i8 = board_snapshot[0..6].iter().map(|&v| (-v).max(0)).sum();
-        let total:   i8 = board_snapshot.iter().map(|&v| (-v).max(0)).sum();
+        let total: i8 = board_snapshot.iter().map(|&v| (-v).max(0)).sum();
         all_in_exit = total > 0 && in_exit == total;
         exit_field_test = |f| matches!(f, 1..=6);
     }
@@ -270,6 +319,7 @@ pub fn Board(
                 };
                 view! {
                     <div
+                        id={format!("field-{field_num}")}
                         title=corner_title
                         class=move || {
                             let staged = staged_moves.get();
@@ -402,7 +452,11 @@ pub fn Board(
         match bar_dice {
             None => view! { <div class="bar-die-slot"></div> }.into_any(),
             Some(dice_vals) => {
-                let die_val = if die_idx == 0 { dice_vals.0 } else { dice_vals.1 };
+                let die_val = if die_idx == 0 {
+                    dice_vals.0
+                } else {
+                    dice_vals.1
+                };
                 view! {
                     <div class="bar-die-slot">
                         {move || {
@@ -422,6 +476,38 @@ pub fn Board(
         }
     };
 
+    // §4a — animate checker moves. Deferred to a macrotask so Leptos has time
+    // to mount the Board's field divs before we query the DOM.
+    Effect::new(move |_| {
+        let Some((m1, m2)) = last_moves else { return };
+
+        // Collect the (to_field, dx, dy) pairs we need before moving into spawn_local.
+        let mut animations: Vec<(usize, f32, f32)> = Vec::new();
+        for m in [m1, m2] {
+            if m.get_from() == 0 && m.get_to() == 0 { continue; }
+            let Some((fx, fy)) = field_center(m.get_from(), is_white) else { continue };
+            let Some((tx, ty)) = field_center(m.get_to(), is_white) else { continue };
+            let dx = fx - tx;
+            let dy = fy - ty;
+            if dx.abs() < 1.0 && dy.abs() < 1.0 { continue; }
+            animations.push((m.get_to(), dx, dy));
+        }
+
+        #[cfg(target_arch = "wasm32")]
+        {
+            if let Some((to_field, dx, dy)) = animations.first().copied() {
+                gloo_timers::callback::Timeout::new(0, move || {
+                    apply_slide_animation(to_field, dx, dy);
+                }).forget();
+            }
+            if let Some((to_field, dx, dy)) = animations.get(1).copied() {
+                gloo_timers::callback::Timeout::new(300, move || {
+                    apply_slide_animation(to_field, dx, dy);
+                }).forget();
+            }
+        }
+    });
+
     let (tl, tr, bl, br) = if is_white {
         (&TOP_LEFT_W, &TOP_RIGHT_W, &BOT_LEFT_W, &BOT_RIGHT_W)
     } else {

client_web/src/components/game_screen.rs

@@ -119,6 +119,8 @@ pub fn GameScreen(state: GameUiState) -> impl IntoView {
 
     let is_double_dice = dice.0 == dice.1 && dice.0 != 0;
 
+    let last_moves = state.last_moves;
+
     // ── Capture for closures ───────────────────────────────────────────────────
     let stage = vs.stage.clone();
     let turn_stage = vs.turn_stage.clone();
@@ -214,6 +216,7 @@ pub fn GameScreen(state: GameUiState) -> impl IntoView {
                     bar_dice=show_dice.then_some(dice)
                     bar_is_move=is_move_stage
                     bar_is_double=is_double_dice
+                    last_moves=last_moves
                 />
 
                 // ── Side panel (scoring panels only) ─────────────────────────

client_web/src/trictrac/types.rs

@@ -41,6 +41,8 @@ pub struct ViewState {
     pub dice: (u8, u8),
     /// Jans (scoring events) triggered by the last dice roll.
     pub dice_jans: Vec<JanEntry>,
+    /// Last two checker moves played; default when no move has occurred yet.
+    pub dice_moves: (CheckerMove, CheckerMove),
 }
 
 /// One scoring event from a dice roll.
@@ -73,6 +75,7 @@ impl ViewState {
             ],
             dice: (0, 0),
             dice_jans: Vec::new(),
+            dice_moves: (CheckerMove::default(), CheckerMove::default()),
         }
     }
 
@@ -166,6 +169,7 @@ impl ViewState {
             scores: [score_for(host_store_id), score_for(guest_store_id)],
             dice: (gs.dice.values.0, gs.dice.values.1),
             dice_jans,
+            dice_moves: gs.dice_moves,
         }
     }
 }