feat(ui): Compass component — pinwheel layout, click-to-move wiring

src/lib/Compass.svelte

@@ -0,0 +1,83 @@
+<script lang="ts">
+  import Board from './Board.svelte';
+  import { gameStore } from './stores/game.svelte';
+  import { PLAYER_BOARDS } from '../engine/boards';
+  import type { BoardId, Player, Square } from '../engine/types';
+
+  const COLORS: Record<Player, string> = {
+    N: '#4a90d9', S: '#d6483f', E: '#9d5bd2', W: '#e08a3a',
+  };
+  // Board centre positions inside the 744x744 compass (see spec §5.1).
+  const POS: Record<BoardId, { left: number; top: number }> = {
+    NW: { left: 200, top: 200 }, NE: { left: 544, top: 200 },
+    SW: { left: 200, top: 544 }, SE: { left: 544, top: 544 },
+  };
+  const BOARD_IDS: BoardId[] = ['NW', 'NE', 'SW', 'SE'];
+
+  let view = $derived(gameStore.view);
+  let active = $derived(gameStore.activeBoards);
+
+  /** Ghost squares for a given board. */
+  function ghostsFor(id: BoardId): Square[] {
+    return view.ghosts.filter((g) => g.board === id).map((g) => g.square);
+  }
+
+  /** Highlight payload for a given board, or null. */
+  function highlightFor(id: BoardId) {
+    const h = gameStore.highlight;
+    if (h === null) return null;
+    if (id !== h.boardA && id !== h.boardB) return null;
+    const local = id === h.boardA ? h.onlyA : h.onlyB;
+    const selectedHere = active.includes(id) ? gameStore.selected : null;
+    return { playable: h.playable, local, selected: selectedHere };
+  }
+
+  function handleSquare(id: BoardId, square: Square): void {
+    if (gameStore.isScrubbing) return;
+    if (!active.includes(id)) return; // only the player-to-move's boards are interactive
+    if (gameStore.selected === null) {
+      gameStore.select(square);
+    } else if (gameStore.highlight?.playable.includes(square)) {
+      gameStore.commitTo(square);
+    } else {
+      gameStore.select(square); // re-grab or cancel
+    }
+  }
+</script>
+
+<div class="compass" style="--glow:{COLORS[view.currentPlayer]}">
+  {#each BOARD_IDS as id (id)}
+    <div class="slot" style="left:{POS[id].left}px; top:{POS[id].top}px;">
+      <Board
+        {id}
+        fen={view.fen[id]}
+        colors={COLORS}
+        ghosts={ghostsFor(id)}
+        highlight={highlightFor(id)}
+        active={active.includes(id)}
+        onSquare={(sq) => handleSquare(id, sq)}
+      />
+    </div>
+  {/each}
+
+  <div class="plabel" class:on={view.currentPlayer === 'N'}
+       style="left:372px; top:74px; background:{COLORS.N}">NORTH</div>
+  <div class="plabel" class:on={view.currentPlayer === 'S'}
+       style="left:372px; top:670px; background:{COLORS.S}">SOUTH</div>
+  <div class="plabel vert" class:on={view.currentPlayer === 'E'}
+       style="left:670px; top:372px; background:{COLORS.E}">EAST</div>
+  <div class="plabel vert" class:on={view.currentPlayer === 'W'}
+       style="left:74px; top:372px; background:{COLORS.W}">WEST</div>
+</div>
+
+<style>
+  .compass { position: relative; width: 744px; height: 744px; flex: none; }
+  .slot { position: absolute; transform: translate(-50%, -50%); }
+  .plabel {
+    position: absolute; transform: translate(-50%, -50%);
+    color: #fff; font-size: 12px; font-weight: 700; letter-spacing: 0.09em;
+    padding: 6px 12px; border-radius: 7px; white-space: nowrap;
+  }
+  .plabel.vert { writing-mode: vertical-rl; }
+  .plabel.on { box-shadow: 0 0 14px currentColor; }
+</style>