卫戍协议：盟约 web remake — initial import

Online co-op browser remake of Arknights' Stronghold Protocol: Alliance
(client-simulated combat, official waves/bonds/items/strategies, 3D board,
facing wheel, operator loadout, official emotes, deployment scripts).

public/js/render/prepfield.js

@@ -0,0 +1,70 @@
+// render/prepfield.js — where the prep board is shown (research 09 §1.2, DESIGN §3 / §15): normally the own board
+// (rows 7–12, the stage grid as is); in the Final Assault / Hidden Core prep the player's pieces stand on THEIR half of
+// the boss field — the sim's mapping (server/match/finalAssault.js bossFieldPlacement, sim Battle.mapTile / mapDir):
+// board rows ≥ 7 → row − 7 (board 9–12 → boss 2–5, the bench row 7 → 0, the temp row 8 → 1); the right-hand player
+// (side 'R') is mirrored col c → 20 − c with RIGHT ↔ LEFT (UP / DOWN unchanged, ConvertChessPositionInfoToBossMap).
+// Pieces only ever stand on rows ≥ 7; other board rows (range tiles reaching past the field) shift the same way, so a
+// DOWN range below the bench falls off the grid (row < 0) instead of landing on the boss rows, and `tilesToDisp` drops
+// every tile that is not on the boss field (rows 0–6) — e.g. an UP range past the top wall onto the normal board.
+//
+// The view keeps every public coordinate in BOARD space (the server's, g.move targets, canPlace, highlightTiles,
+// tileScreen, holdPiece, setPieceDir): only what is drawn and picked goes through this transform. Pure functions.
+
+export const BOSS_ROW_SHIFT = -7;
+export const MAX_COL = 20;
+
+const MIRROR = Object.freeze({ RIGHT: 'LEFT', LEFT: 'RIGHT', UP: 'UP', DOWN: 'DOWN' });
+
+/** RIGHT ↔ LEFT (UP / DOWN unchanged); unknown values pass through. */
+export function mirrorDir(d) {
+  return typeof d === 'string' && MIRROR[d.toUpperCase()] ? MIRROR[d.toUpperCase()] : d;
+}
+
+/** The identity transform (normal prep). */
+export const IDENTITY = Object.freeze({
+  kind: 'board', side: 'L', mirror: false,
+  toDisp: (row, col) => ({ row, col }),
+  toBoard: (row, col) => ({ row, col }),
+  dirToDisp: (d) => d,
+  dirToBoard: (d) => d,
+});
+
+/**
+ * Transform of the Final Assault prep on side 'L' | 'R' of the boss field. `toBoard` returns null for display tiles
+ * that are not on the player's half of the boss rows (0–5) — nothing of the board is there.
+ */
+export function bossPrepField(side) {
+  const R = side === 'R';
+  const lo = R ? 10 : 0, hi = R ? MAX_COL : 10;
+  return Object.freeze({
+    kind: 'bossPrep', side: R ? 'R' : 'L', mirror: R,
+    toDisp: (row, col) => ({ row: row + BOSS_ROW_SHIFT, col: R ? MAX_COL - col : col }),
+    toBoard: (row, col) => {
+      if (!Number.isInteger(row) || !Number.isInteger(col) || row < 0 || row > 5 || col < lo || col > hi) return null;
+      return { row: row - BOSS_ROW_SHIFT, col: R ? MAX_COL - col : col };
+    },
+    dirToDisp: (d) => (R ? mirrorDir(d) : d),
+    dirToBoard: (d) => (R ? mirrorDir(d) : d),
+  });
+}
+
+/** Last display row of the boss field band (rows 0–5 + the wall row 6) in the Final Assault prep. */
+export const BOSS_DISP_MAX_ROW = 6;
+
+/**
+ * Map a list of board tiles ([[r,c]] or [{row,col}]) to display tiles ([[r,c]]). In the Final Assault prep tiles that
+ * do not land on the boss field (display rows 0–6, cols 0–20) are dropped.
+ */
+export function tilesToDisp(xf, tiles) {
+  const out = [];
+  if (!Array.isArray(tiles)) return out;
+  const boss = xf && xf.kind === 'bossPrep';
+  for (const t of tiles) {
+    const r = Array.isArray(t) ? t[0] : t?.row, c = Array.isArray(t) ? t[1] : t?.col;
+    if (!Number.isInteger(r) || !Number.isInteger(c)) continue;
+    const d = xf.toDisp(r, c);
+    if (boss && (d.row < 0 || d.row > BOSS_DISP_MAX_ROW || d.col < 0 || d.col > MAX_COL)) continue;
+    out.push([d.row, d.col]);
+  }
+  return out;
+}