v0.3.1 — multiplayer groundwork: 13 engine tests covering 2-4 player games, a seat parameter on snapshot and actionMenu so a player sees their own railroad rather than seat 0's, and the 22 opponent-directed cards held out of every deck until they are built

src/engine/setup.ts

@@ -53,9 +53,20 @@ export type SetupOptions = {
 
 /** Builds the 52-card Home Office deck (§12.1). Unshuffled; caller shuffles with the seeded RNG. */
 export function buildDeck(mode: GameConfig['mode'] = 'competitive'): Card[] {
-  // Q6 — the 22 opponent-directed cards have no legal target in a one-player game, so a solitaire
-  // deck omits them entirely rather than leaving 19% of draws dead.
-  const solitaire = mode === 'solitaire';
+  /**
+   * THE 22 OPPONENT-DIRECTED CARDS ARE OUT OF EVERY DECK FOR NOW, not just the solitaire one.
+   *
+   * Q6 took them out of solitaire because they have no legal target in a one-player game. They are
+   * out of the competitive deck too because `checkPlay` answers both categories `NOT_IMPLEMENTED`:
+   * leaving them in would make ~9% of draws reject outright, which is worse than not dealing them.
+   * Three Enhancements — Facing Point Locks, Water Column and Overpass — exist only to answer these,
+   * and stay dormant until they come back. Recorded in TODO.md as multiplayer work.
+   *
+   * `mode` is still taken so the signature does not move when they return; it is deliberately unused
+   * for these two categories today.
+   */
+  void mode;
+  const opponentCardsInDeck = false;
   const cards: Card[] = [];
   let n = 0;
   const push = (kind: Card['kind']): void => {
@@ -73,7 +84,7 @@ export function buildDeck(mode: GameConfig['mode'] = 'competitive'): Card[] {
   for (const m of MODIFIER_PROFILES) {
     for (let i = 0; i < m.copies; i++) push({ kind: 'modifier', modifier: m.kind });
   }
-  if (!solitaire) {
+  if (opponentCardsInDeck) {
     for (const c of SPACE_USE_CARDS) {
       for (let i = 0; i < c.copies; i++) push({ kind: 'spaceUse', key: c.key });
     }
@@ -87,12 +98,12 @@ export function buildDeck(mode: GameConfig['mode'] = 'competitive'): Card[] {
   for (const c of MANEUVER_CARDS) {
     for (let i = 0; i < c.copies; i++) push({ kind: 'maneuver', key: c.key });
   }
-  if (!solitaire) {
+  if (opponentCardsInDeck) {
     for (const c of ACTION_CARDS) {
       for (let i = 0; i < c.copies; i++) push({ kind: 'action', key: c.key });
     }
   }
-  // Track is IN the deck, 104 cards of it — the single largest category, and the reason building a
+  // Track is IN the deck, 96 cards of it — the single largest category, and the reason building a
   // district costs you the industry or train you did not draw instead.
   for (const t of TRACK_CARDS) {
     for (let i = 0; i < t.copiesInDeck; i++) push({ kind: 'track', geometry: t.geometry, hand: t.hand });