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/web/game.ts

@@ -314,7 +314,7 @@ export type Menu = {
 };
 
 /** The action list as the page shows it: direct actions, plus subject-then-location for the rest. */
-export function actionMenu(game: Game): Menu {
+export function actionMenu(game: Game, seat: PlayerIndex = 0): Menu {
   const { options, groups } = actionGroups(game);
   const direct: ActionGroup[] = [];
   const placeableByTitle = new Map<string, Map<string, Placeable>>();
@@ -367,7 +367,7 @@ export function actionMenu(game: Game): Menu {
    * generate options, so changing the stored order would reshuffle its tie-breaks and invalidate
    * every revenue measurement in TODO.md. `snapshot()` reverses identically for the replay viewers.
    */
-  const handIds = [...(game.state.decks.hands.get(0) ?? [])].reverse();
+  const handIds = [...(game.state.decks.hands.get(seat) ?? [])].reverse();
   const hand: HandAction[] = handIds.map((cardId) => {
     const place = placeable.flatMap((g) => g.items).find((it) => it.subjectKey === `card:${cardId}`);
     let playNow: number | null = null;
@@ -554,7 +554,8 @@ function joinsNote(
 ): string {
   const v = variantsFor(geometry, hand)[variant ?? 0];
   if (!v) return '';
-  const area = areaOf(game.state, 0);
+  // The probe is against the district the placement would be made in, i.e. the actor's own.
+  const area = areaOf(game.state, currentActor(game) ?? 0);
   const probe = {
     geometry: { kind: 'track', geometry, ...v, ...(hand !== 'none' ? { hand } : {}) },
     baseOperationalRail: true, standing: [], facility: null, modifiers: [], enhancements: [],
@@ -601,9 +602,9 @@ function consistTitle(game: Game, trayId: string): string | null {
  * held. The same test the engine applies to `draw.end`, asked here so the page can DISABLE the
  * button with a reason instead of hiding a move that has simply become illegal.
  */
-export function overHandLimit(game: Game): boolean {
-  const hand = game.state.decks.hands.get(0) ?? [];
-  const limit = game.state.decks.redFlags.get(0) ? HAND_LIMIT + 1 : HAND_LIMIT;
+export function overHandLimit(game: Game, seat: PlayerIndex = 0): boolean {
+  const hand = game.state.decks.hands.get(seat) ?? [];
+  const limit = game.state.decks.redFlags.get(seat) ? HAND_LIMIT + 1 : HAND_LIMIT;
   return hand.length > limit;
 }
 
@@ -631,8 +632,8 @@ export function submit(game: Game, intent: Intent): boolean {
  * Modifier with no Facility to sit beside — looks identical to one where everything is available.
  * Derived from `legalActions`, so it cannot disagree with what the buttons offer.
  */
-export function handPlayable(game: Game): boolean[] {
-  const hand = game.state.decks.hands.get(0) ?? [];
+export function handPlayable(game: Game, seat: PlayerIndex = 0): boolean[] {
+  const hand = game.state.decks.hands.get(seat) ?? [];
   const actor = currentActor(game);
   if (actor === null) return hand.map(() => false);
   const playable = new Set(
@@ -643,9 +644,13 @@ export function handPlayable(game: Game): boolean[] {
   return hand.map((id) => playable.has(id));
 }
 
-/** The board as the replay draws it, so the live game and the replay agree. */
-export function view(game: Game): Frame {
-  return snapshot(game.state, [], null);
+/**
+ * The board as the replay draws it, so the live game and the replay agree.
+ *
+ * `seat` is whose railroad and whose hand to show. Solitaire has one seat and never passes it.
+ */
+export function view(game: Game, seat: PlayerIndex = 0): Frame {
+  return snapshot(game.state, [], null, null, null, false, seat);
 }
 
 function record(game: Game, events: GameEvent[], actor: PlayerIndex | null = null): void {