v0.4.1 - bug fixes. initial d12 rolls determine what player in which seat.

src/engine/state.ts

@@ -543,12 +543,19 @@ export type GameState = {
   rngState: number;
   players: Player[];
   /**
-   * Who is sitting where: `seating[seat] = player`.
+   * Who is sitting where: `seating[seat] = player`, seat 0 at the WESTERN end of the chain.
    *
-   * The identity mapping in every game today, which is what makes the seat/player split
-   * behaviour-neutral. Employee Rotation would rotate this array and nothing else.
+   * Decided at setup by §4.4's D12 (`openingRolls.division`) — a real permutation, not the identity,
+   * except in solitaire where one player means one seat. Employee Rotation would rotate this array
+   * and nothing else.
    */
   seating: PlayerIndex[];
+  /**
+   * The two opening D12s, per player, kept so a client can show the rolls rather than only their
+   * outcome — it is the game's first moment of drama (`lobby-and-sessions.md` §4). Indexed by
+   * PLAYER, since that is who rolls.
+   */
+  openingRolls: { division: number[]; superintendent: number[] };
   division: Division;
   officeAreas: Map<SeatIndex, OfficeArea>;
   trays: Map<TrayId, CrewTray>;
@@ -623,6 +630,22 @@ export function playerAtSeat(state: GameState, seat: SeatIndex): PlayerIndex {
 }
 
 /** Where this player is sitting, and therefore which Office Area is theirs. */
+/**
+ * The player `n` seats to the LEFT of this one, wrapping round the table.
+ *
+ * Acting order, the deal and the Fedora are all "starting here and proceeding left" (Gap 1, §4.7,
+ * §5), which is a statement about the physical chain of Offices — so it is seat arithmetic, not
+ * player arithmetic. All three used to do `(player + n) % players`, which was the same thing only
+ * while seating was the identity mapping. It stopped being that when §4.4's D12 started deciding
+ * who sits where.
+ *
+ * "Left" is increasing seat index, i.e. eastward along the chain, matching what the shift-change
+ * tests have always asserted.
+ */
+export function playerLeftOf(state: GameState, player: PlayerIndex, n = 1): PlayerIndex {
+  return playerAtSeat(state, (seatOf(state, player) + n) % state.seating.length);
+}
+
 export function seatOf(state: GameState, player: PlayerIndex): SeatIndex {
   const seat = state.seating.indexOf(player);
   if (seat < 0) throw new Error(`player ${player} is not seated`);