v0.5.3 — a table you size yourself, and games an administrator can see and end

Both halves came out of playing the StartOS build. The wrapper's health
check and admin actions consume this; they land separately.

The host picks the table size (2-4) when creating a game, and the seats
array is built at that length once. Before, it GREW as people joined, so
the four rows on screen were partly fiction — a 2-player game just started
with a 2-long array, while a host who dropped a bot into a later chair
padded it with a null and silently disabled Start behind a one-line note.
A gap can no longer be written down rather than merely being refused.

That also avoided a trap. Compacting seats at Lobby.Start — the obvious
way to support a "closed" chair — would have shifted the player index that
every PlayerSession stamps at join time and that /api/stream and
/api/intent both route by, handing a player somebody else's railroad with
no error anywhere.

And it fixed a live balance bug: minCombinedRevenue is derived from the
player count, but the config was fixed at CREATE while the count wasn't
known until START, so the lobby guessed 4. Every 2-player game ran against
a floor of 60 instead of 30 — and missing the floor means everyone loses,
so a 2-player competitive game was set up to fail for a UI artifact rather
than a rule.

/api/health gained games:{active,lobby}, read from a new cheap summary()
on GameSession rather than exportSave(), which would copy every intent of
every game to answer a question about none of them. Three admin routes are
new behind an ADMIN_SECRET env var in an x-admin-secret header: GET
/api/games, GET /api/games/<id>/save, DELETE /api/games/<id>. Until now a
started game could not be ended by anyone — no route, no player action, no
resignation — so an abandoned game stayed active in the index and was
faithfully resumed on every boot, forever.

Three deliberate choices there: the admin secret is NOT the join secret,
which every player holds and which would therefore let anyone at the table
destroy anyone else's game; unset means the routes 404 exactly as any
unknown path does, with or without a header, so a server never given an
administrator doesn't advertise that it has one; and a delete returns the
deleted game's save, since the intents are the game (D5) — nothing is
destroyed without being handed to whoever destroyed it.

SavedGame gained an optional lastMoveAt (falling back to createdAt) so
"has this stalled?" survives a restart. Kept out of history for the same
reason the turn timings are: a replay must reproduce a game from decisions
alone, and wall-clock is not a decision.

index.ts logs "Resuming N saved games..." before the loop rather than one
line per game after it. Measured a full 4-player game at 100ms to replay,
and only unfinished games are replayed, so listening before loading would
have bought nothing for the cost of a "still loading" state everywhere.

Verified: 667 tests pass (662 + 5), and the new session tests were checked
against two mutations (lastMoveAt never advancing; resume dropping it) to
confirm they fail without the code. Live against a running server: health
counts tracking through the lobby->game transition, admin auth rejecting a
missing and a wrong secret, list/export/delete, the deleted game's files
and index entry actually gone from disk, a second delete 404ing, the admin
routes invisible when ADMIN_SECRET is unset, and a 3-player table refusing
a 4th player and a size of 5 refused at the door.

Also carries the TODO items raised on 2026-08-21: the lobby offering no
game parameters (the floor bug within it now fixed, the form still
missing), and the four optionalRules — of which only reducedVisibility and
emergencyToolbox are read by anything, while sisterTrains and
employeeRotation are declared, defaulted, and consulted nowhere.

src/server/lobby.ts

@@ -81,16 +81,40 @@ export function playerCountAllowed(mode: GameConfig['mode'], count: number): boo
 }
 
 /** The creating player is the host and takes seat 0 (`lobby-and-sessions.md` §2). */
-export function createLobby(config: GameConfig, hostDisplayName: string, gameCode: string): CreateResult {
+/**
+ * THE TABLE SIZE IS FIXED WHEN THE GAME IS CREATED, and `seats.length` is it.
+ *
+ * The host says how many are playing, so the seats array is built at full length with the host in
+ * chair 0 and the rest empty. Nothing ever grows or shrinks it, which is what makes a gap
+ * impossible to express rather than merely illegal — and that matters more than it looks: seats
+ * used to be appended as people joined, so a bot dropped into a later chair padded the array with
+ * a hole that silently blocked Start. It also removes any need to compact the seats at
+ * `Lobby.Start`, and compaction would have shifted the `player` index every `PlayerSession`
+ * already carries (`joinLobby` stamps it at join time, and `/api/stream` and `/api/intent` route
+ * by it) — quietly handing a player somebody else's railroad.
+ *
+ * Knowing the count this early has one more consequence, and it is a bug fix: the config's
+ * `minCombinedRevenue` is derived from the player count, and the lobby previously had to guess it
+ * as 4 before anyone had sat down.
+ */
+export function createLobby(
+  config: GameConfig,
+  hostDisplayName: string,
+  gameCode: string,
+  players: number,
+): CreateResult {
   const gameId = randomUUID();
   const token = randomUUID();
   const session: PlayerSession = { token, gameId, player: 0, displayName: hostDisplayName };
+  const seats: LobbySeat[] = Array.from({ length: players }, (_, i) =>
+    i === 0 ? { kind: 'human', token, displayName: hostDisplayName } : null,
+  );
   const lobby: Lobby = {
     gameId,
     gameCode,
     hostToken: token,
     config,
-    seats: [{ kind: 'human', token, displayName: hostDisplayName }],
+    seats,
     joinOrder: [token],
     createdAt: Date.now(),
   };
@@ -103,10 +127,10 @@ export function createLobby(config: GameConfig, hostDisplayName: string, gameCod
  * play in, but the running count is checked against `playerCountAllowed` at every join too, so a
  * lobby can never grow the seats array past what could legally start). */
 export function joinLobby(lobby: Lobby, displayName: string): JoinResult {
-  const cap = lobby.config.mode === 'solitaire' ? 1 : 4;
-  const empty = lobby.seats.findIndex((s) => s === null);
-  const seatIndex = empty >= 0 ? empty : lobby.seats.length;
-  if (seatIndex >= cap) return { ok: false, code: 'LOBBY_FULL' };
+  // The table was sized at creation, so joining takes an empty chair or none at all — there is no
+  // longer an "append another seat" path for a late arrival to grow the game through.
+  const seatIndex = lobby.seats.findIndex((s) => s === null);
+  if (seatIndex < 0) return { ok: false, code: 'LOBBY_FULL' };
 
   const token = randomUUID();
   const session: PlayerSession = { token, gameId: lobby.gameId, player: seatIndex, displayName };
@@ -124,7 +148,9 @@ export function joinLobby(lobby: Lobby, displayName: string): JoinResult {
  * human seat; the host removes a person by them leaving, not by overwriting their seat. */
 export function setBotSeat(lobby: Lobby, seat: PlayerIndex, filled: boolean): Lobby {
   const seats = [...lobby.seats];
-  while (seats.length <= seat) seats.push(null);
+  // No padding: a seat outside the table the host chose is not a seat, and inventing one is how
+  // the old array grew holes in it.
+  if (seat < 0 || seat >= seats.length) return lobby;
   if (filled) {
     if (seats[seat] !== null) return lobby;
     seats[seat] = { kind: 'bot' };
@@ -157,11 +183,14 @@ export function reassignHost(lobby: Lobby, departingToken: string): Lobby {
  */
 export function startLobby(lobby: Lobby, callerToken: string): StartResult {
   if (callerToken !== lobby.hostToken) return { ok: false, code: 'NOT_HOST' };
-  const filled = lobby.seats.filter((s) => s !== null);
-  if (filled.length !== lobby.seats.length || !playerCountAllowed(lobby.config.mode, filled.length)) {
+  // Every chair at the table must be taken. The size itself was validated at creation and cannot
+  // have moved since, so this is only ever waiting on the last empty seat to fill.
+  if (lobby.seats.some((s) => s === null) || !playerCountAllowed(lobby.config.mode, lobby.seats.length)) {
     return { ok: false, code: 'BAD_PLAYER_COUNT' };
   }
-  const playerNames = filled.map((s) => (s!.kind === 'human' ? s.displayName : 'Bot'));
-  const botSeats = filled.flatMap((s, i) => (s!.kind === 'bot' ? [i as PlayerIndex] : []));
+  // Seat index IS player index — no compaction, because there is nothing to compact past.
+  const taken = lobby.seats as Exclude<LobbySeat, null>[];
+  const playerNames = taken.map((s) => (s.kind === 'human' ? s.displayName : 'Bot'));
+  const botSeats = taken.flatMap((s, i) => (s.kind === 'bot' ? [i as PlayerIndex] : []));
   return { ok: true, playerNames, botSeats };
 }