v0.7.3 — a game that asks before it ends, and a results screen worth reading

Two issues off the tracker, and they are halves of one thing: the end of a game.
Neither ships on the 0.4.9 line — Jesse's call, that line may be complete and
these are not fixes people mid-playtest need.

EXTENDED PLAY (#11). The official result is settled at the original game length
and never changes: in a five-Day game extended to eight, the winner is whoever
led at the end of Day 5. Extending grants exactly one Day and the question is put
again at the end of it — solitaire the player decides alone, multiplayer it is
unanimous and one refusal ends it there. Only days-based endings offer it; a §3.4
collision breach is final, during an extended Day exactly as during the scheduled
game.

It could not be a client-side change. `check` refused every intent once `status`
left `active`; the server never loads a `finished` game back into memory; and a
save is `{ seed, config, history }` replayed through the engine, so a "continue"
the history does not record did not happen. Hence a fourth status,
`awaitingExtension`, and a `game.extend` intent. `config.days` never moves —
`extraDays` counts the borrowed Days and `official` freezes the outcome, the
standings and the statistics at the first ending.

THE RESULTS SCREEN (#16). `GAME OVER — revenueFloor` was `outcome.reason`, an
internal enum interpolated into the page at the one moment the game has the
player's whole attention. Every reason now has a sentence with the game's own
numbers in it. Around it: the result and winner, standings, the rules the game
was dealt under, a per-player breakdown, and the railroad — trains through the
Division and how many worked en route, loads made up and broken, passengers, cars
switched, trains destroyed. It shares the Day-end dialog's blocks rather than
reimplementing them, and stays reopenable so continuing does not cost you the
results.

Statistics are folded, not recorded: `state.tally` counts what the event stream
says happened, hooked at `applyIntent` and `advance` because `reduce` never sees
the phase driver's events — and those are the interesting ones. Nothing in the
rules reads it, and it rides the Frame, so multiplayer gets the same numbers as
solitaire from one implementation.

THREE BUGS FOUND IN TESTING, all of which would have shipped:

  - a saved game containing a vote could not be resumed (NO_ACTOR). A history is
    a flat Intent[] with no seat recorded; the replay derives who acted from the
    turn order, which cannot work for an intent every seat may send in any order.
    `game.extend` carries its voter, checked against the authenticated seat.
  - an all-bot game hung on the question for ever. `driveBots` loops on
    `currentActor`, null the moment the game stops, so it cannot cast a vote, and
    the bot-vote driver returned early with no humans to follow.
  - the balance harness became unbounded — `test/sim.test.ts` went from under a
    second to never finishing. `randomBot` took another Day about half the time,
    so every seeded game ran to playGame's 50,000-turn cap. Fixed in the driver,
    not in a policy, so it holds for bots not yet written.

All three have regression tests. 832 tests pass, against 793 before this change.

NOT BUILT, and a correction. #16's own comment said `trainStoodStill` "is emitted
per Stage, so a run of them is exactly the sat-on-a-siding streak". It is not:
reading advance.ts, it fires once per game and only for a train whose profile
sets `stopEarnsPoint` — the X18 Circus — with `stopPointClaimed` preventing a
second. The streak was built, rendered "1 Stage at (0,0)", and was taken out
again. There is no per-Stage "this train did not move" signal in the engine, so
"longest an engine sat on a siding" needs one first; TODO.md #36 records what it
would take, and the Circus set-up is reported instead. Badges remain the second
pass #16 asks for (TODO.md #33), and because the statistics are derived rather
than recorded, that pass can add any of them retroactively to games already
played and saved.

Extended play has not yet been played at a real table (TODO.md #35): the
multiplayer vote has only been driven through `session.intent`, never through two
browsers.

Closes #11
Closes #16

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EAgJSmeV8zrMh55Mj85ESb

src/engine/tally.ts

@@ -0,0 +1,201 @@
+/**
+ * The event tally — Gitea#16's statistics, folded from the event stream into `GameState.tally`.
+ *
+ * WHERE IT IS HOOKED, and why it is not in `reduce`. `apply.ts`'s `reduce` sees only the events an
+ * INTENT produced; `advance.ts` mutates state directly and pushes its events without reducing them
+ * at all — and `advance` is where `trainCompleted`, `trainsDestroyed` and `trainStoodStill` come
+ * from, which are exactly the numbers this issue asks for. So the fold is hooked at the two places
+ * every event in the game passes through exactly once on its way to a caller:
+ *
+ *   - `applyIntent` (`apply.ts`), beside its `reduce` loop;
+ *   - `advance` (`advance.ts`), which now wraps the phase driver and folds what it returns.
+ *
+ * Exactly once matters in both directions: an event folded twice inflates a count, and an event
+ * folded nowhere is a statistic that silently reads zero. `test/tally.test.ts` pins both by playing
+ * real games and checking the tally against an independent count over the same event array.
+ *
+ * NOTHING HERE IS A RULE. The tally is read by the results screen and by the badge work Gitea#16
+ * leaves to a second pass; no engine decision consults it. That is what makes adding a counter
+ * always safe.
+ *
+ * WHAT IS NOT COUNTED PER PLAYER, and why. `carsCoupled` and `carsDropped` carry a `trayId` and no
+ * `player` — switching is done BY a crew, and the event says which crew rather than which person.
+ * Rather than guess an owner from whose turn it happened to be, those two are table totals only.
+ * The events that do name a player (`loadCompleted`, `passengersBoarded`, `cardPlayed`,
+ * `revenueChanged`, `trainsDestroyed`) are the ones `byPlayer` reports.
+ */
+
+import type { GameEvent } from './events.ts';
+import type { GameState } from './state.ts';
+
+/**
+ * Fold one event into `s.tally`.
+ *
+ * The switch is deliberately not exhaustive — most of the 49 event types say nothing a player would
+ * want counted, and listing them all to `break` would bury the ones that do. A `default` that does
+ * nothing is the honest shape.
+ */
+export function tallyEvent(s: GameState, e: GameEvent): void {
+  const t = s.tally;
+  const mine = 'player' in e && typeof e.player === 'number' ? t.byPlayer[e.player] : undefined;
+
+  switch (e.type) {
+    /**
+     * §X18 — the Circus train set up and was paid for the Stage it spent standing.
+     *
+     * NOT a "longest stand" streak, which is what Gitea#16 wants and what its comment assumed this
+     * event was. It fires once in a game per such train: only trains whose profile sets
+     * `stopEarnsPoint` emit it at all, and `advance.ts` claims it once with `stopPointClaimed`. So
+     * there is nothing to count a run of, and the honest thing to report is the event itself.
+     */
+    case 'trainStoodStill':
+      t.circusStops.push({ trainNumber: e.trainNumber, where: e.where });
+      break;
+
+    /**
+     * DID THIS TRAIN DO ANY SWITCHING — Gitea#16's "switching master" join, kept as it happens
+     * rather than reconstructed afterwards.
+     *
+     * The two halves of the join are in different currencies: switching events name a `trayId` and
+     * completion names a `trainNumber`, and no event carries both. The tray is looked up in LIVE
+     * state, which is sound precisely here — a crew that has just coupled or dropped is still on the
+     * board — where re-deriving it at completion time would not be, the tray having been released by
+     * then. A lookup that misses costs one train its mark on a statistic; it cannot affect a rule.
+     */
+    case 'carsCoupled':
+      t.carsCoupled += e.stock.length;
+      markSwitched(s, e.trayId);
+      break;
+
+    case 'carsDropped':
+      t.carsDropped += e.stock.length;
+      markSwitched(s, e.trayId);
+      break;
+
+    case 'flyingSwitch':
+      t.flyingSwitches += 1;
+      markSwitched(s, e.trayId);
+      break;
+
+    // A tray is reused run after run, so a fresh train starts with a clean sheet.
+    case 'trainMadeUp':
+      t.switchedSince = t.switchedSince.filter((n) => n !== e.trainNumber);
+      break;
+
+    case 'trainCompleted':
+      t.trainsCompleted += 1;
+      if (t.switchedSince.includes(e.trainNumber)) t.trainsCompletedWithWork += 1;
+      t.switchedSince = t.switchedSince.filter((n) => n !== e.trainNumber);
+      break;
+
+    case 'trainsDestroyed':
+      t.trainsDestroyed += e.trains.length;
+      for (const train of e.trains) t.carsDestroyed += train.consist.length;
+      if (mine) mine.collisions += 1;
+      break;
+
+    case 'officeUpgraded':
+      t.officeUpgrades += 1;
+      break;
+
+    case 'dispatchBonusUsed':
+      t.dispatchBonusesUsed += 1;
+      break;
+
+    case 'facilityUnjammed':
+      t.facilitiesUnjammed += 1;
+      break;
+
+    case 'expediteFault':
+      t.expediteFaults += 1;
+      break;
+
+    case 'trainHeld':
+      t.trainsHeld += 1;
+      break;
+
+    case 'trainDiverted':
+      t.trainsDiverted += 1;
+      break;
+
+    case 'secondSectionOrdered':
+      t.secondSections += 1;
+      break;
+
+    case 'extraStarted':
+      t.extrasStarted += 1;
+      break;
+
+    case 'cardDrawn':
+      t.cardsDrawn += 1;
+      break;
+
+    case 'cardPlayed':
+      t.cardsPlayed += 1;
+      if (mine) mine.cardsPlayed += 1;
+      break;
+
+    case 'cardDiscarded':
+      t.cardsDiscarded += 1;
+      break;
+
+    case 'clearanceRequested':
+      t.clearancesRequested += 1;
+      break;
+
+    // §8.1 — a ruling is given either way; only a YES let the other train through.
+    case 'clearanceGiven':
+      if (e.allow) t.clearancesAllowed += 1;
+      break;
+
+    case 'loadStarted':
+      t.loadsStarted += 1;
+      break;
+
+    case 'loadCompleted':
+      t.loadsCompleted += 1;
+      if (mine) mine.loads += 1;
+      break;
+
+    case 'unloadBegan':
+      t.unloadsBegun += 1;
+      break;
+
+    case 'unloadCompleted':
+      t.unloadsCompleted += 1;
+      if (mine) mine.unloads += 1;
+      break;
+
+    case 'passengersBoarded':
+      t.passengersBoarded += 1;
+      if (mine) mine.passengersBoarded += 1;
+      break;
+
+    case 'passengersDetrained':
+      t.passengersDetrained += 1;
+      if (mine) mine.passengersDetrained += 1;
+      break;
+
+    /**
+     * Gained and lost are kept APART because the net is already on `players[i].revenue`. What the
+     * results screen cannot otherwise say is how much of a modest final score was earned and then
+     * handed back at a grade crossing — which is the whole difference between a quiet game and an
+     * eventful one.
+     */
+    case 'revenueChanged':
+      if (mine) {
+        if (e.delta >= 0) mine.revenueGained += e.delta;
+        else mine.revenueLost += -e.delta;
+      }
+      break;
+
+    default:
+      break;
+  }
+}
+
+function markSwitched(s: GameState, trayId: string): void {
+  const n = s.trays.get(trayId)?.trainNumber;
+  if (n === undefined || n === null) return;
+  if (!s.tally.switchedSince.includes(n)) s.tally.switchedSince.push(n);
+}