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/intents.ts

@@ -147,7 +147,28 @@ export type Intent =
   | { type: 'laborer.startLoad'; at: GridCoord }
   | { type: 'laborer.advanceLoad'; at: GridCoord; box: number }
   | { type: 'laborer.beginUnload'; at: GridCoord; carIndex: number }
-  | { type: 'loadUnload.end' };
+  | { type: 'loadUnload.end' }
+  /**
+   * §3.3, EXTENDED PLAY (Gitea#11) — one vote on whether to play one more Day.
+   *
+   * ARRIVES OUT OF TURN, like `mainline.clearance`, and unlike it goes to EVERY seat rather than to
+   * the Superintendent: it is a table decision, not a ruling. Unanimous, and one `agree: false`
+   * ends the game immediately — nobody waits on a player who has already refused.
+   *
+   * It is an intent, rather than a button the client handles by itself, because a save is
+   * `{ seed, config, history }` replayed through the engine: a decision that is not in the history
+   * did not happen, and an extended game would evaporate on the next reload, Undo, or server
+   * restart. This is the record of the table agreeing.
+   *
+   * CARRIES ITS VOTER, uniquely among intents, and it has to. A saved history is a flat `Intent[]`
+   * with no seat recorded against each move: the replay DERIVES who acted from the turn order
+   * (`fromMultiplayerSave`). That works for every other intent, including `mainline.clearance`,
+   * because there is exactly one seat it could have been. Here there is not — every seat may vote,
+   * in any order — so a vote whose voter is not written down cannot be replayed at all, and a
+   * resumed server would refuse the save with `NO_ACTOR`. The server checks this against the seat
+   * it authenticated (`NOT_YOUR_TURN`), so it is a record, never a claim.
+   */
+  | { type: 'game.extend'; player: PlayerIndex; agree: boolean };
 
 export type IntentType = Intent['type'];
 
@@ -276,7 +297,11 @@ export type RejectionCode =
    * §6.2, Jesse's ruling (Gitea#6) — a train card is never discarded. Hold it as long as you like;
    * the only way it leaves your hand is onto the timetable.
    */
-  | 'TRAINS_ARE_NEVER_DISCARDED';
+  | 'TRAINS_ARE_NEVER_DISCARDED'
+  /** §3.3 (Gitea#11) — `game.extend` when the game is not waiting on an extension vote. */
+  | 'NOT_AWAITING_EXTENSION'
+  /** §3.3 (Gitea#11) — this seat has already voted on this extension. */
+  | 'ALREADY_VOTED';
 
 export type Rejection = { code: RejectionCode; message: string };