v0.5.0 — multiplayer Phases 2 and 3: a server that runs a game and survives being restarted

Phases 0-1 shipped in v0.4.0 (seat/identity split, per-player turn state, the Session boundary).
This lands Phase 2 (server core, one game, no lobby) and Phase 3 (persistence and resumption) per
docs/architecture/multiplayer.md §12. Phases 4-6 (lobby/reconnection, the 22 opponent-directed
cards, StartOS packaging) are still ahead.

Phase 2: src/server/session.ts hosts a game in pure logic (no sockets) on top of game.ts's existing
Game/submit/currentActor/actionMenu; it verifies seat === currentActor(game) itself before calling
submit, since submit() trusts its caller and a server can't. src/server/http.ts and index.ts add
POST /api/game, GET /api/stream (SSE, per-seat), POST /api/intent, and static serving of dist/.
src/sim/frame-delta.ts is a purpose-built per-seat board delta for one live push at a time. Found
and fixed along the way: actionMenu(game, seat) only used seat for the hand field, so a server
computing every connected seat's Menu would have handed the acting player's legal moves to a
waiting seat. Verified with a live end-to-end smoke test (2-player game, two SSE streams, a
rejected intent from the wrong seat, an idempotent resend) plus test/server/session.test.ts and
test/redaction.test.ts. Not verified: an actual browser (none available in this environment).

Phase 3: src/server/persistence.ts writes game.json and turn-timings.json, atomic-rewrite-then-
rename. game.ts gained fromMultiplayerSave, fixing a narration-attribution bug found while testing
it (fromSave's replay loop drops the actor argument, invisible in solitaire, unreadable the moment
there's more than one seat — fromSave itself still has this gap, deliberately untouched). Verified
live: server killed and restarted mid-game, both seats reconnected exactly where they left off.

Two rules bugs found while building this: the New Train phase never implemented its car-placement
round (every car of every train was placed by the Superintendent alone, in every mode, all along —
now reads the round position off tray.consist.length); and victory conditions are now one shared,
configurable GameConfig set across solitaire/competitive/coop instead of a fixed length lookup and
a dead firstToTarget condition.

Also folds in the three fixes already released on the patch line as v0.4.9b/c/d: a switching
train's crew badge failing to draw once it left the Office square, an unload that always took the
westmost car regardless of which was picked, and a legal decision that could render with zero
buttons.

docs/testing/0.5.0-test-plan.md and three reported-bug save files (docs/station-master-seed*.json)
included for reproducibility. tools/jitsi-harness/ deliberately left untracked — unrelated
side-project work, not part of this release. 635 tests, 0 failures.

test/train-rules.test.ts

@@ -19,8 +19,11 @@ import { trainRules } from '../src/sim/view.ts';
 
 const config: GameConfig = {
   mode: 'solitaire',
-  victory: 'highestAfterDays',
-  length: 'standard',
+  days: 5,
+  minCombinedRevenue: 0,
+  maxCollisionsPerDay: 0,
+  maxCollisionsTotal: 0,
+  pvpCardsAllowed: false,
   optionalRules: { reducedVisibility: false, sisterTrains: false, employeeRotation: false, emergencyToolbox: false },
 };
 const game = (seed = 5): GameState => createGame({ id: 'g', seed, config, playerNames: ['p'] });
@@ -46,9 +49,9 @@ function switching(
 ): string {
   const area = areaOf(s, 0);
   const office = area.officeCoord;
-  // The crew stands one square west of the Office and works westward. It may NOT stand on the Office
-  // itself: §A.4 forbids leaving Rolling Stock on the Office track, so every drop there is refused
-  // whatever the train's own card says.
+  // The crew stands one square west of the Office and works westward, away from the Office square's
+  // own special-cased drop rule (§A.4 forbids everything but a coach there, v0.5.0) — tests that want
+  // that exception exercise it directly instead.
   const here = { row: office.row, col: office.col - 1 };
   area.grid.set(coordKey(here), straight());
   area.grid.set(coordKey({ row: office.row, col: office.col - 2 }), straight(westCars));
@@ -202,6 +205,41 @@ describe('§7 — the Local keeps its coach (trains 7/8)', () => {
     switching(s, 9, false, [boxcar(), coach()]);
     assert.equal(check(s, 0, { type: 'switch.dropCars', trayId: 't', count: 1 }), null);
   });
+
+  it('may set the coach out at the Office — the one place §A.4 now allows it (v0.5.0)', () => {
+    const s = game();
+    const area = areaOf(s, 0);
+    const office = area.officeCoord;
+    s.trays.set('t', {
+      id: 't',
+      trainNumber: 7,
+      trainIsExtra: false,
+      engineAt: 0,
+      consist: [boxcar(), coach()],
+      direction: 'west',
+      facing: 'w',
+      position: { at: 'grid', seat: 0, coord: office },
+      movesUsed: 0,
+    });
+    s.clock.phase = 'localOps';
+    s.clock.currentActor = 0;
+    turnOf(s, 0).option = 'switch';
+    turnOf(s, 0).movesRemaining = 6;
+
+    assert.equal(
+      check(s, 0, { type: 'switch.dropCars', trayId: 't', count: 1 }),
+      null,
+      'the coach may be cut loose at the Office',
+    );
+    assert.ok(applyIntent(s, 0, { type: 'switch.dropCars', trayId: 't', count: 1 }).ok);
+    const officeCard = area.grid.get(coordKey(office))!;
+    assert.deepEqual(
+      officeCard.standing.map((c) => c.type),
+      ['coach'],
+      'the coach is parked on the Office card',
+    );
+    assert.equal(s.trays.get('t')!.consist.length, 1, 'the coach left the tray');
+  });
 });
 
 describe('§7 — trains Porters may not work', () => {