v0.8.5 — housekeeping from the audit, and the playtest line retired

The third release from the audit; nothing a player sees changes. CHANGELOG has the detail.

The 0.4.9 playtest line is no longer maintained (Jesse, 2026-09-29): the deploy rule that
existed for it is gone and #85 is moot. The table test (#39 #35 #42a #40) is closed — every
line of the checklist was met at a table. #46 is done and cannot regrow: the 36 unused
declarations are removed and `noUnusedLocals`/`noUnusedParameters` are on; two of them were
dead bot functions from rejected candidates the round said it had deleted. The documents no
longer teach `trainCapSlack` (a knob that throws), point at `as-built.md` (deleted in 0.8.2),
model `officeType` (the engine says `tier`) or describe `collisionOccurred` (never emitted);
the README's account of bot flags now matches the bot's. Five playtest saves committed in
`docs/` against the repository's own rule are in the ignored `playtests/`.

What the audit found and did not fix is written down as TODO #112-#117, each with its reason.
#112 is `docs/plans/structure.md`, the proposal for `http.ts`, `main.ts` and `check`. #117 —
`/api/save` hands a seat the seed mid-game — waits on a conversation.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FrCWubm9GAftYCm2hWdKwK

src/engine/advance.ts

@@ -730,7 +730,6 @@ function entryConflict(
 
 /** Puts a train onto a Mainline card with its crossing time already computed. */
 function enterMainline(
-  s: GameState,
   node: Extract<DivisionNode, { kind: 'mainline' }>,
   id: TrayId,
   tray: CrewTray,
@@ -862,7 +861,7 @@ function moveTrain(s: GameState, id: TrayId, tray: CrewTray, events: GameEvent[]
     if (conflict === 'held') return 'held';
     if (conflict === 'collided') return 'moved';
 
-    enterMainline(s, node, id, tray, target);
+    enterMainline(node, id, tray, target);
     const dp = s.division.nodes[dpIndex];
     if (dp?.kind === 'divisionPoint') dp.holding = dp.holding.filter((t) => t !== id);
     events.push({
@@ -926,7 +925,7 @@ function moveTrain(s: GameState, id: TrayId, tray: CrewTray, events: GameEvent[]
       // The wreck's A/D track is released by `collide` itself, which is why it has to be.
       if (conflict === 'collided') return 'moved';
 
-      enterMainline(s, node, id, tray, target);
+      enterMainline(node, id, tray, target);
       area.adOccupancy = area.adOccupancy.filter((t) => t !== id);
       events.push({
         type: 'trainHighballed',
@@ -998,7 +997,7 @@ function moveTrain(s: GameState, id: TrayId, tray: CrewTray, events: GameEvent[]
       if (conflict === 'collided') return 'moved';
 
       node.holding = node.holding.filter((t) => t !== id);
-      enterMainline(s, node, id, tray, index, true);
+      enterMainline(node, id, tray, index, true);
       events.push({
         type: 'trainHighballed',
         trainNumber: tray.trainNumber ?? 0,
@@ -1400,7 +1399,7 @@ function redFlagStop(
     return c?.kind.kind === 'maneuver' && c.kind.key === 'redFlags';
   });
   if (!holdsFlag) return 'proceed';
-  if (!arrivalWouldCollide(s, id, tray, dest.seat)) return 'proceed';
+  if (!arrivalWouldCollide(s, dest.seat)) return 'proceed';
 
   s.clock.pendingDecision = { kind: 'redFlag', train: id, seat: dest.seat, from };
   return 'ask';
@@ -1413,7 +1412,7 @@ function redFlagStop(
  * if these two ever diverge, the prompt offers a flag against a collision that will not happen, or
  * stays silent before one that will.
  */
-function arrivalWouldCollide(s: GameState, id: TrayId, tray: CrewTray, seat: SeatIndex): boolean {
+function arrivalWouldCollide(s: GameState, seat: SeatIndex): boolean {
   const area = areaAtSeat(s, seat);
   const hasInterlocking = [...area.grid.values()].some((c) => c.enhancements.includes('interlocking'));
   const full = area.adOccupancy.length >= officeProfile(area.tier).adTracks;

src/engine/apply.ts

@@ -16,7 +16,6 @@
 
 import {
   FREIGHT_PROFILES,
-  LABORER_ACTIONS_PER_LOAD,
   MAX_CONSIST,
   REALIGNMENTS,
   consistSize,
@@ -65,7 +64,6 @@ import {
   pooled,
   railFacingOf,
   seatOf,
-  spaceOn,
   standingSides,
   trackOrder,
   turnOf,
@@ -647,7 +645,7 @@ function passengerWork(
  * crew is unaffected by all of them.
  */
 /** Which district a tray is standing in; 0 when it is out on the Division. */
-function trayySeat(tray: CrewTray): SeatIndex {
+function traySeat(tray: CrewTray): SeatIndex {
   return tray.position.at === 'grid' ? tray.position.seat : 0;
 }
 
@@ -1578,7 +1576,7 @@ function checkPlay(
         return target && target.kind === 'mainline' ? null : 'NOT_CONNECTED';
       }
       if (!placement) return 'NO_PLACEMENT';
-      return checkEnhancementPlacement(s, area, card.kind.key, placement);
+      return checkEnhancementPlacement(area, card.kind.key, placement);
     }
 
     case 'mainlineModifier':
@@ -1587,7 +1585,7 @@ function checkPlay(
       // copy uses the enhancement's grid placement rather than going onto a Mainline card.
       if (card.kind.key === 'facingPointLocksMainline') {
         if (!placement) return 'NO_PLACEMENT';
-        return checkEnhancementPlacement(s, area, 'facingPointLocks', placement);
+        return checkEnhancementPlacement(area, 'facingPointLocks', placement);
       }
       // The rest are laid on a Mainline card, which is not a grid coordinate — see
       // `mainline.modify`.
@@ -1830,7 +1828,6 @@ function execute(s: GameState, player: PlayerIndex, i: Intent): GameEvent[] {
       const from = trayCoord(s, i.trayId)!;
       const dests = destinationsFor(s, player, i.trayId, from, i.reverse);
       const dest = selectDestination(dests, i.to, i.via)!;
-      const tray = s.trays.get(i.trayId)!;
       // The port the crew pulls out THROUGH — the same one `destinationsFor` explored from, so the
       // cut it recouples on the way out is the cut the walk counted.
       const facingNow = facingPort(s, i.trayId);
@@ -2454,7 +2451,7 @@ export function reduce(s: GameState, e: GameEvent): void {
        * front of `stock` is a drop being undone, so it is refunded on the square it was left on
        * instead of being charged again at the far end.
        */
-      const owner = playerAtSeat(s, trayySeat(tray));
+      const owner = playerAtSeat(s, traySeat(tray));
       const taken = e.recoupled ? e.stock.slice(e.recoupled.stock.length) : e.stock;
       spendFreightBudget(s, owner, tray, e.at, taken);
       if (e.recoupled) refundFreightBudget(s, owner, tray, e.recoupled.at, e.recoupled.stock);
@@ -2477,7 +2474,7 @@ export function reduce(s: GameState, e: GameEvent): void {
        */
       tray.engineAt = e.engineAt;
       // "Spends one move in the yard" — the sort costs a Move.
-      const sorter = turnOf(s, playerAtSeat(s, trayySeat(tray)));
+      const sorter = turnOf(s, playerAtSeat(s, traySeat(tray)));
       sorter.movesRemaining = Math.max(0, sorter.movesRemaining - 1);
       break;
     }
@@ -2524,7 +2521,7 @@ export function reduce(s: GameState, e: GameEvent): void {
         // cars set out to the east leave it where it was.
         card.standingWest = onWestSide ? k + cut.length : k;
       }
-      spendFreightBudget(s, playerAtSeat(s, trayySeat(tray)), tray, e.at, e.stock);
+      spendFreightBudget(s, playerAtSeat(s, traySeat(tray)), tray, e.at, e.stock);
       break;
     }
 
@@ -3184,7 +3181,6 @@ export function watertowersRemovable(area: OfficeArea): GridCoord[] {
  *   - ABS Signals                          → a Mainline card, not the Office Area
  */
 export function checkEnhancementPlacement(
-  s: GameState,
   area: OfficeArea,
   key: string,
   placement: GridCoord,

src/engine/intents.ts

@@ -4,7 +4,7 @@
  * An intent is a PROPOSAL. It may be rejected. Contrast with an event (events.ts), which is a fact.
  */
 
-import type { CarType, Direction, Hand, OfficeTier, TrackGeometry } from './content.ts';
+import type { CarType, Direction, OfficeTier } from './content.ts';
 import type { CardId, GridCoord, PlayerIndex, SeatIndex, TrayId } from './state.ts';
 
 // ---------------------------------------------------------------------------

src/engine/legal.ts

@@ -12,7 +12,7 @@
  * If you find yourself writing a rule here, it belongs in apply.ts.
  */
 
-import type { CarType, Hand, TrackGeometry } from './content.ts';
+import type { CarType } from './content.ts';
 import { enhancementRule, mainlineProfile } from './content.ts';
 import { check, areaOf, destinationsFor, withRouteCache } from './apply.ts';
 import type { Intent } from './intents.ts';
@@ -191,9 +191,6 @@ export function legalSwitchingActions(s: GameState, player: PlayerIndex): Intent
   return withRouteCache(s, () => switchCandidates(s, player).filter((i) => check(s, player, i) === null));
 }
 
-export function isLegal(s: GameState, player: PlayerIndex, i: Intent): boolean {
-  return check(s, player, i) === null;
-}
 
 /**
  * Candidate generation. Over-generates freely — `check` is the authority, so a candidate that

src/engine/rng.ts

@@ -67,9 +67,3 @@ export function createRng(seed: number): Rng {
   };
 }
 
-/** Restore an RNG mid-stream, for rebuilding a game from a snapshot. */
-export function restoreRng(state: number): Rng {
-  // mulberry32 advances from its state before drawing, and createRng seeds state directly,
-  // so restoring is just seeding with the saved state.
-  return createRng(state);
-}

src/engine/setup.ts

@@ -19,7 +19,6 @@ import {
   OPENING_DEALS,
   MAINLINE_DECK,
   houseRules,
-  mainlineProfile,
   TRACK_CARDS,
   ROLLING_STOCK_SUPPLY,
   STAGES_PER_DAY,