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The 0.4.9 playtest line is no longer maintained (Jesse, 2026-09-29): the deploy rule that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;