v0.7.9.1 — the engine was right twice; the screen was not

Gitea#22: the Division map drew every westbound train in the wrong half of
its Mainline card. `regionOfTransit` counts from the end a train entered,
which is what the collision rules ask; the map wanted "which printed box,
left to right" and used the same number, so an eastbound train came out
right by luck and a westbound one came out mirrored. It cost a collision —
Train 3 was cleared to follow T5 and ran into TX17, which the picture had
drawn ahead of T5 rather than behind it. One mirror in `view.ts`, at the
boundary the map is drawn from; the collision rules are untouched.

Gitea#21: a second tank car would not come off at a refinery, and "Blocked
— why nothing is moving" answered by describing the refinery's green box.
The real answer was Train 3's printed rule — the Express works one freight
car per location — so the refusal was correct and the panel sent the player
to spend a Freight Agent action that could not have helped. No rule
changed. The panel now names the budget, asking the reducer's own
predicate so its words cannot drift from the rule.

Both were replayed from the saves attached to the issues and verified in
the exact position each report names. The map fix is proved by mutation:
reverting the mirror fails two tests, and making the renderer ignore the
region fails a third. Every existing region test ran eastbound, where the
mirror is the identity, which is why the bug survived them.

891 tests pass, up from 884.

Closes #21
Closes #22

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E3Qk7uresKCHksdZajXCLg

src/sim/view.ts

@@ -48,7 +48,7 @@ import {
 import type { Intent } from '../engine/intents.ts';
 import type { Facility, GameConfig, GameState, PlayerIndex, SeatIndex, TrackCard, TurnoutOrientation } from '../engine/state.ts';
 import { actingPlayer, carsOn, playerAtSeat, railFacingOf, seatOf, turnOf } from '../engine/state.ts';
-import type { Hand, HouseRules, TrackGeometry } from '../engine/content.ts';
+import type { Direction, Hand, HouseRules, TrackGeometry } from '../engine/content.ts';
 import type { Port } from '../engine/track.ts';
 import { connectionsFor, slopeOfPair, variantsFor } from '../engine/track.ts';
 import type { Impediment } from './narrate.ts';
@@ -1259,10 +1259,31 @@ export function snapshot(
        * one per Stage — and the entry point is what the rules actually move. There is nothing left
        * to reconstruct.
        */
-      // One region per Stage, straight off the card's own count: what a train has LEFT to run says
-      // where it is standing. `regionOfTransit` is the engine's own answer, so the picture and the
-      // collision rule cannot disagree about who is where.
-      const place = (t: { stagesRemaining: number }): number => regionOfTransit(n.card, t.stagesRemaining);
+      /**
+       * AND WHICH WAY IT CAME IN (Gitea#22). `regionOfTransit` counts from the end the train
+       * ENTERED — everything still to run is region 0 — and both directions share that one index
+       * space, which is what the collision rules want and why the engine asks it directly.
+       *
+       * The map is asking a different question: which printed box, LEFT TO RIGHT. East is right
+       * here and always has been, so for an eastbound train the two questions have the same answer
+       * by luck — it enters at the west end, so "just entered" and "leftmost box" coincide. A
+       * westbound train enters at the EAST end, so its region 0 is the right-hand box, and using
+       * the travel index directly drew the whole card mirrored.
+       *
+       * That cost a collision (seed 550943578, undo 187): a westbound TX17 that had just entered
+       * was drawn WEST of a westbound T5 that was nearly across, so the train physically behind
+       * appeared to be the one in front. Train 3 was cleared to follow T5 and ran into TX17 —
+       * where the rules had always had it.
+       *
+       * So the engine's index is turned into a place on the map here, once, at the boundary the
+       * map is drawn from. `regionOfTransit` keeps its meaning and the collision rules are
+       * untouched; only the picture changes.
+       */
+      const place = (t: { stagesRemaining: number; direction: Direction }): number => {
+        const travelled = regionOfTransit(n.card, t.stagesRemaining);
+        const regions = mainlineProfile(n.card).regions;
+        return t.direction === 'west' ? regions - 1 - travelled : travelled;
+      };
       return {
         kind: 'ml',
         label: name,