v0.8.0.10 — playtest fixes: clearance rulings, the log, the map, and a save file

From the first two multiplayer playtests of v0.8.0.9, each traced before fixing.

The engine:

- A train on a card BEHIND the one departing no longer triggers a clearance
  ruling or an opposite-direction bar (#26). Reproduced from the exported
  save: X15 was held over X18 behind it, and X18 then collided into the full
  Whistle Post. Games in progress holding a ruling the engine no longer asks
  for will not resume (28 of 40 recorded four-seat games); shipped as is at
  Jesse's call.
- `mainlineModified` carries the card's previous kind, so the log can say
  what a Realignment converted (#27).

The screen:

- The turn chart and the Division map name the player whose move is on
  screen while bot turns replay, not the live actor (#25).
- The owning player's name is no longer outlined by the turn arrow's stroke,
  which made it unreadable (#24).
- A Mainline card flashes on the map when a Realignment changes it (#28).
- The history is held back with the board and revealed step by step, instead
  of arriving whole while the board is still catching up (#29).
- A ruling made by holding the office reads "Superintendent Player X" (#30),
  and no line names a player twice (#31).
- A seated player can download their own game as a save file: the play
  page's Save replay button, fed by GET /api/save?token=… (#32). The StartOS
  action cannot do this — an action result is text only.

Closes #24
Closes #25
Closes #26
Closes #27
Closes #28
Closes #29
Closes #30
Closes #31
Closes #32

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017nnuCv8UodHucFfx3LWEoX

src/engine/advance.ts

@@ -94,6 +94,18 @@ function nodeIndexOfOffice(s: GameState, seat: SeatIndex): number {
 
 const step = (d: Direction): number => (d === 'east' ? 1 : -1);
 
+/** The Division node a train is standing on — its Office, its Mainline card, or its Division Point. */
+function nodeIndexOfTray(s: GameState, tray: CrewTray): number | null {
+  const at = tray.position;
+  if (at.at === 'grid') return nodeIndexOfOffice(s, at.seat);
+  if (at.at === 'mainline') return at.index;
+  if (at.at === 'divisionPoint') {
+    const side = at.side;
+    return s.division.nodes.findIndex((n) => n.kind === 'divisionPoint' && n.side === side);
+  }
+  return null;
+}
+
 // ---------------------------------------------------------------------------
 // advance
 // ---------------------------------------------------------------------------
@@ -1067,10 +1079,27 @@ function evaluateClearance(
    * constrained. Each Office upgrade to a Control Point splits one in two and buys capacity.
    */
   const subdivision = subdivisions(s).find((group) => group.includes(targetIndex)) ?? [targetIndex];
+  /**
+   * ONLY WHAT IS AHEAD (Gitea#26). §8.1 asks about a train the considered train would FOLLOW, and one
+   * moving TOWARDS it — both of which are ahead of it. A Subdivision runs the length of every Whistle
+   * Post between two Control Points, so it can hold a train BEHIND the one departing: in the reported
+   * game X15 highballed west from an Office while X18, also westbound, was still crossing the card to its
+   * east. Counting X18 put a meaningless ruling to the Superintendent; holding X15 kept the Whistle Post's
+   * one A/D track full, and X18 arrived into it and was destroyed. A train behind and moving away is no
+   * threat at all.
+   *
+   * "Behind" is strictly behind the card the departing train stands on. A train on that same card is still
+   * counted, exactly as before: which of two trains sharing a card is in front is `entryConflict`'s region
+   * question, and this is not the place to answer it.
+   */
+  const from = nodeIndexOfTray(s, tray);
+  const behind = (onCard: number): boolean =>
+    from !== null && from >= 0 && (tray.direction === 'east' ? onCard < from : onCard > from);
   const occupants: { tray: TrayId; onCard: number }[] = [];
   for (const i of subdivision) {
     const n = s.division.nodes[i];
     if (!n || n.kind !== 'mainline') continue;
+    if (behind(i)) continue;
     for (const t of n.transits) if (t.tray) occupants.push({ tray: t.tray, onCard: i });
   }