Expand game engine, replay, tests, and documentation

test/advance.test.ts

@@ -239,8 +239,10 @@ describe('Mainline Phase (§8)', () => {
     s.clock.phase = 'mainline';
     s.movedThisPhase = new Set();
     advance(s);
+    // Q1/Q2 — crossing time is counted in Stages by card speed and Fast/Slow class, so the train
+    // stays on the card until its transit expires rather than stepping through printed cells.
     const pos2 = s.trays.get(id)!.position;
-    assert.ok(pos2.at === 'mainline' && pos2.region === 1, 'one region per Stage');
+    assert.equal(pos2.at, 'mainline', 'still crossing');
   });
 
   it('orders movement by train number, Timetabled before Extra on a tie (Gap 5)', () => {
@@ -288,11 +290,11 @@ describe('collisions are automatic (Gap 2)', () => {
       engineFront: true,
       consist: [{ type: 'coach', loaded: true }],
       direction: 'east',
-      position: { at: 'mainline', index: 1, region: 1 },
+      position: { at: 'mainline', index: 1 },
       movesUsed: 0,
     });
     const ml = s.division.nodes[1];
-    if (ml?.kind === 'mainline') ml.regions[1]!.occupant = id;
+    if (ml?.kind === 'mainline') ml.transits.push({ tray: id, stagesRemaining: 1, direction: 'east' });
 
     s.clock.phase = 'mainline';
     s.movedThisPhase = new Set();
@@ -308,6 +310,8 @@ describe('collisions are automatic (Gap 2)', () => {
     s.officeAreas.get(0)!.adOccupancy = ['blocker'];
     const classBefore = s.yards.classificationYard.length;
 
+    const mlx = s.division.nodes[1];
+    if (mlx?.kind === 'mainline') mlx.transits.push({ tray: 'x', stagesRemaining: 1, direction: 'east' });
     s.trays.set('x', {
       id: 'x',
       trainNumber: 8,
@@ -318,7 +322,7 @@ describe('collisions are automatic (Gap 2)', () => {
         { type: 'caboose', loaded: true },
       ],
       direction: 'east',
-      position: { at: 'mainline', index: 1, region: 1 },
+      position: { at: 'mainline', index: 1 },
       movesUsed: 0,
     });
     s.clock.phase = 'mainline';
@@ -346,11 +350,11 @@ describe('the Superintendent clearance interrupt (§8.1)', () => {
       engineFront: true,
       consist: [],
       direction: 'east',
-      position: { at: 'mainline', index: 1, region: 1 },
+      position: { at: 'mainline', index: 1 },
       movesUsed: 0,
     });
     const ml = s.division.nodes[1];
-    if (ml?.kind === 'mainline') ml.regions[1]!.occupant = 'ahead';
+    if (ml?.kind === 'mainline') ml.transits.push({ tray: 'ahead', stagesRemaining: 2, direction: 'east' });
 
     // A second train at the Western Division Point wanting to follow it.
     s.trays.set('behind', {
@@ -383,11 +387,11 @@ describe('the Superintendent clearance interrupt (§8.1)', () => {
       engineFront: true,
       consist: [],
       direction: 'west',
-      position: { at: 'mainline', index: 1, region: 0 },
+      position: { at: 'mainline', index: 1 },
       movesUsed: 0,
     });
     const ml = s.division.nodes[1];
-    if (ml?.kind === 'mainline') ml.regions[0]!.occupant = 'oncoming';
+    if (ml?.kind === 'mainline') ml.transits.push({ tray: 'oncoming', stagesRemaining: 2, direction: 'west' });
 
     s.trays.set('waiting', {
       id: 'waiting',