Train location in region on cards appears to be wrong for westbound trains. #22

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2026-08-31T03:16:56Z

Jesse.Markowitz commented

2026-08-31 03:16:56 +00:00

See turn, undo 187. Seed 550943578. in attached file.

Received a superintendent query as to whether to allow or hold train three. The display graphically showed train 17 further west than train 5. And the query was Superintendent — may Train 3 follow Train 5 onto the same Mainline card? I allowed train 3 and it collided w/train 17, not train 5 as expected.

Further investigation revealed that the tooltip showed TX17 in region 1 of 2, 2 stages to cross AND T5 in region 2 of 2, 1 stages to cross.

See turn, undo 187. Seed 550943578. in attached file. Received a superintendent query as to whether to allow or hold train three. The display graphically showed train 17 further west than train 5. And the query was Superintendent — may Train 3 follow Train 5 onto the same Mainline card? I allowed train 3 and it collided w/train 17, not train 5 as expected. Further investigation revealed that the tooltip showed TX17 in region 1 of 2, 2 stages to cross AND T5 in region 2 of 2, 1 stages to cross.

station-master-seed550943578-day3.Collision.json

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Jesse.Markowitz referenced this issue from a commit

2026-09-07 15:42:19 +00:00

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

Jesse.Markowitz closed this issue

2026-09-07 15:42:19 +00:00

Jesse.Markowitz commented

2026-09-07 15:50:49 +00:00

Ruling: your reading of the board was correct and the game's picture was wrong. The collision was right; the map was mirrored.

Two separate things share one number here, and that is the bug.

regionOfTransit answers how far along its crossing a train is, counted from the end it entered — a train with everything still to run is in region 0. That is the question the collision rules ask, and it was correct throughout.

The Division map was asking a different question with the same number: which printed box, left to right. East is right on this map, so for an eastbound train the two answers coincide by luck — it enters at the west end, so "just entered" and "leftmost box" are the same box. A westbound train enters at the east end, so its region 0 is the card's right-hand box — and drawing it at the left mirrored the entire card.

Replaying your save to the position the ruling was made in (intent 186):

T5 — 1 Stage left, nearly across, travel index 1
TX17 — 2 Stages left, just entered, travel index 0

Both westbound, so TX17 was physically east of T5 — behind it, in the direction they had both come from. The map drew TX17 at the left, which reads as further west, which reads as further ahead. So when you were asked whether Train 3 could follow Train 5 onto the card, the board you were reading showed the two trains in the wrong order. Train 3 entered behind and ran into TX17, exactly where the rules had always had it.

The tooltip you quoted was reporting the same number, which is why it agreed with the picture rather than correcting it. It now says which way it is counted — region 2 of 2, counted west to east — because beside "2 Stages still to run" a bare number reads as a contradiction.

Fixed in v0.7.9.1 (7ade60e): one mirror where the map is drawn. The collision rules are untouched, since they were never wrong.

Worth recording: every existing test for this ran a train eastbound, where the mirror is the identity — which is why 884 passing tests never caught it.

**Ruling: your reading of the board was correct and the game's picture was wrong. The collision was right; the map was mirrored.** Two separate things share one number here, and that is the bug. `regionOfTransit` answers **how far along its crossing a train is, counted from the end it entered** — a train with everything still to run is in region 0. That is the question the collision rules ask, and it was correct throughout. The Division map was asking a different question with the same number: **which printed box, left to right.** East is right on this map, so for an *eastbound* train the two answers coincide by luck — it enters at the west end, so "just entered" and "leftmost box" are the same box. A **westbound** train enters at the *east* end, so its region 0 is the card's right-hand box — and drawing it at the left mirrored the entire card. Replaying your save to the position the ruling was made in (intent 186): - **T5** — 1 Stage left, nearly across, travel index 1 - **TX17** — 2 Stages left, just entered, travel index 0 Both westbound, so TX17 was physically **east** of T5 — behind it, in the direction they had both come from. The map drew TX17 at the left, which reads as further west, which reads as further ahead. So when you were asked whether Train 3 could follow Train 5 onto the card, the board you were reading showed the two trains in the wrong order. Train 3 entered behind and ran into TX17, exactly where the rules had always had it. **The tooltip you quoted was reporting the same number, which is why it agreed with the picture rather than correcting it.** It now says which way it is counted — `region 2 of 2, counted west to east` — because beside "2 Stages still to run" a bare number reads as a contradiction. Fixed in **v0.7.9.1** (`7ade60e`): one mirror where the map is drawn. The collision rules are untouched, since they were never wrong. Worth recording: every existing test for this ran a train **eastbound**, where the mirror is the identity — which is why 884 passing tests never caught it.

Jesse.Markowitz referenced this issue from a commit

2026-09-07 18:50:41 +00:00

v0.7.9.3 — the reference says what only the code knows, and saves get a rule

Jesse.Markowitz referenced this issue from a commit

2026-09-07 19:01:18 +00:00

v0.7.9.4 — Gitea#20 step 1, and a Red Flag you can see

Jesse.Markowitz referenced this issue from a commit

2026-09-08 00:39:51 +00:00

v0.7.9.5 — two answers to one question, and the copy nobody read

Jesse.Markowitz referenced this issue from a commit

2026-09-08 07:42:19 +00:00

v0.7.9.6 — three things the engine knew and the screen did not