v0.4.5 - fix bug with not being able to drop cars

CHANGELOG.md

@@ -21,6 +21,56 @@ page as `v0.1.0 · <sha> · <date>`, so what is deployed can always be identifie
 
 ## Unreleased
 
+## 0.4.5 — 2026-08-14
+
+### A train can back out of a curve again
+
+**Reported one commit after 0.4.4 shipped:** "seems like I can't drop a car at all. I'm trying to
+switch to get an empty car to an industry, but I can't drop any cars on the siding first."
+
+Setting out a cut needs no Move and is refused almost nowhere — but you may only set out where the
+train **is**, and the Office square is barred outright (§A.4). So "I cannot drop" is nearly always
+"I cannot get there", and getting there means leaving the Running Track through a turnout and a
+curve. 0.4.4 fixed the forward half of exactly that and left the reverse half wrong:
+
+- **Forward** exits by `facing` — fixed in 0.4.4 to read the card's far end rather than assuming
+  `opposite(entry)`.
+- **Reverse** still exited by `opposite(facing)`, which is the other end of a **straight** and of
+  nothing else. A crew facing north on a north-west curve backs out through **west**; `opposite('n')`
+  is a south port the card does not have, and `exploreMoves` returns nothing at all from a port the
+  card lacks.
+
+So 0.4.4 moved the problem rather than solving it. Before it, a crew that rounded a curve could only
+back out; after it, a crew could only carry on. Either way a siding entered one way could not be left
+the other, and a siding that had to be *backed* into could not be entered at all.
+
+`reversePort` now asks the card for its other end, the same way `farPort` does going forward. A train
+always stands on a two-port card — §A.1 forbids finishing a Move on a turnout — so there is exactly
+one other end to find.
+
+**How much of the board this was hiding.** Over 25 bot games, at 1,937 points where a crew could have
+been switching, comparing what the board highlights now against what it highlighted before:
+
+| | |
+| --- | --- |
+| squares offered, before → now | 7,461 → 10,040 (**+35%**) |
+| positions hiding at least one legal square | 694 (**35.8%**) |
+| positions with **no legal move at all** | 300 (**15.5%**) |
+
+Both figures understate it: the "before" reckoning was run with occupancy ignored, so it was allowed
+squares that another train was actually sitting on. A crew counted as stuck was stuck even on the
+generous reading.
+
+**Tests.** The failing case is pinned three ways — backing off a curve, carrying on round one, and
+the whole errand from the report: take a cut off the Running Track into a siding, set it out, and
+come back for the industry. That last one fails on 0.4.4 with *"the crew is stranded on the siding —
+it cannot return to the Running Track"*, which is the report in one line.
+
+`sim.test.ts` needed a wider sample rather than a lower bar: crews now have real switching to do, so
+the bot lays fewer track pieces per game and five seeds no longer produced the 40 placements the
+dead-end **rate** is measured over. Eight seeds now, same stride; the rate itself came out at 0.147
+against a bar of 0.25.
+
 ## 0.4.4 — 2026-08-14
 
 Out of a play session: engines that pointed north, a card whose name collided with five other things,