v0.6.2 — an Extra starts where you put it, a train card is never discarded

Three more from the v0.4.9e gameplay-testing round, filed as Gitea issues, plus two bugs found
underneath them. Gitea#2 is diagnosed but NOT fixed: it needs a ruling, and the reasoning is in
TODO.md under Play Balance.

GITEA#4 — AN EXTRA STARTS WHERE THE PLAYER PUTS IT. Only one Division Point was ever offered,
chosen by number parity. The number no longer decides an Extra's direction — the start does, which
supersedes the recorded ruling that "the number decides, like everything else on the timetable".
The two cannot both hold: an odd, westbound Extra placed at the WEST end would leave the Division
on its first move having crossed nothing, and be paid for the run. Either end now runs the train
away from itself; at an Interchange or a Control Point the player picks the direction. The
Interchange start is a YARD, off the running line, which is what makes the Superintendent clause
work: placing it can never force a collision, a guaranteed one holds it there for another Stage,
and a potential one is the Superintendent's to rule on — exactly evaluateClearance's `blocked` and
`ask`, so nothing new decides collisions. Where an Extra may start is now a house rule
(divisionPointsOnly / ownOffice / anyOffice, defaulting to what the engine already did). The
legacy `atSeat` intent field still replays as it always meant.

FOUND UNDERNEATH IT: an Extra started away from a Division Point ran empty. isBeingMadeUp tested
position alone, so the Control Point start has been shipping since it was added with a train that
could never be given a consist. Found by playing it, not by the tests, which had only asserted
where the tray landed.

FOUND UNDERNEATH IT: collide left the wrecks on the card. Destroyed trains kept their Transit
entries, and evaluateClearance counts every transit as an occupant, so one rear-end collision
permanently poisoned that Mainline card for every later train.

THE MAINLINE CARDS WERE ROLLED, NOT DEALT — drawn from the nine types with replacement, so a
Division could hold two Interchanges and Plains carried the weight of a card printed once. "An
Extra may start at the Interchange if one is on the board" only reads as a rule if the board holds
at most one. Now dealt from the printed deck without replacement, verified over 1600 deals. This
re-deals every seed: the published replays were re-recorded, and the saved games in docs/ are
retired too — two of those were already dead before this release and nobody had noticed.

GITEA#6 — A TRAIN CARD IS NEVER DISCARDED, Timetabled and Extra alike. The forced play needed no
mechanism: nothing discardable plus a hand over the limit leaves exactly one legal way to end the
turn, and playing a train is unconditionally legal, so the corner cannot trap anyone. The bot
needed no rule either. 400/400 games finished, revenue unmoved, trains scheduled 1.2 -> 1.3. The
player is told on the card and on the button.

GITEA#7 — COACH COUNTS. 1/2 Crack Limited 3 -> 2, 5/6 The Sparrow 2 -> 3. A change to the cards,
so Trains3.pdf and the transcription keep the original numbers with a footnote while content.ts
and the Home Deck reference carry what the game plays.

CONTENT.TS COMMENT PASS — no data changed, only comments. Four were factually wrong, including an
office table naming counts doubled long ago and a pointer to a DEALT_DECK_SIZE that has never
existed. Every Enhancement row cited its implementation by line number and every citation had
rotted; they name functions now. Card counts came out of the comments, since they move with play
balance; source-sheet figures and dated measurements stayed.

TODO.md gains an item for a card reference generated from content.ts, in six sections, so the
documentation cannot disagree with the game.

715 tests pass, tsc clean, site builds.

docs/StationMaster-Home-Deck-v0.4.5.md

@@ -98,11 +98,18 @@ Playing a timetabled train card rolls the seeded D12 and places its number in th
 
 The listed consist is a maximum, not a minimum: a train may depart with fewer cars, but must not exceed the listed categories, put a car behind a caboose, or leave with the engine buried among cars. A Crew Tray holds no more than four rolling-stock cars.
 
+> **Changed 2026-08-22 (Gitea#7), Jesse's call:** the coach counts on **1/2 Crack Limited** and
+> **5/6 The Sparrow** were swapped — the Limited drops from three coaches to two, the Sparrow rises
+> from two to three. This is a change to the CARDS, not a correction to this table: `Trains3.pdf` and
+> the transcription in [`rules/implications.md`](rules/implications.md) §5 still show the original
+> numbers, and are right about what the printed cards said. `src/engine/content.ts` and this table
+> carry what the game plays.
+
 | Train | Speed | Direction | Listed maximum consist | Implemented special rule |
 | --- | --- | --- | --- | --- |
-| 1/2 Crack Limited | Fast | 1 west / 2 east | 3 coaches | No switching; passenger work only at Terminals; expedited. |
+| 1/2 Crack Limited | Fast | 1 west / 2 east | **2 coaches** | No switching; passenger work only at Terminals; expedited. |
 | 3/4 Express | Fast | 3 west / 4 east | 2 freight | May exchange at most one freight car at each grid location during its switching turn; expedited. |
-| 5/6 The Sparrow | Fast | 5 west / 6 east | 2 coaches | No switching; expedited. |
+| 5/6 The Sparrow | Fast | 5 west / 6 east | **3 coaches** | No switching; expedited. |
 | 7/8 Local | Slow | 7 west / 8 east | 1 freight, 1 coach | Its coach may not be set out during switching. |
 | 9/10 Heavy Freight | Slow | 9 west / 10 east | 3 freight, 1 caboose | — |
 | 11/12 Drag Freight | Slow | 11 west / 12 east | 2 freight, 1 caboose | — |

docs/StationMaster-Mainline-Deck-v0.4.5.md

@@ -45,9 +45,13 @@ The PDF art labels this card “Yard”; this reference uses the implementation
 | Trestle | 60 mph. |
 | Interchange | 60 mph. A train may be reordered there only through the card’s printed “sort cars” concept; the current engine does **not** provide a Mainline sorting action for it. |
 
-### PDF/code mismatch requiring correction
+### PDF/code mismatch — CORRECTED
 
-`src/engine/content.ts` defines nine `MAINLINE_PROFILES` types: one Plains entry plus the eight other terrain types above. `setup.ts` selects uniformly from that nine-type list. The second Plains card shown in `Mainline Cards.pdf` is therefore not represented as a duplicate card or as extra Plains weight in setup. If the PDF inventory is authoritative, the setup selection needs a second Plains entry (or an equivalent weighted selection).
+**Was:** `src/engine/content.ts` defines nine `MAINLINE_PROFILES` types: one Plains entry plus the eight other terrain types above. `setup.ts` selected uniformly from that nine-type list, **with replacement**. The second Plains card shown in `Mainline Cards.pdf` was therefore not represented as a duplicate card or as extra Plains weight in setup — and, worse than a weighting error, a Division could be dealt two Interchanges, two Tunnels or two Trestles, none of which the deck contains.
+
+**Now:** `MAINLINE_DECK` in `content.ts` is the inventory table above — ten drawable cards, Plains twice and the other eight once each — and `buildDivision` deals from it without replacement. The two Division Point cards are not in that deck: they are the fixed ends of the Division, laid by `buildDivision` itself rather than drawn.
+
+The Interchange is what forced the correction. §7 lets an Extra be started at the Interchange "if one is on the board" (see `docs/rules/implications.md`, §7), which only reads as a rule if the board can hold at most one.
 
 The executable state represents East and West Division Points as fixed end nodes, not as card records. They are functionally present at the ends of the Division, but are not represented as the two PDF cards in the deck/state model.
 

docs/rules/implications.md

@@ -488,13 +488,19 @@ Hotel) are what grow them.
 
 | # | Name | Speed | Consist | Rule |
 | --- | --- | --- | --- | --- |
-| 1/2 | Crack Limited | Fast | 3 coaches | Stop at Terminals only. No switching. Expedite. |
+| 1/2 | Crack Limited | Fast | 3 coaches † | Stop at Terminals only. No switching. Expedite. |
 | 3/4 | Express | Fast | 2 freight | May drop or pick up one freight car at every location. Expedite. |
-| 5/6 | The Sparrow | Fast | 2 coaches | No switching. Expedite. |
+| 5/6 | The Sparrow | Fast | 2 coaches † | No switching. Expedite. |
 | 7/8 | Local | Slow | 1 freight + 1 coach | Coach must remain on station track if switching. |
 | 9/10 | Heavy Freight | Slow | 3 freight + caboose | |
 | 11/12 | Drag Freight | Slow | 2 freight + caboose | |
 
+† **The two coach counts have since been swapped by Jesse** (Gitea#7, 2026-08-22): the Crack Limited
+now carries **2** coaches and The Sparrow **3**. The table above is left as `Trains3.pdf` prints it,
+because that is what this section is for — what the design SAYS. What the game plays is
+`src/engine/content.ts`, with the per-card table in
+[`../StationMaster-Home-Deck-v0.4.5.md`](../StationMaster-Home-Deck-v0.4.5.md).
+
 ### Extras (X13–X22) — ten distinct trains, not four generic ones
 
 Appleseed Extra (MT freight only, may drop but not pick up), Fruit Growers Express (reefers only),
@@ -785,3 +791,122 @@ Crossing is counted in Stages (Q1), so both trains simply run their counters dow
 Until this is settled the clearance buttons describe only what the engine actually does — they say
 the train "closes up behind" rather than promising a −5 risk that cannot occur. Wording that invents
 a consequence is worse than wording that under-sells one.
+
+---
+
+## §7 — where an Extra starts, and which way it runs
+
+**Reported from playing v0.4.9e** (Gitea#4): "When extras are played the player doing so may choose
+where the extra starts. They may choose either division point. And if the interchange mainline card
+has been played, they may start the extra on that card and choose the direction from there. If there
+is potential for conflict with other trains in that area the superintendent may hold the extra."
+
+**This supersedes an earlier ruling**, and the supersession is the interesting part. §2.3 gives every
+train its direction from its number — odd runs west, even runs east — and an earlier pass extended
+that to Extras explicitly: *"the number decides, like everything else on the timetable."* That reading
+cannot survive "either Division Point". An odd Extra placed at the WEST end would run west, leave the
+Division on its first move having crossed nothing, and be paid the completion Revenue for the run.
+
+So for **Extras only**, the start decides the direction:
+
+| Start | Direction |
+| --- | --- |
+| Western Division Point | east |
+| Eastern Division Point | west |
+| Interchange | player's choice |
+| Control Point (any Office above a Whistle Post) | player's choice |
+
+A timetabled train is unchanged: its number still decides. The Extra cards were always printed
+`direction: 'playerChoice'` (§5) and the engine had been overriding it; they now mean it.
+
+### The Interchange start is a YARD, not a spot on the running line
+
+§7's last clause — "the superintendent may hold the extra" — is what settles how this is modelled.
+An Extra started at an Interchange stands in that card's **yard**, off the running line, and highballs
+onto the card itself at a later Mainline Phase. Three things follow, all of them Jesse's rule rather
+than an implementation convenience:
+
+1. **Placing it can never force a collision**, however busy the card is. It is not on the road yet.
+2. **A guaranteed collision holds it in the yard** for another Stage, and it tries again next Stage.
+3. **A potential collision is the Superintendent's to rule on.**
+
+Those last two are exactly §8.1's two answers — an absolute bar against a facing train, a judgment
+call against a following one — so the Extra leaves the yard through the same clearance check a train
+leaves a Division Point through. Nothing new decides collisions.
+
+The Interchange keeps its printed "sort cars in new order" concept, still unimplemented (§6). Being
+the card with a Yard Limit is what makes it the one Mainline card a train can be made up on.
+
+### Which starts are offered is a setting
+
+The Division Points and the Interchange sit on shared ground and belong to nobody; starting an Extra
+inside a player's own district does not. That is a table preference rather than a rule, so it is set
+when the game is dealt (`extraStart`): Division Points and Interchange only, plus the playing
+player's own Control Point, or plus any player's Control Point. A **Whistle Post never qualifies at
+any setting** — being a place an Extra can start is part of what upgrading buys (§11).
+
+### Two bugs found underneath it
+
+- **The Mainline cards were rolled, not dealt.** `buildDivision` drew uniformly from the nine card
+  TYPES **with replacement**, so a Division could be dealt two Interchanges or two Tunnels, and
+  Plains — printed twice in the deck — carried the same weight as cards printed once.
+  `docs/StationMaster-Mainline-Deck-v0.4.5.md` had already flagged the mismatch as needing
+  correction; "an Extra may start at the Interchange if one is on the board" is what forced it, since
+  that only reads as a rule if the board holds at most one. Now dealt from the printed ten-card deck
+  without replacement.
+- **An Extra started anywhere but a Division Point ran empty.** `isBeingMadeUp` asked only "is this
+  tray standing at a Division Point", which was the whole truth while that was the only place to
+  build a train — so the Control Point start had shipped since it was added with a train that could
+  never be given a consist, and the Interchange start would have shipped the same way. Found by
+  playing it, not by the tests, which had only ever asserted where the tray landed.
+
+---
+
+## §6.2 — a train card is never discarded
+
+**Jesse's ruling, v0.4.9e playtest** (Gitea#6): "Players are not allowed to discard Train cards. They
+may keep the card in their hand for multiple stages and even multiple days, but they may not discard
+it. If a player has three train cards in their hand, and they draw a fourth, then they must play one
+of those cards."
+
+**Extras count.** An Extra is a train, even though it runs once and ends in the Salvage Yard where a
+Timetabled card joins the timetable for the rest of the game.
+
+§6.2 as transcribed says only "the player must reduce his hand to no more than three cards" with no
+exception for any card type, so this is a ruling rather than a gap — the prototype rules do not
+address it either way.
+
+### It needs no forcing mechanism, and that is the point
+
+The interesting property of this rule is that the forced play falls out of two rules that already
+exist rather than needing a third:
+
+1. a train card cannot be discarded, so it is not among the ways to shed a card; and
+2. `draw.end` already refuses while the hand is over the limit (§6.2).
+
+A player holding four trains therefore has exactly one legal way to conclude the turn — play one —
+without anything in the engine ever computing "you must play a train". The corner cannot lock a
+player in, because **playing a train card is unconditionally legal**: `card.play`'s train case
+refuses only a board placement, and a train card played when the timetable is full still leaves the
+hand (it simply schedules nothing). Confirmed by playing it: a hand of four trains offers zero
+discards, no `draw.end`, and four plays.
+
+The bot needed no rule of its own either. `legal.ts` enumerates candidates and filters them through
+`check`, so the option stops being offered; and the developer bot already reaches for `card.play`
+before it reaches for a discard. Measured over 400 games: 400/400 finished, revenue unmoved, and
+**trains scheduled 1.2 → 1.3** — the rule's intended effect, small because a bot rarely held four.
+
+### Consequences
+
+- **Two of the three published replays discarded train cards** (2 and 15 of them) and were retired
+  and re-recorded. Jesse's call: "I'm okay with retiring the replays that no longer work under those
+  old rules."
+- **The opening six-card hand is not exempt.** Under *six random cards* a player opens holding six
+  against a limit of three; if four or more are trains, they all go onto the timetable on turn one.
+  Jesse's call: "If the opening hand has lots of trains, then lots of trains will be placed on the
+  board." Rare — roughly 1.5% of deals — but deliberate.
+- **The player is told, on the card and on the button.** `handDiscardable` on the Frame marks which
+  cards may be shed, the hand panel says so in the card's own tooltip, and when EVERY card held is a
+  train the blocked end-turn button changes its text to say a train must be played. That is the
+  Gitea#2 lesson applied: a rule the player cannot see is a board with nothing to click and no reason
+  given.