v0.8.2 — every district opens on a Depot, and the docs are pages now

A second-digit bump for a playtest read back against the save file. Nine questions
were asked of one three-Day game; three were bugs, three were the rules working
and undocumented, three were decisions. Every save on the test server was replayed
against this build BEFORE release, which is how the cost of each rule was known
before it was chosen rather than discovered after.

EVERY DISTRICT OPENS ON A DEPOT. A Whistle Post has one A/D track and is not a
Passenger Facility, so the opening of every game was spent unable to work a
passenger and one arrival away from a collision. Two A/D tracks and passengers
from Stage 1 now; "Players start with Whistle Posts, not Depots" is the harder
game, set when the game is created. The deck follows the choice — starting on
Depots the four Depot upgrade cards are left out, because an upgrade must be to
the next tier and a Depot card at a table of Depots is a dead draw. How much
easier it is showed up as a test failure rather than an argument: the cue-coverage
pool needed widening from 24 seeded games to 60 before it held one collision.

NO SAVE WAS STRANDED BY IT, which took care. This is the one house rule that
changes how a game is DEALT rather than how it plays, so replaying a save under
the wrong opening is a different railroad from intent one — silently, with no
error. `withSavedOpening` fills it on the replay paths ONLY. Putting it in the
resolver instead made a fresh Cutthroat game deal Whistle Posts and read as
Custom, which is how the distinction was found.

THREE BUGS, ALL REPORTED FROM ONE GAME AND ALL CONFIRMED ON ITS SAVE.

An Office held TWO TRAINS ON ONE A/D TRACK. The capacity test passed with nothing
standing, the train the Interlocking had been holding at the Limits was moved into
the free slot, and the arriving train was pushed in after it without anyone asking
again whether there was room — so the collision §8.3 calls for never happened. The
held train keeps priority; the newcomer now takes the consequence it would have
met had the held train arrived first.

THE HISTORY FROZE, permanently, and the log cap was not really the cause. Each
seat's "what have I sent you" bookmark was an INDEX into an array the game trims,
so once a seat's bookmark reached the limit the slice returned nothing for the
rest of the game — at a different moment per seat, because each holds its own.
That game's log ended at exactly the cap. Lines carry a sequence number now, which
survives trimming; proven by pushing twice the cap through a simulated seat.

§8.1 ASKED THE WRONG QUESTION TWICE. "Trains may pass" returned `clear` before the
Subdivision was looked at, so a train entering a Double Track was released however
busy the rest of it was — that, not anything about Control Points, is what let
Train 8 out with no ruling. And a train standing at an Office was invisible to the
scan, so one about to re-enter the very Subdivision being entered counted for
nothing. Capacity is the test, not presence: a Depot with a track free is not in
the way; a Whistle Post with its one track taken is.

THINGS THAT HAPPENED SILENTLY NOW SAY SO — a train held against a facing one, a
train released from the Limits (a side effect of somebody else's arrival, so it
simply appeared at the Office), and the train an Interlocking is holding, whose
explanatory tooltip has existed since #99 with NO renderer ever reading the flag.

WHERE A MOVE IS REFUSED, AND WHY. `exploreMoves` decides where the rails go and the
pick-up restrictions are enforced afterwards in `check`, so a square the rails
reached and the card forbade was reachable, un-offered, and absent from the block
list with nothing said. Those squares are blocked with the rule that blocks them
now, and the reasons are got by ASKING `check` rather than re-deriving: a second
implementation of the rules is exactly the failure the block list exists to avoid.
A train may also always recover its own caboose — X13 prints "may drop but not
pick up anything", and a train needs its caboose to be made up, so one that parted
with it could never legally leave again.

RULES DECIDED IN SEPTEMBER AND APPLIED HERE. A Modifier must sit square against its
host, no diagonals. A passenger Modifier may not be played at a Whistle Post. Both
were built, measured, held back for a fortnight so a playtest could finish, and
applied now. A Second Section costs its card: `SECOND_SECTION` was declared in
content.ts and never dealt, so the action was free and the bot ordered 26
accidental ones in a measured round. The card is dealt and spent — gating on a card
the deck never holds would have deleted the mechanic rather than fixed it.

THE DOCUMENTATION IS A SET OF PAGES, not five text files served as text/plain — a
card reference is mostly tables, and as plain text a table is rows of pipes.
Markdown is still the one copy; the build renders it, and publishes the .md beside
each page. No Markdown library: this project has no runtime dependencies and one
would be a poor first. The pages add what Markdown cannot carry without drifting —
a nav across the set, a contents list built from the headings actually rendered,
an anchor on every heading, a 70-character measure, and tables that are tables.
They print as ink on paper.

The references caught up with the rules, checked rather than assumed: two
statements had gone from stale to misleading (the Quickstart told a new player to
"get a Depot down as soon as one appears"), and four rules nobody could look up
are written down — the Office tier table, §8.1 in practice, what the Circus Train
pays for, and that a Realignment can be a card with no legal target.

Adding one card to the deck reshuffles every seeded deal, which broke five
fixtures. Each was a seed meaning "a game like this" — TODO #84, exactly — so
seeds moved and pools widened rather than assertions weakening, and the clearance
fixture pins its terrain the way `enhancements.test.ts` already does. The three
published replays were re-recorded.

Closes TODO #40, #42a, #108, #109 and #110.

1046 fast tests and 35 sim tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUizFYCMHRWhbWwXhp7WPR

docs/mainline-deck.md

@@ -1,22 +1,19 @@
 # Station Master — Mainline Deck
 
-**Describes the game as built at v0.8.1.0** (2026-09-22). These references are kept current with
-every release rather than versioned as editions, so there is no version in the filename: this file
-is always the latest, and the build it describes is stated here.
+**Version 0.8.2** · 2026-09-23
 
 **Scope:** the tarot-sized Mainline cards placed between Offices — how the deck is dealt, what a
 card does to a train crossing it, and the Home Deck cards played onto one.
 
-> **Per-card numbers live in [`rules/as-built.md`](rules/as-built.md)**, which is GENERATED from
-> `src/engine/content.ts` and checked by `test/card-reference.test.ts`, so it cannot disagree with
-> the game. This document explains how the deck is used; that one is the table of record. Where the
-> two ever differ, as-built is right.
+> **The card table in this document is GENERATED from `src/engine/content.ts`** and checked by a
+> test, so it cannot disagree with the game. `npm run build:cards` rebuilds it; do not edit it by
+> hand. The prose explains how the deck is used; the table is the record of what is in it.
 
 ## How Mainline cards work
 
 At setup the game lays one Mainline card between each neighbouring pair of Offices and one beyond
 each end Office, between it and a Division Point — so a game with *N* players uses **N + 1** cards.
-They are **dealt from a finite deck without replacement** (since v0.6.2), so no Division can hold
+They are **dealt from a finite deck without replacement**, so no Division can hold
 two of a card printed once. The two Division Points are the fixed ends of the Division and are not
 in the deck: `buildDivision` lays them itself.
 
@@ -27,7 +24,7 @@ A card does not belong to either neighbouring Office. It is shared Division.
 A card is divided into **regions**, and a train advances **one region per Stage**. Crossing time is
 therefore `regions − startRegion`, and nothing else. **The printed mph is scenery.**
 
-This is the part most likely to be remembered wrong, because it used to work the other way: mph set
+This is the part most likely to be remembered wrong. The printed mph does not set
 the cost and a Slow train added a Stage to *every* card. It does not. Four things move a train's
 start region and nothing else does:
 
@@ -73,23 +70,45 @@ The PDF art labels the Interchange "Yard". This reference uses **Interchange** t
 it apart from the Division Yard, the Classification Yard, the Yard Office and the Small Yard — five
 different things.
 
-**Region counts and entry points per card are in [`rules/as-built.md`](rules/as-built.md).**
+**Region counts and entry points per card are in the table under § The deck.**
+
+<!-- BEGIN CARDS: mainline -->
+| Card | Regions | Default entry | Fast / slow entry | Trains may pass | Extra may start |
+| --- | ---: | ---: | --- | :---: | :---: |
+| Plains | 1 | 0 | — | — | — |
+| Curves | 2 | 0 | — | — | — |
+| Hilly | 2 | 0 | 1 / 0 | — | — |
+| Heavy Grade | 3 | 0 | — | — | — |
+| Double Track | 1 | 0 | — | yes | — |
+| Uncontrolled Siding | 2 | 1 | — | — | — |
+| Tunnel | 2 | 0 | — | — | — |
+| Trestle | 1 | 0 | — | — | — |
+| Interchange | 2 | 1 | — | — | yes |
+
+The Mainline deck is 10 cards; the two Division Points are the fixed ends of
+the Division and are not dealt. What each card does, in the words the game uses on screen:
+
+- **Plains** — 1 region — one Stage each. · 1 Stage for every train. · One train at a time — anything following has to wait for it to clear.
+- **Curves** — 2 regions — one Stage each. · 2 Stages for every train. · One train at a time — anything following has to wait for it to clear.
+- **Hilly** — 2 regions — one Stage each. · This card reads the train's FAST/SLOW rating: a fast train starts further along and crosses in 1 Stage, a slow one in 2 Stages. No other card cares which it is. · One train at a time — anything following has to wait for it to clear.
+- **Heavy Grade** — 3 regions — one Stage each. · A grade, climbing eastward. 3 Stages to climb it and 3 Stages to run down, before help. Helpers start an UPHILL train a region further on; Brakeman does the same DOWNHILL and Airbrakes another again, and Airbrakes cannot be played without Brakeman. Never less than one Stage. · One train at a time — anything following has to wait for it to clear.
+- **Double Track** — 1 region — one Stage each. · 1 Stage for every train. · TRAINS MAY PASS — two trains may stand on this card at once, so a following train is not held behind a slower one.
+- **Uncontrolled Siding** — 2 regions — one Stage each. · A train with the card to itself starts past the back region and is across in 1 Stage. · UNCONTROLLED SIDING — arrive to find a train already here and you take the siding, a region behind it. You are not in the same place, so you do not run into it; it costs you the extra Stage instead. · One train at a time — anything following has to wait for it to clear.
+- **Tunnel** — 2 regions — one Stage each. · 2 Stages for every train. · One train at a time — anything following has to wait for it to clear.
+- **Trestle** — 1 region — one Stage each. · 1 Stage for every train. · One train at a time — anything following has to wait for it to clear.
+- **Interchange** — 2 regions — one Stage each. · A train with the card to itself starts past the back region and is across in 1 Stage. · An Extra beginning its run here starts in the back region and takes the extra Stage. · One train at a time — anything following has to wait for it to clear. · This is the one Mainline card with a yard, so an Extra Train may be made up and started here. Its printed car-sorting is NOT implemented — a consist is re-ordered at a Small Yard in a district.
+<!-- END CARDS: mainline -->
 
 ## The Interchange, and what it does NOT do
 
 The Interchange prints a car-sorting capability. **It is not implemented, and never has been.** The
 one thing the card's `sortsCars` flag actually gates is that an **Extra Train may be made up and
-started here** — it is the Mainline card with a yard, which is why §7 allows it (v0.6.2). An Extra
+started here** — it is the Mainline card with a yard, which is why §7 allows it. An Extra
 starting here begins in the back region and takes the extra Stage.
 
 Re-ordering a consist is done at a **Small Yard** in an Office Area, for one switching Move. See
 Rules §4.3.
 
-> **Corrected 2026-09-20.** Until this pass the card said "Cars may be sorted into any new order
-> here" — on the board, in the tooltip a player reads, and in the generated reference. A card
-> advertising an action the game will not offer sends a player hunting for a button that does not
-> exist. The description now says what the card does.
-
 ## Heavy Grade modifiers
 
 Home Office cards, played onto a Mainline card during a player's Draw option.
@@ -99,11 +118,17 @@ Home Office cards, played onto a Mainline card during a player's Draw option.
 | Brakeman | Heavy Grade only. A **downhill** train starts one region further on. |
 | Airbrakes | Heavy Grade only, and **Brakeman must already be on that card**. A downhill train starts one region further again. |
 | Helpers | Heavy Grade only. An **uphill** train starts one region further on. |
-| Realignment | Only onto an **unoccupied** Mainline card. Plains → Double Track, Curves → Plains, Uncontrolled Siding → Double Track, Trestle → Uncontrolled Siding. No other card may be realigned. |
+| Realignment | Only onto an **unoccupied** Mainline card, and only these four conversions: Plains → Double Track, Curves → Plains, Uncontrolled Siding → Double Track, Trestle → Uncontrolled Siding. |
 
 A Heavy Grade is 3 regions, so it is 3 Stages to climb and 3 to run down before help. Modifiers
 never reduce a crossing below one Stage.
 
+> **A Realignment can be a card with no legal target.** Only four of the nine Mainline types convert
+> at all — Plains, Curves, Uncontrolled Siding and Trestle — so a Division dealt Heavy Grade, Tunnel
+> and Double Track has nowhere to play one. A card already converted cannot be converted again, and
+> a card with a train on it is refused while the train is there. The card says which four it can
+> convert when you look at it in hand.
+
 ### ABS Signals — an Enhancement, but it lives out here
 
 **ABS Signals is dealt from the Home Office deck as an Enhancement, and it is the one Enhancement
@@ -135,9 +160,6 @@ around decides which modifiers are worth anything and which direction of traffic
 the whole game. Handing that to one of two neighbours advantages them over the other, and neither
 has a fair claim to it.
 
-**Re-opened and closed again on 2026-08-23**, when giving the choice to the Superintendent was
-considered and rejected. Jesse's call: v0.5.0's ruling stands. Rolling from the seed is
-deterministic, roughly even (51/49 east/west over 400 games), identical in solitaire and
-multiplayer, and keeps setup non-interactive — the game has no setup phase, so the question would
-have to interrupt play before the first Local Operations, in the minority of games that deal the
-card at all (20% at one player, rising to 50% at four).
+So the orientation is **rolled from the game's seed**. That is deterministic, roughly even
+(51/49 east/west), identical in solitaire and multiplayer, and keeps setup non-interactive: the game
+has no setup phase, so asking would mean interrupting play before the first Local Operations.