station-master/TODO.md

To do

Things worth coming back to. Anything noted here should either get done or get an explicit decision not to — the point is that nothing quietly evaporates.

Grouped by what kind of work it is — Next, Replay/Save Games, Bot Performance, Play Balance, Multiplayer, Rules Questions, Other — and ordered within each by how much it is currently costing us. Reorganized 2026-08-20 from a flat list; nothing below changed, only where it lives. Two duplicate entries (Heavy Grade orientation, the Local's coach) were merged into one each, and the industry-table item that had been sitting in a "these are all done" section without actually being done was moved out to Rules Questions.

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Next

Queued from the 2026-08-20 multiplayer planning session (reasoning in Multiplayer below), in order:

1. Fix the New Train phase car-placement round — done, see Multiplayer below.
2. Unify victory conditions across solitaire, competitive and coop — done, see Multiplayer below.
3. Phase 2 of docs/architecture/multiplayer.md — server core — done, see Multiplayer below.

Queued 2026-08-21, from playing the StartOS build:

4. The lobby must offer every game parameter the solitaire New Game dialog does — and it currently offers none of them. Reasoning in Multiplayer below; carries a live balance bug with it (the combined-Revenue floor is sized for four players whatever the table's real size), so this is not purely a UI job.
5. Decide what the four optionalRules are before either dialog offers them — two are live, two are read by nothing at all. Reasoning in Multiplayer below.

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Replay / Save Games

The replay viewer, the save format, and how a game gets shared.

• INVESTIGATE: how would a player publish a replay so other people can watch it? Today "Save replay" downloads a JSON file to the player's own machine, and the only way it reaches the site is by sending it to Jesse to drop into public/replays/ and redeploy. The question is what a self-service version would look like.

  **The constraint.** The site is fully static — `dist/` is uploaded to File Browser and Start9
  Pages serves the folder — and the replay list is a build-time `manifest.json` because static
  hosting cannot list a directory. So publishing needs something that accepts a write.
  
  **The one measurement that matters:** a full 5-Day game is **451–1017 bytes** compressed
  (brotli), about **600–1150 characters** base64. A save is the seed plus the intents and the
  engine recomputes the board, so a whole game fits in a URL.
  
  Four shapes, roughly costed:
  1. **Share by link, no server (~1–2 hours).** Put the compressed save in the URL fragment
     (`replays.html#s=…`); "Share replay" copies a link and anyone opening it watches the game.
     The viewer already parses saves and already has a file-open path, so this is compression, a
     hash reader and a copy button. The fragment never reaches the host. It is a link rather than
     a gallery: nobody discovers a game they were not sent.
  2. **A write endpoint (a day or two, and it is a service).** Accepts a POST, validates the save
     by replaying it through the engine — `save-replay.ts` already does exactly that check —
     writes the file and regenerates the manifest. The work is the surround: auth or rate
     limiting, abuse handling for a public write, CORS, and a deploy story. It also ends "static
     hosting is all this needs", which has been load-bearing.
  3. **Browser writes to File Browser directly — rejected.** It needs FB credentials in a static
     page, so anyone viewing source gets write access to the whole File Browser, and the manifest
     would need a read-modify-write from the browser that loses a save when two people publish at
     once.
  4. **Curated, manual (zero code).** What happens today, and it composes with (1): players send
     links, Jesse publishes the good ones.
  
  **The question behind the question is whether a gallery of strangers' games is wanted on a
  personal StartOS box at all.** If it is, (1) is the piece (2) would need anyway, so it is the
  right thing to build first either way.
  

• fromSave's replayed narration loses "Player X" attribution — found 2026-08-20 building multiplayer Phase 3, not fixed there. fromSave's loop (game.ts) calls record(game, result.events) without the actor argument submit() always passes it (game.ts's own record(game, events, actor) — actor is what turns "Chose to draw a card" into "Player X chose to draw a card"). So a restored save, an undone game (undo rebuilds via fromSave internally), or a replayed one all lose attribution on every line — invisible in solitaire because nothing ever compares a fromSave-built log against a live-played one (the one test that compares logs, test/web.test.ts's "leaves nothing in the log describing a move that was taken back", compares undo's fromSave-built log against ANOTHER fromSave-built log, so the missing attribution cancels out both sides), but it would read as broken the moment more than one seat's history is on screen at once — exactly what the replay viewer and any multiplayer post-game replay (D20) need to get right. Fixed in fromMultiplayerSave (multiplayer's version of this function, added for Phase 3) by passing actor through; not touched in fromSave itself since it's used far more widely (undo, save/restore, the replay viewer) and deserves its own careful look rather than a fix bundled into an unrelated change.

• Review the standalone replay against the site's replay viewer. node src/sim/replay.ts --seed 1234 --out replay.html writes a self-contained HTML file; the site instead reads JSON saves from public/replays/. Nothing links to the standalone one and its output is gitignored, so it is a developer tool that happens to look like a product feature. It carries two panels the site viewer does not — the bot's decision trace ("what it chose, why, and what it passed over") and the timetable — which is debugging material rather than something a player wants. Decide: fold the decision trace into the JSON viewer and delete the standalone, or keep it and accept that it is a tool. No action for now.

• The yards are shown on the play page but not in either replay viewer. The Frame carries them, so it is a rendering job, not a modelling one.

• Undo is unlimited step-back, and that is a decision to revisit. The save is the seed plus the intents, so undo() replays without the last one and can walk all the way to the deal. The RNG advances with the replay, so the same play re-rolls the same 1D12 — you cannot undo your way to a better die. But you CAN see a train's departure Stage and then spend the turn differently, which is an ordinary solitaire take-back and also a real information leak. Options if it starts to feel like cheating: make the Stage boundary a commit point, or cap the depth at the current Stage. Deliberately left open until it has been played with. Multiplayer gets nothing until there is a proposal/agreement flow — undo there is a table decision, not a button.

• The 5 MB replay size limit is arbitrary. Invented, not a browser constraint. It has earned its place — it caught a 5.2 MB payload that turned out to be the whole grid re-serialised every frame — but the number itself deserves a reason.

• Save/restore is not version-aware. A save from an older ruleset stops replaying rather than failing loudly, which is the safe direction but says little about what changed. This has now bitten once: both published replays were dead — one got 42 intents into 360, the other 4 of 338 — and nothing said so; they simply ended early and looked like short games. A save should carry a ruleset stamp and the page should say "this replay was recorded under an older ruleset and stops at Stage N" rather than presenting a truncated game as a whole one.

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Bot Performance

What the developer bot can and cannot yet do, measured. Every revenue figure below measured before v0.4.7 is low by roughly half a point — see the stub-industry entry — and the rebalance pass should not read that drop as a deck problem.

• THE BOT DOES NOT KNOW TO BRING AN EXPEDITED TRAIN BACK TO THE STATION — new in v0.4.9. The expediteFault mechanic (§7, Q3) charges 1 Revenue every Mainline Phase an expedited train is left off the Office square, and the bot has no heuristic that accounts for it: measured over 30 fresh games, one left Train 4 (3/4 Express) parked on Secondary Track from Day 3 Stage 10 to the end of the game, drawing the fault 26 times. Not an engine bug — the mechanism fires exactly as designed — but a clear next bot heuristic: prefer ending a switching turn with any expedited crew back on the Office square, at least once it has finished the work it went out for.

• THE BOT CANNOT SPOT A CAR AT A STUB INDUSTRY, and the cut-ordering rules made that visible. Coupling is mandatory on your own square now (v0.4.7), so a crew that sets a car out between itself and the only way out picks it straight back up. At a stub industry that is every set-out the bot makes: its trains run engine-first with all four cars behind, so the tail cut always lands on the exit side. The correct play is §A.5's facing point move — couple the car onto the nose, shove it into the stub, set out off the nose, back away — which is the same cross-turn planning already recorded as out of reach of any bot in "THE RUN-AROUND IS OUT OF REACH OF ANY BOT" below.

  Measured over 200 paired seeds: **-0.55 revenue** (t = -3.63) and freight revenue 1.11 → 0.56.
  Filtering self-recoupling moves out of the bot's options took recoupling from **625 of 1,029
  set-outs in 60 games to 101 of 677**, and all 101 that remain are this case. Nothing is broken —
  the game models the difficulty correctly and the bot cannot yet play it — but **every revenue
  figure in this file measured before v0.4.7 is now low by roughly half a point** and the rebalance
  pass should not read the drop as a deck problem.
  

• BOT DRIFT ACROSS THIS RELEASE — four measurements, all for the rebalance pass. Recorded together so the pattern is visible rather than four relaxed thresholds nobody adds up: - Switching work down ~16%, 1.76 → 1.48 productive acts a game (400 games), because an expedited train now stands at the Office for a Stage instead of passing straight through, and a train on the A/D track and the Office square is in the crew's way. That is the change doing its job rather than a fault — but it is drift. Collisions also went 0.05 → 0.06 and the worst game went −3 → −9, same cause: the Office fills up. Separately, the work > 2 floor that caught this had never actually been met — it read 2.16 at 150 games and 1.76 at 400, so it was passing on which seeds the sample happened to include. Now 400 games and a floor of 1.2. - Track laid badly, 7% → 15% of pieces butting a card that cannot accept them. Forced to shed on turn one, the bot would rather lay a piece than discard it; a player would discard the ones with nowhere good to go. It also means the district-size gain from the new deal is partly padding rather than useful railroad. - Interlocking placed, 15/60 → 7/60 games. Departure Revenue pulls the bot toward other work and it spends its opening on the track it was dealt. - Aimless shuttling in 3 games of 16 — thirteen are clean, so this is a minority behaviour rather than the every-game waste the detector was written for. Each floor was moved to match what is measured, with the reasoning written into the test. None is a crisis on its own; together they say the bot spends its openings worse than it did.

• The bot was partly living off an illegal placement. Barring curves from the Running Track (they have no east-west road and dead-end the main) cost it districts 28.0 → 19.7 cards and revenue ~2.0 → 0.8. It has no plan for where a curve should go once the easy square is gone. Same root cause as "the bot cannot get a crew next to an industry" and "THE RUN-AROUND IS OUT OF REACH OF ANY BOT" below; fix them together, after the rebalance.

• THE BOT'S PRIORITIES ARE NOT THE PROBLEM — measured. Ten heuristic variations, each paired over 400+ seeds. Every reordering of what the bot prefers came out inside the noise; the only thing that moved revenue was refusing to schedule a train the Office cannot hold (+1.09 ± 0.16, t = 6.79 at 1600 seeds, revenue 1.19 → 2.28). Notable failures, all instructive: - Refusing to bury the engine costs more than it saves (−0.35, t = −2.98). It works — burial falls from 8.4 decisions a game to 0.03 — and freight halves with it, because coupling is mandatory (§A.4): the moves that bury the engine ARE the moves that pick cars up. Burial is the price of collecting, not a mistake. - Reserving Moves to get home costs 0.55 (t = −2.32), though 62 of 120 trains left on the board at game end were stranded in the district. The switching work is worth more than the departures. - Granting clearance when the train ahead has one Stage left is −0.98 (t = −5.24). Trains move in numeric order, so a follower can enter the region the leader still occupies before the leader moves. "About to leave" is not "gone". - Preferring coaches at make-up, stocking the platform first, playing Interlocking earlier, hunting the Depot in the Departments: all within noise, and three of them were exact no-ops — Interlocking sits in hand alongside a train card 0.04 decisions a game. The funnel says why: only 8% of Cargo phases have a stocked green box, and the bot already takes 42% of the turns where stocking is productive. The opportunities are not there to be prioritised better. What is left is the economy itself, which is a deck question.

• The bot cannot get a crew next to an industry, so Flying Switch never fires. Industries are now stub-only and the bot places 2.23 a game (was 3.84), in districts averaging under two rows deep. flyingSwitch is exempted by name in the reachability sweep in sim.test.ts; deleting that line is the test that this is fixed. Same root cause as the item below.

• THE RUN-AROUND IS OUT OF REACH OF ANY BOT, AND THE DECK IS WHY — measured, five ways. "Teach the bot to plan across turns" was tried properly and does not work. Every attempt is neutral or negative, and they fail for one reason that the numbers make plain.

  | attempt | result |
  |---|---|
  | hold ALL track for the siding | **−0.70** (t = −3.27) |
  | hold only CURVES, the closing piece | **−0.26** (t = −3.22), district 17.9 → 16.7 cards |
  | finish a run before cutting another way down | 0.00 — 398/400 games identical |
  | treat a second turnout as the closing piece | 0.00 — **400/400 identical** |
  | spend a curve only on a square that CLOSES | −0.11, and only 15 games in 400 differ at all |
  
  **The pieces never meet.** Over 12,000 Local Operations turns: a turnout and a curve are in
  hand together on **0.3%** of them, and a turnout with a MATCHING-hand curve on **0.2%** — about
  once every eight games. A run-around needs five specific pieces of the right hands in a usable
  order; the bot does not get to the two-piece prerequisite.
  
  And it is not hand pressure. The hand is FULL — mean 2.66 cards, at the three-card limit on
  78% of turns. The bot plays 11.4 track cards a game and discards 1.5, so it spends the pieces
  as they arrive because a piece that builds anything outscores holding one that might build
  more later. Holding is the only counter, and holding measures worse every way it is tried.
  
  This is a consequence of moving track into the deck, not a bot weakness: 91 run-arounds per 100
  games when track was a private 26-piece supply the player chose from, 29/100 once it was drawn,
  4/60 now. **If the run-around is meant to be the central switching puzzle — and the rules
  present it that way — the supply has to change, not the player.** Options: give track its own
  hand or yard the way the prototype did, raise the hand limit for track specifically, or print a
  siding as a single card. Nothing else reaches it.
  

• Re-run the three "worth ~0" action-mix experiments against the new floor. Capping the draw, pairing the two halves of a load, and restricting Enhancements were each measured "within noise of zero" over 400 games — but at 400 games the standard error is ±0.33, so a real +0.5 would have looked like nothing. They are nearly free to re-run now and at least one may have been discarded wrongly.

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Play Balance

Numbers chosen to fix a measured problem rather than taken from the design. Revisit once the victory target is settled and freight carries its intended share; read no balance conclusion from a revenue number until the rules stop moving.

• A DISTRICT CAN NOW ONLY WIDEN AS FAR AS ITS MAIN REACHES (v0.4.8) — worth watching in the rebalance rather than acting on now. Track stays inside the Limits at every row, so extending the Running Track is the only way to buy room for sidings, and a straight laid on the sign is worth more than it was. The bot barely notices — it built outside its own Limits 5 times in 100 games — but the bot also builds close to its Office; a human building deliberately hits this on the first wide district, which is how it was reported. If territory turns out to be the real constraint on freight, this is one of the two places to look (the other is the track supply, in Bot Performance).

• REBALANCE, once the rules are right — deliberately deferred. Card counts, industry counts and the track mix all need a pass together, and none of them should move until the rules stop moving. Standing distortions to account for when it happens: offices are doubled (Q12) and industries tripled (Gap 12), both tuned when the deck held 139 cards and no track; it now holds 235 of which 96 are track, so every draw is diluted by 41% — precisely the pressure those multipliers exist to relieve. The 8 sharp curves have already been taken out on that argument; offices and industries are the two left. Until then, read no balance conclusion from the revenue numbers; they are a functionality signal only.

• Superseded 2026-08-20 by the victory-condition redesign (Multiplayer) — kept for the measurements. minCombinedRevenue replaces the fixed target these numbers were read against; re-measure once that lands rather than off this. RE-MEASURE THE BOT AT THE NEW DEFAULTS. Both provisional rules below are now settings on the New Game dialog rather than fixed choices, and the defaults are not what the numbers in this file were measured under: the opening hand defaults to three random cards (the prototype rule) rather than 3+3, and train revenue per transit defaults to 0 rather than 1. That second one is the big move — it was worth ~5.4 of a 7.0 mean, so the bot's revenue should fall to roughly the working freight-and-passenger economy alone, which is the number this game has actually been trying to read all along. Every mean, floor and threshold quoted below and in the tests predates it. The three revenue rates run 0–5, so the useful next step is a sweep rather than a single re-run.

• Not superseded by the 2026-08-20 victory-condition redesign (Multiplayer) — these two stay houseRules dials, separate from the new GameConfig victory dials. Noted only so the two redesigns aren't conflated. REVIEW THE TWO NEW RULES ONCE THEY HAVE BEEN PLAYED — both went in provisional, and both are now selectable rather than fixed. Jesse's call, both implemented and measured, both flagged in rules-v0.2.md. What follows is what was measured when each was the only option.

  **The opening deal (3 track + 3 other, from two separately shuffled piles).** It did what it
  was aimed at, modestly: run-arounds **4/60 → 7/60** and districts **17.9 → 20.3 cards**, with
  revenue unmoved on its own (−0.1, inside noise). Still nowhere near the 91/100 of the
  private-supply era, so the supply question is softened rather than answered. Two things to
  watch at the table: whether opening with six against a limit of three is a real decision or
  just bookkeeping, and whether three is the right number of each.
  
  **~~One Revenue for every train that clears your section.~~ Now: one Revenue to EVERY player
  when a train completes its run.** Jesse's revision in v0.4.2. The first version paid the Office
  a train departed, which on a five-Office railroad paid five separate times for one train and
  paid most to whoever it passed first. It pays once now, when the train runs off the end of the
  Division, and it pays the whole table — getting a train the length of the railroad is the
  shared achievement, and every Office it crossed had to clear it.
  Solitaire is nearly unmoved (7.0 → 7.3 mean over 200 games) because one player's departures and
  completions run at almost the same rate; **in a multi-player game the shape is completely
  different** and needs measuring once multiplayer exists — N players × 1 per completed run
  against the old N payments per train. **The victory-target question stays live**: 20 over 5 Days
  is still reachable largely on traffic, which is either the intent or an argument for raising it
  — and at the new default of 0 per transit it is not reachable on traffic at all, which is the
  first thing a playtest should check.
  

• The marginal Local Operations action is worth ~0, and that is the real ceiling. Three separate attempts to spend the 60 actions better — capping the draw, pairing the two halves of a load, restricting Enhancements — each measured within noise of zero over 400 paired seeds. 76% of the time an outbound industry has neither a stocked green box nor a spotted car, and only 5% of Stages have a single workable facility anywhere, yet redirecting actions at that does nothing. Something upstream limits how much work exists to do at all; find out what before spending more effort on the option mix.

• Freight was stuck at ~2.7 loads a game and three fixes have not moved it. Sidings, facility placement, car selection and the discarded-load leak all raised revenue (3.2 → 6.5) without raising loadStarted past 2.7. The chain is not leaking and the cars are arriving correctly (57% of drops land on a facility that wants them, 0% on one that does not). The binding constraint is now upstream of routing: 60 Local Operations actions a game, and a load needs a stocked green box AND a spotted car AND a free Laborer to line up in the same Stage. Measure how many Stages have all three before changing any heuristic — the answer may be that the economy, not the bot, is what caps freight.

• The rolling stock supply is a guess. ROLLING_STOCK_SUPPLY (coach 8+8, boxcar 10+10, hopper 8+8, reefer 5+5, tank 6+6, caboose 6) is marked provisional in content.ts and was scaled alongside the Gap 12 industry increase. Now that the Classification Yard returns stock only when the Division Yard empties, these numbers set the real supply pressure. Adjust from playtesting rather than theory, and watch whether industry density feels light or heavy at the same time.

• Office card density (Depot 4→8, Station 2→4, Terminal 1→2). Chosen to remove a 25% chance of an unwinnable opening deal. Blunt: it lifts the whole ladder and dilutes every other category. The better answer may be fewer Terminals, a cheaper first upgrade, or more A/D capacity at the Whistle Post itself.

• Industry density (9 → 27, Gap 12). Restored roughly the prototype ratio. The "freight is only 13–18% of gross" figure that motivated this was partly a measurement bug (see the stats.ts item in Done) and partly the car-selection bug; freight now runs at 37%. Worth re-deciding whether 27 is still the right number now that the industries are actually served.

• Train density. Left alone by decision, but noted: 22 train cards in 140 are drawn less often than 22 in 115 were, and trains scheduled fell 2.9 → 2.1 as a side effect of the other density changes.

• Superseded 2026-08-20 by the victory-condition redesign (Multiplayer) — kept for the measurements and the reasoning. LENGTH_PROFILES.target (20 over 5 Days, standard) is retiring in favour of minCombinedRevenue, defaulting to 3 × players × days (15 for 1-player/5-day, not 20) — a different number, deliberately not tuned to match this table. Whether the Office-ladder bottleneck below still applies at the new default is worth re-measuring once the redesign lands, but the fixed "20" this data argues against no longer exists as a target. The victory target (20 over 5 Days) is out of reach by a factor of about four, and the Office ladder is why. Measured over 800 games with the tuned bot, which no longer throws revenue away on collisions (0.0 a game, down from 0.4):

  | trains scheduled | games | revenue |     | Office reached | games | trains | revenue |
  |---|---|---|---|---|---|---|---|
  | 0 | 110 | 0.67 |  | Whistle Post | 297 | 0.81 | 0.62 |
  | 1 | 379 | 1.69 |  | Depot        | 272 | 1.49 | 2.92 |
  | 2 | 234 | 3.72 |  | Station      | 176 | 1.89 | 4.36 |
  | 3 |  68 | 5.68 |  | Terminal     |  55 | 1.93 | 5.04 |
  | 4 |   9 | 5.78 |  | | | | |
  
  Revenue is almost exactly linear in trains scheduled — about **1.9 a train** — and trains are
  capped by A/D capacity, which is the Office tier, which is a card you have to draw. So the
  whole economy hangs off one valve: **37% of games never leave the Whistle Post and earn 0.62;
  53% of all games earn nothing at all.**
  
  Extrapolating the line, 20 Revenue needs roughly **11 trains and therefore 11 A/D tracks**. A
  Terminal has four. The target is not merely missed, it is structurally unreachable under this
  deck at this Office ladder — no amount of bot skill closes it, and the best game seen in 800
  was 26 against a median of 0.
  
  The three ways out are all yours to choose between, and they are different games:
  1. **Lower the target** to what a 5-Day game can produce (6–8 looks like the honest number).
  2. **Open the valve** — more Office cards, or a cheaper first upgrade, or more A/D capacity at
     the Whistle Post, so the ladder is climbed rather than drawn.
  3. **Raise revenue per arrival.** It is 0.46 today; each arrival can in principle pay 2 for
     passengers alone. That is the freight/passenger conversion problem, not the traffic problem.
  
  Nothing here is a bot weakness any more, which is what this measurement was waiting on.
  

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Multiplayer

Deferred while planning the server; decisions and reasoning are in docs/architecture/multiplayer.md.

• Let the game join a call and talk to the table. Long-term. If the game could join a Zoom, Teams or Jitsi call and post into its chat, it could carry the whole table's shared state without anyone alt-tabbing: the history of actions as they happen, and a prompt when someone is holding the game up — "Now waiting on player Alice to complete the Cargo phase." - Further out, audio into the same call: a crash when a collision happens, a bell as the Stage clock turns over. - Further out still, a nudge on a timer — if a player has not moved within some interval, the game says so, by beep or by spoken line: "Still waiting on Alice to complete the Cargo phase." That turns the turn chart's "waiting on" chip into something a distracted table actually notices.

• Multiplayer train make-up is a round, not one player's job. When a new train is built, players take turns adding cars to the consist; in solitaire one player does all of it. The engine currently has no per-player turn within the New Train phase, so this is unbuilt rather than wrong.

• MULTIPLAYER — three things deliberately deferred while planning the server. Decisions and reasoning are in docs/architecture/multiplayer.md §11; these are the ones left open. - Bots should take minimally damaging, defensive actions when a player steps away, so a game is not permanently halted. Deliberately NOT automatic today: a turn timer forfeiting is different from a bot competing, and the clearance ruling is the one decision that changes another player's score. Bots fill empty seats at lobby time only (D8). - Let a player resign and hand their railroad to a bot to finish. Same care needed as above, but it is consented rather than imposed. - A forcing turn timer — explicitly NOT in the design. lobby-and-sessions.md §5 used to specify one: on expiry the server took "the safest legal action", including denying a clearance. Cut in the review, because it is the same objection as a bot playing for an absent player — the clearance decision changes somebody else's score, so anything that answers it automatically changes the game. Explore later if halted games turn out to be a real problem at a real table; the reasoning worth keeping is that deny is the safe default, since a held train costs a Stage and a wrecked one costs 5 Revenue and feeds the collision floor. - The opening D12 for the Eastern Division Point (§4.4) decides nothing. Done in v0.4.1 — it orders the whole chain now, west to east by ascending roll. The lobby still owes it a display: state.openingRolls is kept so clients can show the rolls forming the chain rather than only the result (lobby-and-sessions.md §4). - Revisit the join secret (D14). One server-wide secret, passed out of band, gates create and join. Enough for a private box, probably not enough if stationmaster.<domain> is pointed at the open internet for long. Note that one-game-at-a-time per person is expected usage and deliberately NOT enforced — enforcing it needs cross-game state whose only job is deciding when to release someone, and getting that wrong locks a player out.

• ~WHY DOES A 4-PLAYER COMPETITIVE GAME END AFTER 16 STAGES OF A POSSIBLE 60? Answered 2026-08-20: the collision floor, not the revenue floor. Traced checkVictory (advance.ts:1086-1133): in competitive mode the revenue floor can only fire at the exact Day-5 boundary (Stage 60), so it structurally cannot explain a 16-Stage ending. Only the collision floor can (advance.ts:1076-1080, 3 collisions in one Day, checked at every Stage boundary). collisionsToday is one counter every seat feeds, so a 4-player table burns a fixed shared budget roughly 4x faster than one player would. Also: multiplayer.md §3's 8-game sample predates DEFAULT_HOUSE_RULES (v0.4.2) and most likely ran under what is now LEGACY_HOUSE_RULES — that sizing data is stale on top of the collision-floor explanation. Jesse's call, 2026-08-20: keep the collision caps flat rather than player-scaled (below), so 16-Stage games under default settings are an accepted, deliberate outcome, not something to re-tune away — re-measure multiplayer.md §3's sizing table once the redesign lands, but expect similar early endings by design.

• Victory conditions unified across solitaire, competitive and coop — designed and implemented 2026-08-20. One shared, fully-configurable set of GameConfig dials replaces LENGTH_PROFILES.target, VictoryCondition: 'firstToTarget' (confirmed dead — grepped, never selected anywhere in the codebase today) and the flat COLLISION_FLOOR_PER_DAY constant:

  | dial | meaning | default |
  | --- | --- | --- |
  | `days` | how many Days the game runs | 5, all modes |
  | `minCombinedRevenue` | everyone loses if the table's total Revenue is below this when Days run out | `3 × players × days` — reuses `collectiveRevenueFloor()` (`content.ts:1020`), now also applied to solitaire (1 player) rather than competitive-only |
  | `maxCollisionsPerDay` | everyone loses immediately, mid-game, once collisions in one Day reach this | 3, **flat — not scaled by players.** Jesse's call: more players means more independent chances to collide, not a bigger shared budget, so multiplayer is deliberately riskier than solitaire at the same default |
  | `maxCollisionsTotal` | same, summed across the whole game | 5, flat, same reasoning |
  | `pvpCardsAllowed` | whether the 22 opponent-directed cards (still unbuilt, see below) are in the deck | forced off in solitaire and coop — no valid target for them in either — on by default in competitive |
  
  `0` means "off" for every dial. Win/lose shape is otherwise unchanged from what solitaire
  already does: most Revenue when Days run out wins, unless `minCombinedRevenue` was missed, in
  which case everyone loses — just made configurable per game instead of a fixed `length`
  lookup. Coop keeps its existing "score is the table's total" model, now against a
  configurable floor instead of `profile.target * players.length`.
  
  **New Game dialog:** one shared dialog for all three modes, per Jesse — a mode radio button
  at the top, the same field set underneath for all three, greyed out wherever a mode forces a
  value (the PvP checkbox in solitaire/coop). Solitaire gains the four new dials alongside the
  starting-hand and revenue-rate fields it already has; picking a mode only changes the
  defaults, never the field set. **Deal stays disabled for Competitive/Co-op** with a "needs a
  server" note, since Phase 2 didn't yet expose a way to actually start one from the browser
  (see below) — only Solitaire's Deal path is wired to a real game today.
  

• New Train phase car-placement is one player's job even in competitive mode — fixed 2026-08-20. §7 (rules-v0.2.md:346-363) is explicit: "starting with the Superintendent and working left, each player may place ONE car... the round repeats... until the consist is full," with a worked 2-player example. newTrainPhase (advance.ts:187-282) never implemented the round: enterPhase resets actorOffset = 0 on entering the phase (advance.ts:172) and newTrainPhase never incremented it the way playerPhase does for Local Ops (advance.ts:140), so the actor was always the Superintendent alone, for every car of every train made up that Stage. Fixed by reading the round position off tray.consist.length instead — it already counts placements toward that tray and resets per train with no new state needed. Test in multiplayer.test.ts, "the New Train phase car-placement round rotates."

  **Found in the process, not fixed, logged separately:** `newTrain.passCar`'s `check()`
  (`apply.ts:959-967`) tests whether the *entire* Division Yard is empty rather than whether a
  car suitable for *this* tray exists, and `reduce()` has no case for `carPassed` at all
  (`apply.ts:2246-2247`, falls to `default: break` — applying a pass currently mutates nothing).
  Unreachable in practice today: `trainNeedingCars` only ever flags a tray that already has a
  suitable car waiting, so a legal `passCar` for the flagged tray can't occur. Only matters if a
  future change lets the New Train phase address more than one tray at a time. Not fixed here —
  nothing to verify against an intent that can't legally fire.
  

• The redaction test (multiplayer.md §7) is more done than the plan suggests, but the exhaustive check is still missing. test/multiplayer.test.ts's "the view shows one seat at a time" section (added earlier) already proves snapshot(s, ..., viewer) gives each seat its own hand, board, Revenue and impediments — traced snapshot() itself (src/sim/view.ts:1180-1219): hand reads only s.decks.hands.get(viewer), deck is a count, other seats' hands appear only as .length, and Frame's type has no seed, rngState or card-id-dictionary field for anything to leak through by accident. What exists is all spot-checks, though — "this seat's Frame has the right hand length." What's still missing is the exhaustive one §7 actually calls for: serialize a seat's Frame and assert it contains none of another seat's actual card ids and no deck order, so a future careless edit is caught rather than assumed safe. Doesn't need a server — buildable now against snapshot() and the existing game()/playGame harness already in multiplayer.test.ts. Held for now, 2026-08-20.

• The lobby's seat controls could not express "nobody in this chair" — done in v0.5.3. Raised by Jesse 2026-08-21. The seats array grew as people joined, so the four rows on screen were partly fictional: a 2-player game simply started with a 2-long array, and a host who added a bot to a later chair padded the array with a null that silently disabled Start behind a one-line note. The host now picks the table size (2-4) when creating the game and the array is built at that length once, so a gap cannot be expressed rather than merely being rejected. That also removed the need to compact seats at Lobby.Start — which would have shifted the player index every PlayerSession records at join time and that /api/stream and /api/intent route by, quietly handing a player somebody else's railroad. Tested in test/server/lobby.test.ts ("seat index is player index, with no compaction to shift it", "never grows the table, whoever asks", "refuses a chair that is not at the table").

• THE FOUR optionalRules ARE SETTABLE BY NOTHING, AND TWO OF THEM DO NOTHING. Split out at Jesse's request 2026-08-21, to review on its own rather than as a footnote to the lobby item below. GameConfig.optionalRules (state.ts:585-588) carries reducedVisibility, sisterTrains, employeeRotation and emergencyToolbox. Neither the solitaire New Game dialog nor the lobby exposes any of them, and every construction site in the codebase hardcodes all four to false (web/game.ts, sim/harness.ts, sim/replay.ts, sim/compare.ts), so no game has ever been played with one on.

  **Check what is real before building a form for it.** Only two are wired:
  
  | rule | status |
  | --- | --- |
  | `reducedVisibility` | **live** — read at `advance.ts:53`, gates on `NIGHT_STAGES` |
  | `emergencyToolbox` | **live** — read at `setup.ts:374`, seeds each player's Red Flags |
  | `sisterTrains` | **nothing reads it.** Declared, defaulted, never consulted — and §9a Q9 records that the Second Section card *supersedes* the Sister Trains optional rule, so this flag is most likely dead rather than unbuilt. Decide whether to implement or delete it |
  | `employeeRotation` | **nothing reads it.** Declared, defaulted, never consulted. Note the seat/player split (Phase 0, D9) was built specifically so this rule *could* exist — the groundwork is there, the rule is not |
  
  So a dialog listing all four would offer two working toggles beside two that silently do
  nothing — the exact failure `checkPlay`'s `NOT_IMPLEMENTED` and `enhancementText`'s
  live/dormant/unbuilt table exist to prevent. Either implement the two dead ones, delete
  them, or label them on screen the way an unbuilt Enhancement already labels itself. Doing
  that is what decides whether this is a UI job or a rules job.
  

• THE LOBBY OFFERS NO GAME PARAMETERS AT ALL, AND THE ONE IT INFERS IS WRONG. Raised by Jesse 2026-08-21 after playing the StartOS build. Creating a multiplayer game asks for a display name and a mode, and nothing else — every other dial comes from defaultMultiplayerConfig(mode) (web/game.ts), hardcoded, with no way to change it. Solitaire's New Game dialog (play.html, #ng-*) asks for all of it: seed, starting hand (ng-hand — three random / six random / three track + three other), the three revenue rates (ng-passenger / ng-freight / ng-transit), days, minCombinedRevenue, maxCollisionsPerDay, maxCollisionsTotal and pvpCardsAllowed. Multiplayer should ask for the same set. Note that GameConfig.optionalRules (reduced visibility, sister trains, employee rotation, emergency toolbox) is exposed by NEITHER dialog and is hardcoded false in both — worth deciding on separately rather than folding in silently.

  **~~The bug this hid~~ — fixed in v0.5.3.** `defaultMultiplayerConfig` defaults to
  `players = 4` and `lobby.ts` called it without the argument, so `minCombinedRevenue` was
  always `collectiveRevenueFloor(4, 5)` = 60 whatever the table's real size — a 2-player game
  played against a floor meant for four (60 rather than 3x2x5 = 30), and missing that floor
  means *everyone loses*. It fell out of the seat-control change: the host now picks the table
  size when creating the game, so the real count reaches `defaultMultiplayerConfig` and the
  ordering problem that caused this (config fixed at CREATE, seat count unknown until START)
  no longer exists. **The form itself is still missing** — that is what this item is now.
  

• D19's switching-instrumentation still needs writing, once real people are playing. "13% for the bot" (multiplayer.md D19) was a one-off measurement, not code — nothing in bot.ts or the sim tools logs it today. It needs live human wait-state data, so it can't usefully land before Phase 2 and realistically not before Phase 4 (real people at a lobby, not bots). A few lines when the time comes: log whether a legal local-only action existed for a waiting player, and whether they took it the moment their turn arrived.

• THE 22 OPPONENT-DIRECTED CARDS — 10 Action, 12 Space-use — ARE OUT OF EVERY DECK UNTIL THEY ARE BUILT. Jesse's call. They were already cut from solitaire (Q6, no legal target with one player); they are now cut from the competitive deck too, because checkPlay answers both categories NOT_IMPLEMENTED and dealing them would make ~9% of draws reject outright. Flip opponentCardsInDeck in setup.ts when they land. They are played AT another player — Watertower, Derail, Railroad Crossing and so on — so they are genuinely multiplayer work, and three Enhancements are waiting on them: Facing Point Locks, Water Column and Overpass are wired and read, and fire only against these cards. Until then those three are dormant by design rather than broken.

• Multiplayer proper — Phases 0-4 done (v0.4.0 through v0.5.1), Phases 5-6 to go. The full plan is docs/architecture/multiplayer.md §12. Phase 2 (server core) landed in one pass:

  - `src/sim/frame-delta.ts` — the live per-seat board delta (`deltaFrame`/`applyDelta`), a
    smaller, purpose-written replacement for reusing `replay.ts`'s `compress()` — that function
    interns strings across a whole recorded array, which a live single-frame push has nothing to
    intern against; only its one-step-back "null if unchanged" idea carried over.
  - **Found and fixed a real bug tracing this**: `actionMenu(game, seat)` only used `seat` for the
    `hand` field — everything else came from `currentActor(game)` regardless of who asked, so a
    server computing every connected seat's Menu would have handed the acting player's legal
    moves to a waiting seat, paired with the wrong seat's cards. Fixed in `game.ts` with a guard;
    tested in `multiplayer.test.ts`.
  - The redaction test (§7) is built — `test/redaction.test.ts` — and passed on the first run
    against the existing `snapshot()`, confirming it was already correct, not just apparently so.
  - `src/server/session.ts` — the game session host (pure logic, no sockets, reuses `game.ts`'s
    `Game`/`submit`/`currentActor`/`actionMenu` wholesale rather than re-deriving intent
    application/narration). **Found while building it**: `submit()` derives the acting player from
    `currentActor(game)` itself and does not check who is calling it — safe for `LocalSession`
    (one possible caller) but not for a server, so the session host verifies `seat ===
    currentActor(game)` itself before ever calling `submit`, rejecting with `NOT_YOUR_TURN`
    otherwise. Idempotent resend (a repeat `seq`) and the illegal-intent path (checked via
    `check()` directly, so a rejection never pollutes the shared narration log with "not allowed"
    text meant only for the submitter) are both handled here too.
  - `src/server/http.ts` / `src/server/index.ts` — plain `node:http`, no framework (confirmed
    nothing to reuse and nothing else warranted — zero runtime dependencies anywhere else in the
    project). `POST /api/game`, `GET /api/stream` (SSE, per-seat, with a 20s heartbeat and an
    `id:` line per push), `POST /api/intent`, and static serving of `dist/` so the server can be
    same-origin with itself (D16). No `gameId`/multi-game concept yet — one game per process,
    matching "Phase 2 has no lobby."
  - `src/web/session.ts` gained `createRemoteSession`; `main.ts`'s `start()` switches on `?seat=`
    presence (D4 — one bundle, unchanged). Every `LocalSession`-only call site in `main.ts`
    (`seed()`, `save()`, `undo()`, the New Game dialog) now goes through an `isLocal()` type guard
    rather than assuming, since `session` can now be either.
  - **Found and fixed a real infrastructure bug**: adding `test/server/` broke `npm test`'s glob.
    `"test": "node --test test/**/*.test.ts"` relied on bash's non-globstar behaviour of passing
    the *literal, unexpanded* pattern through to Node (which then globs it correctly itself) —
    that only happens when the pattern matches *no* files at the shell level. The moment a
    subdirectory existed, bash expanded it to just that one file, and `npm test` silently ran only
    the new suite. Fixed by listing both depths explicitly:
    `"test": "node --test test/*.test.ts test/**/*.test.ts"`.
  - Verified two ways: `test/server/session.test.ts` exercises the session host directly (no
    sockets); a live end-to-end curl smoke test (server started, a 2-player game created, two SSE
    streams opened, an intent rejected from the non-acting seat, accepted from the acting seat and
    broadcast to both, a resent `seq` producing no second push, and the board correctly nulled on
    the second push) — see the session transcript. **Not verified**: an actual browser — no
    browser binary exists in this environment, so `RemoteSession`'s DOM-facing code
    (`EventSource`/`fetch` wiring) compiled and typechecks but was not clicked through visually.
  
  **Phase 3 (persistence/resumption) done, same session, 2026-08-21.** Per §12 steps 14-16 and
  `lobby-and-sessions.md` §5-6 (unusually concrete — the exact storage shape was specified, not
  designed here):
  
  - `src/server/persistence.ts` — `game.json` (`{engineVersion, seed, config, playerNames,
    history, status, createdAt}`) and `turn-timings.json`, both atomic-rewrite-then-rename, no
    `gameId`/index yet (one game per process, same deferral as Phase 2's `gameId`).
  - `game.ts` gained `fromMultiplayerSave` — `fromSave`'s multi-player sibling, built on
    `newMultiplayerGame`. **Found while testing it**: `fromSave`'s replay loop calls
    `record(game, result.events)` without the `actor` argument `submit()` itself always passes,
    so every replayed line loses its "Player X" attribution — invisible for solitaire (nothing
    ever compares a `fromSave` replay against a live-played log; `undo`'s rebuilt game is itself
    `fromSave`-built, so the one test that compares logs only ever compares two unattributed
    replays against each other) but immediately visible for multiplayer, where anonymous "Chose
    to..." lines are unreadable the moment there is more than one seat. Fixed in the new function;
    **`fromSave` itself still has the gap** — not touched here, since it is used far more widely
    (undo, save/restore, the replay viewer) and deserves its own careful pass rather than a
    touch-in-passing. Worth its own TODO item if picked up.
  - `session.ts` gained `exportSave()`, `resumeSession()`, and turn-timing tracking — a `TurnTiming`
    span (player, phase, day, stage, start/end wall-clock) closes and reopens whenever the acting
    player, phase, Day or Stage changes; recorded entirely in the session host, never touching the
    engine (which must stay clock-free and deterministic) and never stored inside `history` (a
    replay must reproduce a game from decisions alone). No reporting/aggregation/UI on this data
    yet — §5 calls that "optional... if unobtrusive," and the Phase 3 deliverable is the data
    being recorded, not a view of it.
  - `index.ts` loads `game.json` on boot before starting the HTTP listener: version match →
    `resumeSession`, replayed straight through; mismatch → refused explicitly and loudly (the
    file is left untouched, so rolling the running version back recovers it), server starts with
    no active game rather than replaying under the wrong rules.
  - Verified live, matching this phase's own "done when": server started against a fresh data
    directory, a 2-player game created, intents submitted from both seats, **the server process
    killed and restarted**, both `?seat=` streams reconnected and picked up exactly where they
    left off — same Day/Stage/phase, correct whose-turn-it-is, correct narration attribution.
    Separately confirmed the version-mismatch path: hand-edited `engineVersion` to a bogus value,
    restarted, server logged the refusal and started with no active game (confirmed via `POST
    /api/game` succeeding rather than 409ing).
  
  **Phase 4 (lobby, sessions, reconnection) done, 2026-08-21 — v0.5.1.** Per §12 steps 17-20 and
  `lobby-and-sessions.md` in full:
  
  - `src/server/lobby.ts` — pure logic, no sockets, no filesystem, same split `session.ts`
    already draws. `createLobby`/`joinLobby`/`setBotSeat`/`reassignHost`/`startLobby`, a
    speakable game code (`RAIL-4471` style, from a small railroad-word list rather than a
    dictionary — read aloud across a table, not typed from memory), and the 2-4 player cap
    (`playerCountAllowed`) — see the doc-fix note below.
  - **The server now holds more than one game.** `persistence.ts` gained one directory per
    `gameId` (`games/<gameId>/`) plus a top-level `index.json` naming every game, so `index.ts`
    can resume all of them on boot rather than the one `game.json` Phase 3 assumed.
    `writeGame`/`loadGame`/`appendTiming` needed no signature change — they already took a
    directory directly.
  - **Session tokens replace `?seat=&secret=` on the running-game routes.**
    `lobby-and-sessions.md` §1: the token alone proves identity, so `/api/stream` and
    `/api/intent` now read `?token=` and the join secret's job ends at the lobby door
    (`/api/lobby/create`/`/api/lobby/join`). `web/session.ts`'s `createRemoteSession` takes
    `(token, seat)` — `seat` still passed in rather than learned from a push, since it has to
    answer before any push necessarily arrives, and the caller already has it from the
    join/create/start response.
  - **Bots fill empty seats at `Lobby.Start` only (D8)**, never mid-game. `session.ts` gained
    `driveBots()`: after any accepted intent (and once at construction, for a resume that lands
    exactly on a bot's turn), it plays `developerBot` forward through every consecutive bot seat
    before the push goes out — reuses `legalActions`/`developerBot` wholesale, no new bot logic.
    `SavedGame` gained `botSeats: PlayerIndex[]` so a bot seat survives a restart.
  - **Host rights pass to the earliest-joined remaining player** if the host's LOBBY connection
    closes before start (`lobby-and-sessions.md` §2) — tracked via `Lobby.joinOrder`, a token
    list rather than seat order, since a bot-filled seat has no join time of its own.
  - **Disconnect/reconnect** (§5): `Push` gained an optional `presence` field — connection news
    about ANOTHER seat, built entirely by `http.ts` (which owns the connection table) and never
    routed through `session.ts` or the engine, since a disconnect is transport news about a
    connection, not a `GameEvent`. The page shows a banner naming who has dropped
    (`renderPresence`, `main.ts`) and clears it the moment they reconnect. Reconnect itself needed
    no new engine-side work: `session.connect(seat)` already sent a full un-delta'd `Frame`.
  - **The client lobby** (`src/web/lobby.ts`, wired from `main.ts`'s `start()`): create-or-join
    forms, a live seating screen (host-only bot toggles and Start button, updated over a new
    `/api/lobby/stream` SSE), and `localStorage` in place of `?seat=` for "was I already in a
    game" — found on load, reconnects straight to `createRemoteSession` and skips the lobby
    entirely. A `Multiplayer` button beside `New game` is the entry point; the New Game dialog
    itself is untouched, still solitaire-only, its old "needs a server" note repointed at the
    new button.
  - **Found and fixed while running the live smoke test, not by typechecking:** `/api/intent`
    read its token from the JSON body, but `web/session.ts`'s `submit()` — unchanged from Phase
    2 — sends it in the query string, same as `/api/stream`. Every request failed `no such
    game`. Both sides independently typecheck fine (an HTTP body is `unknown` on the wire), which
    is exactly why the curl-level smoke test exists rather than stopping at `tsc --noEmit`.
  - **Doc fix:** `multiplayer.md`'s D18 said "player cap 6", citing `lobby-and-sessions.md` §2 —
    which actually specifies 2-4 and gives the reasoning (what `test/multiplayer.test.ts` exercises).
    The two had drifted apart; "6" was never implemented or tested anywhere. D18 now says 2-4.
  - Verified: `test/server/lobby.test.ts` (pure logic — creating, joining, capacity, bot seats,
    host transfer, starting) plus new coverage in `session.test.ts` (bot-driving, including two
    bots in one game) and `web.test.ts`. A live smoke test through `curl`: create a lobby, join a
    second player, start, submit intents from both (including the wrong-actor rejection and an
    idempotent resend), reconnect after a real server kill-and-restart, a bot-filled coop lobby
    starting and never stalling on the bot's seat, and a disconnect/reconnect presence notice
    observed on an open stream. **Not verified: an actual browser** walking through the lobby
    screens — none is available in this environment, the same limitation Phase 2's `RemoteSession`
    shipped under.
  

---

Other

Doesn't fit the above.

• Real audio, as committed assets. Everything the game plays is synthesised from oscillators (src/web/sound.ts), which was the honest choice for a site that fetches nothing — but it is a placeholder, not the finished sound. Sound therefore defaults to OFF. - "All aboard" most of all. It currently goes through the browser's speechSynthesis, so it is whatever system voice the player happens to have — a robot, not a conductor. A real clip is the single biggest improvement available here. - arrive (a train pulling into an Office), depart (a train highballing out of one) and crash (§10 — a collision) are now synthesised too, v0.4.9 — three chuffing/screeching cues built from the same oscillator-and-filtered-noise toolkit as stage, wired to trainArrived, trainHighballed (Office departures only), and trainsDestroyed. Good enough to keep as the real thing rather than a placeholder — no WAV clips needed for these three. - Find and add the rest as assets: steam whistle, grade-crossing bell, couplers clashing. Every file added needs three things recorded alongside it: the sound file itself, its source (where it was obtained from), and its license. The preferred license is CC0 ("Creative Commons Zero") — a public-domain dedication: the creator waives all copyright and related rights, so the file may be used, modified, and redistributed for any purpose, including commercial, with no attribution required and no restriction. That is the cleanest fit for a file committed straight into the repo, since it needs no attribution to track going forward. Only fall back to an equally-permissive alternative (e.g. a license that explicitly permits redistribution with no ongoing obligation) if CC0 isn't available for a given sound, and record that license's actual terms plainly rather than assuming they match CC0. Files also need to be small enough to commit, and a check that the "fetches nothing external" test still passes — assets must be served from the site's own folder, never hot-linked. - Keep the synthesised versions as the fallback for anything not sourced, so a missing file is a quieter game rather than a broken one.
• Regions as the primary model (the other half of §8.2). The Division map now DRAWS regions, deriving position from what the crossing already cost. The engine still models a crossing as a countdown of Stages, so two things printed on the cards remain unimplemented: - entryPoints is declared on every Mainline profile and read nowhere. The Heavy Grade card has five named Start positions, and playing Brakeman is supposed to move your entry point along the card. The engine gets the same ANSWER by taking a Stage off the crossing, which is why the derived drawing looks right — but the mechanism is not the printed one, so a card whose starts do not correspond to its speed would be drawn wrong. - implications.md §6 calls this "the single largest mechanical gap" and asks for typed cards with speeds and named entries, with crossing time DERIVED from the region walk. Doing it properly changes movement, so it invalidates every balance figure — revenue 8.7, the freight numbers, all of it — and needs a full paired re-measure over 400 seeds. Needs the source Start-position art for the ten card types before it can begin.
• card-reference.md's industry table may still be stale beyond Grocer's Warehouse, the Oil Refinery and Freight House (corrected v0.5.0) — Mine Tipple, Produce Shed and Power Plant were NOT re-verified. The v0.5.0 pass corrected three rows (and the "Freight House is not a card" claim across card-reference.md, glossary.md, rules-v0.2.md and open-questions.md) on Jesse's explicit call. Checking content.ts while making that change turned up that mineTipple and powerPlant are ALSO base 1 out/in + 1 Laborer in the engine — the same uniform model as the three that were corrected — while card-reference.md still prints Mine Tipple 3/3/4 and Power Plant 3/3/4, and the "Throughput — why these Laborer counts" section right below the table is built entirely on those higher numbers. Flagged inline in card-reference.md rather than silently rewritten — this needs the same kind of decision Jesse made for the other three, not an assumption that the same correction applies, since raising or lowering Laborer counts is also a balance question, not only a docs one.

---

Done, kept for the reasoning

• Put rolling stock back into circulation. The Classification Yard was write-only — seven writers, no readers — so 37% of all rolling stock left the game by Day 5. Returning it at the Day boundary is +2.32 ± 0.52 (t = 8.79), the largest single change measured on this bot, and it was ranked THIRD and predicted not to matter because the Division Yard never runs dry. The aggregate was the wrong measure; having the right commodity at the right moment is what counts.
• Make Enhancements reachable at all. The bot never laid a straight on the Running Track (0.00 in 100 games) because two-arc run-arounds do not need one — so 13 of the 18 Enhancement cards had nowhere to go, including Interlocking, the only cure for the only penalty in the game (no free A/D track, 27% of gross). One scored straight fixed it: enhancements placed 0.64 → 3.01, collision cost 2.70 → 1.91, worst game −47 → −24. Revenue +0.70 ± 0.74 paired over 400 seeds — real but not significant alone; the variance reduction is the clearer win.
• Stop the bot discarding its own freight. canStockProductively did not check the Division Yard while the engine's stockOutbound does, so Freight Agent was chosen when nothing could be stocked and the follow-through fell through to an unjam that threw a waiting load out of the green box — 3.10 a game against 2.71 started. Now 0.00. Revenue 6.0 → 6.5, wins 5 → 8 in 100. Also confirmed routing was never the problem: 0% of drops land on a facility that does not want the car.
• Why switching work did not become Revenue. Answered: it was the freight the crew shuffled, not the shuffling. The chain never leaked — 95% of started loads finished — it was barely entered, because a load needs a matching empty car spotted and half the industries never asked for one. Three fixes later (sidings, facility placement, car selection) revenue is 3.2 → 6.0 and freight 26% → 37% of gross.
• Fix car selection. Three of six industries were invisible to wantedCars — a hand-written industry→car map naming two industries that do not exist and omitting three that do — so tank cars were dropped 0 times in 100 games. Derived from INDUSTRY_PROFILES now, and the second commodity of the two-commodity industries is reachable. Revenue 5.0 → 6.0, freight share 25% → 37%, wins 1 → 5 in 100.
• Put the industries on the run-around. Facility placement was unscored — the first legal square — so 0.00 facilities a game sat on a loop; now 1.08. The instructive part was the second bug: scoring facilities onto the siding row dropped run-arounds 91→36, because the anchor test asked a card's KIND rather than its PORTS and an industry in the line read as a dead end. Revenue 4.1 → 5.0. Freight did not follow, which is the item above.
• Make the bot build sidings that are sidings. 0 run-arounds in 100 games → 91. Three bugs, all scoring on local shape without checking it reached anything; the decisive one was that bestTrackLay never declined a piece, so it spent the track supply on whatever was legal.
• Teach the bot what a siding is for. Nose coupling (§A.3) implemented, so approach direction decides which car is droppable; the bot runs around rather than setting out, when the drop can follow. Switching activity transformed, revenue unchanged.
• Curve geometry. Curves were topologically identical duplicates of turnouts, and nothing reached north, so a district could only be a vertical column. Now two-port rotatable arcs.
• Q10 — when track may be laid. During the "draw a card" option, one piece a turn. Track was a card when §6.2 was written; a 26-piece supply has no hand to bound it.
• Q11 — which way a Heavy Grade climbs. Answered from the card: it prints "(Up)" and "Player sets orientation", so it is a property of the placed card, not a compass constant.
• §6.2's reshuffle. Implemented, and the deckReshuffled event it had already declared and narrated — but never emitted or reduced — is now real. Not yet reached in play: solitaire Campaign ends with 168.8 of 243 in the deck and four-player Campaign with 86.6, and no run of any length has emptied it. It is a safety net rather than a live mechanic today, which is worth knowing before tuning draw rates.
• Q12 — Whistle Post lock-in. Players always start at a Whistle Post; office density doubled instead.
• CLEARING AN INBOUND BOX MINTS A CAR — measured at 1.29 a game against a supply of 80. Re-audited in v0.4.3: rolling stock is EXACTLY CONSERVED, 100 games out of 100, range 0..0. The old audit's premise was right — the two directions were not symmetrical — but the asymmetry has since been closed from the other end. unloadBegan and passengersDetrained now take their replacement empty OUT of the Division Yard rather than conjuring it, so a load is a car that moved rather than a car that appeared: one leaves the yard, one arrives in Classification. Jesse's description of the tabletop procedure confirms this is the intended model — the token you push along the MEN|AT|WORK sign IS the car, fetched from the yard by the Freight Agent and swapped onto the industry track at the end. Both conjuring fallbacks now throw rather than minting, so the leak cannot silently return; neither fired across the suite or 100 audited games. ROLLING_STOCK_SUPPLY is therefore unblocked — it was waiting on this and can now be tuned in the rebalance pass. (The first audit's own arithmetic was off in the same way mine was on the first attempt: cars set out on a card, in card.standing, are easy to leave out of the count and make a conserved game look like a leaking one.)
• state = fold(events) was not true, and the docs said it was. Settled: the INTENTS are canonical. Measured before deciding — advance.ts never calls reduce, so 14 of the 46 event types are never reduced: the clock, and the entire Mainline phase, which is every train movement in the game. Folding the log rebuilds a district and not a railroad. Jesse's call, and the cheap one: the plan never needed fold — persistence is { engineVersion, seed, config, history } (multiplayer.md §10) and the wire carries Frames, not events (D2/D3), so reconnection is a fresh Frame rather than an event tail. Making the phase driver reduce would have been a rewrite of the most rule-dense code in the project to buy something nothing uses. Corrected in the README, four architecture documents and six source comments; test/events.test.ts pins the unreduced set so that closing the gap later is a deliberate act, and asserts the property that does hold. If you ever do make the phase driver reduce, that test fails and tells you which docs now understate the engine.
• Measure with error bars from now on. Built: node src/sim/compare.ts 1600 <tweak>=<n> runs the current bot and one variant over the same deals and reports the paired difference. Pairing drops σ from ~9 on the level to 5.3 on the difference, so 1600 seeds gives ±0.13 in about 1m45s — the noise floor is now ~±0.15 rather than ±1.0. Threshold to keep a heuristic is t ≥ 3, and the report prints the better/worse/identical split beside the mean, because a mean carried by a skewed tail is a different claim from broad improvement.
• Confirm the Classification Yard rule against the source. Confirmed, and the guess was wrong. The rule is: used Rolling Stock to the Classification Yard, used engines and cabooses straight back to the Division Yard, and the Classification Yard empties ONLY when the Division Yard is bare — then all at once. The Day-boundary version I had invented was far more generous and worth +2.42 revenue a game the game does not actually grant. Corrected; revenue 9.67 → 7.25.
• Enhancements are placed but mostly do nothing. Measured: forbidding every Enhancement except Interlocking is worth -0.01 ± 0.41 (t = -0.04) over 400 paired seeds. They neither pay nor cost. Left alone. Unlocking the Running Track straight put nine kinds on the board (telegraph 0.73, waterColumn 0.57 …), but only Interlocking has a measured effect. The Telegraph/Telephone/Radio chain adds to the other train's number when dispatching facing trains, which may be worth nothing in solitaire; Water Column removes a Watertower; Facing Point Locks prevents Derail, which is multiplayer-only. Worth measuring what each is actually worth before the bot spends actions on them.
• stats.ts undercounts freight. Fixed: both halves counted, freight share 39% → 49%. Worth revisiting the industry density decision in Play Balance, which was taken on the old number.
• LEFT AND RIGHT ARE ON THE WRONG DIAGONAL — for turnouts and for curves, the same way. The engine's left turnout is {stem:'w', through:'e', diverge:'s'}: a train entering at the points from the west heads east and the diverging route leaves to its right. The engine's left curve is arc sw, which turns an eastbound train right as well. One consistent sign error in the hand↔diagonal mapping, and it mislabels every track card a player ever holds. The artwork is right and does not change — board-svg.ts:462 draws rails from connectionsFor() geometry alone, so only words are wrong. Decision: flip the hand value on the TRACK_CARDS rows AND the two variant tables in the same commit, so the code keeps speaking left/right like the physical supply and now means it. Keep the row order in TRACK_CARDS untouched: setup.ts:95 builds the deck by iterating that array, so flipping only the labels leaves pre-shuffle slot 32 holding a ne_sw curve before and after, and variantsFor(…)[0] still 'sw' — same seed, same board, and every published replay still plays. Also: track.ts:126 arc fallback, track.ts:191-212 doc block, view.ts:1041 and view.ts:1208 diagonal phrases, bot.ts:837-852 arcInHand, seven test files, and the prose plus ~14 data-tip="Turnout · left" strings in docs/design/track-geometry.html — which has no generator and must be hand-edited. Verify by fingerprinting a fixed seed's board before and after: identical geometry, different words.
• A turnout should be playable as an UPGRADE, on top of a card already down. On a straight, or on a curve whose arc matches the turnout's diverging leg. Nothing like this exists — the only "upgrade" in the game is the Office tier change, which is explicitly not a card swap (apply.ts:1290), and canPlaceAt hard-stops at if (existing && !isMovableSign) return false (track.ts:518). Decision: cars AND enhancements both block it — standing.length > 0 → UPGRADE_OCCUPIED, enhancements.length > 0 → UPGRADE_ENHANCED, so an Interlocked straight stays a straight. Express the curve rule on arcs, not hands, so it survives the flip above. No extra connection requirement: all four turnout orientations are port supersets of a straight and of any same-arc curve, so an upgrade can never sever an existing join, and the new leg is allowed to dangle — that is what it is for. The lifted card leaves play, which is already how board cards behave (apply.ts:1249 salvages only cards that were not placed). Reuse card.play with a placement on an occupied square; legal.ts:252 must offer those squares for turnouts, and the attachments set at legal.ts:137 is already exactly that list. The other half of this report needs no work: a turnout carries the through route (carriesThroughTrack), so it is already legal at a Limit, along the Running Track and on Secondary Track. Confirmed, not re-investigated.
• A Depot shows three MEN AT WORK boxes it can never work. Offices are Passenger Facilities — no freight — but setup.ts:176 gives every one a three-slot menAtWork array, and the three renderers loop it with no guard while the green and red rows beside them are guarded (board-svg.ts:548, panels.ts:218, replay.ts:522). Decision: all three tiers — Depot, Station and Terminal are all Passenger Facilities and all get laborers: 0, so the boxes are inert on every one. Fix it in the model, not the renderers, so it cannot reappear in a fourth place: make menAtWork nullable and null for passenger facilities, which is what the "Freight only" comment at state.ts:153 has claimed all along. Freight handling must be neither allowed nor displayed there. Two more artifacts of the same "an Office is a Facility" modelling go with it: board-svg.ts:562 calls a Depot "SHIPS + RECEIVES", an industry's flow word, and board-svg.ts:599's Math.max(1, trackCap) draws it a siding slot although its industry track has length 0. FacilityView needs a kind field; it has no freight/passenger flag today.
• Two Ice Houses can be built in one district. Industries already ban duplicates per Office Area — isLockedOut (apply.ts:1774) covers the Mine Tipple half of the report — but Ice House is a Modifier, not an industry, and checkPlay's modifier branch (apply.ts:662) has no duplicate check at all. Decision: extend the ban to modifier kinds, leave enhancements alone. An Interlocking is a plant at one junction, so a second on another straight is a different installation, and the Telegraph → Telephone → Radio chain is already gated per card. Expect modifiers with copies > 1 to go partly dead in solitaire, where there is one Office Area — correct, since the spare copies exist for other players' districts.
• A drawn card lands at the far end of the hand with nothing to mark it. apply.ts:1219 pushes, the hand renders in state order (game.ts:355), and with flex-wrap the newest card is exactly where the eye is least likely to be. Decision: reverse in the display layer, not the engine — view.ts:898-899 (reversing hand and handWhat identically, or they desync) covers the replay viewer and the standalone replay together, and game.ts:355 covers the play page. Keeping hand.push means the bot's option-iteration order does not move, so every revenue figure in this file stays comparable; an engine unshift would invalidate the lot. The marker is play-page only — a Frame carries card names, not ids, so a replay cannot say which card arrived that step. Follow the game.scheduled precedent for a justDrawn field, but make the badge persist rather than flash: it says which card is new, not something just happened. A static ::before badge as .handcard.target does it (panels.ts:262), no keyframe — the innerHTML rebuild would restart an animation on every render. Clear it in renderUndo() and after fromSave(), or a fresh page load badges last session's draw.
• The inbound boxes render green in the side panel. Green is outbound and red is inbound everywhere the colour carries direction — board-svg.ts:528-545, replay.ts:452, rules §9.1 — except panels.ts, whose shared boxes() helper (panels.ts:162) emits class f for every filled box regardless of direction, so the red row at panels.ts:222 comes out green. The board SVG on the same page draws it correctly, which makes the panel actively contradict the board. Give boxes() its class from the caller as replay.ts already does, add .box.r in board-svg.ts:820's palette, and take the siding off green in both panels and replay.ts:525.
• An Interlocking on the board is a bare label, and it does nothing. The enhancement text is drawn with no tooltip (board-svg.ts:651) while the copy already exists as data in ENHANCEMENT_CARDS (content.ts:589). Done: every card prints its effect, and the one nothing reads says so. CORRECTED — the first pass had five of the ten statuses wrong. It claimed only Telegraph/Telephone/Radio were live, because the survey grepped for four helper function names and read "no match" as "no implementation". In fact seven are live: those three plus Interlocking (advance.ts:770), Yard Office (advance.ts:750), Small Yard (apply.ts:405) and ABS Signals (advance.ts:599, stored on the Mainline node). Facing Point Locks and Water Column are wired but dormant in solitaire; Overpass alone has no code path at all. The shipped tooltip briefly told players four working cards did nothing, which is worse than the bare label it replaced — enhancements.test.ts had passing tests for all four the whole time.
• A modifier's grant can land on a direction its host cannot use, and nothing says so — corrected in v0.4.7. The earlier "no bug" verdict below was wrong. The reasoning had been that a Grocer's Warehouse is inbound-only. It is not — the card reference says "Both" — so the grant was being dropped on a direction the facility should have had. Reported again in play as "grocer's warehouse didn't get extra outbound slot for truck dock". The suppression machinery itself was right and is kept: it still fires for a passenger Modifier beside a Whistle Post, which is not a Passenger Facility — and v0.4.7 gives that grant BACK when the Office is upgraded, which it never used to. Original note follows. Reported as "Ice House added the laborer but not the outbound slot" — checked, and there is no bug: Ice House prints +1 outbound, a Grocer's Warehouse is flow: 'inbound' so allows.outbound is false, and the capacity was raised on a direction that can never render or be stocked. The laborer arrived because laborers have no direction gate. Decision: an industry's printed flow is absolute — drop the grant on hosts that cannot use it rather than opening the direction up. So applyModifier (apply.ts:1788) gates each capacity grant on allows and grows industryTrack.length only by what was actually applied. Audit all 17 profiles for the same trap: iceHouse, truckDock and forklifts all print addOut: 1 and list grocersWarehouse; waitingArea, restaurant and hotel print addOut: 1 for hosts: ['office'], which includes a Whistle Post. Then say it in both directions — the hand tooltip naming which printed hosts cannot use which half (computable from the profiles, no host on the board needed), and the panel's "prints N, Modifiers add M" line showing a suppressed grant as suppressed instead of quietly omitting it. That delta display already cites the Ice House as the bug that motivated it.
• Q13 — rear-end collisions on a Mainline card. Answered: collide on catching up. Implemented, and not on cards that print "trains may pass". Invisible to a bot that always denies clearance; a bot that always allows drops from 7.34 revenue to -5.13.
• Nine of the twelve special-train rules are declared and read by nothing. Done — all nine enforced, and one of them deleted instead. copiesNextScheduled was never carried by any train card: a Second Section is a Maneuver with its own working intent, so the flag was an unreachable second description of an existing mechanic. Cost 0.8 revenue and half the wins (8.0 → 7.2, 14/200 → 6/200), which is what enforcing restrictions does.
• Carry links forward in replay frames. Done, and the premise was wrong in an instructive way: measured, links was 5% of the cells payload. What actually cost was the what prose (32%), the facility object stored a second time inside its own cell (24%) and the rest of the static identity (26%). All three are interned now — 3415 KB → 1877 KB, and a round-trip test runs the page's own unpacking function.
• Every published replay was dead. All three replayed 2 intents of roughly 400 and presented as short games, exactly as the item below it (now in Replay / Save Games) predicted. Re-recorded from bot games with node src/sim/save-replay.ts, which verifies each save round-trips before writing it, and harness.test.ts now fails if a published replay stops short. The version-stamp item in Replay / Save Games is still worth doing — this catches the breakage, it does not explain it to a player.
• Coordinate labels read Y,X on the board — v0.4.9. Now X,Y everywhere a coordinate is shown to a player: the on-card label (board-svg.ts), the switching-crew tooltip and button (main.ts), the rejected-option and switching-group text (game.ts, view.ts), and the blocked-move text (narrate.ts). Display-only — GridCoord{row,col} already had the right geometry (row increases north, col increases east), and internal Map keys are untouched.
• "No switching" blocked moving a train clear of the mainline — v0.4.9. The six no-switching cards (both expresses, Light Engine, Campaign, Circus, Military) mean may not add or drop cars, not may never be touched. switch.move now refuses only a move that would couple a fresh car — the same way dropOnly was already handled — so these trains can still be shunted onto Secondary Track to clear the mainline. switch.dropCars and switch.sortConsist stay blocked.
• Q3 corrected: Expedite governs WHERE a train may stand, not WHEN it leaves — v0.4.9. The forced same-Stage departure (departsThisStage, the shiftChange expedite pass) is gone; an expedited train now arrives and is released like any other train, switchable in between. New fault instead: left off the Office square when a Mainline Phase begins, it costs 1 Revenue (expediteFault, EXPEDITE_FAULT_PENALTY), every Phase it is still caught there. Resolved "3/4 EXPRESS PRINTS A RULE IT CAN NEVER USE" as a side effect — it can now reach the Local Operations turn its printed freight rule needs. Revealed a bot gap instead: logged above under Bot Performance.
• evaluateClearance checked only the first occupant it found — v0.4.9. Found while explaining a playtest report: the Superintendent was asked to rule on a same-direction train instead of being held against an opposite-direction one also on the card, because the loop returned on whichever occupant it examined first rather than checking all of them — invisible until the Telegraph/Telephone/Radio exception made it possible for a card to hold two trains at once. Now checks every occupant for an absolute bar before offering any judgment call. Pinned with a test that fails against the old single-pass code.
• The splash page now shows the box art — v0.4.9. docs/StationMasterSplashScreen.png (3.0 MB) resized to a 145 KB JPEG (public/images/, copied into the build by build-web.ts) and placed beside the title, tagline, blurb and both buttons in a side-by-side hero, stacking to image-above-text on mobile.
• A coach may now be set out at the Office — v0.5.0, Jesse's call. §A.4's blanket "no Rolling Stock may be left at the Office" now carries one exception: any train (not just 7/8) may drop one or more coaches there; freight and cabooses stay banned. Unlocks the ENGINE boxcar coach arrangement that used to lock completely — measured at 1,181 refused set-outs over 60 games, every one of them this case. canDropCarsAt (track.ts) takes a coachesOnly flag instead of refusing the Office outright; trains 7/8's coachStaysOnStationTrack rule now forbids the coach everywhere EXCEPT the Office, rather than everywhere. The Office's "cars fouling the Running Track" collision (advance.ts) is exempted for coach-only standing cars, so a legally parked coach is not a hazard to the next arrival.
• 3/4 EXPRESS PRINTS A RULE IT CAN NEVER USE — closed, v0.5.0. Confirmed already resolved as a side effect of the v0.4.9 Expedite fix (see that entry above); removed from Rules Questions.
• THE INDUSTRY TABLE VS. THE CARD REFERENCE — v0.5.0, Jesse's call: the engine was right, the docs were stale. card-reference.md printed Grocer's Warehouse and Oil Refinery at 2/2 with 2–3 Laborers, and claimed "'Freight House' is not a card"; the engine already had both industries at 1 out/1 in/1 Laborer and already dealt Freight House as a real sixth industry, 6 copies. Corrected the docs (card-reference.md, glossary.md, rules-v0.2.md, open-questions.md) to match the engine; no engine change. Turned up that Mine Tipple, Produce Shed and Power Plant may be similarly stale — flagged as a new item above rather than assumed.
• Poling — closed, v0.5.0. Confirmed already at 0 copies, the same treatment as Sharp Curves, pinned by mainline-cards.test.ts. No code change; removed from Rules Questions.
• Heavy Grade orientation stays rolled, permanently — v0.5.0, Jesse's call. The card prints "Player sets orientation", but a Heavy Grade sits on the shared Division chain between two players (or beyond an end Division Point, next to one) — never inside one player's own district — so there is no single player with a fair claim to the choice. Settled as random from the seed, identically for solitaire and multiplayer, overriding the card's print. No code change (the roll in setup.ts was already doing this); the comments and implications.md §10 Q11 previously framed it as a placeholder awaiting an interactive setup phase — corrected.
• Engines are not a separate supply from Crew Trays — confirmed, v0.5.0. rules-v0.2.md:339 (Gap 4b) ties Crew Trays and engine pieces together as one combined resource, player count + 3 — not two independently-tracked supplies. The engine already enforces exactly that via crewTrayCount/freeTrays; NO_FREE_TRAY already fires exactly when engine supply would run out too. No code change; corrected the comments that called this provisional or unsourced.
• Player settings, saved — v0.5.0. A localStorage settings object (SETTINGS_KEY, separate from the game save) now persists district auto-focus mode, sound on/off, and board zoom level across reloads — all three previously reset every time. Falls back to today's defaults on a missing, corrupt, or disabled localStorage, the same guard the save already had.
• The test suite's flakiness under npm test — fixed, v0.5.0. Two changes: (1) a pretest npm script now builds the shared dist/ once, before node --test runs, so every test reading dist/ no longer depends on another test in the file having built it first; (2) the one test that actually exercises the build COMMAND now builds into its own dist-test/ directory (BUILD_DIST_DIR env var, scripts/build-web.ts) instead of rebuilding the shared dist/ out from under the tests reading it. dist/ is now single-writer.
• Curves and turnout diverging legs now draw as smooth curves, not two straight segments meeting at a corner — v0.5.0. curvedRail in board-svg.ts replaces the old hard-cornered "run to the frog, then a straight 45° leg" with a sampled cubic-Bezier easement: tangent to horizontal at the east/west edge (so an abutting straight card's rail still reads as one unbroken line) and tangent to exactly 45° at the north/south edge (so two stacked curves still read as one continuous diagonal). Both plain curve cards and a turnout's diverging leg go through this same code path, so both are fixed by the one change.
• Wide boards can now be zoomed — v0.5.0. Discrete zoom presets (75/100/125/150%) for both the district grid and the Division map, applied by resizing the rendered SVG's own pixel dimensions (not a CSS transform), so the existing overflow-x:auto scrollbars keep doing the panning with no new gesture code. Persisted in the new settings object above.