feat: pai gow poker added to the casino

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diff --git a/dev_guide/README.md b/dev_guide/README.md
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+# About this directory
+
+These guides document **engine internals** for developers and code-assisting
+agents: architecture decisions, durability contracts, presentation internals,
+and per-game implementation notes.
+
+World-builder documentation (YAML content, room/object/mob/item guides,
+casino table configuration) lives in [`../building_guide/`](../building_guide/README.md).
+Do not add builder-facing content here, and do not add implementation notes,
+TODOs or assessments to `building_guide/`.
+
+| Guide | Covers |
+|---|---|
+| [bank.md](bank.md) | Bank system session state and dispatch |
+| [concurrency.md](concurrency.md) | Owner loop, durable money, lifecycle transactions, shutdown |
+| [hacking.md](hacking.md) | Terminal objects and the hacking minigame interface |
+| [pai_gow.md](pai_gow.md) | Pai Gow Poker hand evaluation, house way, settlement, Joker art |
+| [roulette.md](roulette.md) | Roulette presentation internals and extension notes |
+| [tick_order.md](tick_order.md) | The canonical per-tick system order (kept in sync with tests) |
+| [video_poker.md](video_poker.md) | Video poker presentation and durable multiplier banks |
diff --git a/dev_guide/bank.md b/dev_guide/bank.md
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+# Bank system internals
+
+Builder-facing bank documentation (booth object, room placement, player
+commands) lives in [../building_guide/bank.md](../building_guide/bank.md).
+This page covers the engine side.
+
+## Session state
+
+`StateBank` (defined in `internal/net/server.go`) is the session state for
+the bank interface. Input is routed through `handleBankInput` in
+`internal/game/cmd_bank.go`.
+
+## Player storage
+
+Bank items are stored in the `Player.Bank` field (`map[int]*InventorySlot`),
+saved in character YAML. Bank slots are sequential and reuse freed slots.
+There is no slot limit.
+
+## Command dispatch
+
+- `bank` is classified as `ClassActive` in `classifyCommand()`
+- `bank` case in `executeCommand()` calls `doBank(sess)`
+- `doUse()` checks for `"bank"` or `"bank booth"` targets and routes to
+  `doBank()`
+- `doBank()` checks for a `bank_booth` object in the current room
+- `handleBankInput()` dispatches deposit/withdraw/browse/leave commands
diff --git a/dev_guide/concurrency.md b/dev_guide/concurrency.md
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+# Concurrency & durability
+
+This guide documents the runtime architecture decisions that keep live game
+state safe: the single-owner loop, single-file durable money, the account
+lifecycle transactions, and the graceful-shutdown sequence.
+
+## Single-owner game state
+
+One goroutine — the **owner loop** (`internal/game/owner.go`) — executes all
+mutation of live game state: session input handlers, connect/disconnect
+transitions, every tick callback (the master per-tick system sequence and all
+dynamically registered callbacks), and admin mutations. Network and admin
+goroutines submit tasks; they never touch live players, sessions, Hub
+membership, or game runtime maps directly.
+
+Rules:
+
+- `Game.RunOnOwner(fn)` (and `Game.HandleSessionOnOwner` for session input)
+  block the caller until the closure has executed on the owner. Connection
+  goroutines submit one task per input line, giving per-client backpressure
+  without ever blocking another client.
+- A FULL task queue applies backpressure: submitters block until the owner
+  drains a task, and a full queue never bypasses the owner — running a task
+  on the caller's goroutine while the owner keeps executing would break the
+  single-owner invariant. A STOPPED owner (graceful shutdown, after
+  admissions have closed) refuses the task and drops it rather than running
+  it on the caller's goroutine: `RunOnOwner` returns without executing the
+  closure, because running it there would mutate live state concurrently
+  with the shutdown sequence and after the final-save barrier. (Synthetic
+  tests that construct a Game without an owner run tasks inline on the
+  caller.)
+- Code already running on the owner must NOT call `Game.RunOnOwner` — it
+  would deadlock waiting for itself. Owner-executed code calls functions
+  directly.
+- Task execution is FIFO, so tick callbacks serialize against session input
+  and admin mutations in submission order. Tick callbacks still run in
+  engine registration-ID order (see tick_order.md); the owner wrapper only
+  moves their execution onto the owner goroutine.
+- Slow clients cannot stall the world: `Session` writes are queued
+  (`net.Session.StartWriter` puts a transport session into queued mode) and a
+  dedicated per-session writer goroutine performs the network I/O with
+  per-message write deadlines. A full queue disconnects only that client.
+- Saves run on the owner and serialize a value snapshot; concurrent
+  read-modify-write cycles of the same files cannot happen.
+- Password work is the one deliberate exception: Argon2id verification and
+  hashing (~64 MiB, tens of milliseconds) run on the CALLER's connection
+  goroutine in `HandleSessionOnOwner` (`StatePassword` and
+  `StateNewAccount` are intercepted before any owner task is submitted).
+  A burst of logins therefore costs memory and CPU on connection
+  goroutines, never a stall of the owner's command/tick queue. The owner
+  task re-checks the stored hash against the one that was verified so a
+  password change mid-login cannot authorize a stale attempt, and
+  `player.hashLimiter` caps concurrent Argon2id computations at 4.
+  All resulting state transitions (echo, session state, account saves)
+  still happen on the owner.
+
+Unit tests construct Games without an owner; such Games run submitted tasks
+inline on the caller's goroutine (legacy behavior), which is fine for
+synthetic tests but production Games always have the owner (started by
+`game.New`).
+
+## Admin editor isolation
+
+All `/api/` routes run through one boundary in `internal/admin/owner.go`:
+
+1. Authenticate, read the request body (maximum 8 MiB) on the HTTP goroutine.
+2. Submit one synchronous `Game.RunAdminOnOwner` task. The **whole handler**
+   runs there: validation against current files, plan construction, file
+   commits, runtime migration/eviction, store reloads, and undo history.
+3. Write the buffered response on the HTTP goroutine after the task finishes.
+
+Reads use the same boundary so editor API reads cannot observe half an edit.
+Neither slow uploads nor slow downloads hold the owner. File I/O does: large
+bulk edits can briefly pause gameplay. This deliberately avoids a second
+transaction scheduler, fine-grained locks, or optimistic plan retries. Use a
+maintenance window for large world reorganizations.
+
+`RunAdminOnOwner` rejects requests during shutdown with HTTP 503, including
+requests queued before shutdown but not yet started. It never executes on the
+HTTP goroutine after the owner stops. A disconnected request is skipped if it
+has not started; once started, its edit completes even if the browser leaves.
+A failed/lost HTTP response is not proof that the edit did not commit.
+
+### Endpoint inventory and callback contract
+
+| API family (all behind the same boundary) | Mutations / live dependencies |
+| --- | --- |
+| `/rooms`, `/rooms/{id}`, `/rooms/new-empty` | Room create/update/delete, room index and runtime room state |
+| `/rooms/link`, `/rooms/insert`, `/rooms/remove`, `/rooms/move`, `/rooms/rename`, `/rooms/swap` | Multi-file room plans, course changes, room-ID migration or eviction where applicable |
+| `/rooms/bulk-edit`, `/rooms/bulk-delete`, `/rooms/resolve-duplicate` | Bulk room changes, indexes and runtime cleanup |
+| `/room-dirs/create`, `/room-dirs/rename` | Room file organization and indexes |
+| `/items`, `/mobs`, `/drops`, `/hazards` and their ID routes | Definitions plus existing cache/index invalidation; items also rebuild crafting |
+| `/objects`, `/techs`, `/modules`, `/triggers` and their ID routes | Definition files; existing manual-reload semantics remain unchanged |
+| Entity `/rename`, `/move`, `/dirs` routes | Definition file organization, undo history, existing cache invalidation |
+| `/courses`, `/courses/{id}` | Course files, exit reconciliation, course store reload |
+| `/files`, `/files/rename` | Raw file data and history; NOT a semantic room-ID migration or automatic cache reload |
+| `/colors`, `/colors/reset` | Persisted config and live color maps |
+| `/undo/undo`, `/undo/redo` | File images, room-ID migration, index/cache rebuilds, history together |
+| Remaining API routes | Read-only queries; serialized to get coherent snapshots |
+
+Register new endpoints on `apiMux`, never outside this boundary. Do not wrap
+individual callbacks in `RunOnOwner`: they are **already on the owner**.
+`cmd/thoi/main.go` wires direct course reload, craft rebuild, casino eviction,
+and `MigrateRoomIDsOnOwner` callbacks. `UndoStack`'s mutex protects history,
+not gameplay: its apply path and the following rebuild must remain in the
+same enclosing API task. Login password rehash saves and history clearing
+also run on the owner, with expensive password hashing outside it.
+
+This guarantees **isolation from gameplay**, not new crash-atomicity or
+rollback guarantees for every editor operation. Existing file transaction
+and error behavior is unchanged. Raw Files edits and external filesystem
+writes still bypass semantic validation/migrations; use structured room
+operations for live renumbering, and stop the game for external bulk edits.
+Some definition editors still need the in-game `reload` command; serialization
+does not add missing cache invalidations or migrate existing spawned entities.
+
+## Durable money (single-file wallet)
+
+Money lives in the character file and **nowhere else**. Every casino money
+mutation is one atomic `AccountStore.SaveCharacter` (`persistence.WriteFile`:
+temp file → fsync → rename → directory fsync) that carries both the balance
+and the `Player.PendingWagers` ledger. There is no second durable store, so
+there is no cross-file crash window to reconcile.
+
+- **Wager** — debits chips then credits and appends a `PendingWager` (its
+  wallet handle plus the exact chips/credits debited) in the SAME save. The
+  entry stays until the round resolves.
+- **Settlement** — `PayCredits(amount, stakeIDs...)` credits the payout and
+  removes the listed stakes in the same save. A table passes the hand's stake
+  IDs (its payout includes their return); a slot win passes its triggering
+  stake (its payout is winnings only). Either way the credit and the stake
+  consumption are atomic, so a crash can never pay the win and refund the
+  stake.
+- **Loss/forfeit** — `ResolveStake`/`ResolveStakes` consume the pending
+  stakes in one save; the round resolved and the stake is gone.
+- **Refund** — `RefundOutstanding` returns every pending stake (chips in
+  kind, credits as credits) and clears the ledger in one save. Graceful
+  shutdown (`Game.runShutdown` → `Casino.RefundAll`) and eviction use it.
+
+A save failure **before replacement** reverts the in-memory balance and
+ledger together. On `persistence.ErrDurabilityUncertain`, every wallet
+operation (wager, payout, stake resolution, refund) instead keeps the applied
+balance and ledger, because the visible file already carries both. The wallet
+logs the storage fault and reports the operation as applied so callers do not
+retry a payout or refund a resolved stake. This does not promise survival of
+a subsequent OS/power crash; it prevents a later save from overwriting the
+visible result with reverted memory.
+
+At startup (`game.New` → `recoverPendingWagers`, `internal/game/money.go`)
+any stake still listed in a character's `PendingWagers` is refunded: a listed
+stake means the process died before its round resolved. That is the entire
+recovery story — no ordering, checkpoints, evidence, or operator queue.
+
+### Two-phase journal recovery is out of scope
+
+This game deliberately does **not** implement a durable money journal or
+two-phase crash recovery. That design was built and then removed: it required
+a second file (`data/economy/journal.jsonl`) plus balance checkpoints, record
+ordering (`Seq`), payout `Covers` linkage, `open_payouts` evidence, and a
+startup recovery pass with per-record ambiguity handling. Its entire purpose
+was to make an ungraceful stop mid-round produce zero credit discrepancies,
+at a cost of ~1,400 lines of engine code and ~2,000 lines of tests.
+
+With the crash-consistency bar deliberately lowered to "a rare ungraceful
+stop may lose or refund one in-flight stake, and must never double-pay", the
+single atomic character save is sufficient: a listed pending stake is
+refunded, and a settlement whose save fails before replacement leaves the
+stake pending and the win unannounced (never paid on top of the refund).
+Post-replacement uncertainty follows the applied-state policy above. Do not reintroduce
+a second money store, per-record ordering, or an operator-inspection queue
+without an explicit decision to restore bank-grade guarantees.
+
+Currency arithmetic is checked (`internal/casino/credits.go`): explicit
+`MaxCredits` cap, bounded `DefaultMaxBet` default (the explicit unlimited
+sentinel is still honored), floor conversion for payout multipliers, and
+overflow rejected instead of wrapping. The cap is shared by the wallet:
+bank withdrawals are rejected when they would push the on-hand balance
+past it, and gameplay credit grants (shop sales, pickups, activity
+payouts) clamp at the cap and log rather than wrap.
+
+## Account lifecycle transactions
+
+Account and character lifecycle operations (create, rename, delete, purge)
+are single journal transactions (`internal/persistence/txn.go`): a journal
+entry with before-images is written durably BEFORE any file changes, the
+operations apply, and the journal is removed at the commit point. Deletes
+sync their parent directory; moves sync both affected directories (once if
+they are the same). Rollback also syncs deletions, including retries where
+the file is already absent, before retiring the journal. An apply failure
+attempts rollback; if rollback fails, the journal stays for recovery. A crash
+mid-commit is rolled back at the next startup by `persistence.Recover`.
+
+Characters carry a stable UUID (`player.Player.ID`) and owner field
+(`player.Player.Account`), assigned at creation and backfilled at first
+startup. Cached membership authorizes by the character file's owner, not by
+its renameable filename, so a stale cached name can never authorize
+connecting, renaming, or deleting a character reassigned to another account.
+
+After any lifecycle mutation, `Game.publishAccountUpdate` republishes the
+account state to every authenticated session of that account — including
+sessions sitting in menus — resetting stale pending selections. The online
+check and the file mutation run as one owner step, closing the
+check-then-rename gap.
+
+## Graceful shutdown
+
+Signals (SIGINT/SIGTERM) and the in-game `shutdown` command converge on
+`Game.RequestShutdown`, which runs the sequence exactly once:
+
+1. **Admissions stop:** session input and disconnect forfeit/save callbacks
+   become no-ops (server-initiated shutdown is not a player disconnect).
+2. **Tick stop and join:** `Engine.StopAndWait` stops the ticker and waits
+   for the in-flight callback to finish.
+3. **Drain and persist (on the owner):** remaining queued commands execute,
+   outstanding wagers are refunded (`Casino.RefundAll`), and every online
+   character is saved. Save failures are logged for the operator.
+4. **Owner stop:** the owner loop drains and stops.
+5. **Transports close:** HTTP(S) servers drain, listeners close, and
+   sessions flush their outbound queues before their sockets drop.
+   `ListenAndServe` returns and main exits normally — no `os.Exit`.
+
+## Room-ID migration
+
+Live room-ID changes (admin rename, swapid) execute as one mutation plan:
+the renamed room's file (id field, filename, self-loop references) plus every
+other room whose references moved, applied as a single journal transaction,
+followed within the same owner task by the full runtime migration
+(`Game.MigrateRoomIDsOnOwner` for the editor): player
+state, Hub room buckets, casino room keys, world room-keyed state (ground
+items, seeded markers, object states), and live mob instances. Undo/redo
+store the whole plan (all before/after images plus the idMap) and apply the
+inverse/forward runtime migration through the same wired callback.
diff --git a/dev_guide/hacking.md b/dev_guide/hacking.md
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+## Hacking
+
+Hacking minigames are played by jacking into terminal objects. Terminals are YAML objects that are registered in Go's `terminalDefs` map.
+
+**The filename is the ID** (`terminal_basic.yaml` → `terminal_basic`); like all objects, the loader derives the ID from the filename — don't add an `id:` field (see `objects.md`).
+
+### Terminal Object YAML
+
+```yaml
+name: basic terminal
+color: "28"
+description: "A battered terminal with a cracked screen. {28}[Level 1 Hacking]{/}"
+inroom_description: "A {28}basic terminal{/} hums quietly against the wall."
+```
+
+- `id` must match a key in `terminalDefs` (Go code in `internal/game/hacking.go`)
+- `name` is used for matching in the `jack` command
+- `color` controls the display color
+- `description` is shown when examining the terminal
+- `inroom_description` is shown in room listings
+- No `behavior` field — terminals are registered in Go, not YAML behaviors
+
+### Adding a New Terminal
+
+1. Create an object YAML file in `data/objects/terminal_<name>.yaml`
+2. Add an entry to `terminalDefs` in `internal/game/hacking.go`
+3. Optionally create a new minigame implementation in `internal/game/hacking_<name>.go`
+4. Place the terminal object in a room's `objects:` list
+
+### Adding a New Minigame
+
+New minigames implement the `HackingMinigame` interface:
+
+```go
+type HackingMinigame interface {
+    Init(level int) string
+    HandleInput(input string) (output string, done bool, won bool)
+    Name() string
+}
+```
+
+Optionally implement `XPBonuser` for bonus XP:
+
+```go
+type XPBonuser interface {
+    BonusXP() int
+}
+```
+
+
diff --git a/dev_guide/pai_gow.md b/dev_guide/pai_gow.md
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+# Pai Gow Poker internals
+
+Builder-facing table configuration and the published Fortune pay table
+live in [../building_guide/pai_gow.md](../building_guide/pai_gow.md).
+This page covers the engine side: hand evaluation, the house way,
+settlement and the Joker art.
+
+## Hand evaluation
+
+The Joker is partially wild: an ace, or any missing card completing a
+straight, flush or straight flush. Five aces beats a royal flush. A2345
+is the second-highest straight (and straight flush), below TJQKA but above
+9TJQK. Low hands recognize only pairs and high cards. Suits do not break
+ties. Copies lose to the dealer. The high hand must strictly outrank the
+low hand.
+
+## House way
+
+This is a **local, deterministic house way**, not a claim to reproduce a
+particular casino's proprietary chart or optimal player strategy:
+
+1. Enumerate the 21 possible splits and discard fouls.
+2. Preserve the strongest available high-hand category.
+3. With two pair or a full house available, also allow splits leaving at
+   least a pair high and a pair low.
+4. Maximize the low hand among these options, then the high hand.
+
+The dealer and automatic player setting use precisely the same algorithm.
+Published main-game house-edge estimates using other house ways do not
+necessarily apply to this implementation.
+
+## Fortune / Envy mathematics
+
+Of the eight published fixed tables compared on the Wizard of Odds page,
+table 8 (the one configured here) has the lowest house edge: 4.4292%
+before Envy, about 0.08% with six players each betting five. With Envy
+disabled, quads improve from 25:1 to 30:1, a custom local schedule
+lowering the published no-Envy edge by about 0.9974 percentage points to
+3.4318%. These are published theoretical side-bet figures, not a
+simulation of this server; Envy value depends on occupancy and wager size.
+
+## Face Up mechanics
+
+The dealer sets and reveals before players act; the automatic ace-high
+push is checked against the dealer's best five-card hand (`pgDealerPush`),
+so ace pairs and ace-headed flushes do not trigger it. Push Ace High
+classes are resolved by `pgPushAceClass`: a Joker in the dealer's seven
+cards pays the Joker rate (a natural ace plus the Joker makes a pair of
+aces, which is NOT ace-high); otherwise 40:1 when the player is also
+ace-high, else the plain rate.
+
+## Settlement
+
+Main, Fortune, Envy and Push Ace High settle in a single wallet
+transaction per player. Failed settlements freeze the result and block
+the next deal; `settle` or the table tick retries payment, never redraws.
+Successful recipients are not paid twice. Shutdown uses the existing
+durable stake-refund mechanism.
+
+## Joker art
+
+The shared Joker is rank `JK`, suit `joker`. `data/cards.yaml` supplies
+`JK` artwork at sizes 1/5/7/9; `internal/game/render_joker.go` also has
+ASCII and no-store fallbacks, including dark/light styles. Existing Joker
+Poker video poker uses the same art.
diff --git a/dev_guide/roulette.md b/dev_guide/roulette.md
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+# Roulette and casino extension readiness
+
+The casino has a usable extension seam: `tableGame`, generic `tableCore`,
+registered constructors/config validation in `registry.go`, structured snapshots,
+shared participation/control routing, and durable per-stake wallet handles.
+Roulette uses those seams rather than adding another command dispatcher.
+
+Example table (one game of each type per room remains the manager's rule):
+
+```yaml
+casino_tables:
+  - id: roulette_single
+    game: roulette
+    min_bet: 1
+    max_bet: 10000
+    betting_ticks: 15
+    roulette:
+      double_zero: false
+      spin_ticks: 4
+```
+
+`double_zero: true` selects the American 38-pocket wheel; otherwise the
+European 37-pocket wheel is used. Spin ticks default to 3; betting ticks use
+the shared default. Ticks follow the server's configured tick length.
+The wheel order is authentic and the outcome is selected uniformly only when
+spinning finishes.
+
+## Presentation
+
+Art is rendered per recipient in `internal/game/render_roulette.go`, so color
+mode and Unicode preference stay per player (the engine snapshot never embeds
+ANSI). The views and betting tracker share one snapshot renderer:
+
+- **Tracker**: a five-line, 74-column strip above the betting board, rendered
+  by `render_roulette_tracker.go`. The betting snapshot leads with a blank line
+  so the tracker is separated from the prose or menu that precedes it. It shows
+  the latest eight hits (newest first), three hot/cold pockets with hit counts,
+  and red/black/zero percentages.
+  All stats use a table-local rolling window of 50 completed spins. Zeros are
+  included in the denominator; ties use numeric order (0, 00, 1, ...).
+  History is copied into snapshots, never sampled before settlement, and
+  survives round resets but not table replacement or server restart.
+  History is copied into snapshots, never sampled before settlement, and
+  survives round resets but not table replacement or server restart.
+- **Snapshot cadence**: the board and tracker are drawn once per round by the
+  betting menu (on join and after settlement) and by an
+  explicit `table`/`table rules`. Placing a wager only confirms the wager; it
+  does not re-send the board snapshot.
+- **Betting board**: numbered grid with zeros in the left lane, red/black
+  pockets, and outside bets. The whole five-row zero lane (three numbered rows
+  plus the two separators between them) carries the green background, and its
+  outer corners are rounded in Unicode mode. A racetrack table draws
+  `renderRouletteRacetrack` above the board: a numbered oval in physical
+  clockwise wheel order, with 26 at the right tip. Interior dividers meet
+  each call bet's pockets, left to right: Tiers du Cylindre, Orphelins,
+  Voisins du Zero, Zero. Labels are centered on the middle row; a label too
+  wide to leave a blank cell against its dividers wraps onto the rows above
+  and below it (e.g. "Tiers du" / "Cylindre"), and only the glyphs are
+  written so the centering padding never paints over the dividers. Connected
+  box-drawing steps separate Tiers from Orphelins; Zero has a curved boundary
+  within Voisins. Neighbors is not drawn on the board, but remains in the
+  payout reference and help.
+- **Menu ordering**: the roulette betting menu prints its balance and
+  heading, then the tracker and board, and only then the wager reminder
+  (`bet <amount> on <target>`, `bet / rebet`, `table / sitout / stop`) so the
+  instructions follow the table they describe. Other games keep their menu
+  above the snapshot.
+- **Spinning**: a stylised 17x9 wheel (wider than tall so it reads as a circle
+  in a terminal cell grid). Only the rim is colored: solid red pockets alternate
+  with a very dark blue that stands in for black (`rouletteWheelBlack`), because
+  pure black vanishes on dark terminals. Pockets are two cells wide except the
+  top and bottom centres, which stay one cell. One pocket is green (plus its
+  diametrically opposite pocket on American wheels). A simple plus marks the
+  croupier's spindle. No pocket numbers are drawn; with color off the pockets
+  fall back to R/B/G so the wheel still reads.
+- **Result**: the winning pocket plus two physical wheel neighbours on each
+  side (five cards) at playing-card size. The pocket number sits on the top row,
+  a rule separates it from the ball (one row above centre), and the color name
+  is spelled out on the bottom row only when color is off. There is no
+  surrounding prose. The smallest (five-row) cards drop the rule so the ball
+  can sit directly under the number. The wheel and result graphics each get a
+  blank line before and after so they do not crowd the prose.
+
+The colored payout tables in `internal/game/render_casino_help.go` use the
+shared ANSI-aware `ui.Table` renderer, respecting ASCII/Unicode and wrap width.
+They show wheel-specific win chances and net profit odds, including call-bet
+exceptions. They appear only with `table` and `table rules`, not ambient art.
+`table help` opens the current game's guide; `help casino` indexes the brief
+casino guides in `data/help/`. `help racetrack` explains chip placements and
+rounding, including `zero`/`jeu zero` versus the straight-number target `0`.
+Each table's one-line
+overview is kept short (`Label | Limits 1-10000 | n/m seated | state`) so it
+fits beside a look minimap; `writeLookSideBySide` also wraps any content line
+that would otherwise run into the map column.
+
+Initial scope is **one wager per player per spin**. A wager covers straight-up
+numbers, outside bets (colors, parity, high/low, 1to12/13to24/25to36, rows),
+and the combination bets: splits, streets, corners, six-lines, trios, and the
+basket. Combination targets are a compact number list (`split 1 2`,
+`street 1-2-3`, `corner 1 2 4 5`, `line 1 2 3 4 5 6`, `trio 0 00 2`,
+`basket`) joined from the tokens after `on`; the leading name is optional
+because the geometry of the covered set identifies the bet. Non-adjacent or
+wrong-shaped sets are rejected rather than silently accepted. Multiple
+simultaneous wagers remain future work: `Participant.Wager` still holds a
+single stake.
+
+Single-zero tables may set `roulette.racetrack: true`. That adds the four
+French call bets (Voisins du Zéro, Tiers du Cylindre, Orphelins, Jeu Zero)
+and the Neighbors bet (a chosen number plus four on each side in wheel order).
+The racetrack is a single-zero layout only: the validator rejects
+`racetrack: true` together with `double_zero: true`. A call bet is **one
+wager** whose amount is the total stake spread evenly over the bet's chips
+(Voisins 9, Tiers 6, Orphelins 5, Jeu Zero 4, Neighbors 9). Because the
+components are ordinary inside bets, each returns `36/covered` when its
+number hits, so a winning pocket can pay a different multiple of the stake
+than another (for example 0 on Voisins pays 24/9, while 4 pays 18/9). The
+engine therefore resolves a wager to exact per-pocket `num/den` shares
+(`roulette_racetrack.go`) instead of a single multiplier; `bet` validates
+every possible return before committing and `settle` floors
+`stake*num/den`. The rack panel is drawn by `renderRouletteRacetrack` above
+the board and lists each bet's wheel-order series.
+
+All returns are checked before debiting a wager. Both winning and losing stakes
+settle through `PayCredits(return, stakeID)`, including a zero return for losses.
+Failures leave the stake pending and do not claim that payment succeeded.
+Shutdown and eviction refund outstanding stakes and reset the round.
+Disconnect refunds are safe because no partial outcome is sampled or exposed.
+
+Settlements are rendered by `settlementText` in `internal/casino/table_ux.go`:
+a colored win/loss/push headline gives the round's net once (the old
+"Net ... | ... returned (stake included)" split is gone), then each named bet
+— a blackjack hand, insurance, or the table's spot — is listed with its own
+net. Wins are green, losses red, pushes white, and a natural keeps the jackpot
+gradient. The engine emits inline color tags (`{casino_result_win}WIN{/}`),
+which `Game.casinoProse` expands per recipient against the session palette, so
+the engine still never embeds ANSI. Casino prose defaults to white
+(`casino_action`), leaving color for emphasized outcomes.
+
+## Assessment and boundaries
+
+This is a sound foundation for more testing-stage table games, not a blanket
+production-readiness certification. New games must test payout math, overflow,
+phase boundaries, disconnects, queued departure, refunds, persistence failure,
+and spectator output. Shared card-game loss settlement still uses the void
+`ResolveStakesByIDs` API: it preserves failed stakes for recovery but cannot
+report that failure to its caller. Roulette avoids that limitation with the
+existing error-returning payment API. Uniform per-stake error-returning
+settlement would be a worthwhile follow-up for older games.
+
+Multiple concurrent wagers need their own explicit ledger/limit model instead
+of reusing the single `Participant.Wager`. Multiple same-game tables in one room
+would also require changing current addressing/validation assumptions.
+
+## Testing shortcut
+
+`data/objects/casino_test_portal.yaml` is placed in starting room 1001.
+`use casino` gives 1000 chips and teleports to vestibule 6100. It is intentionally
+repeatable and uses ordinary trigger/drop/teleport machinery. Keep an inventory
+slot free (ordinary trigger drops fall to the ground when inventory is full).
+Remove the room's `casino_test_portal` reference before production: this grants
+unlimited test funds and bypasses travel/progression. No account roles are needed.
+
+Single-zero room 6182 and double-zero room 6183 are north of ground-floor
+landing 6102. `help roulette` describes player syntax and supported bets.
diff --git a/dev_guide/tick_order.md b/dev_guide/tick_order.md
new file mode 100644
index 0000000..b1246dd
--- /dev/null
+++ b/dev_guide/tick_order.md
@@ -0,0 +1,143 @@
+## Per-Tick System Order
+
+The server runs on a fixed game tick (600ms by default; configurable via
+`tick_length` in `config.yaml`). Each tick, every online player's pending
+commands resolve and a fixed sequence of systems advance world state. The
+**canonical order** in which these per-tick systems fire is a load-bearing
+contract: combat resolution, deplete/restock timers, regen, respawns, and
+sequence-driven triggers all depend on it. Reordering it is a breaking change.
+
+### Source of truth
+
+The authoritative list lives in code, not in this doc:
+
+- `internal/game/tick_systems.go` — the `tickSystemOrder` slice and
+  `(*Game).RunTickSystems()`, the method that fires them in order.
+- `cmd/thoi/main.go` — the master per-tick subscriber, registered with the
+  engine as **subscription ID 1**, whose body is `g.RunTickSystems()`. The
+  engine (`internal/engine/tick.go` `processTick`) sorts subscribers by
+  registration ID, so the master subscriber fires first each tick, before
+  any dynamically-registered combat / aggro / respawn callbacks (which get
+  higher IDs as players act).
+- `internal/game/tick_systems_test.go` — `TestTickSystemOrder` fails if the
+  table drifts from the list below. `TestRunTickSystemsEmptyGameIsSafe`
+  guards the "safe to tick with no players connected" contract every system
+  must uphold (see "Per-system contracts" below).
+
+If you change the order, add a system, or remove one: update `tickSystemOrder`
+in `tick_systems.go`, the `expectedTickSystemOrder` list in
+`tick_systems_test.go`, and the table in this file. All three are intentional
+duplicates so any one of them drifting fails the test loudly.
+
+### Canonical sequence
+
+| #   | System                  | What it does                                                                                                        |
+| --- | ----------------------- | ------------------------------------------------------------------------------------------------------------------ |
+| 1   | `ProcessQueuedCommands` | Drains each player's free-queued commands and the globally timestamp-sorted active queue; advances walk sequences. |
+| 2   | `CasinoTick`            | Advances casino betting deadlines and resolves completed casino rounds.                                            |
+| 3   | `MoveTick`              | Counts down `p.MoveTicks`; on reach-zero, completes a pending run/walk and re-prompts.                             |
+| 4   | `SequenceTick`          | Advances every active trigger `sequence` (per-player and global) one step.                                         |
+| 5   | `TransientMobTick`      | Despawns owned / `DespawnOnLeave` mobs whose owner has left their room.                                            |
+| 6   | `World.Tick`            | World-internal: ground-item respawn/despawn/reserve timers and shared-object deplete timers.                        |
+| 7   | `MobStore.Tick`         | Mob shop restock and mob HP regenerate. Order: by `InstanceID` so processing is stable across ticks.              |
+| 8   | `RegenTick`             | Player HP regeneration, accelerated by tech HP-regen multipliers.                                                  |
+| 9   | `EnergyRegenTick`       | Run-energy regeneration for every online player.                                                                   |
+| 10  | `DisconnectTick`        | Counts down pending disconnects and hard-removes finished sessions (skipping players still in combat).             |
+| 11  | `WanderTick`            | Mob wandering (exit-based) and object wandering (fishing spots), with enter/leave messages to observers.           |
+| 12  | `SharedDepletionTick`   | Ticks shared-object deplete timers up (in use) or down (recovering).                                               |
+| 13  | `FireTick`              | Decays fire objects; on burn-out, spawns the removal item and cancels stokers.                                     |
+| 14  | `AdvanceActions`        | Advances every active player action by one tick; fires completion handlers per action type.                        |
+| 15  | `TechTick`              | Drains battery for active tech, applies equipment / PreserveDrain reductions, and deactivates all on empty.        |
+| 16  | `ConsumeTick`           | Counts down `ConsumeCooldown` and `HomeTransportCooldown`.                                                         |
+| 17  | `BroadcastRespawns`     | Flushes respawned world objects and broadcasts their `respawn_broadcast` lines to players in those rooms.           |
+| 18  | `VisualTick`            | Optional per-player "visual tick" line/counter for AFK feedback.                                                   |
+| 19  | `SneakTick`             | Advances guard watch timers and sneaking players' tick counters.                                                   |
+| 20  | `FarmTick`              | Crops grow, drain water, and yield on harvest (fires every `FarmTickInterval` ticks).                              |
+| 21  | `BuffTick`              | Potion buff duration countdown; expires and removes effects.                                                      |
+| 22  | `SafespotTick`          | Safespot unsafe-chance and decay-chance rolls per player.                                                          |
+| 23  | `HazardTick`            | Room hazard damage to non-GodMode players.                                                                         |
+
+### Determinism contract
+
+Three layers of ordering decide what happens on a given tick, in priority:
+
+1. **Subscriber order** — deterministic. `engine.processTick` sorts
+   subscribers by registration ID. The master subscriber (ID 1, set in
+   `cmd/thoi/main.go`) always fires first; every system in
+   `RunTickSystems` then runs in the table order above. Dynamic combat /
+   aggro / respawn subscribers registered later get higher IDs and fire
+    after the canonical 23 systems. This is asserted by
+   `internal/engine/tick_test.go::TestProcessTickFiresInSubscriptionOrder`.
+
+2. **Per-system iteration order** — deterministic, as of the deterministic
+   per-tick subscriber work. Systems that iterate over players or mobs use
+   stable ordering:
+   - `Hub.AllSessions()` and `Hub.PlayersInRoom` (`internal/net/server.go`)
+     sort sessions by `Session.seq`, a monotonic counter assigned in
+     `Hub.Add` in connection order.
+   - `MobStore.AllInstances()`, `MobStore.MobsInRoom()`, and `MobStore.Tick()`
+     (`internal/world/mob.go`) sort by `MobInstance.InstanceID`.
+
+   This means, for example, that cosmetic "X enters." / "Y leaves."
+   interleavings in `WanderTick`, shop-restock order in `MobStore.Tick`,
+   and per-player processing order in `RegenTick` / `HazardTick` /
+   `SneakTick` etc. are reproducible across runs.
+
+3. **Random-number generation** — **not deterministic across server
+   restarts.** The `math/rand` top-level functions used across the engine
+   (`rand.Float64`, `rand.Intn`, `rand.Int`, `rand.Shuffle`) are
+   auto-seeded at program startup (Go 1.20+; calling `rand.Seed` is
+   deprecated and is never done here). So combat hit rolls, drop rolls,
+   wandering exit picks, and minigame randomness differ between server
+   runs. Two ticks from the same seeded run are reproducible *relative* to
+   each other (the global source is deterministic), but a fresh server
+   start produces a different stream.
+
+   Only `rollAggroRand` (`internal/game/sys_combat.go`) is replaceable for
+   tests; the rest are global-function calls. Reproducible full-tick
+   traces (e.g. for record/replay debugging) would require threading a
+   seeded `*math/rand.Rand`/`math/rand/v2.ChaCha8` through the engine; not
+   currently done.
+
+### Per-system contracts (the empty-game invariant)
+
+Every system in the table must be safe to invoke on a `*Game` that has its
+stores initialized (`World`, `MobStore`, `Hub`, `queue`, etc. via
+`game.New` + `SetHub`) but **no players connected**. Concretely:
+
+- Systems that touch the hub: guard with `if g.Hub == nil { return }` at the
+  top, *or* guard each `Hub.*` call with `if g.Hub != nil`. Either is fine.
+  (`main.go` now calls `SetHub` *before* `Ticks.Start`, so the production
+  server never ticks with a nil hub; the guards are belt-and-braces for a
+  `*Game` that tests construct without `SetHub`, such as
+  `newRunTickSystemsTestGame`.)
+- Systems that iterate over maps/slices held on `*Game` (`sequences`,
+  `restTimers`, `guardWatchTimers`, `hackingStates`, …) must tolerate empty
+  / freshly-initialized maps. `game.New` initializes all of them; tests that
+  build a stub `*Game` must too (see `newRunTickSystemsTestGame`).
+
+Violating either of these is caught by
+`TestRunTickSystemsEmptyGameIsSafe` in `internal/game/tick_systems_test.go`.
+If you add a new system that needs a new field initialized, update that
+helper as well.
+
+### Notes for builders
+
+When writing content that depends on per-tick ordering (a trigger that
+should fire *after* regen, a sequence whose step messages should appear
+*before* the move completes, etc.), consult the table above and remember:
+
+- `MoveTick` (table #3) runs before `SequenceTick` (table #4) — the table
+  fires top-to-bottom, so a move that completes this tick will have its
+  enter-room knock-on triggers fire (inside `ProcessQueuedCommands`, #1, or
+  `MoveTick`, #3) before trigger `sequences` advance in #4.
+- `on_enter` / `on_exit` room triggers fire from command execution, not
+  from a per-tick system; they run inside `ProcessQueuedCommands` (#1)
+  or `MoveTick` (#3) when the move actually completes.
+- Shop restock (`MobStore.Tick`, #7) happens *before* `RegenTick` (#8) and
+  *before* `AdvanceActions` (#14); if a gathering action completes this tick
+  it does so in #14, by which point shop state for this tick has
+  already advanced.
+
+When in doubt, the test in `tick_systems_test.go` is the executable
+specification.
diff --git a/dev_guide/video_poker.md b/dev_guide/video_poker.md
new file mode 100644
index 0000000..46d900e
--- /dev/null
+++ b/dev_guide/video_poker.md
@@ -0,0 +1,45 @@
+# Video poker internals
+
+Builder-facing cabinet configuration, payout tiers and player controls
+live in [../building_guide/video_poker.md](../building_guide/video_poker.md).
+This page covers presentation and money-safety internals.
+
+## Presentation
+
+Pay tables use yellow Unicode borders and dotted hand-name leaders. Blue
+`#000269`, red `#fe0000` (selected coin column), and yellow `#f7e70e` are mapped
+to nearest xterm colors. HELD and wins are bold yellow; no-win text is bold
+white. Results are below cards. Bonus indicators and multipliers sit beside
+cards. Multi-hand art shrinks; hundred-play uses compact Unicode ranks/suits.
+
+Payouts are total coins including stake, not profit. Multiply by denomination
+for credits. Natural royals pay 250 per coin below five coins, 4000 at five.
+Other categories scale linearly. Only the highest-paying category pays.
+All games use fresh 52-card decks except Joker Poker's 53-card deck. Each line
+shares the deal/holds but draws from its own shuffled remaining deck, excluding
+**all five** original cards, including discards.
+
+## Shared banks and money safety
+
+Ultimate X multipliers belong to the **machine**, not the player. Another
+occupant inherits them. Files live at
+`data/casino/video_poker_banks/<room>_<cabinet>.yaml`. Within each file banks
+are keyed by game/tier/denomination/hand-count, preventing denomination or
+edition switching from amplifying an award. Fully consumed banks are removed.
+Missing files are new machines; corrupt/unreadable files block deals.
+
+`casino.PokerWallet` loads banks and atomically settles character credits,
+pending stake removal, and the cabinet file in a multi-file undo-journal
+transaction. There is no package-global persistence callback. The game owner
+serializes writes. The stake is durable before revealing cards; frozen final
+hands and awards survive payment retries without redraws or rerolls. Failed
+transactions leave the old live bank intact. Commit-point failures are recovered
+and reconciled before any retry; unrecoverable storage faults fail closed.
+Startup journal recovery precedes pending-wager recovery. A process crash before
+commit restores both old records, then refunds the unresolved stake. Committed
+payouts cannot replay an old bank. Shutdown/eviction refunds unresolved stakes
+without consuming previously saved multipliers or retaining uncommitted awards.
+
+Old experimental player-owned `video_poker_multipliers` fields are no longer
+read. They are not merged into shared cabinets (multiple player banks cannot
+unambiguously become one physical bank).