Stop rebuilding the hand log after every fold, call and raise

Profiled a long night at a full table — 24 seats, 200 logged hands — because that's the state the tool is slowest in and the one a dealer reaches at 2am. A full re-render cost 30ms, and it runs after every single action. Broken down, 25.7ms of that was renderHandHistory: tearing down and rebuilding 200 rows of a panel that hadn't changed and that nobody is looking at mid-hand. Everything else on the table put together came to about 4ms. The log only changes when a hand is settled or the history is cleared — maybe once every thirty taps. It now carries a cheap signature (length, hand counter, and the newest row) and is skipped when that hasn't moved. Entries are immutable once written and only ever added at the front, so the signature catches a recorded hand, a cleared history, and an undo that puts a hand back. renderAll, every action 30.07ms -> 4.18ms renderHandHistory, skipped 25.74ms -> 0ms renderHandHistory, rebuild 25.74ms -> 9.05ms The rebuild got faster too, for the times it does run — once per hand, where 25ms of jank lands exactly on the "next hand" tap. toLocaleTimeString was the single most expensive call in the loop and a logged hand's timestamp never changes, so the formatted string is kept; and the rows are built into a fragment so the panel lays out once instead of two hundred times. A cache like this is only worth having if it can't go stale — a dealer reading last hand's payouts while settling this one is worse than a slow panel. 10 tests cover the invalidation directly: unchanged through a street of betting, changed by settling, by clearing, by an undo back to a shorter log, by two hands that differ only in the pot, and by the counter moving on. Validated with Playwright against the real page: the rendered rows match the stored history through settling a hand in the wizard, undoing it, clearing the log and recording again. Touch and layout guarantees from the earlier rounds still hold — 0 of 87 controls on touch-action auto, 0 tap-highlighted, every stack still inside its own puck. 109 tests passing. Co-Authored-By: Claude Opus 5 <[email protected]> Claude-Session: https://claude.ai/code/session_015bnp7xKUPFFSpwkYNFaPgb
Make the overlays usable from a keyboard
2026-09-01 04:24:36 -06:00 · 2026-09-01 04:12:55 -06:00 · 2026-09-01 03:54:03 -06:00 · 2026-09-01 03:40:02 -06:00 · 2026-09-01 03:11:39 -06:00 · 2026-09-01 03:00:36 -06:00
31 changed files with 3964 additions and 201 deletions
@@ -0,0 +1,26 @@
+# Unit tests for the Texas Hold'em dealer's money logic.
+#
+# The betting engine, the side-pot calculator and the table state are plain script-tag
+# modules with no build step, so they run directly under Node's built-in test runner —
+# no package.json, no install step, nothing to keep up to date.
+
+name: Hold'em tests
+
+on:
+  pull_request:
+    branches: [ "master" ]
+  push:
+    branches: [ "master" ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Setup Node
+      uses: actions/setup-node@v4
+      with:
+        node-version: 20
+    - name: Run Hold'em unit tests
+      run: node --test tests/holdem/*.test.js
@@ -31,9 +31,13 @@
                        <span id="potBadgeAmount">$0</span>
                    </div>
                </div>
+                <div id="betsLayer" aria-hidden="true"></div>
                <div id="seatsLayer"></div>
            </div>
            <p id="tableHint" class="tableHint"></p>
+            <p class="tableHintActions">
+                <button type="button" id="openRulingsBtn" class="linkBtn">Common rulings</button>
+            </p>
        </section>

        <aside id="holdemSidebar">
@@ -134,7 +138,7 @@
            <details class="sidebarPanel">
                <summary>Table Notes</summary>
                <div class="panelBody">
-                    <textarea id="tableNotes" rows="4" placeholder="Anything else worth tracking — side bets, IOUs, running totals..."></textarea>
+                    <textarea id="tableNotes" rows="4" aria-label="Table notes" placeholder="Anything else worth tracking — side bets, IOUs, running totals..."></textarea>
                </div>
            </details>
        </aside>
@@ -178,6 +182,7 @@
            <span>Stack</span>
            <input type="number" class="stackInput" min="0" step="1" placeholder="table default" />
        </label>
+        <div class="seatBuyIns" hidden></div>
        <div class="seatContribution">
            <div class="chipCounts"></div>
            <label class="fieldRow amountOverrideRow">
@@ -193,8 +198,8 @@

 <template id="chipLegendRowTemplate">
    <div class="chipLegendRow">
-        <input type="color" class="chipColorInput" />
-        <input type="number" class="chipValueInput" min="0" step="0.01" placeholder="value" />
+        <input type="color" class="chipColorInput" aria-label="Chip colour" />
+        <input type="number" class="chipValueInput" min="0" step="0.01" placeholder="value" aria-label="Chip value" />
        <button class="holdemBtn holdemBtnSmall holdemBtnDanger removeChipColorBtn">×</button>
    </div>
 </template>
@@ -234,6 +239,73 @@
    </div>
 </template>

+<div id="addChipsOverlay" hidden>
+    <div id="addChipsSheet" role="dialog" aria-labelledby="addChipsTitle">
+        <div class="seatSheetGrip" aria-hidden="true"></div>
+        <div class="addChipsHeader">
+            <h2 id="addChipsTitle"></h2>
+            <span id="addChipsSubtitle"></span>
+        </div>
+        <div id="addChipsQuick"></div>
+        <div class="addChipsEntry">
+            <span class="addChipsCurrency">$</span>
+            <input type="text" id="addChipsInput" inputmode="decimal" autocomplete="off" aria-label="Amount to add" />
+        </div>
+        <div class="addChipsActions">
+            <button id="addChipsConfirmBtn" class="holdemBtn holdemBtnAccent" type="button">Add to stack</button>
+            <button id="addChipsCancelBtn" data-modal-close class="holdemBtn holdemBtnGhost" type="button">Cancel</button>
+        </div>
+    </div>
+</div>
+
+<div id="rulingsOverlay" hidden>
+    <div id="rulingsSheet" role="dialog" aria-labelledby="rulingsTitle">
+        <div class="seatSheetGrip" aria-hidden="true"></div>
+        <div class="rulingsHeader">
+            <h2 id="rulingsTitle">Common rulings</h2>
+            <button id="closeRulingsBtn" data-modal-close class="holdemBtn holdemBtnSmall holdemBtnGhost" type="button">Done</button>
+        </div>
+
+        <p class="rulingsIntro">
+            The conventions most rooms follow, for the calls that come up mid-hand.
+            Your house rules always win — and settle a dispute before the next hand,
+            not during it.
+        </p>
+
+        <section class="ruling">
+            <h3>Redeal it — misdeal</h3>
+            <ul>
+                <li>The first card goes to the wrong seat.</li>
+                <li>A seat entitled to a hand gets dealt out, or a seat that isn't entitled gets dealt in.</li>
+                <li>Two or more boxed cards turn up on the initial deal.</li>
+                <li>Either of the first two cards is exposed by dealer error.</li>
+            </ul>
+        </section>
+
+        <section class="ruling">
+            <h3>A board card turned too early</h3>
+            <p>
+                If the fourth board card gets turned before the betting round is finished,
+                that card is out of play for the round. Finish the betting, then burn and
+                turn what would have been the fifth card in the fourth card's place.
+            </p>
+        </section>
+
+        <section class="ruling">
+            <h3>Acting out of turn</h3>
+            <p>
+                A one-off is usually just backed up if no one has acted behind them.
+                Doing it repeatedly is what earns a penalty.
+            </p>
+        </section>
+
+        <p class="rulingsSource">
+            Follows the Tournament Directors Association rules, which most rooms and
+            home games take their lead from.
+        </p>
+    </div>
+</div>
+
 <div id="seatMenuOverlay" hidden>
    <div id="seatMenuSheet" role="dialog" aria-labelledby="seatMenuTitle">
        <div class="seatSheetGrip" aria-hidden="true"></div>
@@ -242,7 +314,7 @@
            <span id="seatMenuSubtitle"></span>
        </div>
        <div id="seatMenuActions"></div>
-        <button id="seatMenuCancelBtn" class="holdemBtn holdemBtnGhost" type="button">Cancel</button>
+        <button id="seatMenuCancelBtn" data-modal-close class="holdemBtn holdemBtnGhost" type="button">Cancel</button>
    </div>
 </div>

@@ -252,7 +324,7 @@
        <div class="cardPickerHeader">
            <h2 id="cardPickerTitle"></h2>
            <button id="cardPickerClearBtn" class="holdemBtn holdemBtnSmall" type="button">Clear</button>
-            <button id="cardPickerCloseBtn" class="holdemBtn holdemBtnSmall holdemBtnGhost" type="button">Done</button>
+            <button id="cardPickerCloseBtn" data-modal-close class="holdemBtn holdemBtnSmall holdemBtnGhost" type="button">Done</button>
        </div>
        <div id="cardPickerSlots"></div>
        <div id="cardPickerGrid"></div>
@@ -268,17 +340,17 @@
        <h2 id="confirmTitle"></h2>
        <p id="confirmMessage"></p>
        <div class="confirmActions">
-            <button id="confirmCancelBtn" class="holdemBtn holdemBtnGhost" type="button">Cancel</button>
+            <button id="confirmCancelBtn" data-modal-close class="holdemBtn holdemBtnGhost" type="button">Cancel</button>
            <button id="confirmAcceptBtn" class="holdemBtn holdemBtnDanger" type="button">Confirm</button>
        </div>
    </div>
 </div>

 <div id="potWizardOverlay" hidden>
-    <div id="potWizardModal">
+    <div id="potWizardModal" role="dialog" aria-labelledby="potWizardTitle">
        <div class="potWizardHeader">
-            <h2>Resolve the Pot</h2>
-            <button id="closePotWizardBtn" class="holdemBtn holdemBtnGhost">✕</button>
+            <h2 id="potWizardTitle">Resolve the Pot</h2>
+            <button id="closePotWizardBtn" data-modal-close class="holdemBtn holdemBtnGhost">✕</button>
        </div>
        <div id="potWizardBody"></div>
    </div>
@@ -296,10 +368,12 @@
    <script src="~/js/casino/holdem/render.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/cardPicker.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/seatMenu.js?v=@ViewData["cssVersion"]"></script>
+    <script src="~/js/casino/holdem/addChips.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/betting.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/actionBar.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/shortcuts.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/potWizard.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/handHistoryExport.js?v=@ViewData["cssVersion"]"></script>
+    <script src="~/js/casino/holdem/modal.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/main.js?v=@ViewData["cssVersion"]"></script>
 }
@@ -11,6 +11,11 @@
        <p class="splitSubtitle">Chop a pot without setting up a table.</p>
    </header>

+    <div id="modeToggle" class="chipRow" role="group" aria-label="How the money went in">
+        <button type="button" id="modeEvenBtn" class="choiceChip selected">Everyone matched</button>
+        <button type="button" id="modeUnevenBtn" class="choiceChip">Someone's all-in</button>
+    </div>
+
    <div id="splitResult" aria-live="polite">
        <div id="splitResultLabel">Each player gets</div>
        <div id="splitResultAmount">$0.00</div>
@@ -18,7 +23,18 @@
        <div id="splitDustNote" hidden></div>
    </div>

-    <section class="splitField">
+    <div id="unevenResult" hidden aria-live="polite">
+        <div id="unevenPots"></div>
+        <p id="unevenEmpty" class="unevenEmpty">Enter what each player put in.</p>
+    </div>
+
+    <section class="splitField unevenOnly" hidden>
+        <span class="splitLabel">What each player put in</span>
+        <div id="unevenRows"></div>
+        <button type="button" id="addPlayerBtn" class="splitBtn splitBtnGhost">+ Add player</button>
+    </section>
+
+    <section class="splitField evenOnly">
        <label for="potInput" class="splitLabel">Pot</label>
        <div class="potInputWrap">
            <span class="potCurrency">$</span>
@@ -28,12 +44,12 @@
        </div>
    </section>

-    <section class="splitField">
+    <section class="splitField evenOnly">
        <span class="splitLabel" id="waysLabel">Split between</span>
        <div id="waysChoices" class="chipRow" role="group" aria-labelledby="waysLabel"></div>
    </section>

-    <section class="splitField">
+    <section class="splitField evenOnly">
        <span class="splitLabel" id="chipLabel">Smallest chip in play</span>
        <div id="chipChoices" class="chipRow" role="group" aria-labelledby="chipLabel"></div>
    </section>
@@ -43,12 +59,30 @@
        <a href="/casino/texasholdem" class="splitBtn splitBtnGhost">Full dealer table →</a>
    </div>

-    <p class="splitFootnote">
-        Uneven pots — someone all-in for less — need the side-pot walkthrough on the
-        <a href="/casino/texasholdem">full table</a>.
+    <p class="splitFootnote evenOnly">
+        If somebody was all-in for less than the others, switch to
+        <strong>Someone's all-in</strong> above.
+    </p>
+
+    <p class="splitFootnote unevenOnly" hidden>
+        Pots are listed with who can win each. Award them by hand strength, best hand
+        first. Nothing here is saved — the <a href="/casino/texasholdem">full table</a>
+        keeps a log.
    </p>
 </div>

+<template id="unevenRowTemplate">
+    <div class="unevenRow">
+        <span class="unevenRowLabel"></span>
+        <div class="unevenAmountWrap">
+            <span class="unevenCurrency">$</span>
+            <input type="text" class="unevenAmount" inputmode="decimal" autocomplete="off" placeholder="0" />
+        </div>
+        <button type="button" class="unevenFoldBtn" aria-pressed="false">Folded</button>
+        <button type="button" class="unevenRemoveBtn" aria-label="Remove player">✕</button>
+    </div>
+</template>
+
@section Styles {
    <link href="/css/casino/quicksplit.css?v=@ViewData["cssVersion"]" rel="stylesheet" type="text/css" />
 }
@@ -56,5 +90,6 @@
@section Scripts {
    <script src="~/js/casino/holdem/money.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/splitCalculator.js?v=@ViewData["cssVersion"]"></script>
+    <script src="~/js/casino/holdem/potCalculator.js?v=@ViewData["cssVersion"]"></script>
    <script src="~/js/casino/holdem/quickSplit.js?v=@ViewData["cssVersion"]"></script>
 }
@@ -9,6 +9,58 @@ body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
 }

+/* Same touch handling as the dealer table — see the note there. This page is the one
+   a dealer opens mid-hand to chop a pot, so the ~300ms the browser spends deciding
+   whether a tap was a double-tap-to-zoom is the last thing it needs. */
+button,
+[role="button"],
+input,
+select,
+textarea,
+a {
+    touch-action: manipulation;
+}
+
+button,
+[role="button"],
+input,
+select,
+textarea,
+a {
+    -webkit-tap-highlight-color: transparent;
+}
+
+/* Not on the fields — a dealer typing a pot amount still needs to select it. */
+button,
+[role="button"] {
+    -webkit-user-select: none;
+    user-select: none;
+}
+
+.clearPotBtn:active:not(:disabled),
+.choiceChip:active:not(:disabled),
+.stepBtn:active:not(:disabled),
+.splitBtn:active:not(:disabled),
+.splitBtnGhost:active:not(:disabled),
+.unevenFoldBtn:active:not(:disabled),
+.unevenRemoveBtn:active:not(:disabled) {
+    transform: translateY(1px);
+    filter: brightness(1.25);
+    transition-duration: 0.04s;
+}
+
+@media (prefers-reduced-motion: reduce) {
+    .clearPotBtn:active:not(:disabled),
+    .choiceChip:active:not(:disabled),
+    .stepBtn:active:not(:disabled),
+    .splitBtn:active:not(:disabled),
+    .splitBtnGhost:active:not(:disabled),
+    .unevenFoldBtn:active:not(:disabled),
+    .unevenRemoveBtn:active:not(:disabled) {
+        transform: none;
+    }
+}
+
 #splitApp {
    max-width: 480px;
    margin: 0 auto;
@@ -45,6 +97,171 @@ body {
    font-size: 0.85rem;
 }

+/* ---------- Mode toggle ---------- */
+
+#modeToggle {
+    margin-bottom: 1.1rem;
+}
+
+/* ---------- Uneven amounts ---------- */
+
+#unevenRows {
+    display: flex;
+    flex-direction: column;
+    gap: 0.45rem;
+    margin-bottom: 0.6rem;
+}
+
+.unevenRow {
+    display: flex;
+    align-items: center;
+    gap: 0.45rem;
+}
+
+.unevenRowLabel {
+    flex: none;
+    width: 2rem;
+    color: #8f8f8f;
+    font-size: 0.8rem;
+    font-weight: 600;
+}
+
+.unevenAmountWrap {
+    flex: 1;
+    min-width: 0;
+    display: flex;
+    align-items: center;
+    gap: 0.3rem;
+    background: #141414;
+    border: 1px solid #3a3a3a;
+    border-radius: 10px;
+    padding: 0 0.6rem;
+}
+
+.unevenAmountWrap:focus-within {
+    border-color: #d8b46a;
+}
+
+.unevenCurrency {
+    color: #777;
+}
+
+.unevenAmount {
+    flex: 1;
+    min-width: 0;
+    background: none;
+    border: none;
+    outline: none;
+    color: #f2f2f2;
+    font-family: inherit;
+    font-size: 16px;
+    font-variant-numeric: tabular-nums;
+    padding: 0.6rem 0;
+}
+
+.unevenFoldBtn {
+    flex: none;
+    min-height: 44px;
+    padding: 0 0.6rem;
+    border-radius: 9px;
+    border: 1px solid #3a3a3a;
+    background: #232323;
+    color: #8f8f8f;
+    font-family: inherit;
+    font-size: 0.72rem;
+    cursor: pointer;
+}
+
+.unevenFoldBtn.selected {
+    background: linear-gradient(180deg, #3d1f1f, #2c1515);
+    border-color: #5b2626;
+    color: #ffd6d6;
+}
+
+.unevenRemoveBtn {
+    flex: none;
+    width: 30px;
+    height: 44px;
+    border: none;
+    background: none;
+    color: #6a6a6a;
+    font-size: 0.85rem;
+    cursor: pointer;
+}
+
+.unevenRemoveBtn:disabled {
+    opacity: 0.3;
+    cursor: not-allowed;
+}
+
+#unevenResult {
+    background: linear-gradient(160deg, #1f2a21, #161c17);
+    border: 1px solid #2c3a2f;
+    border-radius: 14px;
+    padding: 0.9rem 1rem;
+    margin-bottom: 1.5rem;
+}
+
+#unevenResult[hidden] {
+    display: none;
+}
+
+.unevenPot {
+    display: flex;
+    align-items: baseline;
+    gap: 0.6rem;
+    padding: 0.3rem 0;
+    font-size: 0.85rem;
+}
+
+.unevenPot + .unevenPot {
+    border-top: 1px solid rgba(255, 255, 255, 0.06);
+}
+
+.unevenPotLabel {
+    flex: none;
+    color: #d8b46a;
+    font-weight: 600;
+}
+
+.unevenPotAmount {
+    flex: none;
+    color: #f2f2f2;
+    font-weight: 600;
+    font-variant-numeric: tabular-nums;
+}
+
+.unevenPotWho {
+    flex: 1;
+    min-width: 0;
+    text-align: right;
+    color: #9a9a9a;
+    font-size: 0.78rem;
+}
+
+.unevenPotReturn .unevenPotLabel,
+.unevenPotReturn .unevenPotAmount {
+    color: #9a9a9a;
+    font-weight: 500;
+}
+
+.unevenPotTotal {
+    margin-top: 0.15rem;
+    border-top: 1px solid rgba(255, 255, 255, 0.14) !important;
+}
+
+.unevenPotTotal .unevenPotLabel {
+    color: #8f9d92;
+    font-weight: 500;
+}
+
+.unevenEmpty {
+    margin: 0;
+    color: #8f9d92;
+    font-size: 0.82rem;
+    line-height: 1.45;
+}
+
 /* ---------- The answer ---------- */

 #splitResult {
@@ -104,6 +321,12 @@ body {
    margin-bottom: 1.35rem;
 }

+/* A `display` declaration outranks the browser's own [hidden] rule, so anything
+   given one has to opt back out explicitly or toggling `hidden` does nothing. */
+[hidden] {
+    display: none !important;
+}
+
 .splitLabel {
    display: block;
    margin-bottom: 0.5rem;
@@ -165,9 +388,11 @@ body {
    cursor: pointer;
 }

-.clearPotBtn:hover {
-    background: #333;
-    color: #ddd;
+@media (hover: hover) {
+    .clearPotBtn:hover {
+        background: #333;
+        color: #ddd;
+    }
 }

 /* ---------- Tap targets ---------- */
@@ -193,9 +418,11 @@ body {
    transition: all 0.15s ease;
 }

-.choiceChip:hover {
-    border-color: #4a4a4a;
-    background: linear-gradient(180deg, #383838, #2a2a2a);
+@media (hover: hover) {
+    .choiceChip:hover {
+        border-color: #4a4a4a;
+        background: linear-gradient(180deg, #383838, #2a2a2a);
+    }
 }

 .choiceChip.selected {
@@ -230,8 +457,10 @@ body {
    cursor: pointer;
 }

-.stepBtn:hover {
-    background: #333;
+@media (hover: hover) {
+    .stepBtn:hover {
+        background: #333;
+    }
 }

 .waysReadout {
@@ -268,9 +497,11 @@ body {
    transition: all 0.15s ease;
 }

-.splitBtn:hover {
-    border-color: #4a4a4a;
-    background: linear-gradient(180deg, #383838, #2a2a2a);
+@media (hover: hover) {
+    .splitBtn:hover {
+        border-color: #4a4a4a;
+        background: linear-gradient(180deg, #383838, #2a2a2a);
+    }
 }

 .splitBtnGhost {
@@ -11,9 +11,35 @@ const ActionBar = {
    mount(state, hooks) {
        this.state = state;
        this.hooks = hooks;
+        this.watchHeight();
        this.render();
    },

+    // The bar is fixed to the bottom of the screen, so everything else has to know how
+    // tall it is or the table simply runs underneath it — on a 640px-tall phone the
+    // bottom seats of the oval were sitting behind the Fold button. Its height isn't a
+    // constant either: opening the raise pad grows it. Publishing the measured height
+    // as a custom property lets the layout and the toast both stay clear of it without
+    // anyone guessing a number.
+    watchHeight() {
+        const host = document.getElementById("actionBar");
+        if (!host || this.heightWatcher) return;
+
+        const publish = () => {
+            const visible = !host.hidden;
+            const height = visible ? host.getBoundingClientRect().height : 0;
+            document.documentElement.style.setProperty("--actionBarHeight", `${Math.round(height)}px`);
+        };
+
+        if (typeof ResizeObserver === "function") {
+            this.heightWatcher = new ResizeObserver(publish);
+            this.heightWatcher.observe(host);
+        }
+        window.addEventListener("resize", publish);
+        window.addEventListener("orientationchange", publish);
+        publish();
+    },
+
    // Anything to act on? A hand with nobody dealt in doesn't get a bar.
    isRunning() {
        return Betting.liveSeats(this.state).length > 0;
@@ -27,6 +53,7 @@ const ActionBar = {
        if (!this.isRunning()) {
            host.hidden = true;
            document.body.classList.remove("hasActionBar");
+            document.documentElement.style.setProperty("--actionBarHeight", "0px");
            this.stopTankTimer();
            this.tankSeatIndex = null;
            return;
@@ -74,6 +101,16 @@ const ActionBar = {
        players.textContent = `${remaining} ${remaining === 1 ? "player" : "players"}`;
        row.appendChild(players);

+        // Nobody is being asked to act because nobody can — say so, or the bar just
+        // looks like it's waiting for something.
+        if (Betting.isRunningOut(this.state) && !Betting.isHandOver(this.state)) {
+            const runout = document.createElement("span");
+            runout.className = "actionRunout";
+            const stillIn = Betting.liveSeats(this.state).length;
+            runout.textContent = `All-in — running out the board (${stillIn} players)`;
+            row.appendChild(runout);
+        }
+
        const index = this.state.actingSeatIndex;
        if (index !== null && index !== undefined && !Betting.isHandOver(this.state)) {
            const player = this.state.seats[index];
@@ -0,0 +1,92 @@
+// "Add chips" — a rebuy, a top-up, or the first buy-in of the night.
+//
+// Quick amounts come off the table's starting stack, because a rebuy is almost
+// always one buy-in, sometimes half or two. The keypad is there for the times it
+// isn't. Recorded as cash in as well as chips, so at the end of the night the
+// dealer can say what each player actually handed over.
+const AddChips = {
+    state: null,
+    onConfirm: null,
+    seatIndex: null,
+    draft: "",
+
+    open(state, seatIndex, onConfirm) {
+        this.state = state;
+        this.seatIndex = seatIndex;
+        this.onConfirm = onConfirm;
+        this.draft = String(this.baseAmount());
+        this.render();
+        document.getElementById("addChipsOverlay").hidden = false;
+    },
+
+    close() {
+        document.getElementById("addChipsOverlay").hidden = true;
+    },
+
+    // The table's starting stack if there is one, otherwise something sane to nudge
+    // rather than an empty box.
+    baseAmount() {
+        const configured = Number(this.state.defaultStack);
+        if (!Number.isNaN(configured) && configured > 0) return configured;
+        const bb = Number(this.state.bigBlind) || 0;
+        return bb > 0 ? bb * 100 : 100;
+    },
+
+    quickAmounts() {
+        const base = this.baseAmount();
+        return [
+            { label: "½ buy-in", value: Money.round(base / 2) },
+            { label: "Buy-in", value: base },
+            { label: "2 buy-ins", value: base * 2 },
+        ];
+    },
+
+    render() {
+        const player = this.state.seats[this.seatIndex];
+        document.getElementById("addChipsTitle").textContent =
+            `Add chips — ${HoldemState.displayName(player, this.seatIndex)}`;
+
+        const stack = Betting.stackOf(this.state, player);
+        const boughtIn = Number(player.buyIns) || 0;
+        document.getElementById("addChipsSubtitle").textContent = boughtIn > 0
+            ? `${Money.format(stack)} in front · ${Money.format(boughtIn)} in so far`
+            : `${Money.format(stack)} in front`;
+
+        const quick = document.getElementById("addChipsQuick");
+        quick.innerHTML = "";
+        this.quickAmounts().forEach(option => {
+            const btn = document.createElement("button");
+            btn.type = "button";
+            btn.className = "addChipsQuickBtn";
+            btn.classList.toggle("selected", Number(this.draft) === option.value);
+
+            const label = document.createElement("span");
+            label.className = "addChipsQuickLabel";
+            label.textContent = option.label;
+            const amount = document.createElement("span");
+            amount.className = "addChipsQuickAmount";
+            amount.textContent = Money.format(option.value);
+
+            btn.appendChild(label);
+            btn.appendChild(amount);
+            btn.addEventListener("click", () => {
+                this.draft = String(option.value);
+                this.render();
+            });
+            quick.appendChild(btn);
+        });
+
+        const input = document.getElementById("addChipsInput");
+        input.value = this.draft;
+    },
+
+    confirm() {
+        const amount = Math.max(0, Number(document.getElementById("addChipsInput").value) || 0);
+        this.close();
+        if (amount > 0) this.onConfirm(this.seatIndex, Money.round(amount));
+    },
+};
+
+if (typeof module !== "undefined" && module.exports) {
+    module.exports = AddChips;
+}
@@ -18,7 +18,7 @@ const Betting = {
    },

    round(amount) {
-        return Math.round((Number(amount) || 0) * 100) / 100;
+        return Money.round(amount);
    },

    // ---- Reading the table ----
@@ -39,11 +39,16 @@ const Betting = {
        return this.round((Number(player.amountOverride) || 0) + this.committed(player));
    },

+    // Never below zero. A seat can't have negative chips in front of it, and a typo in
+    // the stack field used to come back as-is — which then flowed into putIn(), where
+    // `Math.min(amount, -50)` moves a negative amount and *adds* chips to the table.
    stackOf(state, player) {
        const own = player.stack;
-        if (own !== null && own !== undefined && String(own).trim() !== "") return this.round(own);
+        if (own !== null && own !== undefined && String(own).trim() !== "") {
+            return Math.max(0, this.round(own));
+        }
        const fallback = Number(state.defaultStack);
-        return Number.isNaN(fallback) ? 0 : this.round(fallback);
+        return Number.isNaN(fallback) ? 0 : Math.max(0, this.round(fallback));
    },

    toCall(state, player) {
@@ -70,15 +75,28 @@ const Betting = {
        for (let step = 1; step <= count; step++) {
            const index = this.seatAt(state, fromIndex, step);
            const player = state.seats[index];
-            if (player.inHand && !player.folded && this.stackOf(state, player) >= 0) return index;
+            if (player.inHand && !player.folded) return index;
        }
        return null;
    },

-    seatAt(state, fromIndex, step) {
+    // Who the dealer asks next. A player who is all-in is still in the hand and still
+    // wins pots, but has no decision left, so the action passes over them.
+    nextToAct(state, fromIndex) {
        const count = state.seatCount;
-        const delta = state.direction === "counterclockwise" ? -step : step;
-        return ((fromIndex + delta) % count + count) % count;
+        for (let step = 1; step <= count; step++) {
+            const index = this.seatAt(state, fromIndex, step);
+            const player = state.seats[index];
+            if (player.inHand && !player.folded && this.stackOf(state, player) > this.EPSILON_CHIPS) return index;
+        }
+        return null;
+    },
+
+    // Which chair sits `step` places along in the direction of play. The table owns
+    // this — walking the seats is exactly where the button, the blinds and the action
+    // used to drift apart from each other, so there is one implementation of it.
+    seatAt(state, fromIndex, step) {
+        return HoldemState.nextSeatIndex(state, fromIndex, step);
    },

    // A street is done when everyone still live has either matched the bet or has
@@ -156,7 +174,7 @@ const Betting = {
    },

    passAction(state, index) {
-        state.actingSeatIndex = this.isStreetComplete(state) ? null : this.nextLiveIndex(state, index);
+        state.actingSeatIndex = this.isStreetComplete(state) ? null : this.nextToAct(state, index);
    },

    // ---- Street and hand boundaries ----
@@ -184,15 +202,74 @@ const Betting = {

        const nextStreetIndex = this.STREETS.indexOf(state.street || "preflop") + 1;
        state.street = this.STREETS[nextStreetIndex] || "river";
-        state.actingSeatIndex = this.liveSeats(state).length > 1
-            ? this.nextLiveIndex(state, state.dealerSeatIndex)
-            : null;
+
+        // It takes two players with chips to have a bet. Once everyone left is all-in
+        // the rest of the board is just dealt out.
+        if (!this.canStillBet(state)) {
+            state.actingSeatIndex = null;
+            return;
+        }
+
+        // After the flop the first live player left of the button acts — which heads-up
+        // is the big blind, since the button is the small blind. Naming the big blind
+        // directly also covers a button parked on a seat nobody is sitting in, and it
+        // still has to be someone with chips left to bet.
+        const { bbIndex, headsUp } = HoldemState.getBlindSeats(state);
+        const bigBlindCanAct =
+            headsUp &&
+            bbIndex !== null &&
+            !state.seats[bbIndex].folded &&
+            this.stackOf(state, state.seats[bbIndex]) > this.EPSILON_CHIPS;
+
+        state.actingSeatIndex = bigBlindCanAct
+            ? bbIndex
+            : this.nextToAct(state, state.dealerSeatIndex);
    },

    isHandOver(state) {
        return this.liveSeats(state).length <= 1;
    },

+    // Players still in the hand who have chips left to put in. Fewer than two of them
+    // means the betting is finished even though the hand isn't.
+    seatsWithChips(state) {
+        return this.liveSeats(state).filter(s => this.stackOf(state, s.player) > this.EPSILON_CHIPS);
+    },
+
+    EPSILON_CHIPS: Money.EPSILON,
+
+    canStillBet(state) {
+        return this.liveSeats(state).length > 1 && this.seatsWithChips(state).length > 1;
+    },
+
+    // True when the hand is still live but nobody can bet again — the dealer is just
+    // running the board out.
+    isRunningOut(state) {
+        return this.liveSeats(state).length > 1 && !this.canStillBet(state);
+    },
+
+    // True while nothing has happened in this hand except the blinds going in. Up to
+    // that point the dealer can still move the button or rename the blinds and have
+    // it cost nothing — which is the state a home game spends a lot of time in,
+    // arguing about whose turn it is before the cards come out.
+    onlyBlindsIn(state) {
+        return (state.street || "preflop") === "preflop" && state.seats.every(p => !p.hasActed);
+    },
+
+    // Pulls the blinds back off the table and posts them again from wherever the
+    // button and the blind assignment now say they belong. Refunding first is what
+    // keeps the chip count straight when the button gets passed round three or four
+    // times before anybody is happy with it.
+    repostBlinds(state) {
+        state.seats.forEach(player => {
+            const back = this.committed(player);
+            if (back > 0) player.stack = this.round(this.stackOf(state, player) + back);
+            player.committed = 0;
+            player.hasActed = false;
+        });
+        this.beginHand(state);
+    },
+
    // Deals a fresh betting round: blinds posted, action to the seat after the big
    // blind, which is where a dealer expects to be looking when the cards go out.
    beginHand(state) {
@@ -200,6 +277,11 @@ const Betting = {
        state.currentBet = 0;
        state.lastRaiseSize = 0;

+        // Position is read off the button all through the hand, so it has to be on
+        // somebody before the blinds are worked out — not on the empty seat 1 a
+        // brand-new table starts on.
+        HoldemState.ensureButtonOnPlayer(state);
+
        state.seats.forEach(player => {
            player.committed = 0;
            player.hasActed = false;
@@ -207,15 +289,26 @@ const Betting = {

        const sb = Number(state.smallBlind) || 0;
        const bb = Number(state.bigBlind) || 0;
-        const sbIndex = this.seatAt(state, state.dealerSeatIndex, 1);
-        const bbIndex = this.seatAt(state, state.dealerSeatIndex, 2);
+        const { sbIndex, bbIndex, headsUp } = HoldemState.getBlindSeats(state);

-        if (sb > 0 && state.seats[sbIndex].inHand) this.putIn(state, sbIndex, sb);
-        if (bb > 0 && state.seats[bbIndex].inHand) this.putIn(state, bbIndex, bb);
+        if (sbIndex === null || bbIndex === null) {
+            state.currentBet = 0;
+            state.actingSeatIndex = null;
+            return;
+        }
+
+        if (sb > 0) this.putIn(state, sbIndex, sb);
+        if (bb > 0) this.putIn(state, bbIndex, bb);

        state.currentBet = this.round(Math.max(this.committed(state.seats[sbIndex]), this.committed(state.seats[bbIndex])));
        state.lastRaiseSize = bb || 0;
-        state.actingSeatIndex = this.nextLiveIndex(state, bbIndex);
+
+        // Heads-up the button is the small blind and acts first before the flop; with
+        // three or more it's the seat after the big blind. Either way, a blind big
+        // enough to put that player all-in leaves them nothing to decide.
+        state.actingSeatIndex = headsUp
+            ? (this.stackOf(state, state.seats[sbIndex]) > this.EPSILON_CHIPS ? sbIndex : this.nextToAct(state, sbIndex))
+            : this.nextToAct(state, bbIndex);
    },

    // Winners get their share put back in front of them.
@@ -15,6 +15,10 @@ const HandHistoryExport = {
        }
    },

+    // Money columns go in as bare numbers. Written as "$1,250,000.00" they import as
+    // text, so the one thing anybody opens this file to do — total a column and see
+    // who owes what — doesn't work without cleaning every cell first. The commas were
+    // quoted correctly, so the file parsed; it just wouldn't add up.
    toCsv(handHistory, standings = []) {
        const rows = [["Hand #", "Time", "Pot", "Payouts"]];
        // handHistory is stored newest-first; the export reads better oldest-first.
@@ -25,7 +29,7 @@ const HandHistoryExport = {
            rows.push([
                entry.handNumber,
                this.formatTimestamp(entry.timestamp),
-                Money.format(entry.pot),
+                Money.forSheet(entry.pot),
                payouts,
            ]);
        });
@@ -35,9 +39,19 @@ const HandHistoryExport = {
        if (standings.length > 0) {
            rows.push([]);
            rows.push(["Session Standings"]);
-            rows.push(["Player", "Paid In", "Won", "Net"]);
+            // Bought in and chips now are what a cash-out is settled from; paid in and
+            // won describe the hands. Both belong in the file the dealer hands over.
+            rows.push(["Player", "Paid In", "Won", "Net", "Bought In", "Chips Now", "Up/Down"]);
            standings.forEach(row => {
-                rows.push([row.name, Money.format(row.in), Money.format(row.won), Money.formatSigned(row.net)]);
+                rows.push([
+                    row.name,
+                    Money.forSheet(row.in),
+                    Money.forSheet(row.won),
+                    Money.forSheet(row.net),
+                    Money.forSheet(row.boughtIn || 0),
+                    Money.forSheet(row.chipsNow || 0),
+                    Money.forSheet(row.cashPosition || 0),
+                ]);
            });
        }

@@ -1,10 +1,27 @@
 document.addEventListener("DOMContentLoaded", () => {
    const state = HoldemState.load();

+    // Focus, Tab-trapping and Escape for every overlay, wired once by watching the
+    // `hidden` attribute they all already toggle.
+    Modal.mount();
+
+    // Undo works by swapping the whole table back to a snapshot. `state` is handed out
+    // by reference to every module at mount time, so it has to be refilled in place —
+    // reassigning the variable would leave the renderer and the betting bar pointing at
+    // the old object and quietly ignoring the undo.
+    const snapshotState = () => JSON.parse(JSON.stringify(state));
+
+    const restoreState = snapshot => {
+        Object.keys(state).forEach(key => delete state[key]);
+        Object.assign(state, snapshot);
+        HoldemState.save(state);
+        Render.renderAll();
+    };
+
    // A gesture on a seat is a shortcut for something the dealer could do the long
    // way, so each one is undoable the same way the header buttons are.
    const seatAction = (index, message, mutate) => {
-        const snapshot = JSON.parse(JSON.stringify(state));
+        const snapshot = snapshotState();
        mutate(state.seats[index], index);
        HoldemState.save(state);
        Render.renderAll();
@@ -12,10 +29,7 @@ document.addEventListener("DOMContentLoaded", () => {
        Toast.show(message, {
            actionLabel: "Undo",
            onAction: () => {
-                Object.keys(state).forEach(key => delete state[key]);
-                Object.assign(state, snapshot);
-                HoldemState.save(state);
-                Render.renderAll();
+                restoreState(snapshot);
                Toast.show("Undone.", { duration: 2500 });
            },
            duration: 6000,
@@ -42,6 +56,7 @@ document.addEventListener("DOMContentLoaded", () => {
        },

        onSeatLongPress: index => SeatMenu.open(state, seatMenuHooks, index),
+        onGiveButton: index => seatMenuHooks.makeDealer(index),
    };

    const seatMenuHooks = {
@@ -49,14 +64,81 @@ document.addEventListener("DOMContentLoaded", () => {
        unfold: index => seatAction(index, `${nameOf(index)} is back in the hand.`, p => { p.folded = false; }),
        allIn: index => seatAction(index, `${nameOf(index)} is all-in.`, () => Betting.allIn(state, index)),
        toggleDealtIn: index => {
-            const dealtIn = state.seats[index].inHand;
-            seatAction(index, dealtIn ? `${nameOf(index)} sits out.` : `${nameOf(index)} is dealt in.`, p => {
+            const player = state.seats[index];
+            const dealtIn = player.inHand;
+            const handRunning = !Betting.onlyBlindsIn(state) || Betting.potSoFar(state) > 0;
+            const alreadyIn = Betting.handTotal(player);
+
+            // Somebody walking away mid-hand doesn't get their chips back — they're
+            // dead money the winner collects. Say so, because the pot total pointedly
+            // does not go down and a dealer needs to know that's deliberate.
+            const message = dealtIn
+                ? (alreadyIn > 0
+                    ? `${nameOf(index)} is out — their ${Money.format(alreadyIn)} stays in the pot.`
+                    : `${nameOf(index)} sits out.`)
+                : (handRunning
+                    ? `${nameOf(index)} is in from the next hand.`
+                    : `${nameOf(index)} is dealt in.`);
+
+            seatAction(index, message, p => {
                p.inHand = !dealtIn;
-                if (!p.inHand) p.folded = false;
+                if (!p.inHand) {
+                    // Their chips stay put; only the fold flag is cleared, since being
+                    // out of the hand already covers not winning it.
+                    p.folded = false;
+                    if (state.actingSeatIndex === index) Betting.passAction(state, index);
+                } else if (handRunning) {
+                    // Joining a hand already in progress means sitting this one out —
+                    // you can't buy into a pot you haven't been paying for. `folded`
+                    // is exactly that state, and the next hand clears it.
+                    p.folded = true;
+                }
            });
        },
-        makeDealer: index => seatAction(index, `Button on ${nameOf(index)}.`, () => { state.dealerSeatIndex = index; }),
+
+        makeDealer: index => seatAction(index, `Button on ${nameOf(index)}.`, () => {
+            state.dealerSeatIndex = index;
+            // Before anyone has acted the blinds are still just sitting there, so
+            // moving the button moves them too — a home game passes it round several
+            // times before the cards come out, and the posted chips have to follow.
+            if (Betting.onlyBlindsIn(state)) Betting.repostBlinds(state);
+        }),
+
+        assignBlind: (index, which) => {
+            const blinds = HoldemState.getBlindSeats(state);
+            const other = which === "sb" ? blinds.bbIndex : blinds.sbIndex;
+            // Naming one blind pins the other where it already is, so the dealer only
+            // has to state the part they're changing. If that would land both on one
+            // player, the other blind moves to the next seat along.
+            let partner = other !== null && other !== undefined && other !== index
+                ? other
+                : Betting.nextLiveIndex(state, index);
+            if (partner === index || partner === null) partner = Betting.nextLiveIndex(state, index);
+
+            const label = which === "sb" ? "small blind" : "big blind";
+            seatAction(index, `${nameOf(index)} posts the ${label}.`, () => {
+                state.blindOverride = which === "sb"
+                    ? { sbIndex: index, bbIndex: partner }
+                    : { sbIndex: partner, bbIndex: index };
+                if (Betting.onlyBlindsIn(state)) Betting.repostBlinds(state);
+            });
+        },
+
+        clearBlindOverride: () => seatAction(state.dealerSeatIndex, "Blinds follow the button again.", () => {
+            state.blindOverride = null;
+            if (Betting.onlyBlindsIn(state)) Betting.repostBlinds(state);
+        }),
+
        editSeat: index => Render.toggleSeatEditor(index),
+
+        addChips: index => AddChips.open(state, index, (seatIndex, amount) => {
+            seatAction(seatIndex, `${nameOf(seatIndex)} added ${Money.format(amount)}.`, player => {
+                // Chips in front and cash in are different questions — the stack moves
+                // every hand, what they've handed over only moves when they buy.
+                player.stack = Money.round(Betting.stackOf(state, player) + amount);
+                player.buyIns = Money.round((Number(player.buyIns) || 0) + amount);
+            });
+        }),
    };

    Render.mount(state, hooks);
@@ -95,7 +177,7 @@ document.addEventListener("DOMContentLoaded", () => {
        resolvePot: openPotWizard,

        beginAction: label => {
-            actionHistory.push({ label, snapshot: JSON.parse(JSON.stringify(state)) });
+            actionHistory.push({ label, snapshot: snapshotState() });
            if (actionHistory.length > MAX_UNDO_STEPS) actionHistory.shift();
        },

@@ -104,10 +186,7 @@ document.addEventListener("DOMContentLoaded", () => {
        undoLast: () => {
            const step = actionHistory.pop();
            if (!step) return;
-            Object.keys(state).forEach(key => delete state[key]);
-            Object.assign(state, step.snapshot);
-            hooks.save(state);
-            Render.renderAll();
+            restoreState(step.snapshot);
            Toast.show(`Took back ${step.label}.`, { duration: 2500 });
        },
    });
@@ -154,7 +233,7 @@ document.addEventListener("DOMContentLoaded", () => {
    // would notice a misclick. The snapshot is deliberately in-memory only: an
    // undo is for the mistake you just made, not one from last night's session.
    const runUndoable = (message, mutate) => {
-        const snapshot = JSON.parse(JSON.stringify(state));
+        const snapshot = snapshotState();
        mutate();
        // Starting or settling a hand invalidates the per-action history: those
        // snapshots describe a hand that's over. The whole-step Undo below replaces it.
@@ -165,19 +244,44 @@ document.addEventListener("DOMContentLoaded", () => {
        Toast.show(message, {
            actionLabel: "Undo",
            onAction: () => {
-                Object.keys(state).forEach(key => delete state[key]);
-                Object.assign(state, snapshot);
-                hooks.save(state);
-                Render.renderAll();
+                restoreState(snapshot);
                Toast.show("Undone.", { duration: 2500 });
            },
        });
    };

-    document.getElementById("seatCountInput").addEventListener("change", e => {
-        HoldemState.resizeSeats(state, Number(e.target.value));
-        hooks.save(state);
-        Render.renderAll();
+    // A seat that has anything of a player in it — a name, chips, cash in, or a hand
+    // in progress. Shrinking the table throws these away permanently, and it also
+    // orphans them in the session standings, where they keep their winnings but lose
+    // the stack and buy-in the settle-up is worked out from.
+    const seatHasSomeoneIn = player =>
+        !!(player.name && player.name.trim()) ||
+        player.inHand ||
+        (Number(player.stack) || 0) > 0 ||
+        (Number(player.buyIns) || 0) > 0 ||
+        (Number(player.amountOverride) || 0) > 0;
+
+    document.getElementById("seatCountInput").addEventListener("change", async e => {
+        const requested = Math.max(2, Math.min(24, Math.floor(Number(e.target.value)) || state.seatCount));
+        const losing = state.seats.slice(requested).filter(seatHasSomeoneIn);
+
+        if (losing.length > 0) {
+            const who = losing
+                .map((p, i) => HoldemState.displayName(p, requested + state.seats.slice(requested).indexOf(p)))
+                .join(", ");
+            const ok = await Dialog.confirm({
+                title: `Remove ${losing.length} ${losing.length === 1 ? "player" : "players"}?`,
+                message: `Going down to ${requested} seats takes ${who} off the table along with their chips and buy-ins, and their session totals stop adding up.`,
+                confirmLabel: "Remove them",
+                danger: true,
+            });
+            if (!ok) {
+                e.target.value = state.seatCount;
+                return;
+            }
+        }
+
+        runUndoable(`Table set to ${requested} seats.`, () => HoldemState.resizeSeats(state, requested));
    });

    document.getElementById("directionSelect").addEventListener("change", e => {
@@ -260,6 +364,24 @@ document.addEventListener("DOMContentLoaded", () => {

    document.getElementById("closeSeatEditorBtn").addEventListener("click", () => Render.closeSeatEditor());

+    document.getElementById("addChipsConfirmBtn").addEventListener("click", () => AddChips.confirm());
+    document.getElementById("addChipsCancelBtn").addEventListener("click", () => AddChips.close());
+    document.getElementById("addChipsOverlay").addEventListener("click", e => {
+        if (e.target.id === "addChipsOverlay") AddChips.close();
+    });
+    document.getElementById("addChipsInput").addEventListener("keydown", e => {
+        if (e.key === "Enter") AddChips.confirm();
+    });
+
+    // Escape is Modal's job now, for this sheet and the five others that never had it.
+    const rulingsOverlay = document.getElementById("rulingsOverlay");
+    const closeRulings = () => { rulingsOverlay.hidden = true; };
+    document.getElementById("openRulingsBtn").addEventListener("click", () => { rulingsOverlay.hidden = false; });
+    document.getElementById("closeRulingsBtn").addEventListener("click", closeRulings);
+    rulingsOverlay.addEventListener("click", e => {
+        if (e.target === rulingsOverlay) closeRulings();
+    });
+
    document.getElementById("seatMenuCancelBtn").addEventListener("click", () => SeatMenu.close());
    document.getElementById("seatMenuOverlay").addEventListener("click", e => {
        if (e.target.id === "seatMenuOverlay") SeatMenu.close();
@@ -0,0 +1,147 @@
+// Keyboard and screen-reader behaviour for every overlay in the tool, in one place.
+//
+// There are six of them — seat menu, card picker, add chips, rulings, pot wizard,
+// confirm — opened and closed by five different modules, and each one was missing
+// the same three things: focus never moved into the dialog, Tab walked straight out
+// of it into the page behind the scrim, and Escape did nothing (only the rulings
+// sheet handled it). Measured before this: 0 of 5 moved focus in, 5 of 5 leaked Tab,
+// 1 of 5 closed on Escape.
+//
+// Rather than patch that into five modules, this watches the `hidden` attribute every
+// overlay already toggles. Nothing else had to change, and an overlay added later
+// gets the same behaviour without anyone remembering to wire it up — which is the
+// failure this is fixing in the first place.
+const Modal = {
+    // `:not([hidden])` matters — a sheet that is itself hidden inside an open overlay
+    // must not be a Tab stop.
+    FOCUSABLE: [
+        "a[href]",
+        "button:not([disabled])",
+        'input:not([disabled]):not([type="hidden"])',
+        "select:not([disabled])",
+        "textarea:not([disabled])",
+        '[tabindex]:not([tabindex="-1"])',
+    ].join(","),
+
+    open: [],
+
+    mount() {
+        document.querySelectorAll('[id$="Overlay"]').forEach(overlay => this.watch(overlay));
+        // Capture phase: the dialog gets first refusal on Escape and Tab, before any
+        // table-level shortcut sees them.
+        document.addEventListener("keydown", e => this.onKeyDown(e), true);
+    },
+
+    watch(overlay) {
+        const sync = () => {
+            const isOpen = !overlay.hidden;
+            const known = this.open.some(entry => entry.overlay === overlay);
+            if (isOpen && !known) this.onOpened(overlay);
+            else if (!isOpen && known) this.onClosed(overlay);
+        };
+        new MutationObserver(sync).observe(overlay, { attributes: true, attributeFilter: ["hidden"] });
+        sync();
+    },
+
+    sheetOf(overlay) {
+        return overlay.querySelector('[role="dialog"], [role="alertdialog"]') || overlay.firstElementChild || overlay;
+    },
+
+    focusableIn(overlay) {
+        return [...overlay.querySelectorAll(this.FOCUSABLE)].filter(el => {
+            if (el.closest("[hidden]")) return false;
+            const rect = el.getBoundingClientRect();
+            return rect.width > 0 && rect.height > 0;
+        });
+    },
+
+    onOpened(overlay) {
+        const sheet = this.sheetOf(overlay);
+        // aria-modal is only true while the thing is actually open, so it's set here
+        // rather than baked into the markup.
+        if (sheet) sheet.setAttribute("aria-modal", "true");
+
+        this.open.push({ overlay, returnFocus: document.activeElement });
+
+        // Focus the first real control. A dialog that leaves focus on the button
+        // behind it reads, to a screen reader, as though nothing happened at all.
+        // Content-only sheets get focus on the sheet so the title is announced.
+        const focusable = this.focusableIn(overlay);
+        const target = focusable[0];
+        if (target) {
+            target.focus({ preventScroll: true });
+        } else if (sheet) {
+            if (!sheet.hasAttribute("tabindex")) sheet.setAttribute("tabindex", "-1");
+            sheet.focus({ preventScroll: true });
+        }
+    },
+
+    onClosed(overlay) {
+        const index = this.open.findIndex(entry => entry.overlay === overlay);
+        if (index === -1) return;
+        const [entry] = this.open.splice(index, 1);
+
+        const sheet = this.sheetOf(overlay);
+        if (sheet) sheet.removeAttribute("aria-modal");
+
+        // Put the dealer back where they were. Without this, closing the pot wizard
+        // drops focus to the top of the document and the next Tab starts from the
+        // page header.
+        const back = entry.returnFocus;
+        if (back && back.isConnected && typeof back.focus === "function") {
+            back.focus({ preventScroll: true });
+        }
+    },
+
+    topmost() {
+        return this.open.length ? this.open[this.open.length - 1] : null;
+    },
+
+    // Escape presses the dialog's own cancel/close button rather than just hiding the
+    // overlay, so whatever that button does — resolving the confirm promise, clearing
+    // the add-chips draft — still happens. Only if there isn't one does it hide the
+    // overlay directly.
+    dismiss(overlay) {
+        const closer = overlay.querySelector("[data-modal-close]");
+        if (closer) closer.click();
+        else overlay.hidden = true;
+    },
+
+    onKeyDown(event) {
+        const top = this.topmost();
+        if (!top) return;
+
+        if (event.key === "Escape") {
+            event.preventDefault();
+            event.stopPropagation();
+            this.dismiss(top.overlay);
+            return;
+        }
+
+        if (event.key !== "Tab") return;
+
+        // Keep Tab inside the dialog. Everything behind the scrim is unreachable by
+        // mouse, so letting the keyboard wander back there is a trap with no way out.
+        const focusable = this.focusableIn(top.overlay);
+        if (focusable.length === 0) {
+            event.preventDefault();
+            return;
+        }
+
+        const first = focusable[0];
+        const last = focusable[focusable.length - 1];
+        const active = document.activeElement;
+
+        if (event.shiftKey && (active === first || !top.overlay.contains(active))) {
+            event.preventDefault();
+            last.focus({ preventScroll: true });
+        } else if (!event.shiftKey && (active === last || !top.overlay.contains(active))) {
+            event.preventDefault();
+            first.focus({ preventScroll: true });
+        }
+    },
+};
+
+if (typeof module !== "undefined" && module.exports) {
+    module.exports = Modal;
+}
@@ -1,10 +1,51 @@
-// Shared money formatting for every casino surface. Kept apart from the table's
-// rendering so the quick-split calculator can pull in the formatter without dragging
-// the whole seat/chip UI along with it.
+// Shared money handling for every casino surface. Kept apart from the table's
+// rendering so the quick-split calculator can pull it in without dragging the whole
+// seat/chip UI along with it.
+//
+// Everything the dealer touches is money, and money is decimal, so every module used
+// to carry its own `Math.round(x * 100) / 100`. That's one rounding rule written out
+// sixteen times in six files, which is sixteen chances for one of them to drift.
+// It lives here now, and the modules that do arithmetic call these instead.
 const Money = {
+    // Half a cent. Chip comparisons need a tolerance: a stack that lands on
+    // 0.0000000001 after a split is empty as far as a dealer is concerned, and an
+    // exact `> 0` would treat that player as still having chips to bet.
+    EPSILON: 0.004,
+
+    // All money maths goes through cents, so 0.1 + 0.2 never reaches a payout.
+    toCents(amount) {
+        return Math.round((Number(amount) || 0) * 100);
+    },
+
+    fromCents(cents) {
+        return cents / 100;
+    },
+
+    round(amount) {
+        return this.toCents(amount) / 100;
+    },
+
+    // Cents only when there are cents.
+    //
+    // A chip game deals in whole numbers nearly all the time, and a trailing ".00"
+    // is two characters that say nothing — measured at ~22px, against the 64px a
+    // seat puck has to show a stack in. "$1,250,000.00" doesn't fit and wraps;
+    // "$1,250,000" does. Amounts that genuinely carry cents still show them, so a
+    // 25c-blind game reads exactly as it did.
    format(amount) {
        const value = Number(amount) || 0;
-        return `$${value.toLocaleString(undefined, { minimumFractionDigits: 2, maximumFractionDigits: 2 })}`;
+        const hasCents = this.toCents(value) % 100 !== 0;
+        return `$${value.toLocaleString(undefined, {
+            minimumFractionDigits: hasCents ? 2 : 0,
+            maximumFractionDigits: 2,
+        })}`;
+    },
+
+    // The same amount for a spreadsheet rather than for a person: no currency symbol
+    // and no thousands separators, because those are what make a column of money
+    // import as text and refuse to add up.
+    forSheet(amount) {
+        return (this.toCents(amount) / 100).toFixed(2);
    },

    // "+$40.00" / "-$40.00" rather than "$-40.00" — a standings column is read at a
@@ -4,7 +4,7 @@
 // A "contribution entry" is { id, remaining, folded }. `remaining` starts as the amount
 // that player put in the pot and is whittled down round by round as money gets paid out.
 const PotCalculator = {
-    EPSILON: 0.004,
+    EPSILON: Money.EPSILON,

    // Builds the initial entry list from raw contributions, keeping folded players in
    // (their chips are still "dead money" owed to whoever wins) while excluding anyone
@@ -33,24 +33,39 @@ const PotCalculator = {
    // to their own contribution, and only players who reached that height can win it.
    // Folded money stays in — it's dead money owed to whoever wins the layer it fell in.
    layers(players) {
-        const live = players.filter(p => p.contribution > this.EPSILON);
+        // Uncalled chips were never played for, so they come off the top before any
+        // pot is built. Deriving the pots from what's left is what keeps this function
+        // and uncalledReturns() from disagreeing about the same money — they used to
+        // decide "uncontested" separately, and an overbet that its own bettor was
+        // still live for got announced as a side pot only they could win.
+        const returned = new Map(this.uncalledReturns(players).map(r => [r.id, Money.toCents(r.amount)]));
+        const live = players
+            .map(p => ({ ...p, cents: Money.toCents(p.contribution) - (returned.get(p.id) || 0) }))
+            .filter(p => p.cents > 0);
        if (live.length === 0) return [];

-        const heights = [...new Set(live.map(p => Math.round(p.contribution * 100)))].sort((a, b) => a - b);
+        const heights = [...new Set(live.map(p => p.cents))].sort((a, b) => a - b);

        const layers = [];
        let floor = 0;
        heights.forEach(height => {
            const band = height - floor;
-            const payers = live.filter(p => Math.round(p.contribution * 100) >= height);
+            const payers = live.filter(p => p.cents >= height);
            const amount = band * payers.length;
            const eligible = payers.filter(p => !p.folded).map(p => p.id);

-            // A band nobody can win isn't a pot — it's an overbet that never got
-            // called, and it goes back to whoever put it in. Announcing it as a side
-            // pot would overstate what's actually being played for.
-            if (amount > 0 && eligible.length > 0) {
-                layers.push({ amount: amount / 100, eligible });
+            if (amount > 0) {
+                if (eligible.length > 0) {
+                    layers.push({ amount: Money.fromCents(amount), eligible });
+                } else if (layers.length > 0) {
+                    // Everyone who reached this height folded, so it isn't a pot of its
+                    // own — it's dead money owed to whoever wins the layer underneath.
+                    // Dropping it would quietly shrink the announced pot.
+                    const below = layers[layers.length - 1];
+                    below.amount = Money.round(below.amount + Money.fromCents(amount));
+                }
+                // With no layer underneath either, nobody in the hand is live at all.
+                // That's a fold flag the dealer needs to fix, not a payout to guess at.
            }
            floor = height;
        });
@@ -66,7 +81,7 @@ const PotCalculator = {
                previous.eligible.every(id => layer.eligible.includes(id));

            if (sameEligibility) {
-                previous.amount = Math.round((previous.amount + layer.amount) * 100) / 100;
+                previous.amount = Money.round(previous.amount + layer.amount);
            } else {
                merged.push({ ...layer });
            }
@@ -79,21 +94,28 @@ const PotCalculator = {
    },

    // Chips nobody could call, which the dealer pushes back rather than into the pot.
-    // Anything above the biggest live contribution was never contested — most often an
-    // overbet by someone who then folded.
+    //
+    // A bet is only called up to what somebody *else* was willing to put in, so the
+    // ceiling for each player is the largest contribution among everyone but them.
+    // Measuring against the whole table instead — including the bettor's own chips —
+    // makes the biggest bet its own yardstick, so the one case this exists for (you
+    // shove, a short stack calls for less) comes back empty.
    uncalledReturns(players) {
        const contributing = players.filter(p => p.contribution > this.EPSILON);
-        const liveCents = contributing.filter(p => !p.folded).map(p => Math.round(p.contribution * 100));

        // Nobody live at all means the fold flags are wrong, not that every chip on
        // the table was uncalled. That's a correction for the dealer to make, so say
        // nothing here and let the wizard ask them to fix it.
-        if (liveCents.length === 0) return [];
+        if (contributing.filter(p => !p.folded).length === 0) return [];

-        const cap = Math.max(...liveCents);
+        const cents = contributing.map(p => Money.toCents(p.contribution));

        return contributing
-            .map(p => ({ id: p.id, amount: (Math.round(p.contribution * 100) - cap) / 100 }))
+            .map((p, index) => {
+                const others = cents.filter((_, i) => i !== index);
+                const cap = others.length > 0 ? Math.max(...others) : 0;
+                return { id: p.id, amount: Money.fromCents(cents[index] - cap) };
+            })
            .filter(r => r.amount > this.EPSILON);
    },

@@ -113,12 +135,12 @@ const PotCalculator = {
            if (e.remaining <= this.EPSILON) return e;
            const used = Math.min(e.remaining, cap);
            payoutPool += used;
-            return { ...e, remaining: Math.round((e.remaining - used) * 100) / 100 };
+            return { ...e, remaining: Money.round(e.remaining - used) };
        });

-        payoutPool = Math.round(payoutPool * 100) / 100;
-        const baseShareCents = Math.floor((payoutPool * 100) / winners.length);
-        let leftoverCents = Math.round(payoutPool * 100) - baseShareCents * winners.length;
+        payoutPool = Money.round(payoutPool);
+        const baseShareCents = Math.floor(Money.toCents(payoutPool) / winners.length);
+        let leftoverCents = Money.toCents(payoutPool) - baseShareCents * winners.length;

        const perWinner = winnerIds
            .filter(id => winners.some(w => w.id === id))
@@ -133,7 +155,7 @@ const PotCalculator = {
            i++;
        }

-        const result = perWinner.map(w => ({ id: w.id, amount: w.amountCents / 100 }));
+        const result = perWinner.map(w => ({ id: w.id, amount: Money.fromCents(w.amountCents) }));
        const remainingContenders = this.getContenders(updatedEntries);

        return {
@@ -18,10 +18,22 @@ const PotWizard = {
        this.playerLabelById = new Map(
            players.map(p => [p.id, this.labelFor(p, state.seats.indexOf(p))])
        );
+        this.seatIndexById = new Map(players.map(p => [p.id, state.seats.indexOf(p)]));
+        // The label carries name and cards together for the log and the payout lines;
+        // the choice rows want them separately so each can be styled and read on its own.
+        this.nameById = new Map(
+            players.map(p => [p.id, HoldemState.displayName(p, state.seats.indexOf(p))])
+        );
+        this.cardsById = new Map(
+            players.map(p => [p.id, (p.cards || []).filter(Boolean)])
+        );
        const contributions = players.map(p => ({
            id: p.id,
            contribution: HoldemState.computeContribution(p, state.chipLegend, state.basePotAmount),
-            folded: p.folded,
+            // A seat switched off mid-hand still has its chips in the pot, but it
+            // can no more win them than a folded one can — same dead money, and the
+            // wizard must not offer it as a winner.
+            folded: p.folded || HoldemState.isDeadMoney(p),
        }));
        this.entries = PotCalculator.buildEntries(contributions);
        // Kept so the wizard can show the whole breakdown up front, not just the layer
@@ -49,6 +61,20 @@ const PotWizard = {
        this.totals.set(id, (this.totals.get(id) || 0) + amount);
    },

+    // A chopped pot rarely divides exactly, and the odd chip goes to the first player
+    // left of the button — not to whoever the dealer happened to tick first. The
+    // calculator hands leftovers out in the order it's given the winners, so ordering
+    // them here is what makes the payout match the rule.
+    orderFromButton(ids) {
+        const distance = new Map();
+        for (let step = 1; step <= this.state.seatCount; step++) {
+            distance.set(HoldemState.nextSeatIndex(this.state, this.state.dealerSeatIndex, step), step);
+        }
+        return [...ids].sort((a, b) =>
+            (distance.get(this.seatIndexById.get(a)) ?? 0) - (distance.get(this.seatIndexById.get(b)) ?? 0)
+        );
+    },
+
    renderStep() {
        // Auto-resolve any round where only one player is left standing — nothing to ask.
        let contenders = PotCalculator.getContenders(this.entries);
@@ -105,13 +131,46 @@ const PotWizard = {
        contenders.forEach(c => {
            const label = document.createElement("label");
            label.className = "potWizardChoice";
+
            const checkbox = document.createElement("input");
            checkbox.type = "checkbox";
            checkbox.value = c.id;
-            const text = document.createElement("span");
-            text.textContent = `${this.playerLabelById.get(c.id)} — up to ${Money.format(c.remaining)}`;
+            // The row is the target, not the box — so the row has to look chosen too.
+            checkbox.addEventListener("change", () => {
+                label.classList.toggle("chosen", checkbox.checked);
+            });
            label.appendChild(checkbox);
+
+            const text = document.createElement("span");
+            text.className = "potWizardChoiceText";
+
+            const name = document.createElement("span");
+            name.className = "potWizardChoiceName";
+            name.textContent = this.nameById.get(c.id);
+            text.appendChild(name);
+
+            const upTo = document.createElement("span");
+            upTo.className = "potWizardChoiceUpTo";
+            upTo.textContent = `up to ${Money.format(c.remaining)}`;
+            text.appendChild(upTo);
            label.appendChild(text);
+
+            // Cards sit apart from the name rather than inside it, so a dealer reading
+            // a row across the table sees the hand, not a sentence.
+            const cards = this.cardsById.get(c.id) || [];
+            if (cards.length > 0) {
+                const cardsEl = document.createElement("span");
+                cardsEl.className = "potWizardChoiceCards";
+                cards.forEach((card, i) => {
+                    if (i > 0) cardsEl.appendChild(document.createTextNode(" "));
+                    const span = document.createElement("span");
+                    if (/[HD]$/i.test(card)) span.className = "cardRed";
+                    span.textContent = Render.formatCard(card);
+                    cardsEl.appendChild(span);
+                });
+                label.appendChild(cardsEl);
+            }
+
            choices.appendChild(label);
        });
        round.appendChild(choices);
@@ -127,7 +186,7 @@ const PotWizard = {
        confirmBtn.addEventListener("click", () => {
            const selected = Array.from(choices.querySelectorAll("input:checked")).map(i => i.value);
            if (selected.length === 0) return;
-            const result = PotCalculator.resolveRound(this.entries, selected);
+            const result = PotCalculator.resolveRound(this.entries, this.orderFromButton(selected));
            this.recordRound(result);
            this.entries = result.updatedEntries;
            this.renderStep();
@@ -15,12 +15,28 @@ const QuickSplit = {
    ways: 2,
    chip: 1,

+    // "even" is the common case — one pot, everyone matched. "uneven" is the one this
+    // screen used to send people back to the full table for: somebody all-in for less,
+    // so the money splits into a main pot and side pots.
+    mode: "even",
+    entries: [],
+
    mount() {
        this.potInput = document.getElementById("potInput");
        this.clearPotBtn = document.getElementById("clearPotBtn");
+        this.entries = [{ amount: "", folded: false }, { amount: "", folded: false }, { amount: "", folded: false }];

        this.renderWayChoices();
        this.renderChipChoices();
+        this.renderUnevenRows();
+
+        document.getElementById("modeEvenBtn").addEventListener("click", () => this.setMode("even"));
+        document.getElementById("modeUnevenBtn").addEventListener("click", () => this.setMode("uneven"));
+        document.getElementById("addPlayerBtn").addEventListener("click", () => {
+            this.entries.push({ amount: "", folded: false });
+            this.renderUnevenRows();
+            this.update();
+        });

        this.potInput.addEventListener("input", () => {
            this.sanitizePotInput();
@@ -127,7 +143,112 @@ const QuickSplit = {
        });
    },

+    setMode(mode) {
+        this.mode = mode;
+        document.getElementById("modeEvenBtn").classList.toggle("selected", mode === "even");
+        document.getElementById("modeUnevenBtn").classList.toggle("selected", mode === "uneven");
+
+        document.querySelectorAll(".evenOnly").forEach(el => { el.hidden = mode !== "even"; });
+        document.querySelectorAll(".unevenOnly").forEach(el => { el.hidden = mode !== "uneven"; });
+        document.getElementById("splitResult").hidden = mode !== "even";
+        document.getElementById("unevenResult").hidden = mode !== "uneven";
+
+        this.update();
+    },
+
+    renderUnevenRows() {
+        const host = document.getElementById("unevenRows");
+        const template = document.getElementById("unevenRowTemplate");
+        host.innerHTML = "";
+
+        this.entries.forEach((entry, index) => {
+            const row = template.content.firstElementChild.cloneNode(true);
+            row.querySelector(".unevenRowLabel").textContent = `P${index + 1}`;
+
+            const amount = row.querySelector(".unevenAmount");
+            amount.value = entry.amount;
+            amount.setAttribute("aria-label", `Player ${index + 1} amount`);
+            amount.addEventListener("input", () => {
+                entry.amount = amount.value.replace(/[^0-9.]/g, "").replace(/(\..*)\./g, "$1");
+                if (entry.amount !== amount.value) amount.value = entry.amount;
+                this.update();
+            });
+
+            // Folded money stays in the pot as dead money, but its owner can't win any
+            // of it — which is exactly the distinction that makes side pots tricky.
+            const fold = row.querySelector(".unevenFoldBtn");
+            fold.classList.toggle("selected", entry.folded);
+            fold.setAttribute("aria-pressed", String(entry.folded));
+            fold.addEventListener("click", () => {
+                entry.folded = !entry.folded;
+                this.renderUnevenRows();
+                this.update();
+            });
+
+            const remove = row.querySelector(".unevenRemoveBtn");
+            remove.disabled = this.entries.length <= 2;
+            remove.addEventListener("click", () => {
+                this.entries.splice(index, 1);
+                this.renderUnevenRows();
+                this.update();
+            });
+
+            host.appendChild(row);
+        });
+    },
+
+    updateUneven() {
+        const players = this.entries
+            .map((entry, index) => ({ id: `P${index + 1}`, contribution: Number(entry.amount) || 0, folded: entry.folded }))
+            .filter(p => p.contribution > 0);
+
+        const pots = PotCalculator.layers(players);
+        const returns = PotCalculator.uncalledReturns(players);
+
+        const host = document.getElementById("unevenPots");
+        const empty = document.getElementById("unevenEmpty");
+        host.innerHTML = "";
+
+        if (pots.length === 0 && returns.length === 0) {
+            empty.hidden = false;
+            empty.textContent = players.length === 0
+                ? "Enter what each player put in."
+                : "Nobody left who can win — un-fold whoever should take it.";
+            return;
+        }
+        empty.hidden = true;
+
+        const addRow = (label, amount, who, className) => {
+            const row = document.createElement("div");
+            row.className = `unevenPot ${className || ""}`;
+            const name = document.createElement("span");
+            name.className = "unevenPotLabel";
+            name.textContent = label;
+            const value = document.createElement("span");
+            value.className = "unevenPotAmount";
+            value.textContent = Money.format(amount);
+            const eligible = document.createElement("span");
+            eligible.className = "unevenPotWho";
+            eligible.textContent = who;
+            row.appendChild(name);
+            row.appendChild(value);
+            row.appendChild(eligible);
+            host.appendChild(row);
+        };
+
+        pots.forEach(pot => addRow(pot.label, pot.amount, pot.eligible.join(", ")));
+        returns.forEach(ret => addRow("Uncalled", ret.amount, `back to ${ret.id}`, "unevenPotReturn"));
+
+        const total = players.reduce((sum, p) => sum + p.contribution, 0);
+        addRow("On the table", Money.round(total), "", "unevenPotTotal");
+    },
+
    update() {
+        if (this.mode === "uneven") {
+            this.updateUneven();
+            return;
+        }
+
        const potValue = Number(this.potInput.value);
        const pot = Number.isNaN(potValue) ? 0 : potValue;
        this.clearPotBtn.hidden = this.potInput.value === "";
@@ -16,6 +16,10 @@ const Render = {
        this.state = state;
        this.hooks = hooks;
        this.selectedSeatIndex = null;
+        // A reset hands over a different table entirely, so nothing cached about the
+        // last one still applies.
+        this.lastHistorySignature = null;
+        this.handTimeCache.clear();
        this.renderAll();
    },

@@ -69,13 +73,85 @@ const Render = {
    // ---- Seats around the table (compact pucks) ----

    seatPosition(index, count) {
+        return this.positionOnRing(index, count, 44, 42);
+    },
+
+    // Bets sit on the felt between their player and the pot, the way chips actually
+    // do — closer in than the seats, on the same spoke. The bets layer is inset to
+    // match the seat ring (see the CSS), so this one radius holds at every size.
+    betPosition(index, count) {
+        return this.positionOnRing(index, count, 27, 25);
+    },
+
+    positionOnRing(index, count, rx, ry) {
        const angle = -90 + (360 / count) * index;
        const radians = (angle * Math.PI) / 180;
-        const rx = 44;
-        const ry = 42;
-        const left = 50 + rx * Math.cos(radians);
-        const top = 50 + ry * Math.sin(radians);
-        return { left, top };
+        return {
+            left: 50 + rx * Math.cos(radians),
+            top: 50 + ry * Math.sin(radians),
+        };
+    },
+
+    // Colour a bet by the biggest chip that fits it, so a table with a chip legend
+    // gets bets that look like the chips actually being pushed out.
+    chipColorFor(amount) {
+        const legend = [...(this.state.chipLegend || [])]
+            .filter(chip => Number(chip.value) > 0)
+            .sort((a, b) => Number(b.value) - Number(a.value));
+        const match = legend.find(chip => amount >= Number(chip.value));
+        return (match || legend[legend.length - 1] || {}).color || "#8a8a8a";
+    },
+
+    // ---- Bets on the felt ----
+
+    makeBetChip(bet) {
+        const chip = document.createElement("div");
+        chip.className = "betChip";
+
+        const disc = document.createElement("span");
+        disc.className = "betChipDisc";
+        disc.style.background = this.chipColorFor(bet);
+
+        const amount = document.createElement("span");
+        amount.className = "betChipAmount";
+        amount.textContent = Money.format(bet);
+
+        chip.appendChild(disc);
+        chip.appendChild(amount);
+        return chip;
+    },
+
+    // A phone's felt has no room for a third ring: measured every radius between the
+    // seats and the pot badge and each one collides with one or the other. So on a
+    // narrow screen the bet clings to its own puck instead — same chip, no ring —
+    // sitting on whichever side faces the middle of the table.
+    renderBets() {
+        const layer = document.getElementById("betsLayer");
+        if (!layer) return;
+        layer.innerHTML = "";
+
+        const anchorToSeat = window.matchMedia("(max-width: 700px)").matches;
+
+        this.state.seats.forEach((player, index) => {
+            const bet = Betting.committed(player);
+            if (bet <= 0) return;
+
+            const chip = this.makeBetChip(bet);
+            const pos = this.betPosition(index, this.state.seatCount);
+
+            if (anchorToSeat) {
+                const seat = document.querySelector(`.seat[data-seat-index="${index}"]`);
+                if (!seat) return;
+                const seatPos = this.seatPosition(index, this.state.seatCount);
+                chip.classList.add("betChipAnchored", seatPos.top > 50 ? "betChipAbove" : "betChipBelow");
+                seat.appendChild(chip);
+                return;
+            }
+
+            chip.style.left = `${pos.left}%`;
+            chip.style.top = `${pos.top}%`;
+            layer.appendChild(chip);
+        });
    },

    puckLabel(player, seatIndex) {
@@ -86,7 +162,7 @@ const Render = {
        const layer = document.getElementById("seatsLayer");
        layer.innerHTML = "";
        const template = document.getElementById("seatTemplate");
-        const { dealerIndex, sbIndex, bbIndex } = HoldemState.getBlindSeats(this.state);
+        const { dealerIndex, sbIndex, bbIndex, manual: manualBlinds } = HoldemState.getBlindSeats(this.state);

        this.state.seats.forEach((player, index) => {
            const node = template.content.firstElementChild.cloneNode(true);
@@ -100,15 +176,26 @@ const Render = {
            const dealerChip = node.querySelector(".dealerChip");
            dealerChip.classList.toggle("active", index === dealerIndex);
            dealerChip.classList.toggle("hidden", !!this.state.dedicatedDealer);
+            // Tapping the puck is the same act as "Give the button" in the seat menu,
+            // so it goes through the same hook — otherwise this one path would move
+            // the button without moving the blinds that follow it.
            dealerChip.addEventListener("click", e => {
                e.stopPropagation();
-                this.state.dealerSeatIndex = index;
-                this.hooks.save(this.state);
-                this.renderSeats();
+                this.hooks.onGiveButton(index);
            });

-            node.querySelector(".sbBadge").classList.toggle("visible", index === sbIndex);
-            node.querySelector(".bbBadge").classList.toggle("visible", index === bbIndex);
+            const sbBadge = node.querySelector(".sbBadge");
+            const bbBadge = node.querySelector(".bbBadge");
+            sbBadge.classList.toggle("visible", index === sbIndex);
+            bbBadge.classList.toggle("visible", index === bbIndex);
+            // A blind the dealer named by hand isn't where the button would have put
+            // it, so it's marked — otherwise the table looks like it's just wrong.
+            // The `!!` matters: getBlindSeats leaves `manual` undefined when the
+            // blinds are positional, and classList.toggle with an undefined second
+            // argument *flips* the class instead of clearing it, so the marker
+            // appeared and disappeared on alternate renders.
+            sbBadge.classList.toggle("blindManual", !!manualBlinds && index === sbIndex);
+            bbBadge.classList.toggle("blindManual", !!manualBlinds && index === bbIndex);

            this.updatePuckContent(node, player, index);
            node.classList.toggle("seatSelected", index === this.selectedSeatIndex);
@@ -118,6 +205,8 @@ const Render = {

            layer.appendChild(node);
        });
+
+        this.renderBets();
    },

    isRedSuit(card) {
@@ -168,17 +257,22 @@ const Render = {
            span.textContent = this.formatCard(card);
            cardsEl.appendChild(span);
        });
-        // What's in front of them this street reads as the live number during betting;
-        // between hands it falls back to their total for the hand.
-        const streetBet = Betting.committed(player);
-        const total = streetBet > 0
-            ? streetBet
+        // Always this player's total for the hand. What they've just pushed out on this
+        // street is shown as a chip on the felt instead — the puck used to flip between
+        // the two meanings depending on the moment, which is a bad thing for a number
+        // sitting next to a stack size to do.
+        const handTotal = Betting.handTotal(player);
+        const total = handTotal > 0
+            ? handTotal
            : HoldemState.computeContribution(player, this.state.chipLegend, this.state.basePotAmount);
-        node.querySelector(".seatPuckTotal").textContent = total > 0 ? Money.format(total) : "";
+        const totalEl = node.querySelector(".seatPuckTotal");
+        totalEl.textContent = total > 0 ? Money.format(total) : "";
+        this.fitAmount(totalEl);

        const stackEl = node.querySelector(".seatPuckStack");
        const stack = Betting.stackOf(this.state, player);
        stackEl.textContent = !empty && stack > 0 ? Money.format(stack) : "";
+        this.fitAmount(stackEl);

        node.classList.toggle("seatActing", index === this.state.actingSeatIndex);
        node.classList.toggle("seatEmpty", empty);
@@ -187,6 +281,17 @@ const Render = {
        node.classList.toggle("seatLive", player.inHand && !player.folded);
    },

+    // A seat puck is 64px of usable width. A tournament stack doesn't fit in that and,
+    // because the number has no spaces to break on, it doesn't wrap or ellipsise
+    // either — it just draws straight out over the neighbouring seat. Stepping the
+    // font down keeps every digit, which matters: a dealer misreading a stack is a
+    // worse outcome than a small one, so this shrinks rather than abbreviating.
+    fitAmount(el) {
+        const length = (el.textContent || "").length;
+        el.classList.toggle("puckAmountLong", length >= 8 && length < 10);
+        el.classList.toggle("puckAmountHuge", length >= 10);
+    },
+
    // Cheaper than a full renderSeats() — used after edits so the seat editor's inputs
    // (which live in a separate panel) never lose focus.
    refreshPuck(index) {
@@ -415,6 +520,13 @@ const Render = {
            });
        });

+        // What they've handed over tonight, shown next to what's in front of them so a
+        // cash-out is one subtraction rather than a memory test.
+        const boughtIn = Number(player.buyIns) || 0;
+        const boughtInEl = form.querySelector(".seatBuyIns");
+        boughtInEl.textContent = boughtIn > 0 ? `Bought in ${Money.format(boughtIn)}` : "";
+        boughtInEl.hidden = boughtIn <= 0;
+
        const stackInput = form.querySelector(".stackInput");
        stackInput.value = player.stack ?? "";
        stackInput.addEventListener("input", () => {
@@ -595,24 +707,57 @@ const Render = {

    // ---- Hand counter + history ----

+    // toLocaleTimeString is the single most expensive call in the history panel, and a
+    // logged hand's timestamp never changes, so the answer is worth keeping.
+    handTimeCache: new Map(),
+
    formatHandTime(timestamp) {
+        if (this.handTimeCache.has(timestamp)) return this.handTimeCache.get(timestamp);
+        let formatted = "";
        try {
-            return new Date(timestamp).toLocaleTimeString(undefined, { hour: "2-digit", minute: "2-digit" });
+            formatted = new Date(timestamp).toLocaleTimeString(undefined, { hour: "2-digit", minute: "2-digit" });
        } catch {
-            return "";
+            formatted = "";
        }
+        this.handTimeCache.set(timestamp, formatted);
+        return formatted;
    },

-    renderHandHistory() {
+    // Cheap stand-in for "has the log changed". Entries are immutable once written and
+    // only ever added at the front, so the length, the counter and the newest row
+    // between them catch a recorded hand, a cleared history and an undo.
+    historySignature() {
+        const history = this.state.handHistory || [];
+        const newest = history[0];
+        return [
+            history.length,
+            this.state.handNumber || 1,
+            newest ? newest.handNumber : "",
+            newest ? newest.timestamp : "",
+            newest ? newest.pot : "",
+        ].join("|");
+    },
+
+    // Rebuilding this panel measured 25.7ms of the 30ms a full re-render costs — and a
+    // full re-render runs after every fold, call and raise. The log only changes when a
+    // hand is settled or the history is cleared, perhaps once every thirty taps, so it
+    // is skipped unless it actually did change. Everything else on the table reflects
+    // the current hand and still redraws every time.
+    renderHandHistory(force = false) {
+        const signature = this.historySignature();
+        if (!force && signature === this.lastHistorySignature) return;
+        this.lastHistorySignature = signature;
+
        document.getElementById("handCounterBadge").textContent = `Hand #${this.state.handNumber || 1}`;

        const list = document.getElementById("handHistoryList");
        const emptyHint = document.getElementById("handHistoryEmptyHint");
        const history = this.state.handHistory || [];
-        list.innerHTML = "";
        emptyHint.hidden = history.length > 0;
        document.getElementById("exportHistoryBtn").disabled = history.length === 0;

+        // Built off-document so the panel is laid out once instead of once per row.
+        const fragment = document.createDocumentFragment();
        const template = document.getElementById("handHistoryRowTemplate");
        history.forEach(entry => {
            const row = template.content.firstElementChild.cloneNode(true);
@@ -623,8 +768,10 @@ const Render = {
            const payoutsEl = row.querySelector(".handHistoryPayouts");
            payoutsEl.textContent = entry.payouts.map(p => `${p.label} ${Money.format(p.amount)}`).join(", ");

-            list.appendChild(row);
+            fragment.appendChild(row);
        });
+        list.innerHTML = "";
+        list.appendChild(fragment);
    },
 };

@@ -32,6 +32,10 @@ const SeatMenu = {
            actions.push({ label: "Un-fold", run: () => this.hooks.unfold(index) });
        }

+        // The most common interruption in a cash game, and until now it meant opening
+        // the editor and retyping a stack from memory.
+        actions.push({ label: "Add chips…", run: () => this.hooks.addChips(index) });
+
        actions.push({
            label: dealtIn ? "Sit out" : "Deal in",
            run: () => this.hooks.toggleDealtIn(index),
@@ -41,6 +45,24 @@ const SeatMenu = {
            actions.push({ label: "Give the button", run: () => this.hooks.makeDealer(index) });
        }

+        // Naming a blind by hand. Only offered while nothing but the blinds are in —
+        // once somebody has called, moving a blind would mean unpicking a bet that
+        // has already been answered, and that's a decision for the dealer's mouth,
+        // not a menu item. Which blind a seat already has is shown rather than
+        // offered again.
+        if (dealtIn && Betting.onlyBlindsIn(this.state)) {
+            const blinds = HoldemState.getBlindSeats(this.state);
+            if (blinds.sbIndex !== index) {
+                actions.push({ label: "Make small blind", run: () => this.hooks.assignBlind(index, "sb") });
+            }
+            if (blinds.bbIndex !== index) {
+                actions.push({ label: "Make big blind", run: () => this.hooks.assignBlind(index, "bb") });
+            }
+            if (this.state.blindOverride) {
+                actions.push({ label: "Blinds follow the button again", run: () => this.hooks.clearBlindOverride() });
+            }
+        }
+
        actions.push({ label: "Edit seat…", run: () => this.hooks.editSeat(index) });
        return actions;
    },
@@ -32,14 +32,12 @@ const Shortcuts = {
        return tag === "INPUT" || tag === "TEXTAREA" || tag === "SELECT" || el.isContentEditable;
    },

-    // An overlay owns the keyboard while it's up: the confirm dialog already binds
-    // Enter and Escape, and the card picker and seat menu are modal.
+    // An overlay owns the keyboard while it's up. Asking the document which overlays
+    // are open, rather than listing them, means a sheet added later can't quietly
+    // start letting "f" fold the table behind it — the same reason Modal watches for
+    // them instead of being told about each one.
    overlayOpen() {
-        return ["confirmOverlay", "potWizardOverlay", "cardPickerOverlay", "seatMenuOverlay"]
-            .some(id => {
-                const el = document.getElementById(id);
-                return el && !el.hidden;
-            });
+        return [...document.querySelectorAll('[id$="Overlay"]')].some(el => !el.hidden);
    },

    onKey(e) {
@@ -7,7 +7,7 @@
 const SplitCalculator = {
    // Everything is done in cents to keep 0.1 + 0.2 out of a payout.
    toCents(amount) {
-        return Math.round((Number(amount) || 0) * 100);
+        return Money.toCents(amount);
    },

    split(potAmount, ways, chipAmount) {
@@ -40,11 +40,11 @@ const SplitCalculator = {

    // Sanity check for the UI: what the split actually hands out has to equal the pot.
    accountedFor(result) {
-        return (
-            Math.round(result.each * 100) * result.players +
-            Math.round(result.chip * 100) * result.oddChips +
-            Math.round(result.dust * 100)
-        ) / 100;
+        return Money.fromCents(
+            Money.toCents(result.each) * result.players +
+            Money.toCents(result.chip) * result.oddChips +
+            Money.toCents(result.dust)
+        );
    },
 };

@@ -31,6 +31,8 @@ const HoldemState = {
            stack: null,
            committed: 0,
            hasActed: false,
+            // Cash handed over tonight, which only moves when they buy chips.
+            buyIns: 0,
        };
    },

@@ -56,6 +58,12 @@ const HoldemState = {
            currentBet: 0,
            lastRaiseSize: 0,
            actingSeatIndex: null,
+            // Set when the dealer names the blinds by hand instead of letting them
+            // follow the button — { sbIndex, bbIndex }. Home games do this constantly
+            // ("you had it last time", someone arriving late owing a blind), and the
+            // button order is the wrong answer often enough that it has to be
+            // overridable. Cleared at the start of every hand.
+            blindOverride: null,
        };
    },

@@ -71,7 +79,8 @@ const HoldemState = {
            // Tables saved before live betting existed are missing its fields; fill
            // them in rather than making the dealer reset a table mid-session.
            const defaults = this.createDefault();
-            ["smallBlind", "bigBlind", "defaultStack", "street", "currentBet", "lastRaiseSize", "actingSeatIndex"]
+            ["smallBlind", "bigBlind", "defaultStack", "street", "currentBet", "lastRaiseSize",
+                "actingSeatIndex", "blindOverride"]
                .forEach(key => {
                    if (parsed[key] === undefined) parsed[key] = defaults[key];
                });
@@ -79,6 +88,7 @@ const HoldemState = {
                if (player.stack === undefined) player.stack = null;
                if (player.committed === undefined) player.committed = 0;
                if (player.hasActed === undefined) player.hasActed = false;
+                if (player.buyIns === undefined) player.buyIns = 0;
            });

            return parsed;
@@ -121,9 +131,14 @@ const HoldemState = {
    },

    // Contribution the table calculator will treat this player as having put in.
+    //
+    // Chips already pushed into the middle count whether or not the player is still
+    // in the hand. Someone who storms off, gets taken out by the dealer, or is
+    // dealt out mid-hand leaves their money on the felt — it's dead money owed to
+    // whoever wins, and it is not theirs to take back. Reading `inHand` first is
+    // how those chips used to disappear out of the pot the instant a seat was
+    // switched off, quietly shrinking the payout by whatever they had posted.
    computeContribution(player, chipLegend, basePotAmount) {
-        if (!player.inHand) return 0;
-
        const override = player.amountOverride;
        if (override !== null && override !== undefined && String(override).trim() !== "") {
            const parsed = Number(override);
@@ -136,10 +151,22 @@ const HoldemState = {
        }, 0);
        if (chipTotal > 0) return chipTotal;

+        // The table-wide default is the one thing that stays tied to being dealt in:
+        // it's a stand-in for "everyone put the same amount in", so applying it to
+        // empty chairs would invent a contribution from every seat nobody is using.
+        if (!player.inHand) return 0;
+
        const base = Number(basePotAmount);
        return Number.isNaN(base) ? 0 : Math.max(0, base);
    },

+    // Anyone whose chips are in the pot, whether or not they're still in the hand.
+    // A seat that's been switched off mid-hand is dead money: it counts towards the
+    // pot but can never be picked as a winner, exactly like a fold.
+    isDeadMoney(player) {
+        return !player.inHand;
+    },
+
    totalPot(state) {
        return state.seats.reduce(
            (sum, p) => sum + this.computeContribution(p, state.chipLegend, state.basePotAmount),
@@ -156,18 +183,101 @@ const HoldemState = {
        return ((fromIndex + delta) % count + count) % count;
    },

+    // The button passes to the next player, not the next chair. Moving it one seat at
+    // a time parks it on empty chairs — with four players spread around ten seats it
+    // sits on nobody most hands — and that isn't only untidy: position and blinds are
+    // supposed to come round to each player at the same rate, and they don't if the
+    // button is rotating past chairs nobody is sitting in.
    advanceButton(state) {
+        for (let step = 1; step <= state.seatCount; step++) {
+            const index = this.nextSeatIndex(state, state.dealerSeatIndex, step);
+            if (state.seats[index].inHand) {
+                state.dealerSeatIndex = index;
+                return;
+            }
+        }
+        // Nobody is dealt in; move it along anyway so it doesn't look stuck.
        state.dealerSeatIndex = this.nextSeatIndex(state, state.dealerSeatIndex, 1);
    },

+    // Seats dealt into this hand, in blind order starting from the seat after the
+    // button. Blinds follow the players, not the chairs — the seats immediately left
+    // of the button are empty often enough that counting chairs posts them to nobody.
+    liveOrderFromButton(state) {
+        const order = [];
+        for (let step = 1; step <= state.seatCount; step++) {
+            const index = this.nextSeatIndex(state, state.dealerSeatIndex, step);
+            if (state.seats[index].inHand) order.push(index);
+        }
+        return order;
+    },
+
+    // A button sitting on an empty chair is only cosmetic until you try to read
+    // position off it. On the very first hand of a fresh table it starts on seat 1
+    // whether or not anybody is sitting there, and a table that empties out around it
+    // leaves it stranded. Move it to a real player before a hand is dealt.
+    ensureButtonOnPlayer(state) {
+        if (state.seats[state.dealerSeatIndex] && state.seats[state.dealerSeatIndex].inHand) return;
+        for (let step = 0; step < state.seatCount; step++) {
+            const index = this.nextSeatIndex(state, state.dealerSeatIndex, step);
+            if (state.seats[index].inHand) {
+                state.dealerSeatIndex = index;
+                return;
+            }
+        }
+    },
+
+    // A hand-picked blind is only usable if that seat is actually in the hand — a
+    // dealer who names a blind and then deals that player out shouldn't have the
+    // table quietly post to nobody.
+    validBlindOverride(state) {
+        const o = state.blindOverride;
+        if (!o) return null;
+        const ok = i => Number.isInteger(i) && i >= 0 && i < state.seatCount && state.seats[i] && state.seats[i].inHand;
+        if (!ok(o.sbIndex) || !ok(o.bbIndex) || o.sbIndex === o.bbIndex) return null;
+        return o;
+    },
+
+    // Who posts what. Heads-up is its own rule: with two players the button posts the
+    // small blind, which is the opposite of the usual order.
    getBlindSeats(state) {
-        const sbIndex = this.nextSeatIndex(state, state.dealerSeatIndex, 1);
-        const bbIndex = this.nextSeatIndex(state, state.dealerSeatIndex, 2);
-        return { dealerIndex: state.dealerSeatIndex, sbIndex, bbIndex };
+        const live = this.liveOrderFromButton(state);
+        const dealerIndex = state.dealerSeatIndex;
+
+        // A blind the dealer named by hand wins over anything positional. Heads-up is
+        // still reported honestly so the betting order stays right — who posts what
+        // is the dealer's call, but two-handed play acting in reverse is a rule.
+        const override = this.validBlindOverride(state);
+        if (override) {
+            return {
+                dealerIndex,
+                sbIndex: override.sbIndex,
+                bbIndex: override.bbIndex,
+                headsUp: live.length === 2,
+                manual: true,
+            };
+        }
+
+        if (live.length < 2) {
+            return { dealerIndex, sbIndex: null, bbIndex: null, headsUp: false };
+        }
+
+        if (live.length === 2) {
+            const buttonIsPlaying = state.seats[dealerIndex].inHand;
+            const sbIndex = buttonIsPlaying ? dealerIndex : live[0];
+            const bbIndex = live.find(i => i !== sbIndex);
+            return { dealerIndex, sbIndex, bbIndex, headsUp: true };
+        }
+
+        return { dealerIndex, sbIndex: live[0], bbIndex: live[1], headsUp: false };
    },

    startNextHand(state) {
        this.advanceButton(state);
+        // A hand-picked blind applies to the hand it was picked for. Carrying it into
+        // the next one would freeze the blinds on two players for the rest of the
+        // night, which is the opposite of what naming them once is for.
+        state.blindOverride = null;
        state.seats.forEach(p => {
            p.folded = false;
            p.cards = ["", ""];
@@ -176,6 +286,8 @@ const HoldemState = {
            p.committed = 0;
            p.hasActed = false;
        });
+        // Anyone who joined mid-hand is a full player again from here.
+        this.ensureButtonOnPlayer(state);
    },

    // Appends a resolved-pot record to the running session log a dealer can point to
@@ -236,13 +348,32 @@ const HoldemState = {
            });
        });

+        // Cash bought in and chips currently in front don't come from the hand log at
+        // all, so they're read off the seat rather than summed — a rebuy isn't a hand.
+        const seatById = new Map(state.seats.map(p => [p.id, p]));
+
        return Array.from(totals.values())
-            .map(t => ({
-                ...t,
-                in: Math.round(t.in * 100) / 100,
-                won: Math.round(t.won * 100) / 100,
-                net: Math.round((t.won - t.in) * 100) / 100,
-            }))
+            .map(t => {
+                const seat = seatById.get(t.id);
+                const boughtIn = seat ? Money.round(Number(seat.buyIns) || 0) : 0;
+                const chipsNow = seat ? Money.round(Number(seat.stack) || 0) : 0;
+                // Chips already pushed into the hand in progress are still this
+                // player's money until it's won. Leaving them out makes the cash
+                // position disagree with the hand log for as long as a hand is open —
+                // and blinds are posted the instant the previous one settles, so that
+                // window is almost always.
+                const inFrontOfThem = seat ? (Number(seat.amountOverride) || 0) + (Number(seat.committed) || 0) : 0;
+
+                return {
+                    ...t,
+                    in: Money.round(t.in),
+                    won: Money.round(t.won),
+                    net: Money.round(t.won - t.in),
+                    boughtIn,
+                    chipsNow,
+                    cashPosition: Money.round(chipsNow + inFrontOfThem - boughtIn),
+                };
+            })
            .sort((a, b) => b.net - a.net);
    },
 };
@@ -0,0 +1,43 @@
+# Hold'em dealer tests
+
+Unit tests for the money logic behind `/Casino/TexasHoldem` — the betting engine, the
+side-pot calculator, the split calculator and the table state.
+
+```bash
+node --test tests/holdem/*.test.js
+```
+
+No install step, no `package.json`, no dependencies. The browser modules are plain
+script-tag files that each end with a `module.exports` guard, so Node can require them
+as-is; `load.js` puts them on `globalThis` under the same names they use to find each
+other in the page, in the load order from `TexasHoldem.cshtml`.
+
+## What's covered
+
+| File | Covers |
+| --- | --- |
+| `potCalculator.test.js` | Main and side pots, dead money, uncalled bets, odd-cent distribution |
+| `betting.test.js` | Blinds, street completion, raises reopening the action, all-in run-outs |
+| `state.test.js` | Button rotation, which seats post blinds, session standings |
+| `splitCalculator.test.js` | Chopped pots, odd chips, unmakeable denominations |
+| `invariants.test.js` | 1000 randomised hands per property (see below) |
+
+## Why the randomised suite exists
+
+Every correctness bug found in this tool so far has been shape-dependent: blinds posted
+to empty chairs, the button skipping past players, heads-up acting out of order, an
+overbet announced as a side pot. None of them show up on a full six-handed table with
+equal stacks, which is the table anyone writes a fixed example for.
+
+`invariants.test.js` deals a thousand hands across random seat counts, random empty
+chairs, random stack depths and random dealer input, and checks the things a dealer
+would notice being wrong:
+
+- chips are never created or destroyed during play
+- the pot breakdown plus the uncalled returns always equal the money that went in
+- paying the pot out settles it to the cent
+- once uncalled chips are handed back, nobody is still betting above the whole table
+- the button and both blinds always land on players who are actually in the hand
+
+The generator is seeded, so a failure reproduces from the seed printed in the message
+rather than being a flake to re-run.
@@ -0,0 +1,198 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Betting, makeTable, chipsOnTable } = require("./load");
+
+describe("Betting.beginHand", () => {
+    test("blinds are posted and the seat after the big blind acts first", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0, smallBlind: 1, bigBlind: 2 });
+        Betting.beginHand(state);
+
+        assert.equal(state.seats[1].committed, 1, "small blind");
+        assert.equal(state.seats[2].committed, 2, "big blind");
+        assert.equal(state.currentBet, 2);
+        assert.equal(state.actingSeatIndex, 3, "under the gun");
+    });
+
+    test("heads-up, the button posts the small blind and acts first pre-flop", () => {
+        const state = makeTable({ seatCount: 6, seated: [2, 5], dealerSeatIndex: 2 });
+        Betting.beginHand(state);
+
+        assert.equal(state.seats[2].committed, 1, "the button is the small blind");
+        assert.equal(state.seats[5].committed, 2);
+        assert.equal(state.actingSeatIndex, 2, "the small blind acts first pre-flop heads-up");
+    });
+
+    test("heads-up, the big blind acts first once the flop is out", () => {
+        const state = makeTable({ seatCount: 6, seated: [2, 5], dealerSeatIndex: 2 });
+        Betting.beginHand(state);
+        Betting.call(state, 2);
+        Betting.check(state, 5);
+        Betting.closeStreet(state);
+
+        assert.equal(state.street, "flop");
+        assert.equal(state.actingSeatIndex, 5, "the big blind is first to act after the flop");
+    });
+
+    test("a blind bigger than a stack puts that player all-in without stalling the action", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1], dealerSeatIndex: 0, smallBlind: 50, bigBlind: 100 });
+        state.seats[0].stack = 10; // can't cover the small blind
+
+        Betting.beginHand(state);
+        assert.equal(state.seats[0].stack, 0, "all-in for what they had");
+        assert.equal(state.seats[0].committed, 10);
+        assert.notEqual(state.actingSeatIndex, 0, "a player with no chips has nothing to decide");
+    });
+
+    test("posting blinds never invents or destroys chips", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], stack: 100 });
+        const before = chipsOnTable(state);
+        Betting.beginHand(state);
+        assert.equal(chipsOnTable(state), before);
+    });
+});
+
+describe("Betting street completion", () => {
+    test("a street ends once everyone has matched the bet and had a turn", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+
+        Betting.call(state, 3);
+        Betting.call(state, 0);
+        Betting.call(state, 1);
+        assert.equal(Betting.isStreetComplete(state), false, "the big blind still has an option");
+
+        Betting.check(state, 2);
+        assert.equal(Betting.isStreetComplete(state), true);
+        assert.equal(state.actingSeatIndex, null);
+    });
+
+    test("a raise reopens the action for everyone who had already called", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+
+        Betting.call(state, 3);
+        Betting.call(state, 0);
+        assert.equal(state.seats[3].hasActed, true);
+
+        Betting.raiseTo(state, 1, 10);
+        assert.equal(state.seats[3].hasActed, false, "seat 3 owes a response again");
+        assert.equal(state.seats[0].hasActed, false);
+        assert.equal(state.currentBet, 10);
+        assert.equal(Betting.isStreetComplete(state), false);
+    });
+
+    test("the action skips a player who is all-in but still in the hand", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        state.seats[3].stack = 5;
+        Betting.beginHand(state);
+
+        Betting.allIn(state, 3);
+        assert.equal(state.seats[3].stack, 0);
+        assert.notEqual(state.actingSeatIndex, 3);
+        // They are still live and can still win the pot.
+        assert.ok(Betting.liveSeats(state).some(s => s.index === 3));
+    });
+
+    test("closing a street sweeps chips into hand totals and resets the bet", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.call(state, 3);
+        Betting.call(state, 0);
+        Betting.call(state, 1);
+        Betting.check(state, 2);
+
+        const before = chipsOnTable(state);
+        Betting.closeStreet(state);
+
+        assert.equal(state.currentBet, 0);
+        assert.equal(state.street, "flop");
+        assert.equal(chipsOnTable(state), before, "sweeping moves chips, it doesn't change the total");
+        state.seats.forEach(p => assert.equal(p.committed, 0));
+        assert.equal(Betting.handTotal(state.seats[2]), 2);
+    });
+});
+
+describe("Betting all-in run-outs", () => {
+    test("with everyone all-in there is nobody left to ask", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], stack: 20, dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.allIn(state, 2);
+        Betting.allIn(state, 0);
+        Betting.allIn(state, 1);
+
+        assert.equal(Betting.canStillBet(state), false);
+        assert.equal(Betting.isRunningOut(state), true, "the board just gets dealt out");
+
+        Betting.closeStreet(state);
+        assert.equal(state.actingSeatIndex, null, "no phantom action on the flop");
+    });
+
+    test("one player with chips against an all-in cannot bet alone", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        state.seats[1].stack = 5;
+        Betting.beginHand(state);
+        Betting.fold(state, 2);
+        Betting.allIn(state, 0);
+        Betting.allIn(state, 1);
+
+        assert.equal(Betting.canStillBet(state), false);
+        assert.equal(Betting.isHandOver(state), false, "two players are still live for the showdown");
+    });
+
+    test("everyone folding to one player ends the hand", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.fold(state, 3);
+        Betting.fold(state, 0);
+        Betting.fold(state, 1);
+
+        assert.equal(Betting.isHandOver(state), true);
+    });
+});
+
+describe("Betting money handling", () => {
+    test("a player can never put in more than they have", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], stack: 30, dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        const moved = Betting.putIn(state, 0, 500);
+        assert.equal(moved, 30);
+        assert.equal(state.seats[0].stack, 0);
+    });
+
+    test("raise-to is what a dealer says out loud, not raise-by", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.raiseTo(state, 3, 10);
+        assert.equal(state.seats[3].committed, 10, "their street total is 10, not 10 on top");
+        assert.equal(state.seats[3].stack, 90);
+    });
+
+    test("the minimum raise has to match the last one", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        assert.equal(Betting.minRaiseTo(state), 4, "a big blind of 2 makes the first raise 4");
+
+        Betting.raiseTo(state, 3, 10);
+        assert.equal(Betting.minRaiseTo(state), 18, "an 8-chip raise means the next one is to 18");
+    });
+
+    test("winnings land back in front of the player", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.creditWinnings(state, [{ id: state.seats[0].id, amount: 42.5 }]);
+        assert.equal(state.seats[0].stack, 142.5, "the button posts nothing three-handed");
+    });
+
+    test("fractional blinds don't drift into floating-point dust", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], stack: 10, smallBlind: 0.1, bigBlind: 0.2 });
+        Betting.beginHand(state);
+        Betting.call(state, 0); // button limps
+        Betting.call(state, 1); // small blind completes
+        Betting.check(state, 2); // big blind is happy
+        Betting.closeStreet(state);
+
+        assert.equal(chipsOnTable(state), 30, "0.1 + 0.2 arithmetic didn't lose a chip");
+        assert.equal(Betting.potSoFar(state), 0.6);
+        state.seats.forEach(p => assert.equal(p.stack, 9.8));
+    });
+});
@@ -0,0 +1,118 @@
+// The hand-history panel is only rebuilt when its signature changes, which takes a
+// full re-render from ~30ms to ~3ms. The whole saving depends on that signature
+// noticing every way the log can actually change — a stale panel would have the
+// dealer reading last hand's payouts while settling this one.
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Render, HoldemState, makeTable } = require("./load");
+
+// historySignature() reads Render.state, so point it at a table for each case.
+const signatureOf = state => {
+    Render.state = state;
+    return Render.historySignature();
+};
+
+const tableWithHands = (count) => {
+    const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+    for (let i = 0; i < count; i++) {
+        state.seats[0].amountOverride = 2;
+        state.seats[1].amountOverride = 2;
+        HoldemState.recordHand(state, [{ id: state.seats[0].id, label: "Ann", amount: 4 }]);
+    }
+    return state;
+};
+
+describe("the history panel knows when to redraw", () => {
+    test("nothing changes while a hand is being played", () => {
+        const state = tableWithHands(3);
+        const before = signatureOf(state);
+
+        // A whole street of betting touches no part of the log.
+        state.seats[0].committed = 5;
+        state.seats[1].folded = true;
+        state.actingSeatIndex = 2;
+        state.street = "flop";
+
+        assert.equal(signatureOf(state), before, "betting must not force a rebuild");
+    });
+
+    test("settling a hand changes it", () => {
+        const state = tableWithHands(3);
+        const before = signatureOf(state);
+        HoldemState.recordHand(state, [{ id: state.seats[1].id, label: "Ben", amount: 12 }]);
+        assert.notEqual(signatureOf(state), before);
+    });
+
+    test("clearing the history changes it", () => {
+        const state = tableWithHands(5);
+        const before = signatureOf(state);
+        HoldemState.clearHistory(state);
+        assert.notEqual(signatureOf(state), before);
+    });
+
+    test("undoing back to a shorter log changes it", () => {
+        const state = tableWithHands(2);
+        const snapshot = JSON.parse(JSON.stringify(state));
+        HoldemState.recordHand(state, [{ id: state.seats[0].id, label: "Ann", amount: 30 }]);
+        const afterRecord = signatureOf(state);
+
+        // The undo path swaps the state's contents in place.
+        Object.keys(state).forEach(k => delete state[k]);
+        Object.assign(state, snapshot);
+
+        assert.notEqual(signatureOf(state), afterRecord, "an undone hand must disappear from the panel");
+    });
+
+    test("two hands that differ only in payout are told apart", () => {
+        const a = tableWithHands(1);
+        const b = tableWithHands(1);
+        // Same count and hand number; different pot.
+        b.handHistory[0].pot = a.handHistory[0].pot + 25;
+        assert.notEqual(signatureOf(a), signatureOf(b));
+    });
+
+    test("the hand counter moving on changes it", () => {
+        // The counter badge is drawn by the same function, so a new hand number has
+        // to invalidate even when the log itself is untouched.
+        const state = tableWithHands(2);
+        const before = signatureOf(state);
+        state.handNumber += 1;
+        assert.notEqual(signatureOf(state), before);
+    });
+
+    test("an empty log has a stable signature of its own", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1] });
+        const first = signatureOf(state);
+        assert.equal(signatureOf(state), first);
+
+        HoldemState.recordHand(state, [{ id: state.seats[0].id, label: "Ann", amount: 4 }]);
+        assert.notEqual(signatureOf(state), first, "the first hand ever must draw the panel");
+    });
+});
+
+describe("the hand-time cache", () => {
+    test("the same timestamp is only formatted once, and formats the same", () => {
+        Render.handTimeCache.clear();
+        const stamp = Date.UTC(2026, 8, 1, 15, 4);
+        const first = Render.formatHandTime(stamp);
+        assert.equal(Render.handTimeCache.size, 1);
+
+        const second = Render.formatHandTime(stamp);
+        assert.equal(second, first);
+        assert.equal(Render.handTimeCache.size, 1, "not re-formatted");
+    });
+
+    test("different timestamps still format differently", () => {
+        Render.handTimeCache.clear();
+        const a = Render.formatHandTime(Date.UTC(2026, 8, 1, 15, 4));
+        const b = Render.formatHandTime(Date.UTC(2026, 8, 1, 18, 47));
+        assert.notEqual(a, b);
+        assert.equal(Render.handTimeCache.size, 2);
+    });
+
+    test("a nonsense timestamp doesn't throw", () => {
+        Render.handTimeCache.clear();
+        assert.doesNotThrow(() => Render.formatHandTime(undefined));
+        assert.doesNotThrow(() => Render.formatHandTime("not a date"));
+    });
+});
@@ -0,0 +1,213 @@
+// Randomised whole-hand play against the invariants a dealer would notice being broken.
+//
+// These ran once, by hand, in a browser console while the betting engine was being
+// fixed, and then went away with the tab. The bugs they caught (blinds posted to empty
+// chairs, the button skipping players, heads-up acting out of order) are all cases you
+// only hit on a particular table shape, so a fixed set of examples misses them. Keeping
+// the generator means the next change gets checked against the same thousand tables.
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Betting, PotCalculator, HoldemState, Money, makeTable, chipsOnTable, contributions } = require("./load");
+
+// Deterministic PRNG: a failure has to be reproducible from the seed printed with it,
+// otherwise a randomised suite is just a flaky one.
+function rng(seed) {
+    let s = seed >>> 0;
+    return () => {
+        s = (s * 1664525 + 1013904223) >>> 0;
+        return s / 4294967296;
+    };
+}
+
+// Plays one hand to completion with random but legal-ish dealer input.
+function playHand(random) {
+    const seatCount = 2 + Math.floor(random() * 9);
+    const seatIndexes = [...Array(seatCount).keys()];
+    const seated = seatIndexes.filter(() => random() < 0.7);
+    if (seated.length < 2) seated.push(...seatIndexes.filter(i => !seated.includes(i)).slice(0, 2 - seated.length));
+
+    const bigBlind = [2, 5, 0.5][Math.floor(random() * 3)];
+    const state = makeTable({
+        seatCount,
+        seated,
+        stack: 0,
+        smallBlind: bigBlind / 2,
+        bigBlind,
+        dealerSeatIndex: Math.floor(random() * seatCount),
+    });
+
+    // Varied stack depths, so short stacks and side pots actually happen.
+    seated.forEach(i => {
+        state.seats[i].stack = Money.round(bigBlind * (1 + Math.floor(random() * 60)));
+    });
+
+    const startingChips = chipsOnTable(state);
+    Betting.beginHand(state);
+
+    let guard = 0;
+    while (!Betting.isHandOver(state) && state.street !== "done" && guard++ < 400) {
+        if (state.actingSeatIndex === null) {
+            if (state.street === "river" || !Betting.canStillBet(state)) break;
+            Betting.closeStreet(state);
+            continue;
+        }
+
+        const index = state.actingSeatIndex;
+        const player = state.seats[index];
+        const toCall = Betting.toCall(state, player);
+        const roll = random();
+
+        if (roll < 0.15) Betting.fold(state, index);
+        else if (roll < 0.25) Betting.allIn(state, index);
+        else if (toCall > 0) Betting.call(state, index);
+        else if (roll < 0.75) Betting.check(state, index);
+        else Betting.raiseTo(state, index, Betting.minRaiseTo(state));
+    }
+
+    Betting.sweepToHandTotals(state);
+    return { state, startingChips, seated };
+}
+
+describe("randomised hands hold the dealer's invariants", () => {
+    const HANDS = 1000;
+
+    test(`${HANDS} hands never create or destroy a chip`, () => {
+        const random = rng(20260901);
+        for (let hand = 0; hand < HANDS; hand++) {
+            const { state, startingChips } = playHand(random);
+            assert.equal(
+                chipsOnTable(state),
+                startingChips,
+                `hand ${hand}: chips on the table changed during play`
+            );
+        }
+    });
+
+    test(`${HANDS} hands: pots plus uncalled returns always equal the money in`, () => {
+        const random = rng(778899);
+        let sidePotHands = 0;
+        let returnHands = 0;
+
+        for (let hand = 0; hand < HANDS; hand++) {
+            const { state } = playHand(random);
+            const players = contributions(state);
+            const inThePot = players.reduce((sum, p) => sum + p.contribution, 0);
+            if (inThePot <= 0) continue;
+
+            // Fold flags can leave nobody live, which the calculator deliberately
+            // refuses to guess at — that's a dealer correction, not an invariant.
+            if (players.every(p => p.folded)) continue;
+
+            const layered = PotCalculator.layers(players).reduce((s, l) => s + l.amount, 0);
+            const returned = PotCalculator.uncalledReturns(players).reduce((s, r) => s + r.amount, 0);
+
+            assert.equal(
+                Money.toCents(layered + returned),
+                Money.toCents(inThePot),
+                `hand ${hand}: pot breakdown doesn't add up to what went in`
+            );
+
+            if (PotCalculator.layers(players).length > 1) sidePotHands++;
+            if (returned > 0) returnHands++;
+        }
+
+        assert.ok(sidePotHands > 20, `expected side pots to occur; saw ${sidePotHands}`);
+        assert.ok(returnHands > 20, `expected uncalled bets to occur; saw ${returnHands}`);
+    });
+
+    test(`${HANDS} hands: what's left after returns is money somebody actually matched`, () => {
+        // The rule the pot breakdown rests on: you are only called up to what somebody
+        // else was willing to put in. Once the uncalled chips are handed back, no
+        // player should still be sitting above every other player at the table.
+        //
+        // A single-eligible pot is *not* the thing to look for here — that's legitimate
+        // when a player called and then folded, leaving dead money one contender
+        // collects. The bug this guards against is subtler: chips nobody ever matched
+        // being dressed up as a pot to play for.
+        const random = rng(13579);
+        for (let hand = 0; hand < HANDS; hand++) {
+            const { state } = playHand(random);
+            const players = contributions(state);
+            if (players.every(p => p.folded)) continue;
+
+            const returns = PotCalculator.uncalledReturns(players);
+            assert.ok(returns.length <= 1, `hand ${hand}: only the biggest bet can go uncalled`);
+
+            returns.forEach(r => {
+                const player = players.find(p => p.id === r.id);
+                assert.ok(r.amount <= player.contribution + 0.001, `hand ${hand}: returned more than was put in`);
+            });
+
+            const returned = new Map(returns.map(r => [r.id, r.amount]));
+            const capped = players.map(p => Money.toCents(p.contribution - (returned.get(p.id) || 0)));
+
+            capped.forEach((cents, index) => {
+                const others = capped.filter((_, i) => i !== index);
+                const mostAnyoneElsePaid = others.length ? Math.max(...others) : 0;
+                assert.ok(
+                    cents <= mostAnyoneElsePaid,
+                    `hand ${hand}: a player is still ${Money.fromCents(cents - mostAnyoneElsePaid)} ` +
+                    `above everyone else after returns — that money was never matched`
+                );
+            });
+        }
+    });
+
+    test(`${HANDS} hands: paying the pot out settles it exactly`, () => {
+        const random = rng(24680);
+        for (let hand = 0; hand < HANDS; hand++) {
+            const { state } = playHand(random);
+            const players = contributions(state);
+            if (players.every(p => p.folded)) continue;
+
+            // Take the uncalled money off first, the way the dealer would.
+            const returned = new Map(PotCalculator.uncalledReturns(players).map(r => [r.id, r.amount]));
+            const contested = players.map(p => ({
+                ...p,
+                contribution: Money.round(p.contribution - (returned.get(p.id) || 0)),
+            }));
+
+            let entries = PotCalculator.buildEntries(contested);
+            const potBefore = PotCalculator.totalPot(entries);
+            let paidOut = 0;
+            let rounds = 0;
+
+            while (PotCalculator.getContenders(entries).length > 0 && rounds++ < 30) {
+                const contenders = PotCalculator.getContenders(entries);
+                const winner = contenders[Math.floor(random() * contenders.length)];
+                const result = PotCalculator.resolveRound(entries, [winner.id]);
+                paidOut += result.perWinner.reduce((s, w) => s + w.amount, 0);
+                entries = result.updatedEntries;
+            }
+
+            assert.equal(
+                Money.toCents(paidOut),
+                Money.toCents(potBefore),
+                `hand ${hand}: paying out the pot left ${potBefore - paidOut} unaccounted for`
+            );
+        }
+    });
+
+    test(`${HANDS} hands: the button and blinds land on real players`, () => {
+        const random = rng(112233);
+        for (let hand = 0; hand < HANDS; hand++) {
+            const seatCount = 2 + Math.floor(random() * 9);
+            const seated = [...Array(seatCount).keys()].filter(() => random() < 0.6);
+            if (seated.length < 2) continue;
+
+            const state = makeTable({ seatCount, seated, dealerSeatIndex: Math.floor(random() * seatCount) });
+            HoldemState.advanceButton(state);
+            assert.ok(state.seats[state.dealerSeatIndex].inHand, `hand ${hand}: button on an empty chair`);
+
+            const { sbIndex, bbIndex, headsUp } = HoldemState.getBlindSeats(state);
+            assert.ok(state.seats[sbIndex].inHand, `hand ${hand}: small blind on an empty chair`);
+            assert.ok(state.seats[bbIndex].inHand, `hand ${hand}: big blind on an empty chair`);
+            assert.notEqual(sbIndex, bbIndex, `hand ${hand}: both blinds on one player`);
+
+            if (seated.length === 2) {
+                assert.ok(headsUp, `hand ${hand}: two players should be heads-up`);
+                assert.equal(sbIndex, state.dealerSeatIndex, `hand ${hand}: heads-up button posts the small blind`);
+            }
+        }
+    });
+});
@@ -0,0 +1,85 @@
+// Loads the dealer's browser modules into Node so they can be tested directly.
+//
+// The modules are plain script-tag files: each one declares a `const` namespace and
+// ends with a `module.exports` guard. In the browser they find each other as globals,
+// so the same names have to exist on `globalThis` here or `Betting` can't reach
+// `HoldemState`. Load order matches the <script> order in TexasHoldem.cshtml.
+const path = require("path");
+
+const SRC = path.join(__dirname, "..", "..", "JoshHeaps.Net", "wwwroot", "js", "casino", "holdem");
+
+function load(name) {
+    const mod = require(path.join(SRC, `${name}.js`));
+    globalThis[name.charAt(0).toUpperCase() + name.slice(1)] = mod;
+    return mod;
+}
+
+const Money = load("money");
+const PotCalculator = load("potCalculator");
+const SplitCalculator = load("splitCalculator");
+const Betting = load("betting");
+const HandHistoryExport = load("handHistoryExport");
+
+// render.js exports { Render } rather than the namespace directly.
+const Render = require(path.join(SRC, "render.js")).Render;
+globalThis.Render = Render;
+
+// state.js exports `HoldemState`, which doesn't match its filename.
+const HoldemState = require(path.join(SRC, "state.js"));
+globalThis.HoldemState = HoldemState;
+
+// ---- Table builders ----------------------------------------------------------
+
+// A table with `seatCount` chairs where `seated` (a list of seat indexes) are dealt
+// in with `stack` chips each. Everything else is the app's own defaults, so a test
+// that forgets to set a field gets whatever a real dealer would get.
+function makeTable({ seatCount = 6, seated = null, stack = 100, smallBlind = 1, bigBlind = 2, dealerSeatIndex = 0 } = {}) {
+    const state = HoldemState.createDefault();
+    HoldemState.resizeSeats(state, seatCount);
+    state.smallBlind = smallBlind;
+    state.bigBlind = bigBlind;
+    state.dealerSeatIndex = dealerSeatIndex;
+
+    const sitting = seated || state.seats.map((_, i) => i);
+    state.seats.forEach((player, index) => {
+        player.inHand = sitting.includes(index);
+        player.stack = sitting.includes(index) ? stack : null;
+        player.name = `P${index + 1}`;
+    });
+    return state;
+}
+
+// Total chips the table is accountable for: what's in front of everyone, plus what
+// they've pushed in this street, plus what's already banked into the pot.
+function chipsOnTable(state) {
+    return Money.round(
+        state.seats.reduce(
+            (sum, p) => sum + (Number(p.stack) || 0) + (Number(p.committed) || 0) + (Number(p.amountOverride) || 0),
+            0
+        )
+    );
+}
+
+// Contributions in the shape PotCalculator wants them.
+function contributions(state) {
+    return state.seats
+        .filter(p => p.inHand)
+        .map(p => ({
+            id: p.id,
+            contribution: Betting.handTotal(p),
+            folded: p.folded,
+        }));
+}
+
+module.exports = {
+    Money,
+    Render,
+    HandHistoryExport,
+    PotCalculator,
+    SplitCalculator,
+    Betting,
+    HoldemState,
+    makeTable,
+    chipsOnTable,
+    contributions,
+};
@@ -0,0 +1,260 @@
+// Home games are messy. People walk up mid-hand, storm off mid-hand, argue about
+// whose blind it is, and pass the button round three times before anyone deals.
+// These are the cases the positional rules quietly get wrong.
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Betting, HoldemState, PotCalculator, Money, makeTable, chipsOnTable, contributions } = require("./load");
+
+const potOf = state => HoldemState.totalPot(state);
+
+describe("a player leaves in the middle of a hand", () => {
+    test("their chips stay in the pot", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.call(state, 3); Betting.call(state, 0); Betting.call(state, 1); Betting.check(state, 2);
+        Betting.sweepToHandTotals(state);
+
+        const before = potOf(state);
+        assert.equal(before, 8);
+
+        state.seats[1].inHand = false; // dealer takes them out
+
+        assert.equal(potOf(state), before, "the pot must not shrink when a player is taken out");
+    });
+
+    test("they cannot be paid out of a pot they walked away from", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.call(state, 0); Betting.call(state, 1); Betting.check(state, 2);
+        Betting.sweepToHandTotals(state);
+
+        state.seats[1].inHand = false;
+
+        const players = state.seats
+            .filter(p => HoldemState.computeContribution(p, state.chipLegend, state.basePotAmount) > 0)
+            .map(p => ({
+                id: p.id,
+                contribution: HoldemState.computeContribution(p, state.chipLegend, state.basePotAmount),
+                folded: p.folded || HoldemState.isDeadMoney(p),
+            }));
+
+        const layers = PotCalculator.layers(players);
+        assert.ok(!layers[0].eligible.includes(state.seats[1].id), "a departed player can't win");
+        assert.equal(layers.reduce((s, l) => s + l.amount, 0), 6, "but their money is still being played for");
+    });
+
+    test("taking out the player who is to act moves the action on", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        const acting = state.actingSeatIndex;
+
+        state.seats[acting].inHand = false;
+        Betting.passAction(state, acting);
+
+        assert.notEqual(state.actingSeatIndex, acting, "the table can't wait on somebody who left");
+        assert.ok(state.actingSeatIndex === null || state.seats[state.actingSeatIndex].inHand);
+    });
+
+    test("an empty chair still contributes nothing, base pot or not", () => {
+        // The table-wide default must not be read as an ante from seats nobody is in.
+        const state = makeTable({ seatCount: 6, seated: [0, 1], dealerSeatIndex: 0 });
+        state.basePotAmount = 25;
+        assert.equal(HoldemState.computeContribution(state.seats[4], state.chipLegend, 25), 0);
+    });
+});
+
+describe("a player joins in the middle of a hand", () => {
+    test("they sit the hand out rather than joining a pot they never paid into", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        Betting.call(state, 0); Betting.call(state, 1); Betting.check(state, 2);
+        Betting.sweepToHandTotals(state);
+
+        // Walks up and is dealt in — the app marks them folded for this hand.
+        state.seats[4].inHand = true;
+        state.seats[4].stack = 100;
+        state.seats[4].folded = true;
+
+        assert.ok(!Betting.liveSeats(state).some(s => s.index === 4), "not live this hand");
+        assert.equal(HoldemState.computeContribution(state.seats[4], state.chipLegend, state.basePotAmount), 0);
+    });
+
+    test("they are a full player again on the next hand", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        state.seats[4].inHand = true;
+        state.seats[4].stack = 100;
+        state.seats[4].folded = true;
+
+        HoldemState.startNextHand(state);
+        Betting.beginHand(state);
+
+        assert.equal(state.seats[4].folded, false);
+        assert.ok(Betting.liveSeats(state).some(s => s.index === 4), "dealt in like anyone else");
+    });
+});
+
+describe("passing the button around before the cards come out", () => {
+    test("moving the button re-posts the blinds and keeps the chip count straight", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        const startingChips = chipsOnTable(state);
+        Betting.beginHand(state);
+
+        assert.equal(state.seats[1].committed, 1);
+        assert.equal(state.seats[2].committed, 2);
+
+        state.dealerSeatIndex = 2;
+        Betting.repostBlinds(state);
+
+        assert.equal(state.seats[1].committed, 0, "the old small blind got their chip back");
+        assert.equal(state.seats[3].committed, 1, "and the new one has posted");
+        assert.equal(state.seats[0].committed, 2);
+        assert.equal(chipsOnTable(state), startingChips, "no chips created or lost in the shuffle");
+    });
+
+    test("passing it round many times still balances", () => {
+        const state = makeTable({ seatCount: 8, seated: [0, 2, 3, 5, 7], dealerSeatIndex: 0 });
+        const startingChips = chipsOnTable(state);
+        Betting.beginHand(state);
+
+        [2, 5, 7, 3, 0, 5].forEach(seat => {
+            state.dealerSeatIndex = seat;
+            Betting.repostBlinds(state);
+            assert.equal(chipsOnTable(state), startingChips, `chips drifted after passing to seat ${seat}`);
+        });
+
+        const { sbIndex, bbIndex } = HoldemState.getBlindSeats(state);
+        assert.equal(Betting.committed(state.seats[sbIndex]), 1);
+        assert.equal(Betting.committed(state.seats[bbIndex]), 2);
+    });
+
+    test("once somebody has acted, the blinds are settled", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        Betting.beginHand(state);
+        assert.equal(Betting.onlyBlindsIn(state), true, "nothing but blinds so far");
+
+        Betting.call(state, 3);
+        assert.equal(Betting.onlyBlindsIn(state), false, "a call means the blinds are set where they are");
+    });
+});
+
+describe("naming the blinds by hand", () => {
+    test("a named blind wins over the button order", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        state.blindOverride = { sbIndex: 3, bbIndex: 0 };
+
+        const { sbIndex, bbIndex, manual } = HoldemState.getBlindSeats(state);
+        assert.equal(sbIndex, 3);
+        assert.equal(bbIndex, 0);
+        assert.equal(manual, true);
+
+        Betting.beginHand(state);
+        assert.equal(state.seats[3].committed, 1);
+        assert.equal(state.seats[0].committed, 2);
+        assert.equal(state.seats[1].committed, 0, "the positional small blind posts nothing");
+    });
+
+    test("a named blind on a player who isn't dealt in is ignored", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        state.blindOverride = { sbIndex: 4, bbIndex: 0 }; // seat 4 is an empty chair
+
+        const { sbIndex, manual } = HoldemState.getBlindSeats(state);
+        assert.ok(!manual, "falls back to the button order rather than posting to nobody");
+        assert.ok(state.seats[sbIndex].inHand);
+    });
+
+    test("both blinds on one player is refused", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2], dealerSeatIndex: 0 });
+        state.blindOverride = { sbIndex: 1, bbIndex: 1 };
+        const { sbIndex, bbIndex } = HoldemState.getBlindSeats(state);
+        assert.notEqual(sbIndex, bbIndex);
+    });
+
+    test("naming blinds heads-up still acts in the right order", () => {
+        const state = makeTable({ seatCount: 6, seated: [2, 5], dealerSeatIndex: 2 });
+        state.blindOverride = { sbIndex: 5, bbIndex: 2 }; // deliberately the reverse
+
+        Betting.beginHand(state);
+        assert.equal(state.seats[5].committed, 1);
+        assert.equal(state.seats[2].committed, 2);
+        assert.equal(state.actingSeatIndex, 5, "the small blind acts first pre-flop heads-up");
+
+        Betting.call(state, 5);
+        Betting.check(state, 2);
+        Betting.closeStreet(state);
+        assert.equal(state.actingSeatIndex, 2, "and the big blind leads after the flop");
+    });
+
+    test("the naming only lasts the hand it was made for", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        state.blindOverride = { sbIndex: 3, bbIndex: 0 };
+        Betting.beginHand(state);
+
+        HoldemState.startNextHand(state);
+        assert.equal(state.blindOverride, null, "blinds go back to following the button");
+    });
+});
+
+describe("the first hand on a fresh table", () => {
+    test("the button never starts on an empty chair", () => {
+        const state = HoldemState.createDefault();
+        HoldemState.resizeSeats(state, 9);
+        [4, 6, 7].forEach(i => { state.seats[i].inHand = true; state.seats[i].stack = 100; });
+        assert.equal(state.dealerSeatIndex, 0, "a fresh table starts the button on seat 1");
+        assert.equal(state.seats[0].inHand, false, "which nobody is sitting in");
+
+        Betting.beginHand(state);
+
+        assert.ok(state.seats[state.dealerSeatIndex].inHand, "the button moved to a real player");
+        const { sbIndex, bbIndex } = HoldemState.getBlindSeats(state);
+        assert.ok(state.seats[sbIndex].inHand);
+        assert.ok(state.seats[bbIndex].inHand);
+        assert.notEqual(sbIndex, bbIndex);
+    });
+
+    test("a table that empties out around the button recovers", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 3 });
+        state.seats[3].inHand = false; // the player holding the button leaves
+        HoldemState.ensureButtonOnPlayer(state);
+        assert.ok(state.seats[state.dealerSeatIndex].inHand);
+    });
+
+    test("two players left after everyone else walks is heads-up, blinds reversed", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], dealerSeatIndex: 0 });
+        [2, 3].forEach(i => { state.seats[i].inHand = false; });
+
+        HoldemState.startNextHand(state);
+        Betting.beginHand(state);
+
+        const { sbIndex, headsUp } = HoldemState.getBlindSeats(state);
+        assert.equal(headsUp, true);
+        assert.equal(sbIndex, state.dealerSeatIndex, "heads-up the button posts the small blind");
+    });
+});
+
+describe("chips survive a messy table", () => {
+    test("joining, leaving and passing the button never changes the chip count", () => {
+        const state = makeTable({ seatCount: 8, seated: [0, 1, 2, 3], stack: 100, dealerSeatIndex: 0 });
+        state.seats[6].stack = 100; // sitting down but not dealt in yet
+        const startingChips = chipsOnTable(state);
+
+        Betting.beginHand(state);
+        state.dealerSeatIndex = 2;
+        Betting.repostBlinds(state);
+
+        state.seats[6].inHand = true;   // walks up mid-hand
+        state.seats[6].folded = true;
+        assert.equal(chipsOnTable(state), startingChips);
+
+        Betting.call(state, state.actingSeatIndex);
+        state.seats[1].inHand = false;  // and someone storms off
+        Betting.sweepToHandTotals(state);
+
+        assert.equal(chipsOnTable(state), startingChips, "every chip is still accounted for");
+        assert.equal(
+            Money.toCents(potOf(state) + state.seats.reduce((s, p) => s + (Number(p.stack) || 0), 0)),
+            Money.toCents(startingChips),
+            "and the pot plus the stacks is the whole table"
+        );
+    });
+});
@@ -0,0 +1,126 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Money, HandHistoryExport } = require("./load");
+
+describe("Money.format", () => {
+    test("whole amounts drop the pointless cents", () => {
+        assert.equal(Money.format(12), "$12");
+        assert.equal(Money.format(450), "$450");
+        assert.equal(Money.format(1250000), "$1,250,000");
+        assert.equal(Money.format(0), "$0");
+    });
+
+    test("amounts that carry cents still show them", () => {
+        assert.equal(Money.format(12.5), "$12.50");
+        assert.equal(Money.format(0.25), "$0.25");
+        assert.equal(Money.format(3.01), "$3.01");
+    });
+
+    test("a quarter-blind game reads exactly as it did", () => {
+        // The case that would be ruined by dropping cents unconditionally.
+        [0.25, 0.5, 1.75, 12.05].forEach(v => {
+            assert.match(Money.format(v), /\.\d\d$/, `${v} lost its cents`);
+        });
+    });
+
+    test("floating-point dust doesn't invent cents", () => {
+        assert.equal(Money.format(0.1 + 0.2), "$0.30");
+        assert.equal(Money.format(1.0000000001), "$1");
+    });
+
+    test("signed amounts put the sign out front, both scales", () => {
+        assert.equal(Money.formatSigned(87500), "+$87,500");
+        assert.equal(Money.formatSigned(-87500), "-$87,500");
+        assert.equal(Money.formatSigned(-12.5), "-$12.50");
+        assert.equal(Money.formatSigned(0), "$0");
+    });
+
+    test("rubbish in doesn't produce rubbish out", () => {
+        assert.equal(Money.format(null), "$0");
+        assert.equal(Money.format(undefined), "$0");
+        assert.equal(Money.format("nonsense"), "$0");
+    });
+});
+
+describe("Money.forSheet", () => {
+    test("a bare number a spreadsheet will add up", () => {
+        assert.equal(Money.forSheet(1250000), "1250000.00");
+        assert.equal(Money.forSheet(12.5), "12.50");
+        assert.equal(Money.forSheet(-87500), "-87500.00");
+    });
+
+    test("no currency symbol and no thousands separators", () => {
+        const written = Money.forSheet(1234567.89);
+        assert.ok(!written.includes("$"), "a $ makes the cell text");
+        assert.ok(!written.includes(","), "a comma makes the cell text");
+        assert.equal(Number(written), 1234567.89, "and it parses straight back to a number");
+    });
+});
+
+describe("the exported CSV", () => {
+    const history = [
+        { handNumber: 2, timestamp: 0, pot: 1250000, payouts: [{ id: "a", label: "Alexandra", amount: 1250000 }] },
+        { handNumber: 1, timestamp: 0, pot: 24.5, payouts: [{ id: "b", label: "Bob", amount: 24.5 }] },
+    ];
+    const standings = [
+        { id: "a", name: "Alexandra", in: 1250000, won: 1250000, net: 0, boughtIn: 3200000, chipsNow: 3200000, cashPosition: 0 },
+        { id: "b", name: "Bob", in: 24.5, won: 0, net: -24.5, boughtIn: 100, chipsNow: 75.5, cashPosition: -24.5 },
+    ];
+
+    // Splitting on commas isn't good enough: the timestamp column legitimately holds
+    // one ("1/1/1970, 5:00:00 PM") and is quoted for exactly that reason.
+    const splitRow = line => {
+        const fields = [];
+        let field = "";
+        let quoted = false;
+        for (let i = 0; i < line.length; i++) {
+            const c = line[i];
+            if (quoted) {
+                if (c === '"' && line[i + 1] === '"') { field += '"'; i++; }
+                else if (c === '"') quoted = false;
+                else field += c;
+            } else if (c === '"') quoted = true;
+            else if (c === ",") { fields.push(field); field = ""; }
+            else field += c;
+        }
+        fields.push(field);
+        return fields;
+    };
+
+    test("every money cell parses as a number", () => {
+        const csv = HandHistoryExport.toCsv(history, standings);
+        const lines = csv.split("\r\n");
+
+        lines.slice(1, 3).forEach(line => {
+            const cell = splitRow(line)[2]; // Pot
+            assert.ok(cell !== "" && !Number.isNaN(Number(cell)), `pot cell "${cell}" isn't a number`);
+        });
+
+        // Standings rows: every column after the name has to be numeric.
+        const standingsStart = lines.findIndex(l => l.startsWith("Player,"));
+        lines.slice(standingsStart + 1).filter(Boolean).forEach(line => {
+            splitRow(line).slice(1).forEach(cell => {
+                assert.ok(cell !== "" && !Number.isNaN(Number(cell)), `standings cell "${cell}" isn't a number`);
+            });
+        });
+    });
+
+    test("a million-dollar pot doesn't need quoting any more", () => {
+        const csv = HandHistoryExport.toCsv(history, []);
+        assert.ok(csv.includes("1250000.00"), "written plainly");
+        assert.ok(!csv.includes('"$1,250,000'), "not as a quoted, unsummable string");
+    });
+
+    test("names and payout descriptions stay human", () => {
+        const csv = HandHistoryExport.toCsv(history, standings);
+        assert.ok(csv.includes("Alexandra"), "the name column is still a name");
+        assert.ok(csv.includes("Alexandra: $1,250,000"), "the payout column still reads like a sentence");
+    });
+
+    test("a name with a comma is still quoted properly", () => {
+        const csv = HandHistoryExport.toCsv([], [
+            { id: "x", name: "Smith, John", in: 0, won: 0, net: 0, boughtIn: 0, chipsNow: 0, cashPosition: 0 },
+        ]);
+        assert.ok(csv.includes('"Smith, John"'), "the CSV escaping still applies where it's needed");
+    });
+});
@@ -0,0 +1,124 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { PotCalculator } = require("./load");
+
+const p = (id, contribution, folded = false) => ({ id, contribution, folded });
+
+describe("PotCalculator.layers", () => {
+    test("one pot when everyone put in the same", () => {
+        const layers = PotCalculator.layers([p("a", 50), p("b", 50), p("c", 50)]);
+        assert.equal(layers.length, 1);
+        assert.equal(layers[0].amount, 150);
+        assert.equal(layers[0].label, "Main pot");
+        assert.deepEqual(layers[0].eligible.sort(), ["a", "b", "c"]);
+    });
+
+    test("a short all-in opens a side pot only the deeper players can win", () => {
+        // a is all-in for 20, b and c keep betting to 60.
+        const layers = PotCalculator.layers([p("a", 20), p("b", 60), p("c", 60)]);
+        assert.equal(layers.length, 2);
+
+        assert.equal(layers[0].amount, 60); // 20 x 3
+        assert.deepEqual(layers[0].eligible.sort(), ["a", "b", "c"]);
+
+        assert.equal(layers[1].amount, 80); // 40 x 2
+        assert.deepEqual(layers[1].eligible.sort(), ["b", "c"]);
+        assert.equal(layers[1].label, "Side pot 1");
+    });
+
+    test("folded money stays in the pot as dead money but wins nothing", () => {
+        const layers = PotCalculator.layers([p("a", 50), p("b", 50), p("folder", 50, true)]);
+        assert.equal(layers.length, 1);
+        assert.equal(layers[0].amount, 150, "the folder's chips are still in the middle");
+        assert.ok(!layers[0].eligible.includes("folder"));
+    });
+
+    test("layers with the same eligible players are announced as one pot", () => {
+        // Two folders at different heights would each open a band, but a dealer
+        // announces one pot between the two players who can actually win it.
+        const layers = PotCalculator.layers([
+            p("a", 100),
+            p("b", 100),
+            p("f1", 20, true),
+            p("f2", 40, true),
+        ]);
+        const eligibleSets = layers.map(l => l.eligible.slice().sort().join(","));
+        assert.deepEqual(eligibleSets, ["a,b"], "one announceable pot, not three");
+        assert.equal(layers[0].amount, 260);
+    });
+
+    test("layer amounts always sum to the contested money", () => {
+        const players = [p("a", 12.5), p("b", 33.25), p("c", 33.25), p("d", 5, true)];
+        const total = players.reduce((s, x) => s + x.contribution, 0);
+        const uncalled = PotCalculator.uncalledReturns(players).reduce((s, r) => s + r.amount, 0);
+        const layered = PotCalculator.layers(players).reduce((s, l) => s + l.amount, 0);
+        assert.equal(Math.round((layered + uncalled) * 100), Math.round(total * 100));
+    });
+
+    test("nobody contributed means no pots, not an empty main pot", () => {
+        assert.deepEqual(PotCalculator.layers([p("a", 0), p("b", 0)]), []);
+    });
+});
+
+describe("PotCalculator.uncalledReturns", () => {
+    test("an overbet nobody called goes back to whoever bet it", () => {
+        // b shoves 200, a calls only 50 and everyone else folds.
+        const returns = PotCalculator.uncalledReturns([p("a", 50), p("b", 200)]);
+        assert.deepEqual(returns, [{ id: "b", amount: 150 }]);
+    });
+
+    test("a called bet leaves nothing to return", () => {
+        assert.deepEqual(PotCalculator.uncalledReturns([p("a", 50), p("b", 50)]), []);
+    });
+
+    test("the cap is the biggest live contribution, so a folder's overbet comes back", () => {
+        const returns = PotCalculator.uncalledReturns([p("live", 30), p("bully", 90, true)]);
+        assert.deepEqual(returns, [{ id: "bully", amount: 60 }]);
+    });
+
+    test("with nobody live it stays quiet rather than refunding the table", () => {
+        // Every fold flag set is a dealer mistake to correct, not a signal that
+        // every chip on the felt was uncalled.
+        assert.deepEqual(PotCalculator.uncalledReturns([p("a", 10, true), p("b", 20, true)]), []);
+    });
+});
+
+describe("PotCalculator.resolveRound", () => {
+    test("a single winner takes the layer they were matched for", () => {
+        const entries = PotCalculator.buildEntries([p("a", 50), p("b", 50)]);
+        const result = PotCalculator.resolveRound(entries, ["a"]);
+        assert.equal(result.payoutPool, 100);
+        assert.deepEqual(result.perWinner, [{ id: "a", amount: 100 }]);
+        assert.equal(result.remainingContenders.length, 0);
+    });
+
+    test("an all-in winner only takes what everyone matched, the rest rolls forward", () => {
+        const entries = PotCalculator.buildEntries([p("short", 20), p("b", 60), p("c", 60)]);
+        const result = PotCalculator.resolveRound(entries, ["short"]);
+        assert.equal(result.capApplied, 20);
+        assert.equal(result.payoutPool, 60, "20 from each of three players");
+        // b and c still have 40 each left to play for.
+        assert.deepEqual(result.remainingContenders.map(e => e.id).sort(), ["b", "c"]);
+        assert.equal(PotCalculator.totalPot(result.updatedEntries), 80);
+    });
+
+    test("a chopped pot splits evenly", () => {
+        const entries = PotCalculator.buildEntries([p("a", 30), p("b", 30)]);
+        const result = PotCalculator.resolveRound(entries, ["a", "b"]);
+        assert.deepEqual(result.perWinner, [{ id: "a", amount: 30 }, { id: "b", amount: 30 }]);
+    });
+
+    test("odd cents go to the winners in selection order and nothing is lost", () => {
+        // A $10.01 pot three ways doesn't divide: 3.34 / 3.34 / 3.33.
+        const entries = PotCalculator.buildEntries([p("a", 3.34), p("b", 3.34), p("c", 3.33)]);
+        const result = PotCalculator.resolveRound(entries, ["a", "b", "c"]);
+        const paid = result.perWinner.reduce((s, w) => s + w.amount, 0);
+        assert.equal(Math.round(paid * 100), Math.round(result.payoutPool * 100), "no chips lost to rounding");
+        assert.ok(result.perWinner[0].amount >= result.perWinner[2].amount, "odd cent goes to the first selected");
+    });
+
+    test("selecting nobody who can win is an error, not a silent no-op", () => {
+        const entries = PotCalculator.buildEntries([p("a", 50), p("b", 50)]);
+        assert.throws(() => PotCalculator.resolveRound(entries, ["ghost"]), /No valid winners/);
+    });
+});
@@ -0,0 +1,144 @@
+// Values a dealer can actually produce with a typo, and the ones a corrupted save
+// can produce on its own. None of these should be able to move chips.
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { Betting, HoldemState, makeTable, chipsOnTable } = require("./load");
+
+describe("a stack can never go negative", () => {
+    test("a mistyped negative stack reads as empty, not as owing chips", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.seats[0].stack = -50;
+        assert.equal(Betting.stackOf(state, state.seats[0]), 0);
+    });
+
+    test("a negative stack can't be bet with", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.seats[0].stack = -50;
+        const before = state.seats.reduce((s, p) => s + Math.max(0, Number(p.stack) || 0), 0);
+
+        const moved = Betting.putIn(state, 0, 25);
+
+        assert.equal(moved, 0, "nothing moves out of an empty stack");
+        assert.ok(Betting.stackOf(state, state.seats[0]) >= 0);
+        assert.equal(state.seats[0].committed, 0, "and nothing appears in front of them");
+        assert.ok(state.seats.reduce((s, p) => s + Math.max(0, Number(p.stack) || 0), 0) <= before);
+    });
+
+    test("a negative table default doesn't hand everyone a negative stack", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.seats.forEach(p => { p.stack = null; });
+        state.defaultStack = -100;
+        state.seats.forEach(p => assert.equal(Betting.stackOf(state, p), 0));
+    });
+
+    test("a negative stack doesn't make a player look like they can still bet", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.seats[0].stack = -50;
+        assert.ok(!Betting.seatsWithChips(state).some(s => s.index === 0));
+    });
+});
+
+describe("blinds that can't be posted", () => {
+    test("negative blinds post nothing rather than paying players to sit down", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.smallBlind = -5;
+        state.bigBlind = -10;
+        const before = chipsOnTable(state);
+
+        Betting.beginHand(state);
+
+        state.seats.forEach(p => assert.equal(p.committed, 0));
+        assert.equal(chipsOnTable(state), before);
+    });
+
+    test("an unreadable blind doesn't wedge the hand", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2] });
+        state.bigBlind = NaN;
+        state.smallBlind = 1;
+
+        Betting.beginHand(state);
+
+        assert.ok(Number.isFinite(state.currentBet), "the bet to match is still a number");
+        assert.ok(!Number.isNaN(Betting.potSoFar(state)));
+    });
+
+    test("blinds nobody can cover put those players all-in and move on", () => {
+        const state = makeTable({ seatCount: 4, seated: [0, 1, 2], stack: 10 });
+        state.smallBlind = 500;
+        state.bigBlind = 1000;
+        const before = chipsOnTable(state);
+
+        Betting.beginHand(state);
+
+        assert.equal(chipsOnTable(state), before, "no chips invented covering a blind");
+        state.seats.forEach(p => assert.ok((Number(p.stack) || 0) >= 0));
+        assert.ok(state.actingSeatIndex === null || state.seats[state.actingSeatIndex].inHand);
+    });
+});
+
+describe("a saved table that comes back damaged", () => {
+    test("unreadable storage falls back to a fresh table", () => {
+        // load() has to survive whatever is in localStorage, because the alternative
+        // is a dealer opening the tool mid-session to a blank screen.
+        const original = globalThis.localStorage;
+        globalThis.localStorage = {
+            getItem: () => "{not json at all",
+            setItem: () => {},
+            removeItem: () => {},
+        };
+        const state = HoldemState.load();
+        globalThis.localStorage = original;
+
+        assert.equal(state.seats.length, HoldemState.DEFAULT_SEAT_COUNT);
+        assert.equal(state.handNumber, 1);
+    });
+
+    test("a save missing its seats is treated as no save at all", () => {
+        const original = globalThis.localStorage;
+        globalThis.localStorage = {
+            getItem: () => JSON.stringify({ handNumber: 7, smallBlind: 3 }),
+            setItem: () => {},
+            removeItem: () => {},
+        };
+        const state = HoldemState.load();
+        globalThis.localStorage = original;
+
+        assert.ok(Array.isArray(state.seats) && state.seats.length > 0);
+    });
+
+    test("a save from before a field existed gets the field, not undefined", () => {
+        const original = globalThis.localStorage;
+        globalThis.localStorage = {
+            getItem: () => JSON.stringify({
+                seats: [{ id: "a", name: "Ann", inHand: true }, { id: "b", name: "Ben", inHand: true }],
+                handNumber: 4,
+            }),
+            setItem: () => {},
+            removeItem: () => {},
+        };
+        const state = HoldemState.load();
+        globalThis.localStorage = original;
+
+        assert.equal(state.blindOverride, null);
+        assert.equal(state.street, "preflop");
+        state.seats.forEach(p => {
+            assert.equal(p.committed, 0);
+            assert.equal(p.hasActed, false);
+            assert.equal(p.buyIns, 0);
+        });
+        // And it has to be playable, not just parseable.
+        assert.doesNotThrow(() => Betting.beginHand(state));
+    });
+
+    test("storage that refuses to be written doesn't take the table down", () => {
+        const original = globalThis.localStorage;
+        globalThis.localStorage = {
+            getItem: () => null,
+            setItem: () => { throw new Error("QuotaExceededError"); },
+            removeItem: () => {},
+        };
+        const state = HoldemState.createDefault();
+        assert.doesNotThrow(() => HoldemState.save(state), "a full disk must not break the hand in progress");
+        globalThis.localStorage = original;
+    });
+});
@@ -0,0 +1,65 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { SplitCalculator, Money } = require("./load");
+
+describe("SplitCalculator.split", () => {
+    test("an even chop hands everyone the same stack", () => {
+        const result = SplitCalculator.split(90, 3, 1);
+        assert.equal(result.each, 30);
+        assert.equal(result.oddChips, 0);
+        assert.equal(result.dust, 0);
+        assert.equal(SplitCalculator.accountedFor(result), 90);
+    });
+
+    test("what won't divide is called out as odd chips, not rolled into a stack", () => {
+        // $100 three ways in $5 chips: 20 chips, 6 each, 2 left over.
+        const result = SplitCalculator.split(100, 3, 5);
+        assert.equal(result.each, 30);
+        assert.equal(result.oddChips, 2);
+        assert.equal(SplitCalculator.accountedFor(result), 100);
+    });
+
+    test("a pot that isn't a whole number of chips surfaces the remainder", () => {
+        // $47 in $5 chips: 9 chips ($45) and $2 that no chip in play can pay.
+        const result = SplitCalculator.split(47, 2, 5);
+        assert.equal(result.dust, 2, "the dealer picked a denomination the pot can't make");
+        assert.equal(SplitCalculator.accountedFor(result), 47);
+    });
+
+    test("every split accounts for the whole pot", () => {
+        const chips = [0.25, 0.5, 1, 5, 25, 100];
+        for (let pot = 1; pot <= 400; pot += 7) {
+            for (let ways = 2; ways <= 6; ways++) {
+                chips.forEach(chip => {
+                    const result = SplitCalculator.split(pot, ways, chip);
+                    assert.equal(
+                        Money.toCents(SplitCalculator.accountedFor(result)),
+                        Money.toCents(pot),
+                        `${pot} split ${ways} ways in ${chip} chips lost money`
+                    );
+                });
+            }
+        }
+    });
+
+    test("odd chips are always fewer than the number of players", () => {
+        for (let pot = 1; pot <= 200; pot += 3) {
+            for (let ways = 2; ways <= 8; ways++) {
+                const result = SplitCalculator.split(pot, ways, 1);
+                assert.ok(result.oddChips < ways, "a whole extra chip each would have been dealt out");
+            }
+        }
+    });
+
+    test("an empty pot isn't a valid split", () => {
+        assert.equal(SplitCalculator.split(0, 3, 1).valid, false);
+        assert.equal(SplitCalculator.split(-5, 3, 1).valid, false);
+    });
+
+    test("nonsense inputs fall back to something a dealer can read", () => {
+        const result = SplitCalculator.split(50, 0, 0);
+        assert.equal(result.players, 1, "a split has to be at least one way");
+        assert.equal(result.chip, 0.01, "and at least one cent a chip");
+        assert.equal(SplitCalculator.accountedFor(result), 50);
+    });
+});
@@ -0,0 +1,147 @@
+const { test, describe } = require("node:test");
+const assert = require("node:assert/strict");
+const { HoldemState, makeTable } = require("./load");
+
+describe("HoldemState.advanceButton", () => {
+    test("the button moves to the next player, not the next empty chair", () => {
+        // Four players spread around a ten-seat table: 0, 3, 4, 8.
+        const state = makeTable({ seatCount: 10, seated: [0, 3, 4, 8], dealerSeatIndex: 0 });
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 3, "skips the three empty chairs between");
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 4);
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 8);
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 0, "wraps back round to the first player");
+    });
+
+    test("every player gets the button once per orbit", () => {
+        const seated = [1, 2, 6, 7, 9];
+        const state = makeTable({ seatCount: 12, seated, dealerSeatIndex: 1 });
+        const visited = [];
+        for (let i = 0; i < seated.length; i++) {
+            visited.push(state.dealerSeatIndex);
+            HoldemState.advanceButton(state);
+        }
+        assert.deepEqual(visited.slice().sort((a, b) => a - b), seated);
+    });
+
+    test("it still moves when nobody is dealt in, rather than looking stuck", () => {
+        const state = makeTable({ seatCount: 6, seated: [], dealerSeatIndex: 2 });
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 3);
+    });
+
+    test("counterclockwise play runs the button the other way", () => {
+        const state = makeTable({ seatCount: 6, seated: [0, 2, 4], dealerSeatIndex: 4 });
+        state.direction = "counterclockwise";
+        HoldemState.advanceButton(state);
+        assert.equal(state.dealerSeatIndex, 2);
+    });
+});
+
+describe("HoldemState.getBlindSeats", () => {
+    test("blinds follow the players, not the chairs left of the button", () => {
+        // Seats 1 and 2 are empty, so the blinds belong on 3 and 7.
+        const state = makeTable({ seatCount: 9, seated: [0, 3, 7], dealerSeatIndex: 0 });
+        const { sbIndex, bbIndex, headsUp } = HoldemState.getBlindSeats(state);
+        assert.equal(headsUp, false);
+        assert.equal(sbIndex, 3);
+        assert.equal(bbIndex, 7);
+    });
+
+    test("heads-up, the button posts the small blind", () => {
+        const state = makeTable({ seatCount: 6, seated: [2, 5], dealerSeatIndex: 2 });
+        const { sbIndex, bbIndex, headsUp } = HoldemState.getBlindSeats(state);
+        assert.equal(headsUp, true);
+        assert.equal(sbIndex, 2, "the button is the small blind heads-up");
+        assert.equal(bbIndex, 5);
+    });
+
+    test("heads-up with the button on an empty chair still posts both blinds", () => {
+        const state = makeTable({ seatCount: 6, seated: [1, 4], dealerSeatIndex: 0 });
+        const { sbIndex, bbIndex, headsUp } = HoldemState.getBlindSeats(state);
+        assert.equal(headsUp, true);
+        assert.equal(sbIndex, 1);
+        assert.equal(bbIndex, 4);
+        assert.notEqual(sbIndex, bbIndex, "two blinds never land on one player");
+    });
+
+    test("fewer than two players means no blinds to post", () => {
+        const state = makeTable({ seatCount: 6, seated: [3], dealerSeatIndex: 0 });
+        const { sbIndex, bbIndex } = HoldemState.getBlindSeats(state);
+        assert.equal(sbIndex, null);
+        assert.equal(bbIndex, null);
+    });
+});
+
+describe("HoldemState.sessionStandings", () => {
+    test("a player's cash position counts chips in front plus chips in the pot", () => {
+        const state = makeTable({ seatCount: 3, seated: [0, 1, 2], stack: 0 });
+        const [a] = state.seats;
+        a.buyIns = 100;
+        a.stack = 60;
+        a.amountOverride = 25; // banked into the hand in progress
+        a.committed = 15;      // still in front of them on this street
+
+        HoldemState.recordHand(state, [{ id: a.id, label: "P1", amount: 0 }]);
+        const standings = HoldemState.sessionStandings(state);
+        const row = standings.find(s => s.id === a.id);
+
+        // 60 in front + 40 in the pot - 100 bought in = level.
+        assert.equal(row.cashPosition, 0, "money in the pot is still theirs until it's won");
+        assert.equal(row.boughtIn, 100);
+        assert.equal(row.chipsNow, 60);
+    });
+
+    test("hand results accumulate across the session", () => {
+        const state = makeTable({ seatCount: 2, seated: [0, 1], stack: 0 });
+        const [a, b] = state.seats;
+        a.amountOverride = 10;
+        b.amountOverride = 10;
+        HoldemState.recordHand(state, [{ id: a.id, label: "P1", amount: 20 }]);
+
+        a.amountOverride = 5;
+        b.amountOverride = 5;
+        HoldemState.recordHand(state, [{ id: b.id, label: "P2", amount: 10 }]);
+
+        const standings = HoldemState.sessionStandings(state);
+        assert.equal(standings.find(s => s.id === a.id).net, 5);
+        assert.equal(standings.find(s => s.id === b.id).net, -5);
+        assert.equal(state.handNumber, 3, "the counter moved on twice");
+    });
+
+    test("the history is capped so a long session can still be saved", () => {
+        const state = makeTable({ seatCount: 2, seated: [0, 1], stack: 0 });
+        for (let i = 0; i < HoldemState.MAX_HISTORY_ENTRIES + 25; i++) {
+            HoldemState.recordHand(state, [{ id: state.seats[0].id, label: "P1", amount: 1 }]);
+        }
+        assert.equal(state.handHistory.length, HoldemState.MAX_HISTORY_ENTRIES);
+        assert.equal(state.handHistory[0].handNumber, HoldemState.MAX_HISTORY_ENTRIES + 25, "newest first");
+    });
+});
+
+describe("HoldemState.resizeSeats", () => {
+    test("the table is clamped to a size a dealer could actually run", () => {
+        const state = makeTable({ seatCount: 6 });
+        HoldemState.resizeSeats(state, 100);
+        assert.equal(state.seatCount, 24);
+        HoldemState.resizeSeats(state, 1);
+        assert.equal(state.seatCount, 2);
+    });
+
+    test("an unreadable seat count falls back to a standard table", () => {
+        // Empty or non-numeric input (and zero, which is equally meaningless)
+        // lands on the default rather than a two-seat table.
+        const state = makeTable({ seatCount: 6 });
+        HoldemState.resizeSeats(state, NaN);
+        assert.equal(state.seatCount, HoldemState.DEFAULT_SEAT_COUNT);
+    });
+
+    test("shrinking past the button brings it back onto the table", () => {
+        const state = makeTable({ seatCount: 9, dealerSeatIndex: 8 });
+        HoldemState.resizeSeats(state, 4);
+        assert.ok(state.dealerSeatIndex < 4);
+    });
+});