JoshHeaps.Net/Pages/Casino/TexasHoldem.cshtml

@@ -399,6 +399,22 @@
             </p>
         </section>
 
+        <section class="ruling" data-short="Who shows first">
+            <h3>Who turns their hand over first</h3>
+            <p>
+                If there was a bet on the river, the last player to bet or raise shows
+                first. If the river was checked all the way round, it's the first live
+                player left of the button. Nobody has to be asked twice — a player may
+                always turn their hand over early if they want to.
+            </p>
+            <p>
+                When everyone is all-in before the river there was no final round to
+                lead, so it falls to whoever last put money in, on whichever street that
+                was. The action bar names the seat and the reason at every showdown, so
+                the call is already made before anyone asks.
+            </p>
+        </section>
+
         <section class="ruling" data-short="Odd chip">
             <h3>The odd chip in a split pot</h3>
             <p>

JoshHeaps.Net/wwwroot/css/casino/holdem.css

@@ -1957,6 +1957,16 @@ button,
     color: #e07b7b;
 }
 
+/* The showdown call, sat above the resolve button. Loud enough to be read across a
+   table at a glance — this is something the dealer says out loud — but not so loud it
+   competes with the button underneath it. */
+.showdownCall {
+    margin: 0 0 0.45rem;
+    text-align: center;
+    font-size: 0.82rem;
+    color: #f0d98c;
+}
+
 .handHistoryFilterRow {
     display: flex;
     align-items: center;

JoshHeaps.Net/wwwroot/js/casino/holdem/actionBar.js

@@ -691,13 +691,41 @@ const ActionBar = {
         return wrap;
     },
 
+    // "Dee shows first — last to raise." The call the dealer has to make at every
+    // showdown and that nobody at the table volunteers for, said out loud with the
+    // reason attached so it can be repeated to whoever argues with it.
+    showdownCall() {
+        const call = Betting.showdownOrder(this.state);
+        if (!call) return null;
+
+        const who = HoldemState.displayName(this.state.seats[call.index], call.index);
+        const because = {
+            aggressor: "last to bet or raise",
+            // Semicolon, not a second dash: the sentence already spends its dash on
+            // "shows first —", and two of them in one line reads as a stutter.
+            allInAggressor: "last to put money in; nobody could bet the river",
+            leftOfButton: "checked round, first left of the button",
+        }[call.reason];
+
+        const line = document.createElement("p");
+        line.className = "showdownCall";
+        line.textContent = `${who} shows first — ${because}.`;
+        return line;
+    },
+
     renderStreetDone() {
-        const row = document.createElement("div");
-        row.className = "actionButtons";
+        const wrap = document.createElement("div");
 
         const isRiver = this.state.street === "river";
         const label = isRiver ? "Showdown — resolve pot" : `Deal ${Betting.streetLabel(Betting.STREETS[Betting.STREETS.indexOf(this.state.street) + 1])}`;
 
+        if (isRiver) {
+            const call = this.showdownCall();
+            if (call) wrap.appendChild(call);
+        }
+
+        const row = document.createElement("div");
+        row.className = "actionButtons";
         row.appendChild(this.button(label, "actionAdvance", () => {
             if (isRiver) {
                 this.hooks.resolvePot();
@@ -705,22 +733,33 @@ const ActionBar = {
             }
             this.commit(`dealing the ${Betting.streetLabel(Betting.STREETS[Betting.STREETS.indexOf(this.state.street) + 1]).toLowerCase()}`, () => Betting.closeStreet(this.state));
         }));
+        wrap.appendChild(row);
 
-        return row;
+        return wrap;
     },
 
     renderHandOver() {
-        const row = document.createElement("div");
-        row.className = "actionButtons";
+        const wrap = document.createElement("div");
         const live = Betting.liveSeats(this.state);
         const winner = live.length === 1 ? HoldemState.displayName(live[0].player, live[0].index) : null;
 
+        // Two or more still in with the betting finished is a showdown however it was
+        // arrived at — including everyone all-in on the flop, where the cards go on
+        // their backs and the order still decides who turns over first.
+        if (!winner) {
+            const call = this.showdownCall();
+            if (call) wrap.appendChild(call);
+        }
+
+        const row = document.createElement("div");
+        row.className = "actionButtons";
         row.appendChild(this.button(
             winner ? `Award pot to ${winner}` : "Resolve pot",
             "actionAdvance",
             () => this.hooks.resolvePot()
         ));
-        return row;
+        wrap.appendChild(row);
+        return wrap;
     },
 };
 

JoshHeaps.Net/wwwroot/js/casino/holdem/betting.js

@@ -276,6 +276,11 @@ const Betting = {
 
         if (newBet > previousBet) {
             const increase = this.round(newBet - previousBet);
+            // Aggression, whether or not it was a full raise — a short all-in doesn't
+            // reopen the betting, but the player who made it is still the last one who
+            // put money in, and at the showdown they are still the one who shows first.
+            state.streetAggressorIndex = index;
+            state.handAggressorIndex = index;
             // What a full raise would have had to be: at least as much again as the
             // last one, or the big blind if there hasn't been a raise yet.
             const fullRaise = this.round(state.lastRaiseSize || state.bigBlind || 0);
@@ -337,6 +342,10 @@ const Betting = {
 
         state.currentBet = 0;
         state.lastRaiseSize = 0;
+        // Whoever led this street stops being the answer the moment the next one opens.
+        // The hand's aggressor is deliberately left alone: it's the fallback for a
+        // river nobody could bet on.
+        state.streetAggressorIndex = null;
 
         const nextStreetIndex = this.STREETS.indexOf(state.street || "preflop") + 1;
         state.street = this.STREETS[nextStreetIndex] || "river";
@@ -424,6 +433,11 @@ const Betting = {
         state.street = "preflop";
         state.currentBet = 0;
         state.lastRaiseSize = 0;
+        // Posting a blind isn't aggression — a hand limped and checked all the way
+        // down has no aggressor at all, which is exactly the case the showdown rule
+        // sends to the seat left of the button.
+        state.streetAggressorIndex = null;
+        state.handAggressorIndex = null;
 
         // Deal around anyone with no chips, before anything else reads the table.
         //
@@ -504,6 +518,45 @@ const Betting = {
             : this.nextToAct(state, bbIndex);
     },
 
+    // Who turns their hand over first.
+    //
+    // A call the dealer makes at every showdown that isn't a fold, and one nobody at
+    // the table volunteers for — everyone would rather see a hand than show one. The
+    // tool knew who last raised and who sits left of the button and said neither, so
+    // the dealer was working it out from memory while five people waited.
+    //
+    // Three cases, in the order the rule asks them:
+    //   * somebody bet or raised on the final round — they show first;
+    //   * the round was checked through — first live player left of the button;
+    //   * nobody could bet, because the chips were already in — the last player who
+    //     did put money in, on whichever round that was.
+    //
+    // Returns null when there's nothing to call: one player left, or none.
+    showdownOrder(state) {
+        const live = this.liveSeats(state);
+        if (live.length < 2) return null;
+
+        const seatOf = index =>
+            Number.isInteger(index) && live.some(s => s.index === index) ? index : null;
+
+        const streetAggressor = seatOf(state.streetAggressorIndex);
+        if (streetAggressor !== null) {
+            return { index: streetAggressor, reason: "aggressor" };
+        }
+
+        // Nobody could have bet this round, so "no bet on the final round" isn't a
+        // choice anybody made and the seat left of the button hasn't earned the
+        // obligation. It falls to whoever last put money in.
+        if (!this.canStillBet(state)) {
+            const handAggressor = seatOf(state.handAggressorIndex);
+            if (handAggressor !== null) return { index: handAggressor, reason: "allInAggressor" };
+        }
+
+        const order = HoldemState.liveOrderFromButton(state)
+            .filter(index => live.some(s => s.index === index));
+        return order.length > 0 ? { index: order[0], reason: "leftOfButton" } : null;
+    },
+
     // Winners get their share put back in front of them.
     creditWinnings(state, payouts) {
         payouts.forEach(payout => {

JoshHeaps.Net/wwwroot/js/casino/holdem/state.js

@@ -86,6 +86,12 @@ const HoldemState = {
             // seating as it stands, because by then the people it needs to know about
             // are exactly the ones who have got up and gone.
             postedBlinds: null,
+            // Who last bet or raised, on this street and anywhere in the hand. Kept
+            // apart because the showdown rule needs both: normally the aggressor of the
+            // final betting round shows first, but a round nobody could bet in — chips
+            // already all-in — falls back to the last one who could.
+            streetAggressorIndex: null,
+            handAggressorIndex: null,
             // Player ids that were dealt in the last hand actually dealt. What makes a
             // seat recognisable as having *just* joined — new to the table, or back
             // from sitting out — which is the whole question behind owing a blind.
@@ -173,7 +179,8 @@ const HoldemState = {
             // them in rather than making the dealer reset a table mid-session.
             const defaults = this.createDefault();
             ["smallBlind", "bigBlind", "defaultStack", "street", "currentBet", "lastRaiseSize",
-                "actingSeatIndex", "blindOverride", "postedBlinds"]
+                "actingSeatIndex", "blindOverride", "postedBlinds",
+                "streetAggressorIndex", "handAggressorIndex"]
                 .forEach(key => {
                     if (parsed[key] === undefined) parsed[key] = defaults[key];
                 });

tests/holdem/showdownOrder.test.js

@@ -0,0 +1,202 @@
+// Who turns their hand over first.
+//
+// A call the dealer makes at every showdown that isn't a fold, and one nobody at the
+// table volunteers for — everyone would rather see a hand than show one. The tool knew
+// who last raised and who sits left of the button and said neither.
+const test = require("node:test");
+const { describe } = require("node:test");
+const assert = require("node:assert");
+const { HoldemState, Betting, makeTable } = require("./load");
+
+const NAMES = ["Ann", "Ben", "Cal", "Dee"];
+const table = (dealerSeatIndex = 0, stack = 200) => {
+    const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], stack, dealerSeatIndex });
+    NAMES.forEach((name, i) => { state.seats[i].name = name; });
+    Betting.beginHand(state);
+    return state;
+};
+
+const call = state => {
+    const answer = Betting.showdownOrder(state);
+    return answer && { who: state.seats[answer.index].name, reason: answer.reason };
+};
+
+// Everybody left just calls whatever is in front of them, then the street closes.
+const checkRound = state => {
+    let guard = 0;
+    while (state.actingSeatIndex !== null && guard++ < 12) {
+        const index = state.actingSeatIndex;
+        if (Betting.toCall(state, state.seats[index]) > 0) Betting.call(state, index);
+        else Betting.check(state, index);
+    }
+    Betting.closeStreet(state);
+};
+
+describe("a bet on the river", () => {
+    test("the last player to raise shows first", () => {
+        const state = table(0);                 // blinds Ben and Cal
+        checkRound(state);                      // pre-flop
+        checkRound(state);                      // flop
+        checkRound(state);                      // turn
+
+        Betting.raiseTo(state, state.actingSeatIndex, 20);
+        const raiser = state.seats.findIndex(p => Betting.committed(p) === 20);
+        while (state.actingSeatIndex !== null) Betting.call(state, state.actingSeatIndex);
+
+        assert.deepEqual(call(state), { who: state.seats[raiser].name, reason: "aggressor" });
+    });
+
+    test("a re-raise moves it to the last one, not the first", () => {
+        const state = table(0);
+        checkRound(state); checkRound(state); checkRound(state);
+
+        const first = state.actingSeatIndex;
+        Betting.raiseTo(state, first, 20);
+        const second = state.actingSeatIndex;
+        Betting.raiseTo(state, second, 60);
+        while (state.actingSeatIndex !== null) {
+            const i = state.actingSeatIndex;
+            if (Betting.toCall(state, state.seats[i]) > 0) Betting.call(state, i); else Betting.check(state, i);
+        }
+
+        assert.equal(call(state).who, state.seats[second].name);
+    });
+
+    test("a short all-in still shows first, even though it doesn't reopen the betting", () => {
+        // The rule about reopening is about who may raise. It says nothing about who
+        // shows, and the player who shoved is still the last one who put money in.
+        const state = table(0);
+        checkRound(state); checkRound(state); checkRound(state);
+
+        const bettor = state.actingSeatIndex;
+        Betting.raiseTo(state, bettor, 40);
+        const shortStack = state.actingSeatIndex;
+        // Over the $40 but only by $15, where a full raise would need $40 more. Going
+        // *under* the bet would be a short call, not a short raise, and wouldn't make
+        // them the aggressor at all.
+        state.seats[shortStack].stack = 55;
+        Betting.allIn(state, shortStack);
+        assert.equal(Betting.committed(state.seats[shortStack]), 55, "raised, if not by enough");
+        while (state.actingSeatIndex !== null) {
+            const i = state.actingSeatIndex;
+            if (Betting.toCall(state, state.seats[i]) > 0) Betting.call(state, i); else Betting.check(state, i);
+        }
+
+        assert.equal(call(state).who, state.seats[shortStack].name);
+    });
+});
+
+describe("a river checked through", () => {
+    test("the first live player left of the button shows first", () => {
+        const state = table(0);                 // button Ann
+        checkRound(state); checkRound(state); checkRound(state); checkRound(state);
+
+        assert.deepEqual(call(state), { who: "Ben", reason: "leftOfButton" });
+    });
+
+    test("an earlier street's raiser doesn't carry over to the river", () => {
+        // The rule is about the *final* round. Leading the flop and then checking the
+        // river doesn't oblige anyone.
+        const state = table(0);
+        checkRound(state);                      // pre-flop
+        Betting.raiseTo(state, state.actingSeatIndex, 20);   // leads the flop
+        while (state.actingSeatIndex !== null) Betting.call(state, state.actingSeatIndex);
+        Betting.closeStreet(state);
+        checkRound(state);                      // turn
+        checkRound(state);                      // river
+
+        assert.equal(call(state).reason, "leftOfButton");
+    });
+
+    test("it skips a folded seat rather than naming somebody who isn't in the hand", () => {
+        const state = table(0);                 // button Ann, so Ben would be first
+        checkRound(state); checkRound(state); checkRound(state);
+        Betting.fold(state, 1);                 // Ben gets out on the river
+        while (state.actingSeatIndex !== null) {
+            const i = state.actingSeatIndex;
+            if (Betting.toCall(state, state.seats[i]) > 0) Betting.call(state, i); else Betting.check(state, i);
+        }
+        Betting.closeStreet(state);
+
+        assert.equal(call(state).who, "Cal", "the next one round who is still in");
+    });
+});
+
+describe("everyone all-in before the river", () => {
+    test("the last player who could put money in shows first", () => {
+        // There was no final round to lead, so "checked round" isn't a choice anybody
+        // made and the seat left of the button hasn't earned the obligation.
+        const state = table(0, 30);
+        checkRound(state);                      // pre-flop
+
+        const shover = state.actingSeatIndex;
+        Betting.allIn(state, shover);
+        while (state.actingSeatIndex !== null) Betting.call(state, state.actingSeatIndex);
+        Betting.closeStreet(state);
+
+        assert.equal(Betting.canStillBet(state), false, "nobody has chips left to bet");
+        assert.deepEqual(call(state), { who: state.seats[shover].name, reason: "allInAggressor" });
+    });
+
+    test("a hand where everyone got in for the blind and nobody raised falls to the button", () => {
+        // Two-dollar stacks against a two-dollar blind: everyone is all-in by calling,
+        // and calling is not aggression. Nobody chose to lead, so nobody is on the hook
+        // and it goes back to the seat left of the button.
+        const state = table(0, 2);
+        checkRound(state);
+
+        assert.equal(Betting.canStillBet(state), false, "nobody has a chip behind");
+        assert.equal(state.handAggressorIndex, null, "and nobody ever raised");
+        const answer = call(state);
+        assert.ok(answer, "there is still a showdown to order");
+        assert.equal(answer.reason, "leftOfButton");
+    });
+});
+
+describe("when there is nothing to call", () => {
+    test("one player left isn't a showdown", () => {
+        const state = table(0);
+        [1, 2, 3].forEach(i => Betting.fold(state, i));
+        assert.equal(Betting.showdownOrder(state), null);
+    });
+
+    test("an aggressor who has since folded doesn't get named", () => {
+        // Can't happen in play — you don't fold after raising unopposed — but the
+        // index is a number on the state and a reset table could hold a stale one.
+        const state = table(0);
+        checkRound(state); checkRound(state); checkRound(state); checkRound(state);
+        state.streetAggressorIndex = 1;
+        state.seats[1].folded = true;
+
+        const answer = call(state);
+        assert.notEqual(answer.who, "Ben");
+        assert.equal(answer.reason, "leftOfButton");
+    });
+
+    test("an index pointing at no seat at all is ignored", () => {
+        const state = table(0);
+        checkRound(state); checkRound(state); checkRound(state); checkRound(state);
+        state.streetAggressorIndex = 99;
+        assert.equal(call(state).reason, "leftOfButton");
+    });
+});
+
+describe("the tracking resets when it should", () => {
+    test("a new hand starts with nobody on the hook", () => {
+        const state = table(0);
+        checkRound(state); checkRound(state); checkRound(state);
+        Betting.raiseTo(state, state.actingSeatIndex, 20);
+        assert.notEqual(state.handAggressorIndex, null);
+
+        HoldemState.startNextHand(state);
+        Betting.beginHand(state);
+        assert.equal(state.streetAggressorIndex, null);
+        assert.equal(state.handAggressorIndex, null, "last night's raise isn't this hand's business");
+    });
+
+    test("posting a blind is not aggression", () => {
+        const state = table(0);
+        assert.equal(state.streetAggressorIndex, null);
+        assert.equal(state.handAggressorIndex, null);
+    });
+});