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

@@ -532,11 +532,26 @@ const Betting = {
     //
     // Facing no bet this is a plain pot-sized bet — toCall is zero and currentBet is
     // zero, so it comes out as the pot, which is the right answer there too.
+    // Rounded up to something the table's chips can actually build. Half the pot is
+    // constantly a half-chip amount — pre-flop at 1/2 it is $4.50, and the smallest
+    // chip in the default legend is a dollar, so the button offered a number the
+    // dealer would have to round themselves every single time.
+    //
+    // Only when the legend describes this game. A smallest chip *larger* than the big
+    // blind means the denominations were never set for these stakes, and rounding a
+    // 5c/10c table up to whole dollars would be the tool doing real damage on the
+    // strength of a field somebody forgot to fill in. Left exact there, and the wrong
+    // legend stays visible rather than being quietly applied.
     potRaiseTo(state, index, fraction = 1) {
         const player = state.seats[index];
         if (!player) return 0;
         const potAfterCall = this.round(this.potSoFar(state) + this.toCall(state, player));
-        return this.round((state.currentBet || 0) + potAfterCall * fraction);
+        const exact = this.round((state.currentBet || 0) + potAfterCall * fraction);
+
+        const step = Money.fromCents(Money.chipStepCents(state.chipLegend));
+        const bigBlind = Number(state.bigBlind) || 0;
+        if (step <= 0 || (bigBlind > 0 && step > bigBlind)) return exact;
+        return Money.upToChip(exact, state.chipLegend);
     },
 
     // Who turns their hand over first.

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

@@ -63,6 +63,29 @@ const Money = {
     // Anything the smallest chip can't make comes back as `remainder` rather than being
     // rounded away: a 50c share in a game whose smallest chip is a dollar is a real
     // problem for the dealer to solve, not a rounding error to hide.
+    // The smallest chip the table has said it plays with, in cents. Zero when no
+    // denominations are set, which means the tool has been told nothing about what
+    // chips exist and shouldn't pretend otherwise.
+    chipStepCents(legend) {
+        const values = (legend || [])
+            .map(chip => this.toCents(chip.value))
+            .filter(cents => cents > 0);
+        return values.length > 0 ? Math.min(...values) : 0;
+    },
+
+    // Rounds an amount up to something the table can actually build out of its chips.
+    //
+    // Up rather than down or nearest: these are bet sizes, and a pot-sized bet that
+    // has been shaved is no longer a pot-sized bet. Rounding up also can't drop an
+    // amount below a legal minimum, which rounding the other way can.
+    upToChip(amount, legend) {
+        const step = this.chipStepCents(legend);
+        if (step <= 0) return this.round(amount);
+        const cents = this.toCents(amount);
+        if (cents <= 0) return this.round(amount);
+        return this.fromCents(Math.ceil(cents / step) * step);
+    },
+
     chipBreakdown(amount, legend) {
         let cents = this.toCents(amount);
         if (cents <= 0) return { chips: [], remainder: 0 };

tests/holdem/potRaise.test.js

@@ -9,7 +9,7 @@
 const test = require("node:test");
 const { describe } = require("node:test");
 const assert = require("node:assert");
-const { Betting, makeTable } = require("./load");
+const { Betting, Money, makeTable } = require("./load");
 
 describe("pre-flop at 1/2", () => {
     const dealt = () => {
@@ -25,11 +25,13 @@ describe("pre-flop at 1/2", () => {
         assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex), 7);
     });
 
-    test("half pot is $4.50, which is above the $4 minimum rather than equal to it", () => {
+    test("half pot is $5 — $4.50 rounded up to something the chips can make", () => {
         // The old arithmetic gave $3.50, which clamped up to the minimum and put the
-        // same $4 on two buttons side by side.
+        // same $4 on two buttons side by side. The honest half-pot is $4.50, and the
+        // smallest chip in the default legend is a dollar, so the button would have
+        // offered an amount the dealer had to round themselves every single time.
         const state = dealt();
-        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5), 4.5);
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5), 5);
         assert.notEqual(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5),
             Betting.minRaiseTo(state), "the two quick buttons say different things");
     });
@@ -111,3 +113,68 @@ describe("it stays sane at the edges", () => {
         assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex), 0.35);
     });
 });
+
+describe("the amounts are ones the table can actually build", () => {
+    const CENTS = [{ value: 0.25 }, { value: 0.05 }, { value: 0.01 }];
+    const DOLLARS = [{ value: 1 }, { value: 5 }, { value: 25 }, { value: 100 }];
+
+    const table = (legend, smallBlind, bigBlind, stack = 200) => {
+        const state = makeTable({ seatCount: 6, seated: [0, 1, 2, 3], stack, smallBlind, bigBlind });
+        state.chipLegend = legend;
+        Betting.beginHand(state);
+        return state;
+    };
+
+    test("a half-pot that lands on a half chip is rounded up, not offered as it is", () => {
+        const state = table(DOLLARS, 1, 2);
+        // Honestly $4.50. No dollar chip makes fifty cents.
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5), 5);
+        assert.equal(Money.chipBreakdown(5, DOLLARS).remainder, 0);
+    });
+
+    test("up rather than down — a shaved pot bet is not a pot bet", () => {
+        const state = table(DOLLARS, 1, 2);
+        assert.ok(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5) > 4.5);
+    });
+
+    test("an amount the chips already make is left exactly alone", () => {
+        const state = table(DOLLARS, 1, 2);
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex), 7, "the pot raise was already whole");
+    });
+
+    test("a cent table keeps its cents", () => {
+        const state = table(CENTS, 0.05, 0.1);
+        // Pot $0.15, owes $0.10: call to $0.25, raise $0.25 → $0.35, which cent chips make.
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex), 0.35);
+        assert.equal(Money.chipBreakdown(0.35, CENTS).remainder, 0);
+    });
+
+    test("a legend that plainly isn't for these stakes is not applied", () => {
+        // Dollar chips on a 5c/10c game means somebody never filled the legend in.
+        // Rounding those blinds up to whole dollars would be the tool doing real
+        // damage on the strength of a stale field, so the amounts stay exact and the
+        // wrong legend stays visible.
+        const state = table(DOLLARS, 0.05, 0.1);
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex), 0.35);
+    });
+
+    test("a table with no legend at all gets exact amounts", () => {
+        const state = table([], 1, 2);
+        assert.equal(Betting.potRaiseTo(state, state.actingSeatIndex, 0.5), 4.5);
+    });
+
+    test("every fraction comes out buildable, and never shaved", () => {
+        const state = table(DOLLARS, 1, 2);
+        const index = state.actingSeatIndex;
+        const potAfterCall = Betting.potSoFar(state) + Betting.toCall(state, state.seats[index]);
+
+        [0.1, 0.25, 0.5, 0.75, 1].forEach(fraction => {
+            const value = Betting.potRaiseTo(state, index, fraction);
+            const exact = state.currentBet + potAfterCall * fraction;
+            assert.ok(value >= exact, `${fraction} of the pot should never be rounded down`);
+            assert.ok(value - exact < 1, `${fraction} of the pot should round by less than a chip`);
+            assert.equal(Money.chipBreakdown(value, DOLLARS).remainder, 0,
+                `${fraction} of the pot should be buildable from the table's chips`);
+        });
+    });
+});