From eeb8bfef1597b76d6cfe52b372fe55d30cdd8776 Mon Sep 17 00:00:00 2001
From: krokosik <krokosik@pm.me>
Date: Sun, 16 Aug 2026 18:00:09 +0200
Subject: [PATCH] fix: preserve cents in equal splits

---
 src/store/addStore.ts      |  5 ++++-
 src/tests/addStore.test.ts |  1 +
 src/tests/number.test.ts   | 12 ++++++++++++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/store/addStore.ts b/src/store/addStore.ts
index 1ba4f41b1..0dbf1d40b 100644
--- a/src/store/addStore.ts
+++ b/src/store/addStore.ts
@@ -348,7 +348,10 @@ export function calculateParticipantSplit(
 
     if (canSplitScreenClosed) {
       let penniesLeft = updatedParticipants.reduce((acc, p) => acc + (p.amount ?? 0n), 0n);
-      const participantsToPick = updatedParticipants.filter((p) => p.amount);
+      const participantsToPick =
+        splitType === SplitType.EQUAL
+          ? updatedParticipants.filter((p) => p.id !== paidBy?.id && 0n !== getSplitShare(p))
+          : updatedParticipants.filter((p) => p.amount);
       const seed =
         cyrb128(
           `${participantsToPick
diff --git a/src/tests/addStore.test.ts b/src/tests/addStore.test.ts
index ffc82790c..026f654d0 100644
--- a/src/tests/addStore.test.ts
+++ b/src/tests/addStore.test.ts
@@ -590,6 +590,7 @@ describe('calculateParticipantSplit', () => {
       const totalAmount = result.participants.reduce((sum, p) => sum + (p.amount ?? 0n), 0n);
 
       expect(totalAmount).toBe(0n);
+      expect(result.participants.some((p) => -1n === p.amount)).toBe(true);
     });
   });
 });
diff --git a/src/tests/number.test.ts b/src/tests/number.test.ts
index 0cec4f20f..15c14456a 100644
--- a/src/tests/number.test.ts
+++ b/src/tests/number.test.ts
@@ -70,6 +70,18 @@ describe('getCurrencyHelpers', () => {
           expect(toUIString(value)).toBe(expected);
         });
       });
+
+      describe('NZD', () => {
+        const { toSafeBigInt, toUIString } = getCurrencyHelpers({
+          locale: 'en-NZ',
+          currency: 'NZD',
+        });
+
+        it('preserves one cent when parsing and displaying an amount', () => {
+          expect(toSafeBigInt('0.01')).toBe(1n);
+          expect(toUIString(1n, false, true)).toBe('0.01');
+        });
+      });
     });
 
     describe('bg-BG locale', () => {