feat: #420 Add helper for formatting key price display in XLM with correct decimal places

src/utils/__tests__/keyPriceDisplay.utils.test.ts

@@ -3,6 +3,7 @@ import {
 	formatCreatorKeyPriceDisplay,
 	formatDisplayKeyPrice,
 	resolveCreatorKeyPriceStroops,
+	formatKeyPrice,
 } from '../keyPriceDisplay.utils';
 import { STROOPS_PER_XLM } from '@/constants/stellar';
 
@@ -41,3 +42,26 @@ describe('formatCreatorKeyPriceDisplay', () => {
 		);
 	});
 });
+
+describe('formatKeyPrice', () => {
+	it('formats zero correctly with 4 decimal places', () => {
+		expect(formatKeyPrice(0n)).toBe('0.0000 XLM');
+	});
+
+	it('formats sub-1 XLM values with 4 decimal places', () => {
+		expect(formatKeyPrice(5_000_000n)).toBe('0.5000 XLM');
+		expect(formatKeyPrice(123_456n)).toBe('0.0123 XLM');
+		expect(formatKeyPrice(123_556n)).toBe('0.0124 XLM'); // rounds up
+	});
+
+	it('formats exactly 1 XLM with 2 decimal places', () => {
+		expect(formatKeyPrice(10_000_000n)).toBe('1.00 XLM');
+	});
+
+	it('formats large values with 2 decimal places and commas', () => {
+		expect(formatKeyPrice(15_000_000n)).toBe('1.50 XLM');
+		expect(formatKeyPrice(123_456_789n)).toBe('12.35 XLM');
+		expect(formatKeyPrice(10_000_000_000n)).toBe('1,000.00 XLM');
+	});
+});
+

src/utils/keyPriceDisplay.utils.ts

@@ -58,3 +58,22 @@ export function formatCreatorKeyPriceDisplay(
 ): string {
 	return formatDisplayKeyPrice(resolveCreatorKeyPriceStroops(creator));
 }
+
+/**
+ * Formats a key price in stroops (bigint) to XLM with proper decimal precision.
+ * Always displays 2 decimal places for prices >= 1 XLM, and 4 decimal places for prices < 1 XLM.
+ */
+export function formatKeyPrice(stroops: bigint): string {
+	const STROOPS_PER_XLM_BI = 10_000_000n;
+	const isBelowOneXlm = stroops < STROOPS_PER_XLM_BI;
+	const decimals = isBelowOneXlm ? 4 : 2;
+
+	const xlm = Number(stroops) / 10_000_000;
+	const formattedValue = formatNumber(xlm, {
+		minimumFractionDigits: decimals,
+		maximumFractionDigits: decimals,
+	});
+
+	return `${formattedValue} XLM`;
+}
+