feat(units): port imperial/metric conversion from the kiosk

__tests__/units.test.ts

@@ -0,0 +1,46 @@
+import {
+  convertDistanceFromYards,
+  convertSpeedFromMph,
+  formatCarryRange,
+  formatDistance,
+  formatSpeed,
+  getDistanceUnit,
+  getSpeedUnit,
+  getUnitsLabel,
+} from '../utils/units';
+
+describe('units helpers', () => {
+  it('preserves imperial speed values', () => {
+    expect(convertSpeedFromMph(150, 'imperial')).toBe(150);
+    expect(formatSpeed(150, 'imperial', 1)).toBe('150.0');
+    expect(getSpeedUnit('imperial')).toBe('mph');
+  });
+
+  it('converts mph to km/h with stable rounding', () => {
+    expect(convertSpeedFromMph(100, 'metric')).toBeCloseTo(160.934, 3);
+    expect(formatSpeed(100, 'metric', 1)).toBe('160.9');
+    expect(getSpeedUnit('metric')).toBe('km/h');
+  });
+
+  it('preserves imperial distance values', () => {
+    expect(convertDistanceFromYards(250, 'imperial')).toBe(250);
+    expect(formatDistance(250, 'imperial', 0)).toBe('250');
+    expect(getDistanceUnit('imperial')).toBe('yds');
+  });
+
+  it('converts yards to meters with stable rounding', () => {
+    expect(convertDistanceFromYards(100, 'metric')).toBeCloseTo(91.44, 2);
+    expect(formatDistance(100, 'metric', 0)).toBe('91');
+    expect(getDistanceUnit('metric')).toBe('m');
+  });
+
+  it('joins speed and distance units for chrome labels', () => {
+    expect(getUnitsLabel('imperial')).toBe('mph / yds');
+    expect(getUnitsLabel('metric')).toBe('km/h / m');
+  });
+
+  it('formats carry ranges in the selected unit system', () => {
+    expect(formatCarryRange([200, 220], 'imperial')).toBe('200-220 yds');
+    expect(formatCarryRange([200, 220], 'metric')).toBe('183-201 m');
+  });
+});

utils/units.ts

@@ -0,0 +1,56 @@
+// Imperial/metric conversion mirrored from the OpenFlight kiosk web UI
+// (`ui/src/utils/units.ts` in open-flight/openflight). The two copies are
+// hand-mirrored, not shared: this repository has no build-time dependency on
+// the server repository (see AGENTS.md). Keep the constants and rounding here
+// identical to the kiosk so both clients report the same numbers.
+
+export type UnitSystem = 'imperial' | 'metric';
+
+const MPH_TO_KMH = 1.60934;
+const YARDS_TO_METERS = 0.9144;
+const IMPERIAL_SPEED_UNIT = 'mph';
+const METRIC_SPEED_UNIT = 'km/h';
+const IMPERIAL_DISTANCE_UNIT = 'yds';
+const METRIC_DISTANCE_UNIT = 'm';
+
+export function convertSpeedFromMph(speedMph: number, unitSystem: UnitSystem): number {
+  if (unitSystem === 'metric') {
+    return speedMph * MPH_TO_KMH;
+  }
+
+  return speedMph;
+}
+
+export function convertDistanceFromYards(distanceYards: number, unitSystem: UnitSystem): number {
+  if (unitSystem === 'metric') {
+    return distanceYards * YARDS_TO_METERS;
+  }
+
+  return distanceYards;
+}
+
+export function formatSpeed(speedMph: number, unitSystem: UnitSystem, digits = 1): string {
+  return convertSpeedFromMph(speedMph, unitSystem).toFixed(digits);
+}
+
+export function formatDistance(distanceYards: number, unitSystem: UnitSystem, digits = 0): string {
+  return convertDistanceFromYards(distanceYards, unitSystem).toFixed(digits);
+}
+
+export function getSpeedUnit(unitSystem: UnitSystem): string {
+  return unitSystem === 'metric' ? METRIC_SPEED_UNIT : IMPERIAL_SPEED_UNIT;
+}
+
+export function getDistanceUnit(unitSystem: UnitSystem): string {
+  return unitSystem === 'metric' ? METRIC_DISTANCE_UNIT : IMPERIAL_DISTANCE_UNIT;
+}
+
+export function getUnitsLabel(unitSystem: UnitSystem): string {
+  return `${getSpeedUnit(unitSystem)} / ${getDistanceUnit(unitSystem)}`;
+}
+
+export function formatCarryRange(carryRange: [number, number], unitSystem: UnitSystem): string {
+  const min = formatDistance(carryRange[0], unitSystem, 0);
+  const max = formatDistance(carryRange[1], unitSystem, 0);
+  return `${min}-${max} ${getDistanceUnit(unitSystem)}`;
+}