fix(firms): drop the decimal when fire power rounds to 10 MW

A 9.96 MW detection was labeled 10.0 MW because the one-decimal cutoff ran before rounding.

src/data/firmsCards.test.mjs

@@ -53,6 +53,21 @@ test('buildFireCard: missing acquisition time omits the age segment', () => {
   assert.equal(card.details[0], 'high · N20');
 });
 
+test('buildFireCard: power that rounds to 10 MW drops the decimal', () => {
+  const crossed = buildFireCard(
+    { fire: fire({ frp: 9.96 }), position: {} },
+    NOW,
+  );
+  assert.equal(crossed.title, '▲ 10 MW');
+  const below = buildFireCard(
+    { fire: fire({ frp: 9.94 }), position: {} },
+    NOW,
+  );
+  assert.equal(below.title, '▲ 9.9 MW');
+  const selected = buildSelectedFireCard(fire({ frp: 9.96 }), NOW);
+  assert.equal(selected.title, 'FIRE · 10 MW');
+});
+
 test('buildFireCard: SNPP satellite code renders as SNPP, weak fire is not red', () => {
   const card = buildFireCard({ fire: fire({ satellite: 'N', frp: 0.8, confidence: 0.3 }), position: {} }, NOW);
   assert.match(card.details[0], /SNPP$/);

src/data/firmsLabels.js

@@ -39,6 +39,17 @@ export function accentForSeverity(stopName) {
   return ACCENT_RGB[stopName] || ACCENT_RGB.yellow;
 }
 
+/**
+ * Fire radiative power as shown on a card: "9.9" below 10 MW, "10" once
+ * one-decimal rounding reaches 10. "10.0" would sit beside a whole "10".
+ * @param {number} frp Megawatts.
+ * @returns {string}
+ */
+export function formatFrpMw(frp) {
+  const digits = Number(Number(frp).toFixed(1)) >= 10 ? 0 : 1;
+  return Number(frp).toFixed(digits);
+}
+
 /** Raw FIRMS satellite code → short display name (N = Suomi NPP). */
 export function satelliteShortName(satellite) {
   const s = String(satellite || '')

src/data/firmsLabels.test.mjs

@@ -6,6 +6,7 @@ import {
   FIRMS_AMBIENT_COHORT_LIMIT,
   FIRMS_OVERLAY_SOURCE_ID,
   satelliteShortName,
+  formatFrpMw,
 } from './firmsLabels.js';
 
 test('FIRMS formatting helpers retain the shipped severity palette', () => {
@@ -15,6 +16,14 @@ test('FIRMS formatting helpers retain the shipped severity palette', () => {
   assert.equal(accentForSeverity('chartreuse'), accentForSeverity('yellow'));
 });
 
+test('FIRMS power that rounds to 10 MW drops the decimal', () => {
+  assert.equal(formatFrpMw(9.96), '10');
+  assert.equal(formatFrpMw(9.94), '9.9');
+  assert.equal(formatFrpMw(0.8), '0.8');
+  assert.equal(formatFrpMw(1520.27), '1520');
+  assert.equal(formatFrpMw(210.4), '210');
+});
+
 test('FIRMS satellite names retain the three VIIRS abbreviations', () => {
   assert.equal(satelliteShortName('N20'), 'N20');
   assert.equal(satelliteShortName('N21'), 'N21');

src/layers/firms/model.js

@@ -4,6 +4,7 @@ import {
   satelliteShortName,
   fireDetectionKey,
   accentForSeverity,
+  formatFrpMw,
 } from '../../data/firmsLabels.js';
 import {
   VIEW_PADDING,
@@ -480,14 +481,15 @@ export function createModel({
   }
 
   function formatFrp(frp) {
-    return frp >= 10 ? frp.toFixed(0) : frp.toFixed(1);
+    return formatFrpMw(frp);
   }
 
   /** formatFrp for a card, with the locale's decimal separator ("4,9"). */
 
   function formatFrpLabel(frp) {
-    const digits = frp >= 10 ? 0 : 1;
+    const text = formatFrpMw(frp);
-    return formatNumber(frp, {
+    const digits = text.includes('.') ? 1 : 0;
+    return formatNumber(Number(text), {
       minimumFractionDigits: digits,
       maximumFractionDigits: digits,
       useGrouping: false,