Cross-fade Active Fires markers and heatmap; fix the spot size

The far-zoom heatmap now uses the ½× grid (4096 × 2048, ≈10 km per
pixel, one-pixel blur), so a lone fire's spot matches its marker at the
3,000 km hand-off. The spot size slider and its share option are gone.

Markers and heatmap are both kept built at every zoom and cross-fade by
camera height between 2,400 and 3,600 km on every frame, so a fast zoom
never shows a beat with neither. The heatmap fades by imagery alpha:
hiding a Cesium imagery layer unmaps it from the globe tiles, and showing
it again re-mapped them late, which was the gap at the band edge. Under
the markers the heatmap is built 150 ms after the data or filter changes.

src/layers/firms/queries.js

@@ -8,11 +8,6 @@ import {
   rampTrackGradient,
   sliderPositionForFrp,
 } from '../../data/firmsIntensity.js';
-import {
-  normalizeHeatSpotSize,
-  sliderPositionForSpotSize,
-  spotSizeForSliderPosition,
-} from '../../data/firmsHeatRaster.js';
 import { formatNumber, t } from '../../i18n/index.js';
 import { LOD_LEVELS, REFRESH_INTERVAL_MS } from './policy.js';
 
@@ -28,16 +23,6 @@ export function createQueries({
 }) {
   const { id, name, icon, source } = config;
 
-  /** Spot sizes marked under the spot-size slider, in percent. */
-  const SPOT_SIZE_TICKS = [50, 100, 200, 400];
-
-  /** Spot-size label for a percent ("0.5×", "1×", "1.5×"). */
-  function spotSizeLabel(percent) {
-    return t('{value}×', {
-      value: formatNumber(percent / 100, { maximumFractionDigits: 2 }),
-    });
-  }
-
   /** Whole-megawatt label for a slider value or tick ("0", "20", "1 000"). */
   function frpLabel(frp) {
     return formatNumber(frp, { maximumFractionDigits: 0 });
@@ -98,12 +83,12 @@ export function createQueries({
     updateInterval: REFRESH_INTERVAL_MS,
 
     /**
-     * The intensity filter and the heatmap spot size as layer options (share
-     * token `w`, owner `local-firms` in layerState.js).
-     * @returns {{minFrp: number, confidence: string, spotSize: number}}
+     * The intensity filter as layer options (share token `w`, owner
+     * `local-firms` in layerState.js).
+     * @returns {{minFrp: number, confidence: string}}
      */
     getParams() {
-      return { ...layerState._filter, spotSize: layerState._spotSize };
+      return { ...layerState._filter };
     },
 
     /**
@@ -111,36 +96,24 @@ export function createQueries({
      * value. The filter runs in one place (ingestion.applyFilter) and the LOD
      * rebuild re-derives markers, cells, cards and context registrations from
      * the shown set; a selected fire that no longer passes is deselected.
-     * A spot-size change only marks the heat raster stale: the shown set,
-     * markers and cards stay as they are.
-     * @param {{minFrp?: number, confidence?: string, spotSize?: number}} params
+     * @param {{minFrp?: number, confidence?: string}} params
      * @returns {boolean} True — the request is always accepted.
      */
     setParams(params = {}) {
       const next = normalizeFireFilter(params, layerState._filter);
-      const spotSize =
-        normalizeHeatSpotSize(params?.spotSize) ?? layerState._spotSize;
-      const filterChanged =
-        next.minFrp !== layerState._filter.minFrp ||
-        next.confidence !== layerState._filter.confidence;
-      const spotChanged = spotSize !== layerState._spotSize;
-      if (!filterChanged && !spotChanged) return true;
-      layerState._filter = next;
-      layerState._spotSize = spotSize;
-      if (!layerState._allFires.length) {
-        layerState._rowControlsListener?.();
+      if (
+        next.minFrp === layerState._filter.minFrp &&
+        next.confidence === layerState._filter.confidence
+      )
         return true;
-      }
-      if (filterChanged) {
-        components.ingestion.applyFilter();
-        if (
-          layerState._selectedFire &&
-          !firePassesFilter(layerState._selectedFire, next)
-        ) {
-          components.selection.clearFireSelection();
-        }
-      } else {
-        layerState._heatRaster = null;
+      layerState._filter = next;
+      if (!layerState._allFires.length) return true;
+      components.ingestion.applyFilter();
+      if (
+        layerState._selectedFire &&
+        !firePassesFilter(layerState._selectedFire, next)
+      ) {
+        components.selection.clearFireSelection();
       }
       if (layerState._enabled) components.rendering.renderCurrentLod(true);
       layerState._rowControlsListener?.();
@@ -150,8 +123,8 @@ export function createQueries({
     /**
      * Row controls under the Active Fires row: the log-scale minimum-FRP
      * slider whose track is painted with the intensity ramp (so it doubles as
-     * the legend), the All / Nominal+ / High confidence switch, the far-zoom
-     * heatmap spot-size slider and the "N of M shown" counter.
+     * the legend), the All / Nominal+ / High confidence switch, and the
+     * "N of M shown" counter.
      */
     getRowControls() {
       const { minFrp, confidence } = layerState._filter;
@@ -160,48 +133,27 @@ export function createQueries({
       const shown = layerState._count;
       const total = layerState._totalCount;
       return {
-        sliders: [
-          {
-            id: 'min-frp',
-            label: t('Fire intensity (FRP)'),
-            ariaLabel: t('Minimum fire radiative power, megawatts'),
-            valueText:
-              minFrp > 0
-                ? t('≥ {value} MW', { value: frpLabel(minFrp) })
-                : t('All', { context: 'fire intensity filter' }),
-            min: 0,
-            max: SLIDER_STEPS,
-            step: 1,
-            value: Math.round(sliderPositionForFrp(minFrp) * SLIDER_STEPS),
-            track: rampTrackGradient(),
-            ticks: FRP_SLIDER_TICKS.map((frp) => ({
-              at: sliderPositionForFrp(frp),
-              label: frpLabel(frp),
-            })),
-            params: (value) => ({
-              minFrp: frpForSliderPosition(Number(value) / SLIDER_STEPS),
-            }),
-          },
-          {
-            id: 'heat-spot-size',
-            label: t('Heatmap spot size'),
-            ariaLabel: t('Far-zoom heatmap spot size'),
-            valueText: spotSizeLabel(layerState._spotSize),
-            min: 0,
-            max: SLIDER_STEPS,
-            step: 1,
-            value: Math.round(
-              sliderPositionForSpotSize(layerState._spotSize) * SLIDER_STEPS,
-            ),
-            ticks: SPOT_SIZE_TICKS.map((percent) => ({
-              at: sliderPositionForSpotSize(percent),
-              label: spotSizeLabel(percent),
-            })),
-            params: (value) => ({
-              spotSize: spotSizeForSliderPosition(Number(value) / SLIDER_STEPS),
-            }),
-          },
-        ],
+        slider: {
+          id: 'min-frp',
+          label: t('Fire intensity (FRP)'),
+          ariaLabel: t('Minimum fire radiative power, megawatts'),
+          valueText:
+            minFrp > 0
+              ? t('≥ {value} MW', { value: frpLabel(minFrp) })
+              : t('All', { context: 'fire intensity filter' }),
+          min: 0,
+          max: SLIDER_STEPS,
+          step: 1,
+          value: Math.round(sliderPositionForFrp(minFrp) * SLIDER_STEPS),
+          track: rampTrackGradient(),
+          ticks: FRP_SLIDER_TICKS.map((frp) => ({
+            at: sliderPositionForFrp(frp),
+            label: frpLabel(frp),
+          })),
+          params: (value) => ({
+            minFrp: frpForSliderPosition(Number(value) / SLIDER_STEPS),
+          }),
+        },
         segmented: {
           id: 'confidence',
           label: t('Confidence'),
@@ -359,10 +311,15 @@ export function createQueries({
 
     /** Test seam: render one named LOD band against a near-global view. */
     _renderLodForTest(lodId) {
-      const lod = LOD_LEVELS.find((level) => level.id === lodId);
-      if (lod.mode === 'detections')
-        components.rendering.renderDetections(lod, null);
-      else components.rendering.renderHeat(lod, null);
+      components.rendering.renderBand(
+        LOD_LEVELS.find((level) => level.id === lodId),
+        null,
+      );
+    },
+
+    /** Test seam: one frame of the hand-off fade at the current camera. */
+    _applyHandoffFadeForTest() {
+      components.rendering.applyHandoffFade();
     },
 
     /** Test seam: entities drawn by the layer's data source. */