From 37e751f1e33c179520cecb43ed64681ca55c5369 Mon Sep 17 00:00:00 2001
From: Adrian Sbardella <sbardemadrian@gmail.com>
Date: Tue, 3 Nov 2026 21:06:56 -0300
Subject: [PATCH 1/2] fix(fires): keep retained heat hidden when reenabling an
 empty filter

Add a lifecycle regression and register it in the format scope.
---
 docs/CURRENT-STATE.md                    |  2 ++
 scripts/format-scope.json                |  1 +
 src/layers/firms/heatVisibility.test.mjs | 44 ++++++++++++++++++++++++
 src/layers/firms/lifecycle.js            |  3 +-
 4 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 src/layers/firms/heatVisibility.test.mjs

diff --git a/docs/CURRENT-STATE.md b/docs/CURRENT-STATE.md
index 66dd7068c..c67967183 100644
--- a/docs/CURRENT-STATE.md
+++ b/docs/CURRENT-STATE.md
@@ -2231,6 +2231,8 @@ view), so the weak fires the heatmap shows stay on screen as markers when it
 fades out; it reads each marker's already-built anchor instead of the ground
 floor cache, which only the close band warms. "N FIRES" cards from a 2° / 1° aggregation still label the hottest
 areas; their accent is the strongest fire's FRP color.
+Re-enabling Active Fires keeps the retained heat imagery hidden when the current
+filtered set is empty, including while a new snapshot is pending.
 
 The Active Fires row carries a "Fire intensity (FRP)" slider on a log scale
 whose track is painted with the ramp and ticked at the same six values (its
diff --git a/scripts/format-scope.json b/scripts/format-scope.json
index 3df4155f2..606314960 100644
--- a/scripts/format-scope.json
+++ b/scripts/format-scope.json
@@ -408,6 +408,7 @@
   "src/layers/firms/cards.js",
   "src/layers/firms/index.js",
   "src/layers/firms/ingestion.js",
+  "src/layers/firms/heatVisibility.test.mjs",
   "src/layers/firms/lifecycle.js",
   "src/layers/firms/model.js",
   "src/layers/firms/policy.js",
diff --git a/src/layers/firms/heatVisibility.test.mjs b/src/layers/firms/heatVisibility.test.mjs
new file mode 100644
index 000000000..4926db156
--- /dev/null
+++ b/src/layers/firms/heatVisibility.test.mjs
@@ -0,0 +1,44 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { createLifecycle } from './lifecycle.js';
+
+test('reenabling an empty filtered layer never reveals the retained pre-filter heat raster', async () => {
+  let shown = false;
+  const noop = () => {};
+  const layerState = {
+    _enabled: false,
+    _viewer: {},
+    _dataSource: {},
+    _fires: [],
+    _loading: true,
+    _pickIndexById: new Map(),
+    _heatImagery: {
+      setShow(v) {
+        shown = v;
+      },
+    },
+  };
+  const lifecycle = createLifecycle({
+    layerState,
+    services: {
+      picking: { registerPickOwner: noop, unregisterPickOwner: noop },
+      sprites: { restoreSpriteOrderOnEnable: noop },
+      context: { clearSelectedEntityContextForLayer: noop },
+    },
+    config: { id: 'local-firms', overlayHost: { setVisible: noop } },
+    components: {
+      rendering: { applyHandoffFade: noop },
+      viewport: { installLodWatcher: noop, installMoveEndWatcher: noop },
+      selection: { installClickHandler: noop },
+    },
+  });
+  await lifecycle.methods.enable(layerState._viewer);
+  assert.equal(
+    shown,
+    false,
+    'empty current set must keep the old raster hidden while refresh is pending',
+  );
+  layerState._fires = [{ frp: null, confidence: null }];
+  await lifecycle.methods.enable(layerState._viewer);
+  assert.equal(shown, true, 'nonempty sets still resume their raster');
+});
diff --git a/src/layers/firms/lifecycle.js b/src/layers/firms/lifecycle.js
index 541efca16..90d9cc217 100644
--- a/src/layers/firms/lifecycle.js
+++ b/src/layers/firms/lifecycle.js
@@ -54,7 +54,8 @@ export function createLifecycle({
         layerState._billboards.show = true;
       }
       overlayHost.setVisible(FIRMS_OVERLAY_SOURCE_ID, true);
-      layerState._heatImagery?.setShow(true);
+      // A filter can leave an old raster cached while the current set is empty.
+      layerState._heatImagery?.setShow(layerState._fires.length > 0);
       // The camera can have crossed the hand-off while the layer was off.
       components.rendering.applyHandoffFade(true);
       components.viewport.installLodWatcher();

From 19e85941e63fad99439e77739137666f686bff45 Mon Sep 17 00:00:00 2001
From: Adrian Sbardella <sbardemadrian@gmail.com>
Date: Tue, 3 Nov 2026 21:07:29 -0300
Subject: [PATCH 2/2] docs: add changelog entry for empty-filter heat lifecycle
 fix

---
 changelog.d/1535-fires-empty-heat-reenable.md | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 changelog.d/1535-fires-empty-heat-reenable.md

diff --git a/changelog.d/1535-fires-empty-heat-reenable.md b/changelog.d/1535-fires-empty-heat-reenable.md
new file mode 100644
index 000000000..a862a7b56
--- /dev/null
+++ b/changelog.d/1535-fires-empty-heat-reenable.md
@@ -0,0 +1,2 @@
+- Keep retained Active Fires heat imagery hidden when an empty filtered layer is
+  re-enabled while a new snapshot is pending (radianx, #1535).