diff --git a/scripts/format-scope.json b/scripts/format-scope.json
index 61149f281..c3218943a 100644
--- a/scripts/format-scope.json
+++ b/scripts/format-scope.json
@@ -1080,5 +1080,6 @@
   "src/globe/navara/lines/lineMesh.test.mjs",
   "src/globe/pickDelivery.test.mjs",
   "src/globe/navara/picking.test.mjs",
-  "src/data/selectionDispatcher.test.mjs"
+  "src/data/selectionDispatcher.test.mjs",
+  "src/globe/navara/cascadedLightCopy.test.mjs"
 ]
diff --git a/src/globe/navara/cascadedLightCopy.js b/src/globe/navara/cascadedLightCopy.js
new file mode 100644
index 000000000..dce4273de
--- /dev/null
+++ b/src/globe/navara/cascadedLightCopy.js
@@ -0,0 +1,85 @@
+// Navara 0.2.1 leak fix (phase 3 review): Navara's transparent pass keeps a
+// copy of each scene light and refreshes it every frame with
+// `copy.copy(light, true)`. For the sun's cascaded shadow lights
+// (@navaramap/three-csm CascadedDirectionalLights) that copy clones every
+// cascade, so each frame brings new DirectionalLight objects with new ids,
+// and three's WebGLLights uniforms cache (keyed by light id) grows by about
+// 1.2 KB a frame in looks with a shadowed sun. The patched copy updates the
+// cascades it already has in place (pose, colour, intensity, target, shadow
+// settings and camera) when the cascade counts match, and keeps the original
+// rebuild otherwise. internals.js applies it to the class Navara uses.
+// Upstream ask: copy cascaded lights in place (or sync without copy()).
+
+const PATCHED = Symbol('gev.cascadedLightCopy');
+
+function copyLightInPlace(target, source) {
+  target.position.copy(source.position);
+  target.quaternion.copy(source.quaternion);
+  target.scale.copy(source.scale);
+  target.matrix.copy(source.matrix);
+  target.matrixWorld.copy(source.matrixWorld);
+  target.matrixAutoUpdate = source.matrixAutoUpdate;
+  target.visible = source.visible;
+  target.castShadow = source.castShadow;
+  target.layers.mask = source.layers.mask;
+  target.color.copy(source.color);
+  target.intensity = source.intensity;
+  const to = target.target;
+  const from = source.target;
+  to.position.copy(from.position);
+  to.quaternion.copy(from.quaternion);
+  to.matrix.copy(from.matrix);
+  to.matrixWorld.copy(from.matrixWorld);
+  const shadow = target.shadow;
+  const original = source.shadow;
+  shadow.intensity = original.intensity;
+  shadow.bias = original.bias;
+  shadow.normalBias = original.normalBias;
+  shadow.radius = original.radius;
+  shadow.blurSamples = original.blurSamples;
+  shadow.mapSize.copy(original.mapSize);
+  shadow.camera.copy(original.camera);
+  shadow.camera.updateProjectionMatrix?.();
+}
+
+/**
+ * Patches CascadedDirectionalLights.prototype.copy (idempotent).
+ * @returns {() => void} restore the original copy
+ */
+export function patchCascadedLightCopy(proto) {
+  if (proto.copy[PATCHED]) return proto.copy[PATCHED];
+  const original = proto.copy;
+  if (typeof original !== 'function')
+    throw new Error('CascadedDirectionalLights.copy not found');
+  function copyInPlace(source, recursive) {
+    const mine = this.cascadedLights;
+    const theirs = source?.cascadedLights;
+    if (
+      !Array.isArray(mine) ||
+      !Array.isArray(theirs) ||
+      mine.length === 0 ||
+      mine.length !== theirs.length
+    )
+      return original.call(this, source, recursive);
+    // Object3D's own fields, without children (as the original's
+    // super.copy(source, false)).
+    this.name = source.name;
+    this.position.copy(source.position);
+    this.quaternion.copy(source.quaternion);
+    this.scale.copy(source.scale);
+    this.matrix.copy(source.matrix);
+    this.matrixWorld.copy(source.matrixWorld);
+    this.visible = source.visible;
+    this.direction?.copy?.(source.direction);
+    for (let index = 0; index < mine.length; index++)
+      copyLightInPlace(mine[index], theirs[index]);
+    return this;
+  }
+  copyInPlace.gevInPlace = true;
+  const restore = () => {
+    if (proto.copy === copyInPlace) proto.copy = original;
+  };
+  copyInPlace[PATCHED] = restore;
+  proto.copy = copyInPlace;
+  return restore;
+}
diff --git a/src/globe/navara/cascadedLightCopy.test.mjs b/src/globe/navara/cascadedLightCopy.test.mjs
new file mode 100644
index 000000000..fa901a9c1
--- /dev/null
+++ b/src/globe/navara/cascadedLightCopy.test.mjs
@@ -0,0 +1,73 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import csm from '@navaramap/three-csm';
+import { patchCascadedLightCopy } from './cascadedLightCopy.js';
+
+const { CascadedDirectionalLights } = csm;
+
+function sun(count = 3) {
+  const light = new CascadedDirectionalLights(0xffffff, 2);
+  light.setCount(count);
+  light.cascadedLights.forEach((cascade, index) => {
+    cascade.position.set(index, 2, 3);
+    cascade.target.position.set(index, 0, 0);
+    cascade.updateMatrixWorld(true);
+    cascade.target.updateMatrixWorld(true);
+    cascade.shadow.bias = -0.001 * (index + 1);
+  });
+  return light;
+}
+
+test("Navara 0.2.1's copy clones new lights every call (the leak)", () => {
+  const source = sun();
+  const copy = new CascadedDirectionalLights();
+  copy.copy(source, true);
+  const ids = copy.cascadedLights.map((light) => light.id);
+  copy.copy(source, true);
+  assert.notDeepEqual(
+    copy.cascadedLights.map((light) => light.id),
+    ids,
+  );
+});
+
+test('patched, a copy keeps its lights and takes the values', () => {
+  const restore = patchCascadedLightCopy(CascadedDirectionalLights.prototype);
+  try {
+    const source = sun();
+    const copy = new CascadedDirectionalLights();
+    copy.copy(source, true); // first copy: builds the lights
+    const lights = [...copy.cascadedLights];
+    const targets = lights.map((light) => light.target);
+    source.cascadedLights[1].intensity = 5;
+    source.cascadedLights[1].color.set(0xff0000);
+    source.cascadedLights[2].position.set(9, 9, 9);
+    source.cascadedLights[2].target.position.set(7, 0, 0);
+    source.cascadedLights[2].updateMatrixWorld(true);
+    source.cascadedLights[2].target.updateMatrixWorld(true);
+    source.cascadedLights[0].shadow.camera.left = -77;
+    copy.copy(source, true);
+    assert.deepEqual(copy.cascadedLights, lights, 'the same light objects');
+    assert.deepEqual(
+      copy.cascadedLights.map((light) => light.target),
+      targets,
+    );
+    assert.equal(copy.cascadedLights[1].intensity, 5);
+    assert.equal(copy.cascadedLights[1].color.getHex(), 0xff0000);
+    assert.deepEqual(copy.cascadedLights[2].position.toArray(), [9, 9, 9]);
+    assert.equal(copy.cascadedLights[2].target.matrixWorld.elements[12], 7);
+    assert.equal(copy.cascadedLights[0].shadow.camera.left, -77);
+    assert.equal(copy.cascadedLights[2].shadow.bias, -0.003);
+    // A different cascade count rebuilds, as before.
+    source.setCount(4);
+    copy.copy(source, true);
+    assert.equal(copy.cascadedLights.length, 4);
+    assert.equal(
+      patchCascadedLightCopy(CascadedDirectionalLights.prototype),
+      restore,
+      'idempotent',
+    );
+  } finally {
+    restore();
+  }
+  assert.equal(CascadedDirectionalLights.prototype.copy.gevInPlace, undefined);
+});
diff --git a/src/globe/navara/index.js b/src/globe/navara/index.js
index 2600ca908..d2ffaa156 100644
--- a/src/globe/navara/index.js
+++ b/src/globe/navara/index.js
@@ -6,7 +6,11 @@ import ThreeView from '@navaramap/three';
 import * as geo from '../../geo/index.js';
 import { DefaultPlugin } from '@navaramap/three-default-plugin';
 import { createNavaraEngine } from './createNavaraEngine.js';
-import { forEachLuminanceUniform, navaraHooks } from './internals.js';
+import {
+  forEachLuminanceUniform,
+  keepCascadedLightIds,
+  navaraHooks,
+} from './internals.js';
 import { buildNavaraLook } from './look.js';
 import { createNavaraSharpen } from './sharpen.js';
 import { createNavaraMovers } from './movers/index.js';
@@ -112,6 +116,8 @@ export async function createNavaraGlobe({
       () => engine.clock.frameTime(),
       { forEachLuminanceUniform },
     );
+    // The look's shadowed sun leaked a light per frame (internals.js).
+    keepCascadedLightIds(view);
     engine = createNavaraEngine(view, {
       hooks: navaraHooks(view),
       container,
diff --git a/src/globe/navara/internals.js b/src/globe/navara/internals.js
index 571894777..f97cb31d8 100644
--- a/src/globe/navara/internals.js
+++ b/src/globe/navara/internals.js
@@ -5,6 +5,7 @@
 // found it and the public API that would replace it upstream.
 
 import { ModelMesh } from '@navaramap/three';
+import { patchCascadedLightCopy } from './cascadedLightCopy.js';
 
 export const NAVARA_INTERNALS_VERSION = '0.2.1';
 
@@ -130,6 +131,23 @@ export function forEachLuminanceUniform(handles, visit) {
   );
 }
 
+/**
+ * Phase 3 review (leak): the sun's cascaded shadow lights are re-cloned by
+ * the transparent pass every frame (cascadedLightCopy.js). Finds the
+ * CascadedDirectionalLights class among the view's scene lights (private:
+ * view._scenes.light) and patches its copy to update in place. Returns the
+ * restore function, or null when the look has no cascaded light (the
+ * cinematic sun casts no shadow). Upstream ask: copy cascaded lights in
+ * place.
+ */
+export function keepCascadedLightIds(view) {
+  const lights = view._scenes?.light?.children ?? [];
+  const cascaded = lights.find((light) => Array.isArray(light?.cascadedLights));
+  return cascaded
+    ? patchCascadedLightCopy(Object.getPrototypeOf(cascaded))
+    : null;
+}
+
 /** The hooks createNavaraEngine takes. */
 export const navaraHooks = (view) => ({
   retainTileGeometry,