diff --git a/frontend/src/components/StrategyEditorPage.tsx b/frontend/src/components/StrategyEditorPage.tsx
index 72b7b1a..ba569aa 100644
--- a/frontend/src/components/StrategyEditorPage.tsx
+++ b/frontend/src/components/StrategyEditorPage.tsx
@@ -34,6 +34,7 @@ import {
   normalizeStartCombineOp,
   updateStartCombineOp,
   updateStartCandleTypes,
+  updateBranchRoot,
   type EditorConditionState,
 } from '../utils/strategyConditionSerde';
 import { migrateLogicRootForEditor } from '../utils/strategyConditionNormalize';
@@ -778,6 +779,7 @@ export default function StrategyEditorPage({
     const resolved = typeof next === 'function'
       ? next(currentEditorStateRef.current)
       : next;
+    currentEditorStateRef.current = resolved;
     setCurrentRoot(resolved.root);
     setCurrentLayout(prev => ({
       ...prev,
@@ -790,12 +792,12 @@ export default function StrategyEditorPage({
   }, [setCurrentRoot, setCurrentLayout, scheduleStrategyPersist]);
 
   const handleStartCandleTypesChange = useCallback((startId: string, candleTypes: string[]) => {
-    handleEditorStateChange(updateStartCandleTypes(currentEditorState, startId, candleTypes));
-  }, [handleEditorStateChange, currentEditorState]);
+    handleEditorStateChange(prev => updateStartCandleTypes(prev, startId, candleTypes));
+  }, [handleEditorStateChange]);
 
   const handleStartCombineOpChange = useCallback((op: StartCombineOp) => {
-    handleEditorStateChange(updateStartCombineOp(currentEditorState, op));
-  }, [handleEditorStateChange, currentEditorState]);
+    handleEditorStateChange(prev => updateStartCombineOp(prev, op));
+  }, [handleEditorStateChange]);
 
   const switchSignalTab = useCallback((tab: 'buy' | 'sell') => {
     if (editorMode === 'graph') layoutFlushRef.current?.();
@@ -1328,9 +1330,9 @@ export default function StrategyEditorPage({
   }, []);
 
   const handleAddStartSection = useCallback(() => {
-    handleEditorStateChange(addExtraStartSection(currentEditorState));
+    handleEditorStateChange(prev => addExtraStartSection(prev));
     bumpLayoutSeed(layoutStrategyKey, signalTab);
-  }, [handleEditorStateChange, currentEditorState, bumpLayoutSeed, layoutStrategyKey, signalTab]);
+  }, [handleEditorStateChange, bumpLayoutSeed, layoutStrategyKey, signalTab]);
 
   const applyPalette = useCallback((type: string, value: string, _label: string, composite = false) => {
     if (type === 'start') {
@@ -1338,12 +1340,15 @@ export default function StrategyEditorPage({
       return;
     }
     const newNode = makeNode(type, value, signalTab, DEF, composite ? { composite: true } : undefined);
-    const root = currentRoot;
-    if (!root) setCurrentRoot(newNode);
-    else if (type === 'operator') setCurrentRoot(mergeAtRoot(root, newNode, true));
-    else setCurrentRoot(mergeAtRoot(root, newNode, false));
-    scheduleStrategyPersist();
-  }, [signalTab, DEF, currentRoot, setCurrentRoot, handleAddStartSection, scheduleStrategyPersist]);
+    handleEditorStateChange(prev => {
+      const root = prev.root;
+      if (!root) return updateBranchRoot(prev, START_NODE_ID, newNode);
+      if (type === 'operator') {
+        return updateBranchRoot(prev, START_NODE_ID, mergeAtRoot(root, newNode, true));
+      }
+      return updateBranchRoot(prev, START_NODE_ID, mergeAtRoot(root, newNode, false));
+    });
+  }, [signalTab, DEF, handleEditorStateChange, handleAddStartSection]);
 
   const applyPaletteItem = useCallback((item: PaletteItem) => {
     const stochPair = isStochOverboughtPairPaletteValue(item.value);
@@ -1361,11 +1366,12 @@ export default function StrategyEditorPage({
             ? buildStableStrategyTree(item.value, DEF)
             : makeNode('indicator', item.value, signalTab, DEF, composite ? { composite: true } : undefined);
     if (!newNode) return;
-    const root = currentRoot;
-    if (!root) setCurrentRoot(newNode);
-    else setCurrentRoot(mergeAtRoot(root, newNode, false));
-    scheduleStrategyPersist();
-  }, [signalTab, DEF, currentRoot, setCurrentRoot, scheduleStrategyPersist]);
+    handleEditorStateChange(prev => {
+      const root = prev.root;
+      if (!root) return updateBranchRoot(prev, START_NODE_ID, newNode);
+      return updateBranchRoot(prev, START_NODE_ID, mergeAtRoot(root, newNode, false));
+    });
+  }, [signalTab, DEF, handleEditorStateChange]);
 
   const applySidewaysFilter = useCallback((filterId: string) => {
     const newNode = buildSidewaysFilterNode(filterId, DEF, sidewaysPalette);
diff --git a/frontend/src/components/strategyEditor/StrategyListEditor.tsx b/frontend/src/components/strategyEditor/StrategyListEditor.tsx
index bea77f1..d97e446 100644
--- a/frontend/src/components/strategyEditor/StrategyListEditor.tsx
+++ b/frontend/src/components/strategyEditor/StrategyListEditor.tsx
@@ -41,6 +41,7 @@ import {
   setHtmlPaletteDropRouter,
   setPaletteDragDropHandler,
   subscribePaletteDrag,
+  wasPaletteHtmlDropCommitted,
   type PaletteDragPayload,
 } from '../../utils/paletteDragSession';
 
@@ -108,12 +109,18 @@ const TreeNodeComp: React.FC<TreeNodeProps> = ({
     e.stopPropagation();
     setDragOverKey?.(nodeDropKey);
   };
-  const handleDragLeave = () => setDragOverKey?.(null);
+  const handleDragLeave = (e: React.DragEvent) => {
+    const rel = e.relatedTarget as Node | null;
+    if (!rel) return;
+    if (e.currentTarget.contains(rel)) return;
+    setDragOverKey?.(null);
+  };
   const handleDrop = (e: React.DragEvent) => {
     if (!isLogic) return;
     e.preventDefault();
     e.stopPropagation();
     setDragOverKey?.(null);
+    if (wasPaletteHtmlDropCommitted()) return;
     try {
       const data = JSON.parse(e.dataTransfer.getData('application/json'));
       if (data.type === 'start') {
@@ -338,6 +345,7 @@ function StartSectionBlock({
     e.preventDefault();
     e.stopPropagation();
     setDragOverKey(null);
+    if (wasPaletteHtmlDropCommitted()) return;
     const data = readPaletteHtmlDragData(e);
     if (!data) return;
     applyDrop(null, data);
@@ -375,7 +383,12 @@ function StartSectionBlock({
           e.stopPropagation();
           setDragOverKey(sectionDropKey);
         }}
-        onDragLeave={() => setDragOverKey(null)}
+        onDragLeave={e => {
+          const rel = e.relatedTarget as Node | null;
+          if (!rel) return;
+          if (e.currentTarget.contains(rel)) return;
+          setDragOverKey(null);
+        }}
         onDrop={handleSectionDrop}
       >
         {!root ? (
@@ -561,13 +574,14 @@ export default function StrategyListEditor({
   const handleListDragOver = (e: React.DragEvent) => {
     e.preventDefault();
     e.dataTransfer.dropEffect = 'copy';
-    setDragOverKey(LIST_DROP_KEY);
+    setDragOverKeyThrottled(LIST_DROP_KEY);
   };
 
   const handleListDrop = (e: React.DragEvent) => {
     e.preventDefault();
     e.stopPropagation();
     setDragOverKey(null);
+    if (wasPaletteHtmlDropCommitted()) return;
     const data = readPaletteHtmlDragData(e);
     if (!data) return;
     applyDropRef.current(findPaletteDropKeyAtPoint(e.clientX, e.clientY) ?? LIST_DROP_KEY, data);
@@ -578,7 +592,12 @@ export default function StrategyListEditor({
       className={`se-list-editor sp-dropzone${dragOverKey === LIST_DROP_KEY ? ' se-list-editor--over' : ''}`}
       data-palette-drop-key={LIST_DROP_KEY}
       onDragOver={handleListDragOver}
-      onDragLeave={() => setDragOverKey(null)}
+      onDragLeave={e => {
+        const rel = e.relatedTarget as Node | null;
+        if (!rel) return;
+        if (e.currentTarget.contains(rel)) return;
+        setDragOverKey(null);
+      }}
       onDrop={handleListDrop}
     >
       {sections.map(section => (
@@ -591,7 +610,7 @@ export default function StrategyListEditor({
           signalTab={signalTab}
           def={def}
           dragOverKey={dragOverKey}
-          setDragOverKey={setDragOverKey}
+          setDragOverKey={setDragOverKeyThrottled}
           onRootChange={root => handleRootChange(section.startId, root)}
           onCandleTypesChange={types => handleCandleTypesChange(section.startId, types)}
           onDeleteStart={section.canDelete ? () => handleDeleteStart(section.startId) : undefined}
diff --git a/frontend/src/utils/paletteDragSession.ts b/frontend/src/utils/paletteDragSession.ts
index 6bfdb90..7a013e8 100644
--- a/frontend/src/utils/paletteDragSession.ts
+++ b/frontend/src/utils/paletteDragSession.ts
@@ -78,6 +78,10 @@ type HtmlPaletteDropRouter = (
 let htmlDropRouter: HtmlPaletteDropRouter | null = null;
 let htmlDropCommitted = false;
 
+export function wasPaletteHtmlDropCommitted(): boolean {
+  return htmlDropCommitted;
+}
+
 export function setHtmlPaletteDropRouter(router: HtmlPaletteDropRouter | null): void {
   htmlDropRouter = router;
 }