diff --git a/src/features/editor/components/editor.test.tsx b/src/features/editor/components/editor.test.tsx
index e43244e0..601f6831 100644
--- a/src/features/editor/components/editor.test.tsx
+++ b/src/features/editor/components/editor.test.tsx
@@ -168,8 +168,8 @@ vi.mock('@/shared/state/editor-panel-layout-store', () => ({
       tools: 25,
       preview: 50,
       properties: 25,
-      mainContent: 50,
-      timeline: 50,
+      mainContent: 72,
+      timeline: 28,
     },
     setPanel: vi.fn(),
   }),
@@ -259,12 +259,6 @@ vi.mock('@/shared/ui/editor-layout', async (importOriginal) => {
   const actual = await importOriginal<typeof import('@/shared/ui/editor-layout')>();
   return {
     ...actual,
-    getEditorLayout: () => ({
-      ...actual.getEditorLayout(),
-      timelineDefaultSize: 35,
-      timelineMinSize: 20,
-      timelineMaxSize: 60,
-    }),
     getEditorLayoutCssVars: () => ({}),
   };
 });
diff --git a/src/shared/state/editor-panel-layout-store.test.ts b/src/shared/state/editor-panel-layout-store.test.ts
new file mode 100644
index 00000000..9afdd8bc
--- /dev/null
+++ b/src/shared/state/editor-panel-layout-store.test.ts
@@ -0,0 +1,48 @@
+import { describe, expect, it } from 'vitest';
+import { migrateEditorPanelLayout } from './editor-panel-layout-store';
+import { EDITOR_LAYOUT } from '@/shared/ui/editor-layout';
+
+const v1DefaultState = {
+  panels: {
+    tools: 25,
+    preview: 50,
+    properties: 25,
+    mainContent: 50,
+    timeline: 50,
+  },
+};
+
+describe('migrateEditorPanelLayout', () => {
+  it('moves an untouched v1 default split to the EDITOR_LAYOUT default', () => {
+    const migrated = migrateEditorPanelLayout(v1DefaultState, 1);
+
+    expect(migrated.panels?.timeline).toBe(EDITOR_LAYOUT.timelineDefaultSize);
+    expect(migrated.panels?.mainContent).toBe(100 - EDITOR_LAYOUT.timelineDefaultSize);
+  });
+
+  it('keeps main/timeline summing to 100 after migration', () => {
+    const migrated = migrateEditorPanelLayout(v1DefaultState, 1);
+
+    expect((migrated.panels?.mainContent ?? 0) + (migrated.panels?.timeline ?? 0)).toBe(100);
+  });
+
+  it('preserves the untouched sidebar panel sizes', () => {
+    const migrated = migrateEditorPanelLayout(v1DefaultState, 1);
+
+    expect(migrated.panels?.tools).toBe(25);
+    expect(migrated.panels?.preview).toBe(50);
+    expect(migrated.panels?.properties).toBe(25);
+  });
+
+  it('leaves a user-resized v1 layout alone', () => {
+    const resized = {
+      panels: { ...v1DefaultState.panels, mainContent: 40, timeline: 60 },
+    };
+
+    expect(migrateEditorPanelLayout(resized, 1)).toEqual(resized);
+  });
+
+  it('passes current-version state through untouched', () => {
+    expect(migrateEditorPanelLayout(v1DefaultState, 2)).toEqual(v1DefaultState);
+  });
+});
diff --git a/src/shared/state/editor-panel-layout-store.ts b/src/shared/state/editor-panel-layout-store.ts
index 2bf4187d..6cf96e65 100644
--- a/src/shared/state/editor-panel-layout-store.ts
+++ b/src/shared/state/editor-panel-layout-store.ts
@@ -4,6 +4,7 @@
  */
 import { create } from 'zustand';
 import { persist } from 'zustand/middleware';
+import { EDITOR_LAYOUT } from '@/shared/ui/editor-layout';
 
 export interface EditorPanelSizes {
   tools: number;
@@ -19,10 +20,45 @@ const DEFAULT_PANELS: EditorPanelSizes = {
   tools: 25,
   preview: 50,
   properties: 25,
-  mainContent: 50,
-  timeline: 50,
+  mainContent: 100 - EDITOR_LAYOUT.timelineDefaultSize,
+  timeline: EDITOR_LAYOUT.timelineDefaultSize,
 };
 
+/** The main/timeline split that version 1 of this store shipped with. */
+const V1_DEFAULT_SPLIT = { mainContent: 50, timeline: 50 };
+
+interface PersistedPanelLayout {
+  panels?: EditorPanelSizes;
+}
+
+/**
+ * Version 1 shipped a 50/50 main/timeline split. Layouts still sitting on
+ * that untouched default follow the new default from EDITOR_LAYOUT; anything
+ * the user resized themselves is left alone.
+ */
+export function migrateEditorPanelLayout(
+  persistedState: unknown,
+  version: number
+): PersistedPanelLayout {
+  const state = persistedState as PersistedPanelLayout;
+  if (version >= 2) return state;
+  if (
+    state?.panels &&
+    state.panels.mainContent === V1_DEFAULT_SPLIT.mainContent &&
+    state.panels.timeline === V1_DEFAULT_SPLIT.timeline
+  ) {
+    return {
+      ...state,
+      panels: {
+        ...state.panels,
+        mainContent: DEFAULT_PANELS.mainContent,
+        timeline: DEFAULT_PANELS.timeline,
+      },
+    };
+  }
+  return state;
+}
+
 interface EditorPanelLayoutState {
   panels: EditorPanelSizes;
   setPanel: (panel: EditorPanelId, size: number) => void;
@@ -44,8 +80,9 @@ export const useEditorPanelLayoutStore = create<EditorPanelLayoutState>()(
     }),
     {
       name: 'kubeez-editor-panel-sizes',
-      version: 1,
+      version: 2,
       partialize: (state) => ({ panels: state.panels }),
+      migrate: migrateEditorPanelLayout,
     }
   )
 );