diff --git a/src/generic/resizable/Resizable.test.tsx b/src/generic/resizable/Resizable.test.tsx
new file mode 100644
index 0000000000..446a65719b
--- /dev/null
+++ b/src/generic/resizable/Resizable.test.tsx
@@ -0,0 +1,89 @@
+import {
+  initializeMocks,
+  render,
+  screen,
+} from '@src/testUtils';
+
+import { ResizableBox } from './Resizable';
+
+describe('<ResizableBox>', () => {
+  beforeEach(() => {
+    initializeMocks();
+    window.localStorage.clear();
+  });
+
+  it('reads initial width from localStorage when storageKey is provided', () => {
+    window.localStorage.setItem('test-sidebar-width', JSON.stringify(600));
+
+    render(
+      <ResizableBox
+        data-testid="resizable-box"
+        storageKey="test-sidebar-width"
+        minWidth={400}
+        initialWidth={530}
+      >
+        <div>content</div>
+      </ResizableBox>,
+    );
+
+    const root = screen.getByTestId('resizable-box');
+    expect(root.getAttribute('style')).toContain('600px');
+  });
+
+  it('falls back to initialWidth when no localStorage value exists', () => {
+    render(
+      <ResizableBox
+        data-testid="resizable-box"
+        storageKey="test-sidebar-width"
+        minWidth={400}
+        initialWidth={530}
+      >
+        <div>content</div>
+      </ResizableBox>,
+    );
+
+    const root = screen.getByTestId('resizable-box');
+    expect(root.getAttribute('style')).toContain('530px');
+  });
+
+  it('falls back to minWidth when neither storageKey value nor initialWidth is set', () => {
+    render(
+      <ResizableBox data-testid="resizable-box" minWidth={400}>
+        <div>content</div>
+      </ResizableBox>,
+    );
+
+    const root = screen.getByTestId('resizable-box');
+    expect(root.getAttribute('style')).toContain('400px');
+  });
+
+  it('uses initialWidth when storageKey localStorage value is invalid', () => {
+    window.localStorage.setItem('test-sidebar-width', '"not-a-number"');
+
+    render(
+      <ResizableBox
+        data-testid="resizable-box"
+        storageKey="test-sidebar-width"
+        minWidth={400}
+        initialWidth={530}
+      >
+        <div>content</div>
+      </ResizableBox>,
+    );
+
+    const root = screen.getByTestId('resizable-box');
+    expect(root.getAttribute('style')).toContain('530px');
+  });
+
+  it('merges className onto the root element', () => {
+    render(
+      <ResizableBox data-testid="resizable-box" className="my-class" minWidth={400}>
+        <div>content</div>
+      </ResizableBox>,
+    );
+
+    const root = screen.getByTestId('resizable-box');
+    expect(root).toHaveClass('resizable');
+    expect(root).toHaveClass('my-class');
+  });
+});
diff --git a/src/generic/resizable/Resizable.tsx b/src/generic/resizable/Resizable.tsx
index adfe1606bb..114b368be1 100644
--- a/src/generic/resizable/Resizable.tsx
+++ b/src/generic/resizable/Resizable.tsx
@@ -1,8 +1,10 @@
 import { useWindowSize } from '@openedx/paragon';
+import classNames from 'classnames';
 import React, {
   useRef,
   useState,
   useCallback,
+  useEffect,
   useMemo,
 } from 'react';
 
@@ -12,6 +14,10 @@ interface ResizableBoxProps {
   children: React.ReactNode;
   minWidth?: number;
   maxWidth?: number;
+  initialWidth?: number;
+  storageKey?: string;
+  className?: string;
+  'data-testid'?: string;
 }
 
 /**
@@ -21,11 +27,31 @@ export const ResizableBox = ({
   children,
   minWidth = MIN_WIDTH,
   maxWidth,
+  initialWidth,
+  storageKey,
+  className,
+  'data-testid': dataTestId,
 }: ResizableBoxProps) => {
   const boxRef = useRef<HTMLDivElement>(null);
-  const [width, setWidth] = useState<number>(minWidth); // initial width
+  const [width, setWidth] = useState<number>(() => {
+    if (storageKey) {
+      const stored = window.localStorage.getItem(storageKey);
+      if (stored !== null) {
+        const parsed = Number(JSON.parse(stored));
+        if (Number.isFinite(parsed)) { return parsed; }
+      }
+    }
+    return initialWidth ?? minWidth;
+  });
   const { width: windowWidth } = useWindowSize();
 
+  // Persist width to localStorage when storageKey is set
+  useEffect(() => {
+    if (storageKey) {
+      window.localStorage.setItem(storageKey, JSON.stringify(width));
+    }
+  }, [storageKey, width]);
+
   // Store the start values while dragging
   const startXRef = useRef<number>(0);
   const startWidthRef = useRef<number>(0);
@@ -36,6 +62,11 @@ export const ResizableBox = ({
     return Math.abs(windowWidth * 0.65);
   }, [windowWidth]);
 
+  // Clamp width when constraints change (e.g. window resize)
+  useEffect(() => {
+    setWidth((w) => Math.min(Math.max(w, minWidth), maxWidth || defaultMaxWidth));
+  }, [minWidth, maxWidth, defaultMaxWidth]);
+
   const onMouseMove = useCallback((e: MouseEvent) => {
     const dx = e.clientX - startXRef.current; // positive = mouse moved right
     const newWidth = Math.min(
@@ -62,7 +93,8 @@ export const ResizableBox = ({
 
   return (
     <div
-      className="resizable"
+      className={classNames('resizable', className)}
+      data-testid={dataTestId}
       ref={boxRef}
       style={{ width: `${width}px` }}
     >
diff --git a/src/library-authoring/LibraryAuthoringPage.scss b/src/library-authoring/LibraryAuthoringPage.scss
index 5f0ceb7881..9f5454a467 100644
--- a/src/library-authoring/LibraryAuthoringPage.scss
+++ b/src/library-authoring/LibraryAuthoringPage.scss
@@ -13,12 +13,16 @@
 
 .library-authoring-sidebar {
   z-index: 1000; // same as header
-  flex: 530px 0 0;
+  flex: 0 0 auto;
   position: sticky;
   top: 0;
   right: 0;
   height: 100vh;
-  overflow-y: auto;
+
+  > .w-100 {
+    height: 100%;
+    overflow-y: auto;
+  }
 }
 
 .dropdown-menu {
diff --git a/src/library-authoring/LibraryAuthoringPage.tsx b/src/library-authoring/LibraryAuthoringPage.tsx
index 29f71acfaf..e169cd5c1d 100644
--- a/src/library-authoring/LibraryAuthoringPage.tsx
+++ b/src/library-authoring/LibraryAuthoringPage.tsx
@@ -41,7 +41,7 @@ import { MainFilters } from '@src/library-authoring/library-filters/MainFilters'
 import { useMultiLibraryContext } from '@src/library-authoring/common/context/MultiLibraryContext';
 import { usePublishedFilterContext } from '@src/library-authoring/common/context/PublishedFilterContext';
 import LibraryContent from './LibraryContent';
-import { LibrarySidebar } from './library-sidebar';
+import { LibrarySidebarPanel } from './library-sidebar';
 import { useComponentPickerContext } from './common/context/ComponentPickerContext';
 import { useOptionalLibraryContext } from './common/context/LibraryContext';
 import { SidebarBodyItemId, useSidebarContext } from './common/context/SidebarContext';
@@ -404,11 +404,7 @@ const LibraryAuthoringPage = ({
         </Container>
         {!componentPickerMode && <StudioFooterSlot containerProps={{ size: undefined }} />}
       </div>
-      {!!sidebarItemInfo?.type && (
-        <div className="library-authoring-sidebar box-shadow-left-1 bg-white" data-testid="library-sidebar">
-          <LibrarySidebar />
-        </div>
-      )}
+      {!!sidebarItemInfo?.type && <LibrarySidebarPanel />}
     </div>
   );
 };
diff --git a/src/library-authoring/collections/LibraryCollectionPage.tsx b/src/library-authoring/collections/LibraryCollectionPage.tsx
index 2b482a2a66..ab53daa77b 100644
--- a/src/library-authoring/collections/LibraryCollectionPage.tsx
+++ b/src/library-authoring/collections/LibraryCollectionPage.tsx
@@ -33,7 +33,7 @@ import { useComponentPickerContext } from '../common/context/ComponentPickerCont
 import { useOptionalLibraryContext } from '../common/context/LibraryContext';
 import { SidebarBodyItemId, useSidebarContext } from '../common/context/SidebarContext';
 import messages from './messages';
-import { LibrarySidebar } from '../library-sidebar';
+import { LibrarySidebarPanel } from '../library-sidebar';
 import LibraryCollectionComponents from './LibraryCollectionComponents';
 import LibraryFilterByPublished from '../generic/filter-by-published';
 
@@ -236,11 +236,7 @@ const LibraryCollectionPage = () => {
         </Container>
         {!componentPickerMode && <StudioFooterSlot containerProps={{ size: undefined }} />}
       </div>
-      {!!sidebarItemInfo?.type && (
-        <div className="library-authoring-sidebar box-shadow-left-1 bg-white" data-testid="library-sidebar">
-          <LibrarySidebar />
-        </div>
-      )}
+      {!!sidebarItemInfo?.type && <LibrarySidebarPanel />}
     </div>
   );
 };
diff --git a/src/library-authoring/library-sidebar/LibrarySidebarPanel.tsx b/src/library-authoring/library-sidebar/LibrarySidebarPanel.tsx
new file mode 100644
index 0000000000..ada38cbabb
--- /dev/null
+++ b/src/library-authoring/library-sidebar/LibrarySidebarPanel.tsx
@@ -0,0 +1,15 @@
+import { ResizableBox } from '@src/generic/resizable/Resizable';
+
+import { LibrarySidebar } from '.';
+
+export const LibrarySidebarPanel = () => (
+  <ResizableBox
+    className="library-authoring-sidebar box-shadow-left-1 bg-white"
+    data-testid="library-sidebar"
+    storageKey="library-authoring-sidebar-width"
+    initialWidth={530}
+    minWidth={400}
+  >
+    <LibrarySidebar />
+  </ResizableBox>
+);
diff --git a/src/library-authoring/library-sidebar/index.ts b/src/library-authoring/library-sidebar/index.ts
index 36d2d4a760..55fefea3d1 100644
--- a/src/library-authoring/library-sidebar/index.ts
+++ b/src/library-authoring/library-sidebar/index.ts
@@ -1 +1,2 @@
 export { default as LibrarySidebar } from './LibrarySidebar';
+export { LibrarySidebarPanel } from './LibrarySidebarPanel';
diff --git a/src/library-authoring/section-subsections/LibrarySectionPage.tsx b/src/library-authoring/section-subsections/LibrarySectionPage.tsx
index bb2b488d5b..3cc8c0df5a 100644
--- a/src/library-authoring/section-subsections/LibrarySectionPage.tsx
+++ b/src/library-authoring/section-subsections/LibrarySectionPage.tsx
@@ -13,7 +13,7 @@ import Header from '../../header';
 import SubHeader from '../../generic/sub-header/SubHeader';
 import { SubHeaderTitle } from '../LibraryAuthoringPage';
 import { messages, sectionMessages } from './messages';
-import { LibrarySidebar } from '../library-sidebar';
+import { LibrarySidebarPanel } from '../library-sidebar';
 import { LibraryContainerChildren } from './LibraryContainerChildren';
 import { ContainerEditableTitle, FooterActions, HeaderActions } from '../containers';
 
@@ -114,14 +114,7 @@ export const LibrarySectionPage = () => {
           </Container>
         </Container>
       </div>
-      {!!sidebarItemInfo?.type && (
-        <div
-          className="library-authoring-sidebar box-shadow-left-1 bg-white"
-          data-testid="library-sidebar"
-        >
-          <LibrarySidebar />
-        </div>
-      )}
+      {!!sidebarItemInfo?.type && <LibrarySidebarPanel />}
     </div>
   );
 };
diff --git a/src/library-authoring/section-subsections/LibrarySubsectionPage.tsx b/src/library-authoring/section-subsections/LibrarySubsectionPage.tsx
index de5e525c5d..034dfe40eb 100644
--- a/src/library-authoring/section-subsections/LibrarySubsectionPage.tsx
+++ b/src/library-authoring/section-subsections/LibrarySubsectionPage.tsx
@@ -14,7 +14,7 @@ import Header from '../../header';
 import SubHeader from '../../generic/sub-header/SubHeader';
 import { SubHeaderTitle } from '../LibraryAuthoringPage';
 import { subsectionMessages } from './messages';
-import { LibrarySidebar } from '../library-sidebar';
+import { LibrarySidebarPanel } from '../library-sidebar';
 import { ParentBreadcrumbs } from '../generic/parent-breadcrumbs';
 import { LibraryContainerChildren } from './LibraryContainerChildren';
 import { ContainerEditableTitle, FooterActions, HeaderActions } from '../containers';
@@ -104,14 +104,7 @@ export const LibrarySubsectionPage = () => {
           </Container>
         </Container>
       </div>
-      {!!sidebarItemInfo?.type && (
-        <div
-          className="library-authoring-sidebar box-shadow-left-1 bg-white"
-          data-testid="library-sidebar"
-        >
-          <LibrarySidebar />
-        </div>
-      )}
+      {!!sidebarItemInfo?.type && <LibrarySidebarPanel />}
     </div>
   );
 };
diff --git a/src/library-authoring/units/LibraryUnitPage.tsx b/src/library-authoring/units/LibraryUnitPage.tsx
index 83de6f55a6..b6123b4224 100644
--- a/src/library-authoring/units/LibraryUnitPage.tsx
+++ b/src/library-authoring/units/LibraryUnitPage.tsx
@@ -13,7 +13,7 @@ import Header from '../../header';
 import { useLibraryContext } from '../common/context/LibraryContext';
 import { useSidebarContext } from '../common/context/SidebarContext';
 import { useContentFromSearchIndex, useContentLibrary } from '../data/apiHooks';
-import { LibrarySidebar } from '../library-sidebar';
+import { LibrarySidebarPanel } from '../library-sidebar';
 import { ParentBreadcrumbs } from '../generic/parent-breadcrumbs';
 import { SubHeaderTitle } from '../LibraryAuthoringPage';
 import { LibraryUnitBlocks } from './LibraryUnitBlocks';
@@ -108,14 +108,7 @@ export const LibraryUnitPage = () => {
           </Container>
         </Container>
       </div>
-      {!!sidebarItemInfo?.type && (
-        <div
-          className="library-authoring-sidebar box-shadow-left-1 bg-white"
-          data-testid="library-sidebar"
-        >
-          <LibrarySidebar />
-        </div>
-      )}
+      {!!sidebarItemInfo?.type && <LibrarySidebarPanel />}
     </div>
   );
 };