diff --git a/components/calendar/calendar-app.tsx b/components/calendar/calendar-app.tsx
index 141702b6d..2222e5013 100644
--- a/components/calendar/calendar-app.tsx
+++ b/components/calendar/calendar-app.tsx
@@ -2201,6 +2201,10 @@ export function CalendarApp({ linkSegments: routeSegments }: CalendarAppProps =
           </div>
           {!isNarrow && (
             <ResizeHandle
+              pane="sidebar"
+              value={calSidebarWidth}
+              min={180}
+              max={400}
               onResizeStart={() => { dragStartWidth.current = calSidebarWidth; setIsResizing(true); }}
               onResize={(delta) => setCalSidebarWidth(Math.max(180, Math.min(400, dragStartWidth.current + delta)))}
               onResizeEnd={() => {
diff --git a/components/contacts/contacts-app.tsx b/components/contacts/contacts-app.tsx
index 2897db310..a71b95046 100644
--- a/components/contacts/contacts-app.tsx
+++ b/components/contacts/contacts-app.tsx
@@ -1275,6 +1275,10 @@ function ContactsAppContent({ linkSegments: routeSegments }: ContactsAppProps =
                   </div>
                   {!isNarrow && (
                     <ResizeHandle
+                      pane="sidebar"
+                      value={sidebarWidth}
+                      min={180}
+                      max={400}
                       onResizeStart={() => { sidebarDragStartWidth.current = sidebarWidth; setIsSidebarResizing(true); }}
                       onResize={(delta) => setSidebarWidth(Math.max(180, Math.min(400, sidebarDragStartWidth.current + delta)))}
                       onResizeEnd={() => {
@@ -1390,6 +1394,10 @@ function ContactsAppContent({ linkSegments: routeSegments }: ContactsAppProps =
 
               {!isMobile && (
                 <ResizeHandle
+                  pane="contactList"
+                  value={listWidth}
+                  min={220}
+                  max={500}
                   onResizeStart={() => { listDragStartWidth.current = listWidth; setIsListResizing(true); }}
                   onResize={(delta) => setListWidth(Math.max(220, Math.min(500, listDragStartWidth.current + delta)))}
                   onResizeEnd={() => {
diff --git a/components/email/composer-plugin-sidebars.tsx b/components/email/composer-plugin-sidebars.tsx
index 25360fd45..b3ba0beda 100644
--- a/components/email/composer-plugin-sidebars.tsx
+++ b/components/email/composer-plugin-sidebars.tsx
@@ -242,6 +242,10 @@ export function ComposerPluginSidebar({
   const handle = mode === "docked" && onWidthChange ? (
     <ResizeHandle
       testId={`composer-sidebar-resize-${side}`}
+      pane="sidePanel"
+      value={width}
+      min={MIN_COMPOSER_SIDEBAR_WIDTH}
+      max={MAX_COMPOSER_SIDEBAR_WIDTH}
       className="hidden md:block"
       onResizeStart={() => { dragStart.current = width; }}
       onResize={(delta) => onWidthChange(dragStart.current + (side === "left" ? delta : -delta))}
diff --git a/components/email/email-viewer.tsx b/components/email/email-viewer.tsx
index e11f183d6..45302a079 100644
--- a/components/email/email-viewer.tsx
+++ b/components/email/email-viewer.tsx
@@ -3866,6 +3866,10 @@ export function EmailViewer({
           <>
             {!sidebarOverlay && (
               <ResizeHandle
+                pane="sidePanel"
+                value={detailSidebarWidth}
+                min={200}
+                max={500}
                 onResizeStart={() => { detailSidebarWidthRef.current = detailSidebarWidth; }}
                 onResize={(delta) => {
                   const newWidth = Math.max(200, Math.min(500, detailSidebarWidthRef.current - delta));
diff --git a/components/files/file-browser.tsx b/components/files/file-browser.tsx
index bdb3930db..ebd46612b 100644
--- a/components/files/file-browser.tsx
+++ b/components/files/file-browser.tsx
@@ -1221,6 +1221,10 @@ export function FileBrowser({
             {sidebar}
           </div>
           <ResizeHandle
+            pane="sidebar"
+            value={sidebarWidth}
+            min={180}
+            max={400}
             onResizeStart={() => { dragStartWidth.current = sidebarWidth; setIsResizing(true); }}
             onResize={(delta) => setSidebarWidth(Math.max(180, Math.min(400, dragStartWidth.current + delta)))}
             onResizeEnd={() => {
diff --git a/components/layout/__tests__/resize-handle.test.tsx b/components/layout/__tests__/resize-handle.test.tsx
index fb542a472..c56401daa 100644
--- a/components/layout/__tests__/resize-handle.test.tsx
+++ b/components/layout/__tests__/resize-handle.test.tsx
@@ -1,7 +1,26 @@
 import { describe, it, expect, vi } from 'vitest';
-import { render, fireEvent } from '@testing-library/react';
+import { useRef, useState } from 'react';
+import { render, fireEvent, act } from '@testing-library/react';
 import { ResizeHandle } from '../resize-handle';
 
+/** A pane whose width the handle changes, as the apps wire it up. */
+function Pane({ onSave }: { onSave: (width: number) => void }) {
+  const [width, setWidth] = useState(200);
+  const start = useRef(width);
+  return (
+    <ResizeHandle
+      pane="sidebar"
+      value={width}
+      min={180}
+      max={400}
+      onResizeStart={() => { start.current = width; }}
+      onResize={(delta) => setWidth(Math.max(180, Math.min(400, start.current + delta)))}
+      onResizeEnd={() => onSave(width)}
+    />
+  );
+}
+
+
 describe('ResizeHandle', () => {
   it('should render with separator role', () => {
     const { getByRole } = render(
@@ -14,7 +33,7 @@ describe('ResizeHandle', () => {
   });
 
   describe('keyboard interaction', () => {
-    it('should call onResize with negative delta on ArrowLeft', () => {
+    it('should call onResize with negative delta on ArrowLeft', async () => {
       const onResize = vi.fn();
       const onResizeEnd = vi.fn();
       const { getByRole } = render(
@@ -23,10 +42,11 @@ describe('ResizeHandle', () => {
       const handle = getByRole('separator');
       fireEvent.keyDown(handle, { key: 'ArrowLeft' });
       expect(onResize).toHaveBeenCalledWith(-10);
+      await act(async () => {});
       expect(onResizeEnd).toHaveBeenCalled();
     });
 
-    it('should call onResize with positive delta on ArrowRight', () => {
+    it('should call onResize with positive delta on ArrowRight', async () => {
       const onResize = vi.fn();
       const onResizeEnd = vi.fn();
       const { getByRole } = render(
@@ -35,6 +55,7 @@ describe('ResizeHandle', () => {
       const handle = getByRole('separator');
       fireEvent.keyDown(handle, { key: 'ArrowRight' });
       expect(onResize).toHaveBeenCalledWith(10);
+      await act(async () => {});
       expect(onResizeEnd).toHaveBeenCalled();
     });
 
@@ -49,6 +70,58 @@ describe('ResizeHandle', () => {
       fireEvent.keyDown(handle, { key: 'a' });
       expect(onResize).not.toHaveBeenCalled();
     });
+
+    it('should keep the arrows away from the mail shortcuts on the window', () => {
+      const shortcuts = vi.fn();
+      window.addEventListener('keydown', shortcuts);
+      try {
+        const { getAllByRole } = render(
+          <>
+            <ResizeHandle orientation="horizontal" onResize={vi.fn()} />
+            <ResizeHandle onResize={vi.fn()} />
+          </>
+        );
+        const [horizontal, vertical] = getAllByRole('separator');
+        fireEvent.keyDown(horizontal, { key: 'ArrowDown' });
+        fireEvent.keyDown(horizontal, { key: 'ArrowUp' });
+        fireEvent.keyDown(vertical, { key: 'ArrowLeft' });
+        expect(shortcuts).not.toHaveBeenCalled();
+        // Keys the handle doesn't use still reach them.
+        fireEvent.keyDown(vertical, { key: 'j' });
+        expect(shortcuts).toHaveBeenCalledOnce();
+      } finally {
+        window.removeEventListener('keydown', shortcuts);
+      }
+    });
+
+    it('should step from the current width on every press and save the new one', async () => {
+      const onSave = vi.fn();
+      const { getByRole } = render(<Pane onSave={onSave} />);
+      const handle = getByRole('separator');
+      fireEvent.keyDown(handle, { key: 'ArrowRight' });
+      await act(async () => {});
+      fireEvent.keyDown(handle, { key: 'ArrowRight' });
+      await act(async () => {});
+      expect(handle).toHaveAttribute('aria-valuenow', '220');
+      expect(onSave).toHaveBeenLastCalledWith(220);
+    });
+  });
+
+  describe('name and value', () => {
+    it('should say which pane it resizes and how wide it is', () => {
+      const { getByRole } = render(<Pane onSave={vi.fn()} />);
+      const handle = getByRole('separator', { name: 'resize_sidebar' });
+      expect(handle).toHaveAttribute('aria-valuenow', '200');
+      expect(handle).toHaveAttribute('aria-valuemin', '180');
+      expect(handle).toHaveAttribute('aria-valuemax', '400');
+    });
+
+    it('should fall back to a plain name and no value', () => {
+      const { getByRole } = render(<ResizeHandle onResize={vi.fn()} />);
+      const handle = getByRole('separator');
+      expect(handle).toHaveAccessibleName('resize');
+      expect(handle).not.toHaveAttribute('aria-valuenow');
+    });
   });
 
   describe('double-click', () => {
diff --git a/components/layout/resize-handle.tsx b/components/layout/resize-handle.tsx
index 33e853d90..27a23128a 100644
--- a/components/layout/resize-handle.tsx
+++ b/components/layout/resize-handle.tsx
@@ -13,11 +13,33 @@ interface ResizeHandleProps {
   className?: string;
   /** Stable hook for tests (not user-visible). */
   testId?: string;
+  /**
+   * The pane the handle resizes, which names it for screen readers
+   * ("Resize message list"). Without it the name is a plain "Resize".
+   */
+  pane?: ResizePane;
+  /**
+   * The size of the pane it resizes, in px, and the limits of that size. A
+   * focusable separator must expose its value (WCAG 4.1.2), so screen
+   * readers say how wide the pane is now and how far it can go.
+   */
+  value?: number;
+  min?: number;
+  max?: number;
 }
 
 const KEYBOARD_STEP = 10;
 
-export function ResizeHandle({ onResizeStart, onResize, onResizeEnd, onDoubleClick, orientation = "vertical", className, testId }: ResizeHandleProps) {
+export type ResizePane = "sidebar" | "messageList" | "contactList" | "sidePanel";
+
+const PANE_LABEL_KEYS: Record<ResizePane, string> = {
+  sidebar: "resize_sidebar",
+  messageList: "resize_message_list",
+  contactList: "resize_contact_list",
+  sidePanel: "resize_side_panel",
+};
+
+export function ResizeHandle({ onResizeStart, onResize, onResizeEnd, onDoubleClick, orientation = "vertical", className, testId, pane, value, min, max }: ResizeHandleProps) {
   const t = useTranslations("shell");
   const handleRef = useRef<HTMLDivElement>(null);
   // Id of the pointer that started the drag, or null when idle. Only that
@@ -76,9 +98,17 @@ export function ResizeHandle({ onResizeStart, onResize, onResizeEnd, onDoubleCli
       else return;
     }
     e.preventDefault();
-    onResize(delta);
-    onResizeEnd?.();
-  }, [onResize, onResizeEnd, isHorizontal]);
+    // The arrows belong to the handle: the mail shortcuts listen on the
+    // window and would otherwise also move the selection.
+    e.stopPropagation();
+    // Each step starts from the size the pane has now, as a drag does;
+    // without the start every press moved from the same old width.
+    callbacks.current.onResizeStart?.();
+    callbacks.current.onResize(delta);
+    // The end runs after the new size has rendered, so a caller that saves
+    // the size in its end callback saves this step and not the last one.
+    queueMicrotask(() => callbacks.current.onResizeEnd?.());
+  }, [isHorizontal]);
 
   useEffect(() => {
     const handlePointerMove = (e: PointerEvent) => {
@@ -122,7 +152,10 @@ export function ResizeHandle({ onResizeStart, onResize, onResizeEnd, onDoubleCli
       ref={handleRef}
       role="separator"
       aria-orientation={isHorizontal ? "horizontal" : "vertical"}
-      aria-label={t("resize")}
+      aria-label={t(pane ? PANE_LABEL_KEYS[pane] : "resize")}
+      aria-valuenow={value === undefined ? undefined : Math.round(value)}
+      aria-valuemin={value === undefined ? undefined : min}
+      aria-valuemax={value === undefined ? undefined : max}
       data-testid={testId}
       tabIndex={0}
       onPointerDown={handlePointerDown}
diff --git a/components/mail/mail-app.tsx b/components/mail/mail-app.tsx
index c585e289b..cb032cdd1 100644
--- a/components/mail/mail-app.tsx
+++ b/components/mail/mail-app.tsx
@@ -57,7 +57,7 @@ import { useSettingsStore } from "@/stores/settings-store";
 import { useEffectiveMailLayout } from "@/hooks/use-effective-mail-layout";
 import { useContactStore } from "@/stores/contact-store";
 import { useIdentityStore } from "@/stores/identity-store";
-import { useUIStore } from "@/stores/ui-store";
+import { useUIStore, SIDEBAR_MIN, SIDEBAR_MAX, EMAIL_LIST_MIN, EMAIL_LIST_MAX, EMAIL_LIST_HEIGHT_MIN, EMAIL_LIST_HEIGHT_MAX } from "@/stores/ui-store";
 import { useDeviceDetection } from "@/hooks/use-media-query";
 import { usePaneSize } from "@/hooks/use-pane-size";
 import { usePaneId } from "@/hooks/use-pane-context";
@@ -4922,6 +4922,10 @@ export function MailApp({ linkSegments: routeSegments }: MailAppProps = {}) {
             absent under Mountain View, whose navigation has a fixed width) */}
         {!isMobile && !isTablet && !sidebarCollapsed && !inlineApp && !fullscreenReading && !mvShell && (
           <ResizeHandle
+            pane="sidebar"
+            value={sidebarWidth}
+            min={SIDEBAR_MIN}
+            max={SIDEBAR_MAX}
             onResizeStart={() => { dragStartWidth.current = sidebarWidth; setIsResizing(true); }}
             onResize={(delta) => setSidebarWidth(dragStartWidth.current + delta)}
             onResizeEnd={() => { setIsResizing(false); persistColumnWidths(); }}
@@ -5345,6 +5349,10 @@ export function MailApp({ linkSegments: routeSegments }: MailAppProps = {}) {
           {/* Email list resize handle (desktop only) */}
           {!isMobile && !isTablet && !isFocusedMailLayout && !isHorizontalMailLayout && !shouldHideViewerPane && !fullscreenReading && (
             <ResizeHandle
+              pane="messageList"
+              value={emailListWidth}
+              min={EMAIL_LIST_MIN}
+              max={EMAIL_LIST_MAX}
               onResizeStart={() => { dragStartWidth.current = emailListWidth; setIsResizing(true); }}
               onResize={(delta) => setEmailListWidth(dragStartWidth.current + delta)}
               onResizeEnd={() => { setIsResizing(false); persistColumnWidths(); }}
@@ -5354,6 +5362,10 @@ export function MailApp({ linkSegments: routeSegments }: MailAppProps = {}) {
           {!isMobile && !isTablet && isHorizontalMailLayout && !shouldHideHorizontalViewerPane && !fullscreenReading && (
             <ResizeHandle
               orientation="horizontal"
+              pane="messageList"
+              value={emailListHeight}
+              min={EMAIL_LIST_HEIGHT_MIN}
+              max={EMAIL_LIST_HEIGHT_MAX}
               onResizeStart={() => { dragStartWidth.current = emailListHeight; setIsResizing(true); }}
               onResize={(delta) => setEmailListHeight(dragStartWidth.current + delta)}
               onResizeEnd={() => { setIsResizing(false); persistColumnWidths(); }}
diff --git a/components/settings/settings-app.tsx b/components/settings/settings-app.tsx
index a0c92051b..79b6e25b6 100644
--- a/components/settings/settings-app.tsx
+++ b/components/settings/settings-app.tsx
@@ -1188,6 +1188,10 @@ export function SettingsApp({ linkSegments: routeSegments }: SettingsAppProps =
       </div>
 
       <ResizeHandle
+        pane="sidebar"
+        value={settingsSidebarWidth}
+        min={180}
+        max={400}
         onResizeStart={() => { dragStartWidth.current = settingsSidebarWidth; setIsResizing(true); }}
         onResize={(delta) => setSettingsSidebarWidth(Math.max(180, Math.min(400, dragStartWidth.current + delta)))}
         onResizeEnd={() => {
diff --git a/locales/ar/common.json b/locales/ar/common.json
index 2bfb3644d..2afaaa776 100644
--- a/locales/ar/common.json
+++ b/locales/ar/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "جزء القراءة",
     "name_unread": "{name}، {count} غير مقروءة",
     "expand_folder": "توسيع {name}",
-    "collapse_folder": "طي {name}"
+    "collapse_folder": "طي {name}",
+    "resize_sidebar": "تغيير حجم الشريط الجانبي",
+    "resize_message_list": "تغيير حجم قائمة الرسائل",
+    "resize_contact_list": "تغيير حجم قائمة جهات الاتصال",
+    "resize_side_panel": "تغيير حجم اللوحة الجانبية"
   },
   "plugin_pages": {
     "loading": "جارٍ تحميل الصفحة",
diff --git a/locales/ca/common.json b/locales/ca/common.json
index e11033a56..4c0fb7e99 100644
--- a/locales/ca/common.json
+++ b/locales/ca/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Panell de lectura",
     "name_unread": "{name}, {count} sense llegir",
     "expand_folder": "Desplega {name}",
-    "collapse_folder": "Plega {name}"
+    "collapse_folder": "Plega {name}",
+    "resize_sidebar": "Canvia la mida de la barra lateral",
+    "resize_message_list": "Canvia la mida de la llista de missatges",
+    "resize_contact_list": "Canvia la mida de la llista de contactes",
+    "resize_side_panel": "Canvia la mida del tauler lateral"
   },
   "plugin_pages": {
     "loading": "S'està carregant la pàgina",
diff --git a/locales/cs/common.json b/locales/cs/common.json
index 301602661..579e42ab3 100644
--- a/locales/cs/common.json
+++ b/locales/cs/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Podokno čtení",
     "name_unread": "{name}, Nepřečteno: {count}",
     "expand_folder": "Rozbalit {name}",
-    "collapse_folder": "Sbalit {name}"
+    "collapse_folder": "Sbalit {name}",
+    "resize_sidebar": "Změnit velikost postranního panelu",
+    "resize_message_list": "Změnit velikost seznamu zpráv",
+    "resize_contact_list": "Změnit velikost seznamu kontaktů",
+    "resize_side_panel": "Změnit velikost bočního panelu"
   },
   "plugin_pages": {
     "loading": "Načítání stránky",
diff --git a/locales/da/common.json b/locales/da/common.json
index 7a205874d..b73ce0d33 100644
--- a/locales/da/common.json
+++ b/locales/da/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Læserude",
     "name_unread": "{name}, {count} ulæste",
     "expand_folder": "Udvid {name}",
-    "collapse_folder": "Skjul {name}"
+    "collapse_folder": "Skjul {name}",
+    "resize_sidebar": "Tilpas størrelsen på sidepanelet",
+    "resize_message_list": "Tilpas størrelsen på meddelelseslisten",
+    "resize_contact_list": "Tilpas størrelsen på kontaktlisten",
+    "resize_side_panel": "Tilpas størrelsen på sideruden"
   },
   "plugin_pages": {
     "loading": "Indlæser side",
diff --git a/locales/de/common.json b/locales/de/common.json
index aaadafb08..6eb98b898 100644
--- a/locales/de/common.json
+++ b/locales/de/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Lesebereich",
     "name_unread": "{name}, {count} ungelesen",
     "expand_folder": "{name} aufklappen",
-    "collapse_folder": "{name} zuklappen"
+    "collapse_folder": "{name} zuklappen",
+    "resize_sidebar": "Größe der Seitenleiste ändern",
+    "resize_message_list": "Größe der Nachrichtenliste ändern",
+    "resize_contact_list": "Größe der Kontaktliste ändern",
+    "resize_side_panel": "Größe des Seitenbereichs ändern"
   },
   "plugin_pages": {
     "loading": "Seite wird geladen",
diff --git a/locales/en/common.json b/locales/en/common.json
index c5bbb41f4..54530c04b 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Reading pane",
     "name_unread": "{name}, {count} unread",
     "expand_folder": "Expand {name}",
-    "collapse_folder": "Collapse {name}"
+    "collapse_folder": "Collapse {name}",
+    "resize_sidebar": "Resize sidebar",
+    "resize_message_list": "Resize message list",
+    "resize_contact_list": "Resize contact list",
+    "resize_side_panel": "Resize side panel"
   },
   "plugin_pages": {
     "loading": "Loading page",
diff --git a/locales/es/common.json b/locales/es/common.json
index dad54c55d..f09fc04ad 100644
--- a/locales/es/common.json
+++ b/locales/es/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Panel de lectura",
     "name_unread": "{name}, {count} sin leer",
     "expand_folder": "Expandir {name}",
-    "collapse_folder": "Contraer {name}"
+    "collapse_folder": "Contraer {name}",
+    "resize_sidebar": "Cambiar el tamaño de la barra lateral",
+    "resize_message_list": "Cambiar el tamaño de la lista de mensajes",
+    "resize_contact_list": "Cambiar el tamaño de la lista de contactos",
+    "resize_side_panel": "Cambiar el tamaño del panel lateral"
   },
   "plugin_pages": {
     "loading": "Cargando la página",
diff --git a/locales/et/common.json b/locales/et/common.json
index fff787ecd..0654a9e34 100644
--- a/locales/et/common.json
+++ b/locales/et/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Lugemispaan",
     "name_unread": "{name}, Lugemata: {count}",
     "expand_folder": "Laienda {name}",
-    "collapse_folder": "Ahenda {name}"
+    "collapse_folder": "Ahenda {name}",
+    "resize_sidebar": "Muuda külgriba suurust",
+    "resize_message_list": "Muuda kirjade loendi suurust",
+    "resize_contact_list": "Muuda kontaktide loendi suurust",
+    "resize_side_panel": "Muuda külgpaneeli suurust"
   },
   "plugin_pages": {
     "loading": "Lehe laadimine",
diff --git a/locales/fa/common.json b/locales/fa/common.json
index b538ae258..aa5da3ef8 100644
--- a/locales/fa/common.json
+++ b/locales/fa/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "قاب خواندن",
     "name_unread": "{name}، {count} خوانده‌نشده",
     "expand_folder": "باز کردن {name}",
-    "collapse_folder": "بستن {name}"
+    "collapse_folder": "بستن {name}",
+    "resize_sidebar": "تغییر اندازه نوار کناری",
+    "resize_message_list": "تغییر اندازه فهرست پیام‌ها",
+    "resize_contact_list": "تغییر اندازه فهرست مخاطبین",
+    "resize_side_panel": "تغییر اندازه پنل کناری"
   },
   "plugin_pages": {
     "loading": "در حال بارگذاری صفحه",
diff --git a/locales/fr/common.json b/locales/fr/common.json
index 0dac58ed2..bfa341651 100644
--- a/locales/fr/common.json
+++ b/locales/fr/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Volet de lecture",
     "name_unread": "{name}, {count} non lus",
     "expand_folder": "Développer {name}",
-    "collapse_folder": "Réduire {name}"
+    "collapse_folder": "Réduire {name}",
+    "resize_sidebar": "Redimensionner la barre latérale",
+    "resize_message_list": "Redimensionner la liste des messages",
+    "resize_contact_list": "Redimensionner la liste des contacts",
+    "resize_side_panel": "Redimensionner le panneau latéral"
   },
   "plugin_pages": {
     "loading": "Chargement de la page",
diff --git a/locales/he/common.json b/locales/he/common.json
index 8d1c7eb2c..f93a0aeb9 100644
--- a/locales/he/common.json
+++ b/locales/he/common.json
@@ -5722,7 +5722,11 @@
     "reading_pane": "חלונית קריאה",
     "name_unread": "{name}, {count} שלא נקראו",
     "expand_folder": "הרחב את {name}",
-    "collapse_folder": "כווץ את {name}"
+    "collapse_folder": "כווץ את {name}",
+    "resize_sidebar": "שינוי גודל סרגל הצד",
+    "resize_message_list": "שינוי גודל רשימת ההודעות",
+    "resize_contact_list": "שינוי גודל רשימת אנשי הקשר",
+    "resize_side_panel": "שינוי גודל החלונית הצדדית"
   },
   "plugin_pages": {
     "loading": "טוען את הדף",
diff --git a/locales/hu/common.json b/locales/hu/common.json
index c60fc6bdd..fde8f77d1 100644
--- a/locales/hu/common.json
+++ b/locales/hu/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Olvasóablak",
     "name_unread": "{name}, {count} olvasatlan",
     "expand_folder": "{name} kibontása",
-    "collapse_folder": "{name} összecsukása"
+    "collapse_folder": "{name} összecsukása",
+    "resize_sidebar": "Oldalsáv átméretezése",
+    "resize_message_list": "Üzenetlista átméretezése",
+    "resize_contact_list": "Névjegylista átméretezése",
+    "resize_side_panel": "Oldalpanel átméretezése"
   },
   "plugin_pages": {
     "loading": "Oldal betöltése",
diff --git a/locales/it/common.json b/locales/it/common.json
index 7839786ec..95aa4c7d1 100644
--- a/locales/it/common.json
+++ b/locales/it/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Riquadro di lettura",
     "name_unread": "{name}, {count} non letti",
     "expand_folder": "Espandi {name}",
-    "collapse_folder": "Comprimi {name}"
+    "collapse_folder": "Comprimi {name}",
+    "resize_sidebar": "Ridimensiona la barra laterale",
+    "resize_message_list": "Ridimensiona l'elenco dei messaggi",
+    "resize_contact_list": "Ridimensiona l'elenco dei contatti",
+    "resize_side_panel": "Ridimensiona il pannello laterale"
   },
   "plugin_pages": {
     "loading": "Caricamento della pagina",
diff --git a/locales/ja/common.json b/locales/ja/common.json
index 293b5f12b..fceedd5ee 100644
--- a/locales/ja/common.json
+++ b/locales/ja/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "閲覧ウィンドウ",
     "name_unread": "{name}、未読 {count} 件",
     "expand_folder": "{name}を展開",
-    "collapse_folder": "{name}を折りたたむ"
+    "collapse_folder": "{name}を折りたたむ",
+    "resize_sidebar": "サイドバーのサイズを変更",
+    "resize_message_list": "メッセージ一覧のサイズを変更",
+    "resize_contact_list": "連絡先一覧のサイズを変更",
+    "resize_side_panel": "サイドパネルのサイズを変更"
   },
   "plugin_pages": {
     "loading": "ページを読み込んでいます",
diff --git a/locales/ko/common.json b/locales/ko/common.json
index f80a3fb83..f35078345 100644
--- a/locales/ko/common.json
+++ b/locales/ko/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "읽기 창",
     "name_unread": "{name}, 읽지 않음 {count}개",
     "expand_folder": "{name} 펼치기",
-    "collapse_folder": "{name} 접기"
+    "collapse_folder": "{name} 접기",
+    "resize_sidebar": "사이드바 크기 조정",
+    "resize_message_list": "메시지 목록 크기 조정",
+    "resize_contact_list": "연락처 목록 크기 조정",
+    "resize_side_panel": "사이드 패널 크기 조정"
   },
   "plugin_pages": {
     "loading": "페이지를 불러오는 중",
diff --git a/locales/lv/common.json b/locales/lv/common.json
index d0a34577f..cac59364a 100644
--- a/locales/lv/common.json
+++ b/locales/lv/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Lasīšanas rūts",
     "name_unread": "{name}, Nelasīti: {count}",
     "expand_folder": "Izvērst {name}",
-    "collapse_folder": "Sakļaut {name}"
+    "collapse_folder": "Sakļaut {name}",
+    "resize_sidebar": "Mainīt sānjoslas izmēru",
+    "resize_message_list": "Mainīt ziņojumu saraksta izmēru",
+    "resize_contact_list": "Mainīt kontaktu saraksta izmēru",
+    "resize_side_panel": "Mainīt sānu paneļa izmēru"
   },
   "plugin_pages": {
     "loading": "Ielādē lapu",
diff --git a/locales/mn/common.json b/locales/mn/common.json
index ad827e574..b51bfa446 100644
--- a/locales/mn/common.json
+++ b/locales/mn/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Унших хэсэг",
     "name_unread": "{name}, {count} уншаагүй",
     "expand_folder": "{name}-г дэлгэх",
-    "collapse_folder": "{name}-г хураах"
+    "collapse_folder": "{name}-г хураах",
+    "resize_sidebar": "Хажуугийн самбарын хэмжээг өөрчлөх",
+    "resize_message_list": "Захидлын жагсаалтын хэмжээг өөрчлөх",
+    "resize_contact_list": "Харилцагчдын жагсаалтын хэмжээг өөрчлөх",
+    "resize_side_panel": "Хажуугийн хэсгийн хэмжээг өөрчлөх"
   },
   "plugin_pages": {
     "loading": "Хуудсыг ачаалж байна",
diff --git a/locales/nb/common.json b/locales/nb/common.json
index b9e4c4348..d54a8dd8c 100644
--- a/locales/nb/common.json
+++ b/locales/nb/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Leserute",
     "name_unread": "{name}, {count} uleste",
     "expand_folder": "Utvid {name}",
-    "collapse_folder": "Skjul {name}"
+    "collapse_folder": "Skjul {name}",
+    "resize_sidebar": "Endre størrelse på sidepanelet",
+    "resize_message_list": "Endre størrelse på meldingslisten",
+    "resize_contact_list": "Endre størrelse på kontaktlisten",
+    "resize_side_panel": "Endre størrelse på sideruten"
   },
   "plugin_pages": {
     "loading": "Laster inn siden",
diff --git a/locales/nl/common.json b/locales/nl/common.json
index 5a0705402..9094ea2b1 100644
--- a/locales/nl/common.json
+++ b/locales/nl/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Leesvenster",
     "name_unread": "{name}, {count} ongelezen",
     "expand_folder": "{name} uitvouwen",
-    "collapse_folder": "{name} samenvouwen"
+    "collapse_folder": "{name} samenvouwen",
+    "resize_sidebar": "Formaat van zijbalk wijzigen",
+    "resize_message_list": "Formaat van berichtenlijst wijzigen",
+    "resize_contact_list": "Formaat van contactenlijst wijzigen",
+    "resize_side_panel": "Formaat van zijpaneel wijzigen"
   },
   "plugin_pages": {
     "loading": "Pagina laden",
diff --git a/locales/pl/common.json b/locales/pl/common.json
index 3f4db941c..f5df755db 100644
--- a/locales/pl/common.json
+++ b/locales/pl/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Okienko odczytu",
     "name_unread": "{name}, Nieprzeczytane: {count}",
     "expand_folder": "Rozwiń {name}",
-    "collapse_folder": "Zwiń {name}"
+    "collapse_folder": "Zwiń {name}",
+    "resize_sidebar": "Zmień rozmiar paska bocznego",
+    "resize_message_list": "Zmień rozmiar listy wiadomości",
+    "resize_contact_list": "Zmień rozmiar listy kontaktów",
+    "resize_side_panel": "Zmień rozmiar panelu bocznego"
   },
   "plugin_pages": {
     "loading": "Wczytywanie strony",
diff --git a/locales/pt/common.json b/locales/pt/common.json
index e399daf85..976b5ebde 100644
--- a/locales/pt/common.json
+++ b/locales/pt/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Painel de leitura",
     "name_unread": "{name}, {count} não lidas",
     "expand_folder": "Expandir {name}",
-    "collapse_folder": "Recolher {name}"
+    "collapse_folder": "Recolher {name}",
+    "resize_sidebar": "Redimensionar a barra lateral",
+    "resize_message_list": "Redimensionar a lista de mensagens",
+    "resize_contact_list": "Redimensionar a lista de contatos",
+    "resize_side_panel": "Redimensionar o painel lateral"
   },
   "plugin_pages": {
     "loading": "Carregando a página",
diff --git a/locales/ro/common.json b/locales/ro/common.json
index 268959070..d409c635b 100644
--- a/locales/ro/common.json
+++ b/locales/ro/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Panoul de citire",
     "name_unread": "{name}, {count} necitite",
     "expand_folder": "Extinde {name}",
-    "collapse_folder": "Restrânge {name}"
+    "collapse_folder": "Restrânge {name}",
+    "resize_sidebar": "Redimensionează bara laterală",
+    "resize_message_list": "Redimensionează lista de mesaje",
+    "resize_contact_list": "Redimensionează lista de contacte",
+    "resize_side_panel": "Redimensionează panoul lateral"
   },
   "plugin_pages": {
     "loading": "Se încarcă pagina",
diff --git a/locales/ru/common.json b/locales/ru/common.json
index 1ef7f5ba0..d9d179a11 100644
--- a/locales/ru/common.json
+++ b/locales/ru/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Область чтения",
     "name_unread": "{name}, Непрочитанных: {count}",
     "expand_folder": "Развернуть {name}",
-    "collapse_folder": "Свернуть {name}"
+    "collapse_folder": "Свернуть {name}",
+    "resize_sidebar": "Изменить размер боковой панели",
+    "resize_message_list": "Изменить размер списка писем",
+    "resize_contact_list": "Изменить размер списка контактов",
+    "resize_side_panel": "Изменить размер боковой области"
   },
   "plugin_pages": {
     "loading": "Загрузка страницы",
diff --git a/locales/sk/common.json b/locales/sk/common.json
index 08cedbc7e..b64b9151c 100644
--- a/locales/sk/common.json
+++ b/locales/sk/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Tabla na čítanie",
     "name_unread": "{name}, Neprečítané: {count}",
     "expand_folder": "Rozbaliť {name}",
-    "collapse_folder": "Zbaliť {name}"
+    "collapse_folder": "Zbaliť {name}",
+    "resize_sidebar": "Zmeniť veľkosť bočného panela",
+    "resize_message_list": "Zmeniť veľkosť zoznamu správ",
+    "resize_contact_list": "Zmeniť veľkosť zoznamu kontaktov",
+    "resize_side_panel": "Zmeniť veľkosť bočnej oblasti"
   },
   "plugin_pages": {
     "loading": "Načítava sa stránka",
diff --git a/locales/th/common.json b/locales/th/common.json
index 8341705d5..3f7c71226 100644
--- a/locales/th/common.json
+++ b/locales/th/common.json
@@ -56,7 +56,11 @@
     "reading_pane": "บานหน้าต่างอ่าน",
     "name_unread": "{name}, ยังไม่ได้อ่าน {count}",
     "expand_folder": "ขยาย {name}",
-    "collapse_folder": "ย่อ {name}"
+    "collapse_folder": "ย่อ {name}",
+    "resize_sidebar": "ปรับขนาดแถบด้านข้าง",
+    "resize_message_list": "ปรับขนาดรายการข้อความ",
+    "resize_contact_list": "ปรับขนาดรายชื่อผู้ติดต่อ",
+    "resize_side_panel": "ปรับขนาดแผงด้านข้าง"
   },
   "date": {
     "today": "วันนี้",
diff --git a/locales/tr/common.json b/locales/tr/common.json
index 60b2a40d6..f5a88ab80 100644
--- a/locales/tr/common.json
+++ b/locales/tr/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Okuma bölmesi",
     "name_unread": "{name}, {count} okunmamış",
     "expand_folder": "Genişlet: {name}",
-    "collapse_folder": "Daralt: {name}"
+    "collapse_folder": "Daralt: {name}",
+    "resize_sidebar": "Kenar çubuğunu yeniden boyutlandır",
+    "resize_message_list": "İleti listesini yeniden boyutlandır",
+    "resize_contact_list": "Kişi listesini yeniden boyutlandır",
+    "resize_side_panel": "Yan paneli yeniden boyutlandır"
   },
   "plugin_pages": {
     "loading": "Sayfa yükleniyor",
diff --git a/locales/uk/common.json b/locales/uk/common.json
index f78d3dada..379b6cb26 100644
--- a/locales/uk/common.json
+++ b/locales/uk/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "Область читання",
     "name_unread": "{name}, Непрочитаних: {count}",
     "expand_folder": "Розгорнути {name}",
-    "collapse_folder": "Згорнути {name}"
+    "collapse_folder": "Згорнути {name}",
+    "resize_sidebar": "Змінити розмір бічної панелі",
+    "resize_message_list": "Змінити розмір списку листів",
+    "resize_contact_list": "Змінити розмір списку контактів",
+    "resize_side_panel": "Змінити розмір бічної області"
   },
   "plugin_pages": {
     "loading": "Завантаження сторінки",
diff --git a/locales/zh-TW/common.json b/locales/zh-TW/common.json
index ec6e42e23..26c07b416 100644
--- a/locales/zh-TW/common.json
+++ b/locales/zh-TW/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "閱讀窗格",
     "name_unread": "{name}，{count} 封未讀",
     "expand_folder": "展開 {name}",
-    "collapse_folder": "收合 {name}"
+    "collapse_folder": "收合 {name}",
+    "resize_sidebar": "調整側邊欄大小",
+    "resize_message_list": "調整郵件清單大小",
+    "resize_contact_list": "調整聯絡人清單大小",
+    "resize_side_panel": "調整側面板大小"
   },
   "plugin_pages": {
     "loading": "正在載入頁面",
diff --git a/locales/zh/common.json b/locales/zh/common.json
index 1d2dfff9d..cae9a1a9d 100644
--- a/locales/zh/common.json
+++ b/locales/zh/common.json
@@ -5721,7 +5721,11 @@
     "reading_pane": "阅读窗格",
     "name_unread": "{name}，{count} 封未读",
     "expand_folder": "展开 {name}",
-    "collapse_folder": "折叠 {name}"
+    "collapse_folder": "折叠 {name}",
+    "resize_sidebar": "调整侧边栏大小",
+    "resize_message_list": "调整邮件列表大小",
+    "resize_contact_list": "调整联系人列表大小",
+    "resize_side_panel": "调整侧面板大小"
   },
   "plugin_pages": {
     "loading": "正在加载页面",
diff --git a/stores/ui-store.ts b/stores/ui-store.ts
index bbc857815..275474aff 100644
--- a/stores/ui-store.ts
+++ b/stores/ui-store.ts
@@ -6,15 +6,15 @@ import { uiHooks } from "@/lib/plugin-hooks";
 export type ActiveView = "sidebar" | "list" | "viewer";
 
 // Column width constraints (in pixels)
-const SIDEBAR_MIN = 180;
-const SIDEBAR_MAX = 400;
+export const SIDEBAR_MIN = 180;
+export const SIDEBAR_MAX = 400;
 const SIDEBAR_DEFAULT = 256;
-const EMAIL_LIST_MIN = 240;
-const EMAIL_LIST_MAX = 600;
+export const EMAIL_LIST_MIN = 240;
+export const EMAIL_LIST_MAX = 600;
 const EMAIL_LIST_DEFAULT = 384;
 // Email list height (in pixels) for horizontal "Reading Pane at Bottom" layout
-const EMAIL_LIST_HEIGHT_MIN = 160;
-const EMAIL_LIST_HEIGHT_MAX = 800;
+export const EMAIL_LIST_HEIGHT_MIN = 160;
+export const EMAIL_LIST_HEIGHT_MAX = 800;
 const EMAIL_LIST_HEIGHT_DEFAULT = 320;
 
 interface UIState {