diff --git a/client/src/components/Chat/Messages/Content/ActivityPhaseGroup.tsx b/client/src/components/Chat/Messages/Content/ActivityPhaseGroup.tsx
index 0d786a21a5..431b285ce1 100644
--- a/client/src/components/Chat/Messages/Content/ActivityPhaseGroup.tsx
+++ b/client/src/components/Chat/Messages/Content/ActivityPhaseGroup.tsx
@@ -18,7 +18,7 @@ import { cn } from '~/utils';
 /** Matches `EXPAND_TRANSITION` so the header, the panel, and the card chrome
  *  all resolve on the same curve — three properties animating on two different
  *  easings is what makes a fold read as two separate movements. */
-const FOLD_EASING = 'duration-300 ease-[cubic-bezier(0.16,1,0.3,1)]';
+const FOLD_EASING = 'duration-300 ease-[cubic-bezier(0.16,1,0.3,1)] motion-reduce:transition-none';
 
 type ActivityPhasePart = Extract<TMessageContentParts, { type: ContentTypes.ACTIVITY_LABEL }> & {
   activity_label_type?: 'phase';
@@ -200,7 +200,7 @@ export default function ActivityPhaseGroup({
             </span>
             <ChevronDown
               className={cn(
-                'size-4 shrink-0 transition-transform duration-200 ease-out',
+                'size-4 shrink-0 transition-transform duration-200 ease-out motion-reduce:transition-none',
                 isExpanded && 'rotate-180',
               )}
               aria-hidden="true"
diff --git a/client/src/hooks/Messages/__tests__/useExpandCollapse.spec.tsx b/client/src/hooks/Messages/__tests__/useExpandCollapse.spec.tsx
new file mode 100644
index 0000000000..a09bbd8f8b
--- /dev/null
+++ b/client/src/hooks/Messages/__tests__/useExpandCollapse.spec.tsx
@@ -0,0 +1,54 @@
+import { renderHook } from '@testing-library/react';
+import useExpandCollapse, { EXPAND_TRANSITION } from '../useExpandCollapse';
+
+function stubReducedMotion(reduce: boolean) {
+  window.matchMedia = jest.fn().mockImplementation((query: string) => ({
+    matches: query.includes('prefers-reduced-motion') ? reduce : false,
+    media: query,
+    onchange: null,
+    addListener: jest.fn(),
+    removeListener: jest.fn(),
+    addEventListener: jest.fn(),
+    removeEventListener: jest.fn(),
+    dispatchEvent: jest.fn(),
+  })) as unknown as typeof window.matchMedia;
+}
+
+describe('useExpandCollapse', () => {
+  const original = window.matchMedia;
+
+  afterEach(() => {
+    window.matchMedia = original;
+  });
+
+  test('animates the disclosure by default', () => {
+    stubReducedMotion(false);
+
+    const { result } = renderHook(() => useExpandCollapse(true));
+
+    expect(result.current.style.transition).toBe(EXPAND_TRANSITION);
+    expect(result.current.style.gridTemplateRows).toBe('1fr');
+    expect(result.current.style.opacity).toBe(1);
+  });
+
+  /** The transition is an inline style, so it cannot carry a media query.
+   *  Without this the panel still folds over 300ms for a reader who asked
+   *  the platform for no motion. */
+  test('drops the transition under prefers-reduced-motion', () => {
+    stubReducedMotion(true);
+
+    const { result } = renderHook(() => useExpandCollapse(true));
+
+    expect(result.current.style.transition).toBe('none');
+  });
+
+  test('still collapses to a zero row under reduced motion', () => {
+    stubReducedMotion(true);
+
+    const { result } = renderHook(() => useExpandCollapse(false));
+
+    expect(result.current.style.transition).toBe('none');
+    expect(result.current.style.gridTemplateRows).toBe('0fr');
+    expect(result.current.style.opacity).toBe(0);
+  });
+});
diff --git a/client/src/hooks/Messages/useExpandCollapse.ts b/client/src/hooks/Messages/useExpandCollapse.ts
index dc298c7f6c..2e48e8d6b4 100644
--- a/client/src/hooks/Messages/useExpandCollapse.ts
+++ b/client/src/hooks/Messages/useExpandCollapse.ts
@@ -1,14 +1,22 @@
 import { useRef, useLayoutEffect, useMemo } from 'react';
+import { useMediaQuery } from '@librechat/client';
 import type { CSSProperties } from 'react';
 
 export const EXPAND_TRANSITION =
   'grid-template-rows 0.3s cubic-bezier(0.16, 1, 0.3, 1), opacity 0.3s cubic-bezier(0.16, 1, 0.3, 1)';
 
+/**
+ * The disclosure motion is an inline style, so it cannot carry a
+ * `prefers-reduced-motion` media query the way a utility class can. Resolve
+ * the preference here instead and drop the transition outright — every
+ * expanding panel in the message content shares this hook.
+ */
 export default function useExpandCollapse(isExpanded: boolean): {
   style: CSSProperties;
   ref: React.RefObject<HTMLDivElement>;
 } {
   const ref = useRef<HTMLDivElement>(null);
+  const reducedMotion = useMediaQuery('(prefers-reduced-motion: reduce)');
 
   useLayoutEffect(() => {
     const el = ref.current;
@@ -27,10 +35,10 @@ export default function useExpandCollapse(isExpanded: boolean): {
     () => ({
       display: 'grid',
       gridTemplateRows: isExpanded ? '1fr' : '0fr',
-      transition: EXPAND_TRANSITION,
+      transition: reducedMotion ? 'none' : EXPAND_TRANSITION,
       opacity: isExpanded ? 1 : 0,
     }),
-    [isExpanded],
+    [isExpanded, reducedMotion],
   );
 
   return { style, ref };