diff --git a/client/src/components/Chat/Messages/Content/ToolCallGroup.tsx b/client/src/components/Chat/Messages/Content/ToolCallGroup.tsx
index 40f420208d..1d86ac356d 100644
--- a/client/src/components/Chat/Messages/Content/ToolCallGroup.tsx
+++ b/client/src/components/Chat/Messages/Content/ToolCallGroup.tsx
@@ -24,6 +24,27 @@ interface ToolMeta {
   hasOutput: boolean;
 }
 
+type ToolCallWithNestedContent = Agents.ToolCall & {
+  subagent_content?: TMessageContentParts[];
+};
+
+function hasPendingApprovalInPart(part: TMessageContentParts): boolean {
+  if (part.type !== ContentTypes.TOOL_CALL) {
+    return false;
+  }
+  const toolCall = part[ContentTypes.TOOL_CALL] as ToolCallWithNestedContent | undefined;
+  if (!toolCall) {
+    return false;
+  }
+  if (toolCall.approval != null && (toolCall.output?.length ?? 0) === 0) {
+    return true;
+  }
+  return (
+    Array.isArray(toolCall.subagent_content) &&
+    toolCall.subagent_content.some(hasPendingApprovalInPart)
+  );
+}
+
 function getToolMeta(part: TMessageContentParts): ToolMeta | null {
   if (part.type !== ContentTypes.TOOL_CALL) {
     return null;
@@ -107,18 +128,12 @@ export default function ToolCallGroup({
   const mcpIconMap = useMCPIconMap();
   const rootRef = useRef<HTMLDivElement | null>(null);
   const cancelLayoutReconcileRef = useRef<(() => void) | null>(null);
+  const retainedForPendingApprovalRef = useRef(false);
   const count = parts.length;
 
   const toolMetadata = useMemo(() => parts.map((p) => getToolMeta(p.part)), [parts]);
   const hasPendingApproval = useMemo(
-    () =>
-      parts.some(({ part }) => {
-        if (part.type !== ContentTypes.TOOL_CALL) {
-          return false;
-        }
-        const toolCall = part[ContentTypes.TOOL_CALL] as Agents.ToolCall | undefined;
-        return toolCall?.approval != null && (toolCall.output?.length ?? 0) === 0;
-      }),
+    () => parts.some(({ part }) => hasPendingApprovalInPart(part)),
     [parts],
   );
   const allCompleted = useMemo(
@@ -234,18 +249,37 @@ export default function ToolCallGroup({
       if (event.target !== event.currentTarget) {
         return;
       }
-      if (isExpanded || hasPendingApproval) {
+      if (isExpanded) {
         return;
       }
-      // Approval controls own unsent local form state. Keep unresolved cards
-      // mounted (the collapsed panel is inert/hidden) so collapsing a batch
-      // cannot erase decisions the reviewer already made.
+      if (hasPendingApproval) {
+        // Approval controls own unsent local form state. Keep unresolved cards
+        // mounted (the collapsed panel is inert/hidden) so collapsing a batch
+        // cannot erase decisions the reviewer already made.
+        retainedForPendingApprovalRef.current = true;
+        return;
+      }
+      retainedForPendingApprovalRef.current = false;
       setShouldRenderBody(false);
       notifyLayoutChange();
     },
     [hasPendingApproval, isExpanded, notifyLayoutChange],
   );
 
+  useEffect(() => {
+    if (isExpanded) {
+      retainedForPendingApprovalRef.current = false;
+      return;
+    }
+    if (!hasPendingApproval && retainedForPendingApprovalRef.current) {
+      // A completed collapse transition retained this body only to preserve
+      // approval form state. Release it once the last approval resolves.
+      retainedForPendingApprovalRef.current = false;
+      setShouldRenderBody(false);
+      notifyLayoutChange();
+    }
+  }, [hasPendingApproval, isExpanded, notifyLayoutChange]);
+
   /** Category-aware header verb: subagents and questions read as their own
    *  category (with tense), everything else is the generic "Used N tools". */
   const resolveGroupLabel = (): string => {
diff --git a/client/src/components/Chat/Messages/Content/__tests__/ToolCallGroup.test.tsx b/client/src/components/Chat/Messages/Content/__tests__/ToolCallGroup.test.tsx
index 14c66b0f73..10d61e4482 100644
--- a/client/src/components/Chat/Messages/Content/__tests__/ToolCallGroup.test.tsx
+++ b/client/src/components/Chat/Messages/Content/__tests__/ToolCallGroup.test.tsx
@@ -83,14 +83,14 @@ const makePart = (
     },
   }) as unknown as TMessageContentParts;
 
-const makePendingApprovalPart = (id: string): TMessageContentParts =>
+const makeApprovalPart = (id: string, output = ''): TMessageContentParts =>
   ({
     type: ContentTypes.TOOL_CALL,
     [ContentTypes.TOOL_CALL]: {
       id,
       name: 'approval_probe',
       args: {},
-      output: '',
+      output,
       approval: {
         actionId: 'action-1',
         allowed_decisions: ['approve', 'reject'],
@@ -98,6 +98,21 @@ const makePendingApprovalPart = (id: string): TMessageContentParts =>
     },
   }) as unknown as TMessageContentParts;
 
+const makeSubagentPart = (
+  id: string,
+  subagentContent: TMessageContentParts[],
+): TMessageContentParts =>
+  ({
+    type: ContentTypes.TOOL_CALL,
+    [ContentTypes.TOOL_CALL]: {
+      id,
+      name: Constants.SUBAGENT,
+      args: {},
+      output: '',
+      subagent_content: subagentContent,
+    },
+  }) as unknown as TMessageContentParts;
+
 const imageAttachment: TAttachment = {
   filename: 'foo.png',
   filepath: '/files/foo.png',
@@ -228,8 +243,8 @@ describe('ToolCallGroup image hoisting', () => {
 
   it('keeps unresolved approval bodies mounted while the group is collapsed', () => {
     const approvalParts = [
-      { part: makePendingApprovalPart('t1'), idx: 0 },
-      { part: makePendingApprovalPart('t2'), idx: 1 },
+      { part: makeApprovalPart('t1'), idx: 0 },
+      { part: makeApprovalPart('t2'), idx: 1 },
     ];
     renderGroup({
       ...baseProps,
@@ -253,6 +268,142 @@ describe('ToolCallGroup image hoisting', () => {
     expect(screen.getByTestId('approval-1')).toBeInTheDocument();
   });
 
+  it('keeps deeply nested unresolved approval bodies mounted while the group is collapsed', () => {
+    const nestedApprovalParts = [
+      {
+        part: makeSubagentPart('parent', [
+          makeSubagentPart('child', [makeApprovalPart('grandchild')]),
+        ]),
+        idx: 0,
+      },
+      { part: makePart('sibling'), idx: 1 },
+    ];
+    renderGroup({
+      ...baseProps,
+      parts: nestedApprovalParts,
+      renderPart: (_p: TMessageContentParts, idx: number) => (
+        <div data-testid={`nested-${idx}`} key={idx}>
+          {'nested'}
+        </div>
+      ),
+    });
+
+    const button = screen.getByRole('button', { name: 'Used 2 tools' });
+    const collapsible = button.nextElementSibling as HTMLElement;
+    fireEvent.click(button);
+    fireEvent.transitionEnd(collapsible);
+
+    expect(button).toHaveAttribute('aria-expanded', 'false');
+    expect(screen.getByTestId('nested-0')).toBeInTheDocument();
+    expect(screen.getByTestId('nested-1')).toBeInTheDocument();
+  });
+
+  it('does not retain a collapsed group for an already resolved nested approval', () => {
+    const nestedApprovalParts = [
+      {
+        part: makeSubagentPart('parent', [
+          makeSubagentPart('child', [makeApprovalPart('grandchild', 'done')]),
+        ]),
+        idx: 0,
+      },
+      { part: makePart('sibling'), idx: 1 },
+    ];
+    renderGroup({
+      ...baseProps,
+      parts: nestedApprovalParts,
+      renderPart: (_p: TMessageContentParts, idx: number) => (
+        <div data-testid={`resolved-nested-${idx}`} key={idx}>
+          {'nested'}
+        </div>
+      ),
+    });
+
+    const button = screen.getByRole('button', { name: 'Used 2 tools' });
+    const collapsible = button.nextElementSibling as HTMLElement;
+    fireEvent.click(button);
+    fireEvent.transitionEnd(collapsible);
+
+    expect(screen.queryByTestId('resolved-nested-0')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('resolved-nested-1')).not.toBeInTheDocument();
+  });
+
+  it('unmounts retained approval bodies after every approval in a collapsed group resolves', async () => {
+    const renderPart = (_p: TMessageContentParts, idx: number) => (
+      <div data-testid={`retained-${idx}`} key={idx}>
+        {'approval'}
+      </div>
+    );
+    const propsFor = (
+      firstOutput = '',
+      secondOutput = '',
+    ): React.ComponentProps<typeof ToolCallGroup> => ({
+      ...baseProps,
+      parts: [
+        { part: makeApprovalPart('t1', firstOutput), idx: 0 },
+        { part: makeApprovalPart('t2', secondOutput), idx: 1 },
+      ],
+      renderPart,
+    });
+    const { rerender } = renderGroup(propsFor());
+
+    const button = screen.getByRole('button', { name: 'Used 2 tools' });
+    const collapsible = button.nextElementSibling as HTMLElement;
+    fireEvent.click(button);
+    fireEvent.transitionEnd(collapsible);
+    expect(screen.getByTestId('retained-0')).toBeInTheDocument();
+
+    rerender(
+      <RecoilRoot>
+        <ToolCallGroup {...propsFor('first done')} />
+      </RecoilRoot>,
+    );
+    expect(screen.getByTestId('retained-0')).toBeInTheDocument();
+    expect(screen.getByTestId('retained-1')).toBeInTheDocument();
+
+    rerender(
+      <RecoilRoot>
+        <ToolCallGroup {...propsFor('first done', 'second done')} />
+      </RecoilRoot>,
+    );
+    await waitFor(() => {
+      expect(screen.queryByTestId('retained-0')).not.toBeInTheDocument();
+      expect(screen.queryByTestId('retained-1')).not.toBeInTheDocument();
+    });
+  });
+
+  it('waits for an active collapse transition before unmounting resolved approval bodies', () => {
+    const renderPart = (_p: TMessageContentParts, idx: number) => (
+      <div data-testid={`transitioning-${idx}`} key={idx}>
+        {'approval'}
+      </div>
+    );
+    const propsFor = (output = ''): React.ComponentProps<typeof ToolCallGroup> => ({
+      ...baseProps,
+      parts: [
+        { part: makeApprovalPart('t1', output), idx: 0 },
+        { part: makeApprovalPart('t2', output), idx: 1 },
+      ],
+      renderPart,
+    });
+    const { rerender } = renderGroup(propsFor());
+
+    const button = screen.getByRole('button', { name: 'Used 2 tools' });
+    const collapsible = button.nextElementSibling as HTMLElement;
+    fireEvent.click(button);
+
+    rerender(
+      <RecoilRoot>
+        <ToolCallGroup {...propsFor('done')} />
+      </RecoilRoot>,
+    );
+    expect(screen.getByTestId('transitioning-0')).toBeInTheDocument();
+    expect(screen.getByTestId('transitioning-1')).toBeInTheDocument();
+
+    fireEvent.transitionEnd(collapsible);
+    expect(screen.queryByTestId('transitioning-0')).not.toBeInTheDocument();
+    expect(screen.queryByTestId('transitioning-1')).not.toBeInTheDocument();
+  });
+
   it('reconciles layout after the group collapses from an expanded state', async () => {
     renderGroup(baseProps);