diff --git a/web/src/components/SessionList.directory-action.test.tsx b/web/src/components/SessionList.directory-action.test.tsx
index 2b76e43201..f5243d266f 100644
--- a/web/src/components/SessionList.directory-action.test.tsx
+++ b/web/src/components/SessionList.directory-action.test.tsx
@@ -1,4 +1,4 @@
-import { cleanup, fireEvent, render, screen } from '@testing-library/react'
+import { cleanup, fireEvent, render, screen, waitFor } from '@testing-library/react'
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import type { ReactNode } from 'react'
@@ -95,3 +95,102 @@ describe('SessionList directory action', () => {
         expect(screen.queryByRole('button', { name: 'New session in this directory' })).toBeNull()
     })
 })
+
+describe('SessionList collapse behavior', () => {
+    function renderSessionList(sessions: SessionSummary[], selectedSessionId = 'session-running') {
+        return (
+            <QueryClientProvider client={new QueryClient({
+                defaultOptions: {
+                    queries: { retry: false },
+                    mutations: { retry: false },
+                }
+            })}>
+                <I18nProvider>
+                    <SessionList
+                        sessions={sessions}
+                        selectedSessionId={selectedSessionId}
+                        onSelect={vi.fn()}
+                        onNewSession={vi.fn()}
+                        onRefresh={vi.fn()}
+                        isLoading={false}
+                        renderHeader={false}
+                        api={null}
+                    />
+                </I18nProvider>
+            </QueryClientProvider>
+        )
+    }
+
+    function getProjectPanel(): Element {
+        const header = screen.getByTitle('/work/hapi')
+        const panel = header.nextElementSibling
+        if (!panel) {
+            throw new Error('Expected project collapse panel')
+        }
+        return panel
+    }
+
+    it('keeps a selected running path collapsed across live session-list refreshes', async () => {
+        const baseSessions = [
+            makeSession({
+                id: 'session-running',
+                active: true,
+                thinking: true,
+                pendingRequestsCount: 1,
+                updatedAt: 100,
+                metadata: { path: '/work/hapi', name: 'Running task', flavor: 'codex' },
+            }),
+            makeSession({
+                id: 'session-old',
+                updatedAt: 50,
+                metadata: { path: '/work/hapi', name: 'Older task', flavor: 'codex' },
+            })
+        ]
+        const { rerender } = render(renderSessionList(baseSessions))
+
+        expect(getProjectPanel().getAttribute('data-open')).toBe('true')
+
+        fireEvent.click(screen.getByTitle('/work/hapi'))
+        expect(getProjectPanel().getAttribute('data-open')).toBeNull()
+
+        rerender(renderSessionList([
+            {
+                ...baseSessions[0]!,
+                pendingRequestsCount: 2,
+                updatedAt: 200,
+            },
+            baseSessions[1]!
+        ]))
+
+        await waitFor(() => {
+            expect(getProjectPanel().getAttribute('data-open')).toBeNull()
+        })
+    })
+
+    it('auto-expands the path again when the selected session changes', async () => {
+        const sessions = [
+            makeSession({
+                id: 'session-running',
+                active: true,
+                thinking: true,
+                updatedAt: 100,
+                metadata: { path: '/work/hapi', name: 'Running task', flavor: 'codex' },
+            }),
+            makeSession({
+                id: 'session-next',
+                updatedAt: 90,
+                metadata: { path: '/work/hapi', name: 'Next task', flavor: 'codex' },
+            })
+        ]
+        const { rerender } = render(renderSessionList(sessions))
+
+        fireEvent.click(screen.getByTitle('/work/hapi'))
+        expect(getProjectPanel().getAttribute('data-open')).toBeNull()
+
+        rerender(renderSessionList(sessions, 'session-next'))
+
+        await waitFor(() => {
+            expect(getProjectPanel().getAttribute('data-open')).toBe('true')
+        })
+    })
+})
diff --git a/web/src/components/SessionList.tsx b/web/src/components/SessionList.tsx
index 294fcc364b..8b48a86c51 100644
--- a/web/src/components/SessionList.tsx
+++ b/web/src/components/SessionList.tsx
@@ -739,6 +739,7 @@ export function SessionList(props: {
     const [collapseOverrides, setCollapseOverrides] = useState<Map<string, boolean>>(
         () => new Map()
     )
+    const autoExpandedSelectedSessionKeyRef = useRef<string | null>(null)
     const isGroupCollapsed = (group: SessionGroup): boolean => {
         if (isSearching) return false
         const override = collapseOverrides.get(group.key)
@@ -812,16 +813,26 @@ export function SessionList(props: {
         })
     }
 
-    // Auto-expand group (and machine) containing selected session
+    // Auto-expand group (and machine) containing the selected session only when
+    // the selected-session/group pair changes. Without this guard, every live
+    // session-list refresh (for example tool-call updates from a running selected
+    // session) reopens a path the user just collapsed.
     useEffect(() => {
-        if (!selectedSessionId) return
-        setCollapseOverrides(prev => {
-            const group = allGroups.find(g =>
-                g.sessions.some(s => s.id === selectedSessionId)
-            )
-            if (!group) return prev
-            return expandSelectedSessionCollapseOverrides(prev, group)
-        })
+        if (!selectedSessionId) {
+            autoExpandedSelectedSessionKeyRef.current = null
+            return
+        }
+
+        const group = allGroups.find(g =>
+            g.sessions.some(s => s.id === selectedSessionId)
+        )
+        if (!group) return
+
+        const autoExpandKey = `${selectedSessionId}::${group.key}`
+        if (autoExpandedSelectedSessionKeyRef.current === autoExpandKey) return
+        autoExpandedSelectedSessionKeyRef.current = autoExpandKey
+
+        setCollapseOverrides(prev => expandSelectedSessionCollapseOverrides(prev, group))
     }, [selectedSessionId, allGroups])
 
     // Clean up stale collapse overrides