diff --git a/server-ce/test/project-sharing.spec.ts b/server-ce/test/project-sharing.spec.ts
index ab71cb7dc9..e26439264b 100644
--- a/server-ce/test/project-sharing.spec.ts
+++ b/server-ce/test/project-sharing.spec.ts
@@ -36,14 +36,13 @@ describe('Project Sharing', function () {
     login('user@example.com')
     createProject(projectName)
 
-    // TODO(25342): re-enable
-    // // Add chat message
-    // cy.findByText('Chat').click()
-    // // wait for lazy loading of the chat pane
-    // cy.findByText('Send your first message to your collaborators')
-    // cy.get(
-    //   'textarea[placeholder="Send a message to your collaborators…"]'
-    // ).type('New Chat Message{enter}')
+    // Add chat message
+    cy.findByText('Chat').click()
+    // wait for lazy loading of the chat pane
+    cy.findByText('Send your first message to your collaborators')
+    cy.get(
+      'textarea[placeholder="Send a message to your collaborators…"]'
+    ).type('New Chat Message{enter}')
 
     // Get link sharing links
     enableLinkSharing().then(
@@ -95,9 +94,8 @@ describe('Project Sharing', function () {
   }
 
   function expectChatAccess() {
-    // TODO(25342): re-enable
-    // cy.findByText('Chat').click()
-    // cy.findByText('New Chat Message')
+    cy.findByText('Chat').click()
+    cy.findByText('New Chat Message')
   }
 
   function expectHistoryAccess() {
@@ -111,9 +109,8 @@ describe('Project Sharing', function () {
   }
 
   function expectNoChatAccess() {
-    // TODO(25342): re-enable
-    // cy.findByText('Layout') // wait for lazy loading
-    // cy.findByText('Chat').should('not.exist')
+    cy.findByText('Layout') // wait for lazy loading
+    cy.findByText('Chat').should('not.exist')
   }
 
   function expectNoHistoryAccess() {
diff --git a/services/web/frontend/js/features/ide-react/hooks/use-chat-pane.ts b/services/web/frontend/js/features/ide-react/hooks/use-chat-pane.ts
index 0c6d816181..44b165fd57 100644
--- a/services/web/frontend/js/features/ide-react/hooks/use-chat-pane.ts
+++ b/services/web/frontend/js/features/ide-react/hooks/use-chat-pane.ts
@@ -1,6 +1,7 @@
 import { useLayoutContext } from '@/shared/context/layout-context'
 import useCollapsiblePanel from '@/features/ide-react/hooks/use-collapsible-panel'
-import { useCallback, useRef, useState } from 'react'
+import useDebounce from '@/shared/hooks/use-debounce'
+import { useCallback, useEffect, useRef, useState } from 'react'
 import { ImperativePanelHandle } from 'react-resizable-panels'
 
 export const useChatPane = () => {
@@ -8,6 +9,17 @@ export const useChatPane = () => {
   const [resizing, setResizing] = useState(false)
   const panelRef = useRef<ImperativePanelHandle>(null)
 
+  // Keep track of a debounced local state variable for panel openness and
+  // only update the external openness state when the debounced value changes.
+  // This prevents successive calls to onCollapse and onExpand from
+  // react-resizable-panels updating the openness state multiple times in quick
+  // succession, which causes confusing behaviour that is different in React 17
+  // and 18. Collapsing the chat pane on initialization is necessary because
+  // react-resizable-panels does not provide a way to specify both that a panel
+  // should be collapsed and a default size for the panel when expanded.
+  const [localIsOpen, setLocalIsOpen] = useState(isOpen)
+  const debouncedLocalIsOpen = useDebounce(localIsOpen, 100)
+
   useCollapsiblePanel(isOpen, panelRef)
 
   const togglePane = useCallback(() => {
@@ -15,12 +27,16 @@ export const useChatPane = () => {
   }, [setIsOpen])
 
   const handlePaneExpand = useCallback(() => {
-    setIsOpen(true)
-  }, [setIsOpen])
+    setLocalIsOpen(true)
+  }, [])
 
   const handlePaneCollapse = useCallback(() => {
-    setIsOpen(false)
-  }, [setIsOpen])
+    setLocalIsOpen(false)
+  }, [])
+
+  useEffect(() => {
+    setIsOpen(debouncedLocalIsOpen)
+  }, [debouncedLocalIsOpen, setIsOpen])
 
   return {
     isOpen,