diff --git a/README.md b/README.md
index cb844a5b..6c683fb8 100644
--- a/README.md
+++ b/README.md
@@ -25,7 +25,7 @@ brew tap Jay1/jcode https://github.com/Jay1/jcode
 brew install --cask jcode
 ```
 
-#### Download the latest macOS 
+#### Download the latest macOS
 
 `JCode-<version>-arm64.dmg` or
 `JCode-<version>-x64.dmg`, or the latest Linux `JCode-<version>-x64.AppImage`, from
@@ -33,7 +33,7 @@ brew install --cask jcode
 
 ### Windows
 
-#### Scoop 
+#### Scoop
 
 If you do not have Scoop yet, follow the [official Scoop installation guide](https://scoop.sh/):
 
@@ -42,7 +42,7 @@ scoop bucket add jcode https://github.com/Jay1/scoop-jcode
 scoop install jcode
 ```
 
-#### Winget 
+#### Winget
 
 ```powershell
 winget install Jay1.JCode
diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
index 5db7082b..a83bb428 100644
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -270,6 +270,7 @@ const SIDEBAR_LIST_ANIMATION_OPTIONS = {
   easing: "ease-out",
 } as const;
 const EMPTY_THREAD_JUMP_LABELS = new Map<ThreadId, string>();
+const EMPTY_PROJECT_EXPANDED_MAP = new Map<string, boolean>();
 const EMPTY_SHORTCUT_PARTS: readonly string[] = [];
 const ADD_PROJECT_SNAPSHOT_CATCH_UP_MAX_ATTEMPTS = 6;
 const ADD_PROJECT_SNAPSHOT_CATCH_UP_DELAY_MS = 50;
@@ -3572,7 +3573,26 @@ export default function Sidebar() {
   );
 
   // Reset per-project preview expansion when a folder closes so reopening starts at five rows again.
+  const previousProjectExpandedRef = useRef<ReadonlyMap<string, boolean>>(
+    EMPTY_PROJECT_EXPANDED_MAP,
+  );
   useEffect(() => {
+    const nextExpanded = new Map(
+      standardProjects.map((project) => [project.cwd, project.expanded] as const),
+    );
+    const prev = previousProjectExpandedRef.current;
+    let expandedChanged = nextExpanded.size !== prev.size;
+    if (!expandedChanged) {
+      for (const [cwd, expanded] of nextExpanded) {
+        if (prev.get(cwd) !== expanded) {
+          expandedChanged = true;
+          break;
+        }
+      }
+    }
+    previousProjectExpandedRef.current = nextExpanded;
+    if (!expandedChanged) return;
+
     setExpandedThreadListsByProject((current) =>
       pruneExpandedProjectThreadListsForCollapsedProjects({
         expandedProjectThreadListCwds: current,