diff --git a/packages/app/src/storage/validated-persist-storage.ts b/packages/app/src/storage/validated-persist-storage.ts
index e9a438daf9..fae43edbc9 100644
--- a/packages/app/src/storage/validated-persist-storage.ts
+++ b/packages/app/src/storage/validated-persist-storage.ts
@@ -13,29 +13,43 @@ export function createValidatedPersistStorage<State>(
   });
 
   const accepted = new Map<string, StorageValue<State>>();
+  const reading = new Set<string>();
+
+  async function read(name: string): Promise<StorageValue<State> | null> {
+    const raw = await backingStorage.getItem(name);
+    if (raw === null) return null;
+
+    let decoded: unknown;
+    try {
+      decoded = JSON.parse(raw);
+    } catch {
+      await backingStorage.removeItem(name);
+      return null;
+    }
+
+    const result = envelopeSchema.safeParse(decoded);
+    if (!result.success) {
+      await backingStorage.removeItem(name);
+      return null;
+    }
+    return result.data;
+  }
 
   return {
     getItem: async (name) => {
       accepted.delete(name);
-      const raw = await backingStorage.getItem(name);
-      if (raw === null) return null;
-
-      let decoded: unknown;
+      reading.add(name);
       try {
-        decoded = JSON.parse(raw);
-      } catch {
-        await backingStorage.removeItem(name);
-        return null;
+        return await read(name);
+      } finally {
+        reading.delete(name);
       }
-
-      const result = envelopeSchema.safeParse(decoded);
-      if (!result.success) {
-        await backingStorage.removeItem(name);
-        return null;
-      }
-      return result.data;
     },
     setItem: async (name, value) => {
+      // A store that changes before hydration settles writes the defaults it started with.
+      // Hydration then merges the stored state in memory without writing it back, so that
+      // write would replace the stored state until the next change.
+      if (reading.has(name)) return;
       const previous = accepted.get(name);
       if (
         options.skipUnchanged &&
diff --git a/packages/app/src/stores/workspace-layout-persistence.test.ts b/packages/app/src/stores/workspace-layout-persistence.test.ts
index d386a40298..3a54204598 100644
--- a/packages/app/src/stores/workspace-layout-persistence.test.ts
+++ b/packages/app/src/stores/workspace-layout-persistence.test.ts
@@ -52,3 +52,39 @@ it("skips unchanged reconciliations and immediately saves real layout changes",
     store.getState().layoutByWorkspace[workspaceKey],
   );
 });
+
+it("keeps the saved layout when the shell publishes its layout mode before hydration", async () => {
+  const values = new Map<string, string>();
+  const storage: StateStorage = {
+    getItem: (name) => values.get(name) ?? null,
+    setItem: (name, value) => {
+      values.set(name, value);
+    },
+    removeItem: (name) => {
+      values.delete(name);
+    },
+  };
+  const workspaceKey = "server:workspace";
+  const saved = createWorkspaceLayoutStore(undefined, storage);
+  await saved.persist.rehydrate();
+  saved.getState().openTab({
+    workspaceKey,
+    target: { kind: "file", path: "notes.md" },
+    intent: "reveal",
+  });
+
+  // A page load: the shell publishes its mode from the first commit, before the read settles.
+  const loaded = createWorkspaceLayoutStore(undefined, storage);
+  loaded.getState().setLayoutMode("single-pane");
+  await new Promise<void>((resolve) => loaded.persist.onFinishHydration(() => resolve()));
+  expect(loaded.getState().layoutByWorkspace[workspaceKey]).toEqual(
+    saved.getState().layoutByWorkspace[workspaceKey],
+  );
+
+  // Leaving the page before any other layout change must not lose the tabs.
+  const reloaded = createWorkspaceLayoutStore(undefined, storage);
+  await reloaded.persist.rehydrate();
+  expect(reloaded.getState().layoutByWorkspace[workspaceKey]).toEqual(
+    saved.getState().layoutByWorkspace[workspaceKey],
+  );
+});