diff --git a/CHANGELOG.md b/CHANGELOG.md
index f11f305fd..a2de1ee36 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Toolbar customizations now persist after closing and reopening a session window. (#1455)
 - Pasting copied rows no longer misplaces values when a cell contains a comma (such as a user agent string); each value stays in its own column, and a real NULL is kept distinct from the literal text "NULL".
 - BigQuery: switching to another table now loads its data right away, instead of leaving the grid empty until you close and reopen the tab.
 - Custom and OpenAI-compatible AI providers now work when the base URL already ends in `/v1`, instead of building a doubled `/v1/v1/` path that failed. (#1400)
diff --git a/TablePro/Core/Services/Infrastructure/MainWindowToolbar.swift b/TablePro/Core/Services/Infrastructure/MainWindowToolbar.swift
index 0749c9bc9..1ab57a5f1 100644
--- a/TablePro/Core/Services/Infrastructure/MainWindowToolbar.swift
+++ b/TablePro/Core/Services/Infrastructure/MainWindowToolbar.swift
@@ -13,6 +13,8 @@ import TableProPluginKit
 internal final class MainWindowToolbar: NSObject, NSToolbarDelegate {
     private static let lifecycleLogger = Logger(subsystem: "com.TablePro", category: "NativeTabLifecycle")
 
+    internal static let toolbarIdentifier = NSToolbar.Identifier("com.TablePro.main.toolbar")
+
     weak var coordinator: MainContentCoordinator?
 
     internal let managedToolbar: NSToolbar
@@ -26,14 +28,12 @@ internal final class MainWindowToolbar: NSObject, NSToolbarDelegate {
 
     internal init(coordinator: MainContentCoordinator) {
         self.coordinator = coordinator
-        // Unique identifier per toolbar instance prevents tab-group merging that would collapse
-        // all tabs into one toolbar and leave subsequent windows blank.
-        self.managedToolbar = NSToolbar(identifier: "com.TablePro.main.toolbar.\(UUID().uuidString)")
+        self.managedToolbar = NSToolbar(identifier: Self.toolbarIdentifier)
         super.init()
         self.managedToolbar.delegate = self
         self.managedToolbar.displayMode = .iconOnly
         self.managedToolbar.allowsUserCustomization = true
-        self.managedToolbar.autosavesConfiguration = false
+        self.managedToolbar.autosavesConfiguration = true
     }
 
     func invalidate() {
diff --git a/TableProTests/Services/MainWindowToolbarValidationTests.swift b/TableProTests/Services/MainWindowToolbarValidationTests.swift
index 6605be4f9..a8c408e74 100644
--- a/TableProTests/Services/MainWindowToolbarValidationTests.swift
+++ b/TableProTests/Services/MainWindowToolbarValidationTests.swift
@@ -142,4 +142,39 @@ struct MainWindowToolbarValidationTests {
         let unknown = NSToolbarItem.Identifier("com.test.unknown")
         #expect(MainWindowToolbar.isEnabled(itemIdentifier: unknown, context: context) == true)
     }
+
+    @Test("Toolbar identifier is stable across instances so AppKit autosave can persist customizations")
+    func toolbarIdentifierIsStable() {
+        #expect(MainWindowToolbar.toolbarIdentifier.rawValue == "com.TablePro.main.toolbar")
+    }
+
+    @Test("Toolbar is configured for user customization and autosave")
+    func toolbarConfigurationEnablesAutosave() {
+        let coordinator = makeCoordinator()
+        defer { coordinator.teardown() }
+        let owner = MainWindowToolbar(coordinator: coordinator)
+        #expect(owner.managedToolbar.identifier == MainWindowToolbar.toolbarIdentifier)
+        #expect(owner.managedToolbar.allowsUserCustomization == true)
+        #expect(owner.managedToolbar.autosavesConfiguration == true)
+    }
+
+    @Test("Allowed item identifiers are a superset of defaults so restored items survive autosave")
+    func allowedItemIdentifiersAreSupersetOfDefaults() {
+        let coordinator = makeCoordinator()
+        defer { coordinator.teardown() }
+        let owner = MainWindowToolbar(coordinator: coordinator)
+        let toolbar = owner.managedToolbar
+        let defaults = Set(owner.toolbarDefaultItemIdentifiers(toolbar))
+        let allowed = Set(owner.toolbarAllowedItemIdentifiers(toolbar))
+        #expect(defaults.isSubset(of: allowed))
+    }
+
+    private func makeCoordinator() -> MainContentCoordinator {
+        MainContentCoordinator(
+            connection: TestFixtures.makeConnection(database: "db_a"),
+            tabManager: QueryTabManager(),
+            changeManager: DataChangeManager(),
+            toolbarState: ConnectionToolbarState()
+        )
+    }
 }