From 94a2aa01007a48f2e3fde9866dfb1c09a1a58f5c Mon Sep 17 00:00:00 2001
From: Leonard Hecker <lhecker@microsoft.com>
Date: Fri, 23 May 2025 01:02:58 +0200
Subject: [PATCH] Eagerly persist on WM_ENDSESSION (#18912)

Once an application has returned from handling `WM_ENDSESSION`
the OS may kill the app at any point. This means we must
persist our state while inside the message handler.

Closes #17179

Honestly, none. It's a race condition in the first place.

(cherry picked from commit 26cd15a14b0bfc06a951c800d960336328176173)
Service-Card-Id: PVTI_lADOAF3p4s4AxadtzgaZoI8
Service-Version: 1.23
---
 src/cascadia/WindowsTerminal/WindowEmperor.cpp | 12 ++++++++++--
 src/cascadia/WindowsTerminal/WindowEmperor.h   |  2 +-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/cascadia/WindowsTerminal/WindowEmperor.cpp b/src/cascadia/WindowsTerminal/WindowEmperor.cpp
index 381b7f4c8e..1d274c1f82 100644
--- a/src/cascadia/WindowsTerminal/WindowEmperor.cpp
+++ b/src/cascadia/WindowsTerminal/WindowEmperor.cpp
@@ -897,7 +897,8 @@ LRESULT WindowEmperor::_messageHandler(HWND window, UINT const message, WPARAM c
             RegisterApplicationRestart(nullptr, RESTART_NO_CRASH | RESTART_NO_HANG);
             return TRUE;
         case WM_ENDSESSION:
-            _forcePersistence = true;
+            _finalizeSessionPersistence();
+            _skipPersistence = true;
             PostQuitMessage(0);
             return 0;
         default:
@@ -923,6 +924,13 @@ LRESULT WindowEmperor::_messageHandler(HWND window, UINT const message, WPARAM c
 
 void WindowEmperor::_finalizeSessionPersistence() const
 {
+    if (_skipPersistence)
+    {
+        // We received WM_ENDSESSION and persisted the state.
+        // We don't need to persist it again.
+        return;
+    }
+
     const auto state = ApplicationState::SharedInstance();
 
     // Calling an `ApplicationState` setter triggers a write to state.json.
@@ -932,7 +940,7 @@ void WindowEmperor::_finalizeSessionPersistence() const
         state.PersistedWindowLayouts(nullptr);
     }
 
-    if (_forcePersistence || _app.Logic().Settings().GlobalSettings().ShouldUsePersistedLayout())
+    if (_app.Logic().Settings().GlobalSettings().ShouldUsePersistedLayout())
     {
         for (const auto& w : _windows)
         {
diff --git a/src/cascadia/WindowsTerminal/WindowEmperor.h b/src/cascadia/WindowsTerminal/WindowEmperor.h
index 3024ab7a2c..c232c6cd1a 100644
--- a/src/cascadia/WindowsTerminal/WindowEmperor.h
+++ b/src/cascadia/WindowsTerminal/WindowEmperor.h
@@ -75,7 +75,7 @@ private:
     UINT WM_TASKBARCREATED = 0;
     HMENU _currentWindowMenu = nullptr;
     bool _notificationIconShown = false;
-    bool _forcePersistence = false;
+    bool _skipPersistence = false;
     bool _needsPersistenceCleanup = false;
     std::optional<bool> _currentSystemThemeIsDark;
     int32_t _windowCount = 0;