From 1fe66076c6b1ac1f8d17a33ccaa71049bf79760d Mon Sep 17 00:00:00 2001
From: aclist <92275929+aclist@users.noreply.github.com>
Date: Wed, 17 Jun 2026 22:12:12 +0900
Subject: [PATCH 1/2] fix: validate custom folders before launch

---
 dzgui/managers/offline.py    | 10 +++++++++-
 dzgui/strings/offline.py     |  1 +
 dzgui/views/pages/offline.py | 28 ++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/dzgui/managers/offline.py b/dzgui/managers/offline.py
index 5f49f09..0e50fe7 100644
--- a/dzgui/managers/offline.py
+++ b/dzgui/managers/offline.py
@@ -34,10 +34,18 @@ class OfflineManager:
         self.thread_man = ThreadingManager(controller)
 
         self.appid: int
-        self.mission_folder: str
         self.local_mods: list[str] | None
         self.custom_mods: list[str] | None
 
+    # TODO; more robust test
+    def is_custom_folder_valid(self, folder: str) -> bool:
+        return Path(folder).exists()
+
+    # TODO: set properties as members of offline manager on demand and check them here
+    # rather than passing strings again
+    def is_mission_valid(self, folder: str) -> bool:
+        return is_mission(Path(folder))
+
     def get_mission(self) -> None:
         folder = self.open_folderpicker(dialogs.mission_dialog)
         if folder is None:
diff --git a/dzgui/strings/offline.py b/dzgui/strings/offline.py
index 875c574..3ee1202 100644
--- a/dzgui/strings/offline.py
+++ b/dzgui/strings/offline.py
@@ -13,6 +13,7 @@ local_frame = "Installed mods"
 no_local_mods = "No local mods found"
 no_mods = "No valid mods found"
 no_mission = "Not a valid mission"
+folder_changed = "Folder missing or changed on disk"
 
 custom_eventbox = "Set the root folder. Mods must be in atomic folders and have a meta.cpp file at a minimum."
 mission_eventbox = "Select a single mission folder containing an init.c file."
diff --git a/dzgui/views/pages/offline.py b/dzgui/views/pages/offline.py
index fe20d5f..e10aa3e 100644
--- a/dzgui/views/pages/offline.py
+++ b/dzgui/views/pages/offline.py
@@ -38,6 +38,7 @@ if TYPE_CHECKING:
 class FolderError(Enum):
     NO_VALID_MODS = 1
     NO_VALID_MISSION = 2
+    FOLDER_CHANGED = 3
 
 
 class PageHeading(Gtk.Label):
@@ -65,6 +66,10 @@ class ErrorPopover(Gtk.Popover):
                 prefix = offline.no_mods
             case FolderError.NO_VALID_MISSION:
                 prefix = offline.no_mission
+            case FolderError.FOLDER_CHANGED:
+                prefix = offline.folder_changed
+                self.label.set_label(prefix)
+                return
         self.label.set_label(f"{prefix}: '{msg}'")
 
 
@@ -105,6 +110,11 @@ class FolderHBox(HBox):
         self.pop.set_relative_to(self.button)
         self.pop.connect("unmap", lambda _: self.grab_focus())
 
+        self.sidepop = ErrorPopover()
+        self.sidepop.set_position(Gtk.PositionType.BOTTOM)
+        self.sidepop.set_relative_to(self.scrolled_label)
+        self.sidepop.connect("unmap", lambda _: self.grab_focus())
+
         self.connect("map", self._on_map)
         self.connect("unmap", self._on_unmap)
 
@@ -150,6 +160,10 @@ class FolderHBox(HBox):
         self.unset_button.show()
 
     def present_error(self, error: FolderError, msg: str) -> None:
+        if error == FolderError.FOLDER_CHANGED:
+            self.sidepop.set_label(error, msg)
+            self.sidepop.popup()
+            return
         self.folder = ""
         self.label.set_text("")
         self.unset_button.hide()
@@ -300,6 +314,9 @@ class CustomModFrame(ModFrame):
         self.tree_vbox.hide()
         self.no_mods.hide()
 
+    def present_folder_changed(self, folder: str) -> None:
+        self.custom_hbox.present_error(FolderError.FOLDER_CHANGED, folder)
+
     def present_error(self, folder: str) -> None:
         self.hide_tree()
         self.custom_hbox.present_error(FolderError.NO_VALID_MODS, folder)
@@ -363,6 +380,9 @@ class MissionFrame(HeadingFrame):
     def get_mission(self) -> str:
         return self.mission_hbox.get_folder()
 
+    def present_folder_changed(self, folder: str) -> None:
+        self.mission_hbox.present_error(FolderError.FOLDER_CHANGED, folder)
+
 
 class RadioFrame(HeadingFrame):
     def __init__(self, parent: OfflineLoader, controller: "Controller") -> None:
@@ -482,4 +502,12 @@ class OfflineLoader(Gtk.Box):
         local_mods = self.local_frame.get_mods()
         custom_folder = self.custom_frame.get_folder()
         custom_mods = self.custom_frame.get_mods()
+
+        if custom_folder and not self.offline_man.is_custom_folder_valid(custom_folder):
+            self.custom_frame.present_folder_changed(mission)
+            return
+
+        if mission and not self.offline_man.is_mission_valid(mission):
+            self.mission_frame.present_folder_changed(mission)
+            return
         self.offline_man.launch(appid, mission, local_mods, custom_folder, custom_mods)

From f4d065d766885364b7c9e3415510dbc41563311d Mon Sep 17 00:00:00 2001
From: aclist <92275929+aclist@users.noreply.github.com>
Date: Wed, 17 Jun 2026 22:13:17 +0900
Subject: [PATCH 2/2] fix: typo

---
 dzgui/managers/offline.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dzgui/managers/offline.py b/dzgui/managers/offline.py
index 0e50fe7..15d8ece 100644
--- a/dzgui/managers/offline.py
+++ b/dzgui/managers/offline.py
@@ -37,7 +37,7 @@ class OfflineManager:
         self.local_mods: list[str] | None
         self.custom_mods: list[str] | None
 
-    # TODO; more robust test
+    # TODO: more robust test
     def is_custom_folder_valid(self, folder: str) -> bool:
         return Path(folder).exists()