diff --git a/manifest.json b/manifest.json
index 951300e..9d67590 100644
--- a/manifest.json
+++ b/manifest.json
@@ -8,5 +8,8 @@
   "sources": [
     "src/**/*.cs"
   ],
-  "depends": ["visual_novel_core>=1", "dialog_base>=1", "interactive_base>=1", "time_base>=1", "map_base>=1", "interface>=1"]
+  "depends": ["dialog_base>=1", "interactive_base>=1", "time_base>=1", "map_base>=1", "interface>=1"],
+  "test_suites": [
+    {"id": "windows", "activate": ["--itest=tools_windows"]}
+  ]
 }
diff --git a/test_suites/windows/manifest.json b/test_suites/windows/manifest.json
new file mode 100644
index 0000000..a50f4cb
--- /dev/null
+++ b/test_suites/windows/manifest.json
@@ -0,0 +1,10 @@
+{
+  "name": "Tool Windows Test",
+  "description": "Integration test of the tools mod: opens every registered tool window through ToolFactory exactly like the toolbar button does, checks the chrome and the window's own smoke checks, optionally saves a screenshot of each window (--shots=<dir>) and reports [TEST_RESULT]. Activated by --itest=tools_windows.",
+  "sources": [
+    "src/*.cs"
+  ],
+  "depends": [
+    "visual_novel_core>=1"
+  ]
+}
diff --git a/test_suites/windows/src/ToolWindowsErrorLogger.cs b/test_suites/windows/src/ToolWindowsErrorLogger.cs
new file mode 100644
index 0000000..6864b89
--- /dev/null
+++ b/test_suites/windows/src/ToolWindowsErrorLogger.cs
@@ -0,0 +1,40 @@
+using System.Collections.Generic;
+using Godot;
+
+namespace Cthangover.Tools.Tests.Windows
+{
+    /// <summary>
+    /// Engine logger that records every error Godot reports while the test
+    /// runs. An exception thrown inside a signal handler (a button toggled
+    /// during construction, a draw callback) never reaches the code that opened
+    /// the window — Godot only prints it — so without this the test would pass
+    /// windows that are visibly broken. Errors may arrive from any thread.
+    /// </summary>
+    public partial class ToolWindowsErrorLogger : Logger
+    {
+        private readonly object _lock = new();
+        private readonly List<string> _errors = new();
+
+        /// <summary>Records the error text (rationale or code, whichever is set).</summary>
+        public override void _LogError(string function, string file, int line, string code, string rationale,
+            bool editorNotify, int errorType, Godot.Collections.Array<ScriptBacktrace> scriptBacktraces)
+        {
+            if (errorType == (int)ErrorType.Warning)
+                return;
+
+            lock (_lock)
+                _errors.Add($"{(string.IsNullOrEmpty(rationale) ? code : rationale)} ({file}:{line})");
+        }
+
+        /// <summary>Returns and clears the errors collected so far.</summary>
+        public List<string> Drain()
+        {
+            lock (_lock)
+            {
+                var copy = new List<string>(_errors);
+                _errors.Clear();
+                return copy;
+            }
+        }
+    }
+}
diff --git a/test_suites/windows/src/ToolWindowsExercises.cs b/test_suites/windows/src/ToolWindowsExercises.cs
new file mode 100644
index 0000000..6a8e3b8
--- /dev/null
+++ b/test_suites/windows/src/ToolWindowsExercises.cs
@@ -0,0 +1,132 @@
+using System;
+using System.Linq;
+using Cthangover.Core.UI.Tool.LightEditor;
+using Cthangover.Core.UI.Tool.ScenarioEditor;
+using Cthangover.Tools.InteractiveEditor;
+using Cthangover.Tools.MapEditor;
+using Godot;
+
+namespace Cthangover.Tools.Tests.Windows
+{
+    /// <summary>
+    /// Per-tool interaction checks run on an open window, through the same
+    /// public surface the UI uses: canvas input is delivered by emitting the
+    /// canvas' <c>gui_input</c> signal (the editors subscribe to it), data is
+    /// read back from the canvas' public controller. Nothing is saved — the
+    /// window is closed without writing afterwards.
+    /// </summary>
+    public static class ToolWindowsExercises
+    {
+        /// <summary>Runs the checks for <paramref name="toolId"/>; <paramref name="check"/> records each result.</summary>
+        public static void Run(string toolId, Window window, Action<bool, string> check)
+        {
+            switch (toolId)
+            {
+                case "map_editor":
+                    MapDrawing(window, check);
+                    break;
+                case "interactive_editor":
+                    InteractivePolygon(window, check);
+                    break;
+                case "light_editor":
+                    LightAdd(window, check);
+                    break;
+                case "scenario_editor":
+                    var tree = Find<ScenarioFileTreePanel>(window)?.FindChildren("*", nameof(Tree), true, false).OfType<Tree>().FirstOrDefault();
+                    check(tree?.GetRoot()?.GetChildCount() > 0, "scenario_editor: file tree lists mods with scenarios");
+                    break;
+            }
+        }
+
+        /// <summary>Draws a triangle; the finishing double-click must not add a fourth vertex.</summary>
+        private static void MapDrawing(Window window, Action<bool, string> check)
+        {
+            var canvas = Find<MapEditorCanvas>(window);
+            if (canvas?.Controller == null)
+            {
+                check(false, "map_editor: canvas found");
+                return;
+            }
+
+            var zone = canvas.Controller.StartRegion();
+            canvas.SetMode(MapEditorCanvas.ModeDraw);
+            var rect = canvas.GetBackgroundRect();
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.2f, 0.2f), false);
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.4f, 0.2f), false);
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.3f, 0.4f), false);
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.3f, 0.4f), true);
+
+            check(zone.Points.Count == 3, $"map_editor: drawn region has 3 vertices (got {zone.Points.Count})");
+            check(canvas.Mode == MapEditorCanvas.ModeSelect, "map_editor: double-click finishes drawing");
+            check(Mathf.Abs(zone.Points[0].X - 0.2f) < 0.01f && Mathf.Abs(zone.Points[0].Y - 0.2f) < 0.01f,
+                $"map_editor: vertex lands at the clicked background point (got {zone.Points[0]})");
+        }
+
+        /// <summary>A new object switched to polygon gets 4 vertices; a click on empty background appends one.</summary>
+        private static void InteractivePolygon(Window window, Action<bool, string> check)
+        {
+            var canvas = Find<InteractiveEditorCanvas>(window);
+            if (canvas?.Controller == null)
+            {
+                check(false, "interactive_editor: canvas found");
+                return;
+            }
+
+            var def = canvas.Controller.Add();
+            InteractiveEditorController.SetHitType(def, "polygon");
+            canvas.RebuildHandles();
+            check(def.HitArea.Vertices?.Length == 4, "interactive_editor: rect converts to a 4-vertex polygon");
+
+            var rect = canvas.GetBackgroundRect();
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.97f, 0.97f), false);
+            check(def.HitArea.Vertices?.Length == 5, $"interactive_editor: click on empty background adds a vertex (got {def.HitArea.Vertices?.Length})");
+        }
+
+        /// <summary>A double-click on the background adds a light at that point.</summary>
+        private static void LightAdd(Window window, Action<bool, string> check)
+        {
+            var canvas = Find<LightEditorCanvas>(window);
+            if (canvas?.Controller == null)
+            {
+                check(false, "light_editor: canvas found");
+                return;
+            }
+
+            var before = canvas.Controller.Lights.Count;
+            if (before >= LightEditorController.MaxLights)
+                return;
+
+            var rect = canvas.GetBackgroundRect();
+            Click(canvas, rect.Position + rect.Size * new Vector2(0.75f, 0.25f), true);
+            var light = canvas.Controller.Selected;
+            check(canvas.Controller.Lights.Count == before + 1 && light != null
+                  && Mathf.Abs(light.X - 0.75f) < 0.01f && Mathf.Abs(light.Y - 0.25f) < 0.01f,
+                "light_editor: double-click adds a light at the clicked point");
+        }
+
+        private static void Click(Control target, Vector2 local, bool doubleClick)
+        {
+            var ev = new InputEventMouseButton
+            {
+                ButtonIndex = MouseButton.Left,
+                Pressed = true,
+                DoubleClick = doubleClick,
+                Position = local
+            };
+            target.EmitSignal(Control.SignalName.GuiInput, ev);
+        }
+
+        private static T Find<T>(Node root) where T : Node
+        {
+            foreach (var child in root.GetChildren())
+            {
+                if (child is T match)
+                    return match;
+                var nested = Find<T>(child);
+                if (nested != null)
+                    return nested;
+            }
+            return null;
+        }
+    }
+}
diff --git a/test_suites/windows/src/ToolWindowsTestDriverNode.cs b/test_suites/windows/src/ToolWindowsTestDriverNode.cs
new file mode 100644
index 0000000..03f2796
--- /dev/null
+++ b/test_suites/windows/src/ToolWindowsTestDriverNode.cs
@@ -0,0 +1,216 @@
+using System.Collections.Generic;
+using System.IO;
+using Cthangover.Core.Bootstrap;
+using Cthangover.Core.Games;
+using Cthangover.Core.UI.Tool;
+using Cthangover.Core.Utils;
+using Cthangover.Mods.Interface.Menu;
+using Cthangover.Mods.Interface.Tool;
+using Cthangover.Tools.Hub;
+using Godot;
+
+namespace Cthangover.Tools.Tests.Windows
+{
+    /// <summary>
+    /// Opens every registered tool window one by one through the same path the
+    /// toolbar button uses (<see cref="ToolFactory"/> → <see cref="ToolWindow.ShowWindow"/>),
+    /// lets it lay out for a couple of ticks, checks that it entered the tree
+    /// visible and inside the game viewport, optionally saves a screenshot and
+    /// closes it. A window that throws while constructing or laying out fails
+    /// only its own check, the others still run. Ends with the runner contract
+    /// <c>[TEST_RESULT] name=tools_windows passed=N failed=M</c> and the exit code.
+    /// <para/>
+    /// Launched as the <c>novel_editor</c> game (<c>--game=novel_editor --new</c>)
+    /// it first waits for the collection's entry scene, the
+    /// <see cref="NovelEditorHub"/>, and checks it lists a launcher button for
+    /// every registered tool before opening the windows.
+    /// </summary>
+    public partial class ToolWindowsTestDriverNode : Node
+    {
+        private const string ResultName = "tools_windows";
+        private const float TickSeconds = 0.5f;
+        private const float TimeoutSeconds = 90f;
+        private const int SettleTicks = 4;
+        private const int ExerciseTick = 2;
+
+        private readonly string _shotsDir;
+        private readonly List<IToolProvider> _tools = new();
+        private int _passed;
+        private int _failed;
+        private int _toolIndex = -1;
+        private int _settle;
+        private double _elapsed;
+        private bool _finished;
+        private Window _window;
+        private readonly ToolWindowsErrorLogger _errors = new();
+
+        /// <summary>Creates the driver; <paramref name="shotsDir"/> null or empty disables screenshots.</summary>
+        public ToolWindowsTestDriverNode(string shotsDir)
+        {
+            _shotsDir = shotsDir;
+            OS.AddLogger(_errors);
+            var timer = new Timer { WaitTime = TickSeconds, Autostart = true };
+            AddChild(timer);
+            timer.Timeout += Tick;
+        }
+
+        private void Tick()
+        {
+            if (_finished)
+                return;
+
+            _elapsed += TickSeconds;
+            if (_elapsed >= TimeoutSeconds)
+            {
+                Fail($"timeout ({TimeoutSeconds:0}s) at tool #{_toolIndex}");
+                Finish();
+                return;
+            }
+
+            if (_toolIndex < 0)
+            {
+                var tree = Godot.Engine.GetMainLoop() as SceneTree;
+                if (!Boot.IsReady || tree?.CurrentScene == null)
+                    return;
+
+                var inHub = ActiveGame.Id == NovelEditorHub.SceneName;
+                if (inHub && tree.CurrentScene is not NovelEditorHub)
+                    return;
+
+                _tools.AddRange(ToolFactory.Instance.GetAll());
+                Check(_tools.Count > 0, $"tools registered ({_tools.Count})");
+                if (inHub)
+                    CheckHub(tree.CurrentScene);
+                OpenNext();
+                return;
+            }
+
+            if (_window == null)
+                return;
+
+            if (--_settle == ExerciseTick)
+            {
+                try
+                {
+                    ToolWindowsExercises.Run(_tools[_toolIndex].Id, _window, Check);
+                }
+                catch (System.Exception ex)
+                {
+                    Fail($"{_tools[_toolIndex].Id}: interaction threw {ex.GetType().Name}: {ex.Message}");
+                }
+            }
+
+            if (_settle > 0)
+                return;
+
+            InspectAndClose();
+            OpenNext();
+        }
+
+        private void OpenNext()
+        {
+            _toolIndex++;
+            if (_toolIndex >= _tools.Count)
+            {
+                Finish();
+                return;
+            }
+
+            var tool = _tools[_toolIndex];
+            _errors.Drain();
+            try
+            {
+                _window = ToolWindow.ShowWindow(tool.CreateWindow());
+                _settle = SettleTicks;
+            }
+            catch (System.Exception ex)
+            {
+                Fail($"{tool.Id}: open threw {ex.GetType().Name}: {ex.Message}");
+                _window = null;
+                OpenNext();
+            }
+        }
+
+        /// <summary>Every registered tool has its launcher button on the hub screen.</summary>
+        private void CheckHub(Node hub)
+        {
+            var keys = new HashSet<string>();
+            CollectButtonKeys(hub, keys);
+            foreach (var tool in _tools)
+                Check(keys.Contains(tool.LocaleKey), $"hub: launcher button for {tool.Id}");
+            SaveShot("novel_editor_hub");
+        }
+
+        private static void CollectButtonKeys(Node node, HashSet<string> keys)
+        {
+            if (node is Button button && button.HasMeta(MenuBuilder.LocaleMetaKey))
+                keys.Add(button.GetMeta(MenuBuilder.LocaleMetaKey).AsString());
+            foreach (var child in node.GetChildren())
+                CollectButtonKeys(child, keys);
+        }
+
+        private void InspectAndClose()
+        {
+            var id = _tools[_toolIndex].Id;
+            var window = _window;
+            _window = null;
+
+            var errors = _errors.Drain();
+            Check(errors.Count == 0, $"{id}: no engine errors while opening" + (errors.Count > 0 ? ": " + string.Join(" | ", errors) : ""));
+            Check(GodotObject.IsInstanceValid(window) && window.IsInsideTree() && window.Visible, $"{id}: window visible in tree");
+            if (!GodotObject.IsInstanceValid(window))
+                return;
+
+            var viewport = GetTree().Root.GetVisibleRect().Size;
+            Check(window.Size.X <= viewport.X + 1 && window.Size.Y <= viewport.Y + 1,
+                $"{id}: window {window.Size} fits viewport {viewport}");
+
+            SaveShot(id);
+            window.QueueFree();
+        }
+
+        private void SaveShot(string id)
+        {
+            if (string.IsNullOrEmpty(_shotsDir) || DisplayServer.GetName() == "headless")
+                return;
+
+            var dir = ProjectSettings.GlobalizePath(_shotsDir);
+            Directory.CreateDirectory(dir);
+            var image = GetViewport().GetTexture().GetImage();
+            var path = Path.Combine(dir, id + ".png");
+            image.SavePng(path);
+            Log($"screenshot {path}");
+        }
+
+        private void Check(bool ok, string name)
+        {
+            if (ok)
+            {
+                _passed++;
+                Log($"[PASS] {name}");
+            }
+            else
+            {
+                Fail(name);
+            }
+        }
+
+        private void Fail(string message)
+        {
+            _failed++;
+            Log($"[FAIL] {message}");
+        }
+
+        private void Finish()
+        {
+            if (_finished)
+                return;
+            _finished = true;
+            OS.RemoveLogger(_errors);
+            GameLogger.Log("TEST", $"[TEST_RESULT] name={ResultName} passed={_passed} failed={_failed}");
+            GetTree().Quit(_failed == 0 ? 0 : 1);
+        }
+
+        private static void Log(string message) => GameLogger.Log("TEST", message);
+    }
+}
diff --git a/test_suites/windows/src/ToolWindowsTestInitializer.cs b/test_suites/windows/src/ToolWindowsTestInitializer.cs
new file mode 100644
index 0000000..69af2e7
--- /dev/null
+++ b/test_suites/windows/src/ToolWindowsTestInitializer.cs
@@ -0,0 +1,43 @@
+using System.Linq;
+using Cthangover.Core.Mods;
+using Cthangover.Core.Utils;
+using Godot;
+
+namespace Cthangover.Tools.Tests.Windows
+{
+    /// <summary>
+    /// Entry point of the tool windows GUI test. Activated only by the exact
+    /// user arg <c>--itest=tools_windows</c>; <c>--shots=&lt;dir&gt;</c> additionally
+    /// saves a screenshot of every opened window (needs a real display, e.g.
+    /// xvfb — the headless renderer produces no image). The driver is added to
+    /// the tree deferred because resources-ready fires before the shell scene
+    /// exists; the driver waits for the boot itself.
+    /// </summary>
+    public class ToolWindowsTestInitializer : IModInitializer
+    {
+        private static bool driverQueued;
+
+        /// <summary>Nothing to do per mod: the driver is queued on resources-ready.</summary>
+        public void OnModLoaded(string modId) { }
+
+        /// <summary>Queues the driver once when the activation flag is present.</summary>
+        public void OnModResourcesReady()
+        {
+            if (driverQueued)
+                return;
+
+            var args = OS.GetCmdlineUserArgs();
+            if (!args.Any(a => a == "--itest=tools_windows"))
+                return;
+
+            var shots = args
+                .Where(a => a.StartsWith("--shots=", System.StringComparison.Ordinal))
+                .Select(a => a.Substring("--shots=".Length))
+                .FirstOrDefault();
+
+            driverQueued = true;
+            GameLogger.Log("TEST", $"ToolWindowsTestInitializer: activating tool windows test, shots='{shots ?? ""}'");
+            (Godot.Engine.GetMainLoop() as SceneTree)?.Root?.CallDeferred("add_child", new ToolWindowsTestDriverNode(shots));
+        }
+    }
+}