diff --git a/tests/AcDream.App.Tests/UI/RetailWindowLayoutPersistenceTests.cs b/tests/AcDream.App.Tests/UI/RetailWindowLayoutPersistenceTests.cs
index 848f12eba..67c0abe1f 100644
--- a/tests/AcDream.App.Tests/UI/RetailWindowLayoutPersistenceTests.cs
+++ b/tests/AcDream.App.Tests/UI/RetailWindowLayoutPersistenceTests.cs
@@ -424,6 +424,81 @@ public sealed class RetailWindowLayoutPersistenceTests : IDisposable
         Assert.Equal((77f, 88f), (saved.X, saved.Y));
     }
 
+    // ── 2026-09-07: a resizable plugin markup panel's resized geometry
+    // persists and restores exactly like any other registered window — no
+    // persistence-layer change was needed for this, since RetailWindowLayoutPersistence
+    // already clamps against the frame's own MinWidth/MinHeight/MaxWidth/
+    // MaxHeight (Apply's ClampDimension) for every registered handle. ────────
+
+    [Fact]
+    public void ResizableMarkupPluginPanel_ResizedSize_RoundTripsThroughPersistence()
+    {
+        const string xml =
+            "<panel x=\"0\" y=\"0\" w=\"300\" h=\"200\" resizable=\"true\" minw=\"200\" minh=\"150\"></panel>";
+        var panel = MarkupDocument.Build(xml, new object(), _ => (1u, 32, 32));
+        var store = new SettingsStore(PathName);
+        var root = new UiRoot { Width = 800, Height = 600 };
+        root.AddChild(panel);
+        RetailWindowHandle handle = root.RegisterWindow("plugin-resizable-panel", panel);
+        using var persistence = new RetailWindowLayoutPersistence(
+            root.WindowManager, store, () => "Alice", () => (800, 600));
+
+        handle.MoveTo(60f, 70f);
+        handle.ResizeTo(420f, 260f);
+
+        UiWindowLayout saved = Assert.IsType<UiWindowLayout>(
+            store.LoadWindowLayout("Alice", "800x600", "plugin-resizable-panel", default));
+        Assert.Equal((60f, 70f, 420f, 260f), (saved.X, saved.Y, saved.Width, saved.Height));
+
+        // Simulate a fresh session: rebuild the same markup (a fresh, un-resized
+        // panel) and restore — the saved 420x260 must come back, not the
+        // authored 300x200.
+        var freshPanel = MarkupDocument.Build(xml, new object(), _ => (1u, 32, 32));
+        var freshRoot = new UiRoot { Width = 800, Height = 600 };
+        freshRoot.AddChild(freshPanel);
+        RetailWindowHandle freshHandle = freshRoot.RegisterWindow(
+            "plugin-resizable-panel", freshPanel);
+        using var freshPersistence = new RetailWindowLayoutPersistence(
+            freshRoot.WindowManager, store, () => "Alice", () => (800, 600));
+
+        freshPersistence.RestoreAll();
+
+        Assert.Equal((420f, 260f), (freshPanel.Width, freshPanel.Height));
+        Assert.Equal((60f, 70f), (freshPanel.Left, freshPanel.Top));
+    }
+
+    [Fact]
+    public void ResizableMarkupPluginPanel_RestoreClampsBelowFloorToAuthoredMin()
+    {
+        // A legacy save from before this feature's minw/minh existed (or one
+        // from a plugin update that raised its floor) can carry a size below
+        // the CURRENT authored minimum. Restore must clamp up to that floor —
+        // this is what RetailWindowLayoutPersistence.Apply's ClampDimension
+        // already does against frame.MinWidth/MinHeight for every registered
+        // window; it only bites here because MarkupDocument now sets those
+        // fields from minw/minh instead of leaving them at UiElement's
+        // generic 40x40 default.
+        const string xml =
+            "<panel x=\"0\" y=\"0\" w=\"300\" h=\"200\" resizable=\"true\" minw=\"200\" minh=\"150\"></panel>";
+        var store = new SettingsStore(PathName);
+        store.SaveWindowLayout(
+            "Alice",
+            "800x600",
+            "plugin-resizable-floor",
+            new UiWindowLayout(60f, 70f, 80f, 60f, true, false, false));
+
+        var panel = MarkupDocument.Build(xml, new object(), _ => (1u, 32, 32));
+        var root = new UiRoot { Width = 800, Height = 600 };
+        root.AddChild(panel);
+        root.RegisterWindow("plugin-resizable-floor", panel);
+        using var persistence = new RetailWindowLayoutPersistence(
+            root.WindowManager, store, () => "Alice", () => (800, 600));
+
+        persistence.RestoreAll();
+
+        Assert.Equal((200f, 150f), (panel.Width, panel.Height));
+    }
+
     private static RetailWindowHandle Mount(
         UiRoot root,
         string name,
diff --git a/tests/AcDream.App.Tests/UI/RetailWindowManagerTests.cs b/tests/AcDream.App.Tests/UI/RetailWindowManagerTests.cs
index 9c538bc21..9a245023c 100644
--- a/tests/AcDream.App.Tests/UI/RetailWindowManagerTests.cs
+++ b/tests/AcDream.App.Tests/UI/RetailWindowManagerTests.cs
@@ -250,6 +250,47 @@ public sealed class RetailWindowManagerTests
             transitions);
     }
 
+    // ── 2026-09-07: plugin markup's resizable="true" panel through the real
+    // window-manager ResizeTo path (no host wiring beyond what MarkupDocument
+    // already sets on the panel — Resizable/ResizeX/ResizeY/MinWidth/MinHeight
+    // are ordinary UiElement properties RetailWindowManager.ResizeTo already
+    // respects for any registered window). ───────────────────────────────────
+
+    [Fact]
+    public void ResizableMarkupPluginWindow_AcceptsResizeWithinMinAndParentConstraints()
+    {
+        const string xml =
+            "<panel x=\"0\" y=\"0\" w=\"300\" h=\"200\" resizable=\"true\" minw=\"250\" minh=\"150\"></panel>";
+        var panel = MarkupDocument.Build(xml, new object(), _ => (1u, 32, 32));
+        var root = new UiRoot { Width = 800, Height = 600 };
+        root.AddChild(panel);
+        RetailWindowHandle handle = root.RegisterWindow("plugin-resizable", panel);
+
+        Assert.True(handle.ResizeTo(500f, 400f));
+        Assert.Equal((500f, 400f), (panel.Width, panel.Height));
+
+        // Below the authored floor clamps to minw/minh rather than shrinking further.
+        Assert.True(handle.ResizeTo(50f, 50f));
+        Assert.Equal((250f, 150f), (panel.Width, panel.Height));
+    }
+
+    [Fact]
+    public void NonResizableMarkupPluginWindow_RefusesResize()
+    {
+        const string xml = "<panel x=\"0\" y=\"0\" w=\"300\" h=\"200\"></panel>";
+        var panel = MarkupDocument.Build(xml, new object(), _ => (1u, 32, 32));
+        var root = new UiRoot { Width = 800, Height = 600 };
+        root.AddChild(panel);
+        RetailWindowHandle handle = root.RegisterWindow("plugin-fixed", panel);
+        int resized = 0;
+        handle.Resized += _ => resized++;
+
+        handle.ResizeTo(500f, 400f);
+
+        Assert.Equal((300f, 200f), (panel.Width, panel.Height));
+        Assert.Equal(0, resized);
+    }
+
     private sealed class RecordingController : IRetainedPanelController
     {
         public int ShownCount { get; private set; }