diff --git a/src/AcDream.Plugins.MossTank/mosstank.xml b/src/AcDream.Plugins.MossTank/mosstank.xml
index df2c7b44..dfac61b7 100644
--- a/src/AcDream.Plugins.MossTank/mosstank.xml
+++ b/src/AcDream.Plugins.MossTank/mosstank.xml
@@ -149,7 +149,7 @@
     <field x="734" y="28" w="40" h="16" text="{PetCustomRangeValueText}"
            onchange="{SetPetCustomRangeText}" maxlength="6" background="#E6000000"
            tooltip="Custom pet summon range in meters." />
-    <label x="614" y="48" w="125" h="16" text="Pet Min. Monsters:" color="#FFE8DEC3" />
+    <label x="614" y="48" w="120" h="16" text="Pet Min. Monsters:" color="#FFE8DEC3" />
     <field x="734" y="48" w="40" h="16" text="{PetDensityValueText}"
            onchange="{SetPetDensityText}" maxlength="3" background="#E6000000"
            tooltip="Minimum nearby monsters required before summoning a pet." />
@@ -449,65 +449,75 @@
     <label x="438" y="184" text="{ProfileNotice}" color="#FF9B9072" />
   </group>
 
-  <!-- Buffs: every visible switch maps to the live buff plan, plus VTank's
-       own Extra Buff Spells / Blacklisted Buff Families lists (Campaign VT
-       S7.4, docs/research/vtank-kb/08-ui-views.md §1 "Tab: Buffs" — VTank's
-       REAL Buffs tab is only these two lists + two "Add..." buttons; the
-       category toggles/difficulty/rebuff/Buff-button below are MossTank's
-       own pre-existing extension, kept as a superset and compacted into
-       two columns to make room rather than removed). Any cell click on
-       either list removes that row (PluginCore.cs:7323-7355); "Add..."
-       opens the shared SelfBuffChoiceView-style picker
-       (mosstank-buffpicker.xml). List heights (84, not VTank's 116) and
-       widths (246/256, not VTank's 320) are narrowed to coexist with the
-       retained toggle columns in this tab's fixed 848x194 canvas — a
-       proportion-preserving compromise, not a pixel-for-pixel port
-       (owner's bar: "looks basically the same", never VVS pixels). -->
+  <!-- Buffs: VTank's REAL Buffs tab (docs/research/vtank-kb/08-ui-views.md
+       §1 "Tab: Buffs") is ONLY two lists + two "Add..." buttons — Extra Buff
+       Spells and Blacklisted Buff Families, each VTank's own 320x116, at the
+       far left and far right of the 848-wide canvas (PluginCore.cs:
+       7323-7355 — any cell click removes that row; "Add..." opens the
+       shared SelfBuffChoiceView-style picker, mosstank-buffpicker.xml).
+
+       Fix round B item 2 (owner's silhouette rule: VTank's own controls are
+       never shrunk/moved/reordered to make room for MossTank extras): the
+       category toggles / difficulty / rebuff / Buff-cast-now block below
+       (MossTank's own pre-existing extension, no VTank Buffs-tab
+       counterpart) used to live in the same two columns as the narrowed
+       lists, and its Difficulty "+" button (338,108) overlapped the Extra
+       Buff Spells "Add..." button (336,102) — a real sibling-overlap bug
+       the new AuthoredControlsInTheSameGroupNeverOverlap pin below now
+       catches. Both lists are restored to VTank's full 320x116 at the far
+       left (x=4) and far right (x=524, 848-4-320) with their own
+       120-wide "Add..." row below each list; the whole MossTank-extras
+       block moves into the EMPTY MIDDLE strip between the two lists
+       (x=332..516, the 184px VTank's own layout never uses), stacked
+       compactly: 7 toggles at a 16px pitch, then Difficulty +/-, then
+       Rebuff +/-, then the Buff button + status, then Coverage at y=178
+       (194-16, item 3's bottom-fit rule) — a proportion-preserving
+       compromise fitting a real 184x194 box, not a pixel-for-pixel VVS
+       port (owner's bar: "looks basically the same", never VVS pixels). -->
   <group x="8" y="42" w="848" h="194" visible="{BuffsVisible}">
-    <toggle x="4" y="0" w="160" h="18" text="Trained skills only"
-            checked="{TrainedOnlyEnabled}" onclick="{ToggleTrainedOnly}" />
-    <toggle x="4" y="20" w="160" h="18" text="Attributes"
-            checked="{AttributesEnabled}" onclick="{ToggleAttributes}" />
-    <toggle x="4" y="40" w="160" h="18" text="Protections"
-            checked="{ProtectionsEnabled}" onclick="{ToggleProtections}" />
-    <toggle x="4" y="60" w="160" h="18" text="Weapon auras"
-            checked="{AurasEnabled}" onclick="{ToggleAuras}" />
-
-    <toggle x="168" y="0" w="160" h="18" text="Armor banes"
-            checked="{BanesEnabled}" onclick="{ToggleBanes}" />
-    <toggle x="168" y="20" w="160" h="18" text="Regeneration"
-            checked="{RegenerationEnabled}" onclick="{ToggleRegeneration}" />
-    <toggle x="168" y="40" w="160" h="18" text="Other self-spells"
-            checked="{OtherEnabled}" onclick="{ToggleOther}" />
-
-    <label x="336" y="0" w="246" text="Extra Buff Spells" color="#FFE8DEC3"
+    <label x="4" y="0" w="320" h="16" text="Extra Buff Spells" color="#FFE8DEC3"
            tooltip="Named spell exemplars added beyond the school-driven picks (best similar will be used)." />
-    <list x="336" y="16" w="246" h="84" rowheight="17"
+    <list x="4" y="18" w="320" h="116" rowheight="17"
           items="{ExtraBuffRows}" selected="{SelectedExtraBuffIndex}"
           onchange="{DeleteExtraBuffAt}" tooltip="Click a row to remove it." />
-    <button x="336" y="102" w="120" h="16" text="Add..." onclick="{ShowExtraBuffPicker}" />
+    <button x="4" y="138" w="120" h="18" text="Add..." onclick="{ShowExtraBuffPicker}" />
 
-    <label x="590" y="0" w="256" text="Blacklisted Buff Families" color="#FFE8DEC3"
+    <label x="524" y="0" w="320" h="16" text="Blacklisted Buff Families" color="#FFE8DEC3"
            tooltip="Named buff families never cast, even if otherwise wanted." />
-    <list x="590" y="16" w="256" h="84" rowheight="17"
+    <list x="524" y="18" w="320" h="116" rowheight="17"
           items="{BlacklistedBuffFamilyRows}" selected="{SelectedBlacklistedBuffIndex}"
           onchange="{DeleteBlacklistedBuffFamilyAt}" tooltip="Click a row to remove it." />
-    <button x="590" y="102" w="120" h="16" text="Add..." onclick="{ShowBlacklistedBuffPicker}" />
+    <button x="524" y="138" w="120" h="18" text="Add..." onclick="{ShowBlacklistedBuffPicker}" />
 
-    <label x="4" y="112" w="300" text="{DifficultyText}" color="#FFE8DEC3" />
-    <button x="308" y="108" w="26" h="20" text="-" onclick="{DifficultyDown}"
+    <toggle x="332" y="0" w="180" h="16" text="Trained skills only"
+            checked="{TrainedOnlyEnabled}" onclick="{ToggleTrainedOnly}" />
+    <toggle x="332" y="16" w="180" h="16" text="Attributes"
+            checked="{AttributesEnabled}" onclick="{ToggleAttributes}" />
+    <toggle x="332" y="32" w="180" h="16" text="Protections"
+            checked="{ProtectionsEnabled}" onclick="{ToggleProtections}" />
+    <toggle x="332" y="48" w="180" h="16" text="Weapon auras"
+            checked="{AurasEnabled}" onclick="{ToggleAuras}" />
+    <toggle x="332" y="64" w="180" h="16" text="Armor banes"
+            checked="{BanesEnabled}" onclick="{ToggleBanes}" />
+    <toggle x="332" y="80" w="180" h="16" text="Regeneration"
+            checked="{RegenerationEnabled}" onclick="{ToggleRegeneration}" />
+    <toggle x="332" y="96" w="180" h="16" text="Other self-spells"
+            checked="{OtherEnabled}" onclick="{ToggleOther}" />
+
+    <label x="332" y="116" w="140" text="{DifficultyText}" color="#FFE8DEC3" />
+    <button x="472" y="112" w="20" h="18" text="-" onclick="{DifficultyDown}"
             tooltip="Decrease the skill-over-difficulty margin." />
-    <button x="338" y="108" w="26" h="20" text="+" onclick="{DifficultyUp}"
+    <button x="494" y="112" w="20" h="18" text="+" onclick="{DifficultyUp}"
             tooltip="Increase the skill-over-difficulty margin." />
-    <label x="4" y="134" w="300" text="{RebuffText}" color="#FFE8DEC3" />
-    <button x="308" y="130" w="26" h="20" text="-" onclick="{RebuffDown}"
+    <label x="332" y="136" w="140" text="{RebuffText}" color="#FFE8DEC3" />
+    <button x="472" y="132" w="20" h="18" text="-" onclick="{RebuffDown}"
             tooltip="Rebuff later." />
-    <button x="338" y="130" w="26" h="20" text="+" onclick="{RebuffUp}"
+    <button x="494" y="132" w="20" h="18" text="+" onclick="{RebuffUp}"
             tooltip="Rebuff earlier." />
 
-    <button x="4" y="156" w="140" h="26" text="{BuffButtonText}" onclick="{Buff}" />
-    <label x="164" y="162" text="{BuffStatus}" color="#FFC7B98F" />
-    <label x="4" y="186" text="{Coverage}" color="#FF9B9072" />
+    <button x="332" y="154" w="110" h="18" text="{BuffButtonText}" onclick="{Buff}" />
+    <label x="446" y="158" w="70" text="{BuffStatus}" color="#FFC7B98F" />
+    <label x="332" y="178" w="184" h="16" text="{Coverage}" color="#FF9B9072" />
   </group>
 
   <!-- Route: VTank's navigation-waypoint editor and execution surface.
diff --git a/tests/AcDream.Plugins.MossTank.Tests/MossTankMarkupContractTests.cs b/tests/AcDream.Plugins.MossTank.Tests/MossTankMarkupContractTests.cs
index bdd2e94f..c69f8a38 100644
--- a/tests/AcDream.Plugins.MossTank.Tests/MossTankMarkupContractTests.cs
+++ b/tests/AcDream.Plugins.MossTank.Tests/MossTankMarkupContractTests.cs
@@ -307,6 +307,105 @@ public sealed class MossTankMarkupContractTests
         AssertWithinParent(root);
     }
 
+    /// <summary>
+    /// Fix round B item 2: <see cref="AssertWithinParent"/> only ever proved
+    /// a control fits inside its OWN parent's declared bounds — it never
+    /// caught two SIBLINGS overlapping each other while each individually
+    /// still fit. That's exactly how the Buffs tab's Difficulty "+" button
+    /// (338,108,26,20) ended up drawn on top of the Extra Buff Spells
+    /// "Add..." button (336,102,120,16) before this fix round, and how the
+    /// Options tab's "Pet Min. Monsters:" label (614,48,125,16) overlapped
+    /// the very field it labels (734,48,40,16) by 5px. This walks every
+    /// container in every plugin panel file and asserts no two positioned
+    /// children overlap — except two <c>&lt;group&gt;</c> elements (VTank
+    /// tab pages are mutually exclusive via their own <c>visible="{...}"</c>
+    /// binding, so sharing the same rectangle is by design) and
+    /// <c>&lt;column&gt;</c> (Campaign VT slice 1's <c>&lt;list&gt;&lt;column&gt;</c>
+    /// children have no <c>x</c>/<c>y</c> grammar at all — see
+    /// docs/plugin-ui-markup.md's "Columns" — so every column reads as
+    /// (0,0) and would trivially "overlap" every other column).
+    /// </summary>
+    [Theory]
+    [InlineData("mosstank.xml")]
+    [InlineData("mosstank-advanced.xml")]
+    [InlineData("mosstank-loot-editor.xml")]
+    [InlineData("mosstank-buffpicker.xml")]
+    public void AuthoredControlsInTheSameContainerNeverOverlapASibling(string fileName)
+    {
+        XDocument document = XDocument.Load(
+            Path.Combine(AppContext.BaseDirectory, fileName));
+        XElement root = Assert.IsType<XElement>(document.Root);
+        AssertNoSiblingOverlap(root);
+    }
+
+    /// <summary>Direct pin on the overlap PREDICATE itself (independent of
+    /// any real markup file): two rectangles that truly overlap must be
+    /// caught, touching-but-not-overlapping edges must not be a false
+    /// positive, and two sibling &lt;group&gt;s sharing one rectangle (the
+    /// normal VTank-tab-page shape) must be ignored.</summary>
+    [Fact]
+    public void AssertNoSiblingOverlap_CatchesARealOverlapAndIgnoresGroupPagesAndTouchingEdges()
+    {
+        var overlapping = new XElement("panel",
+            new XAttribute("w", "848"), new XAttribute("h", "194"),
+            new XElement("button", new XAttribute("x", "336"), new XAttribute("y", "102"),
+                new XAttribute("w", "120"), new XAttribute("h", "16")),
+            new XElement("button", new XAttribute("x", "338"), new XAttribute("y", "108"),
+                new XAttribute("w", "26"), new XAttribute("h", "20")));
+        Assert.Throws<Xunit.Sdk.TrueException>(() => AssertNoSiblingOverlap(overlapping));
+
+        var touchingEdges = new XElement("panel",
+            new XAttribute("w", "848"), new XAttribute("h", "194"),
+            new XElement("button", new XAttribute("x", "0"), new XAttribute("y", "0"),
+                new XAttribute("w", "100"), new XAttribute("h", "20")),
+            new XElement("button", new XAttribute("x", "100"), new XAttribute("y", "0"),
+                new XAttribute("w", "100"), new XAttribute("h", "20")));
+        AssertNoSiblingOverlap(touchingEdges); // must not throw
+
+        var twoGroupPages = new XElement("panel",
+            new XAttribute("w", "848"), new XAttribute("h", "236"),
+            new XElement("group", new XAttribute("x", "8"), new XAttribute("y", "42"),
+                new XAttribute("w", "848"), new XAttribute("h", "194")),
+            new XElement("group", new XAttribute("x", "8"), new XAttribute("y", "42"),
+                new XAttribute("w", "848"), new XAttribute("h", "194")));
+        AssertNoSiblingOverlap(twoGroupPages); // must not throw
+    }
+
+    private static void AssertNoSiblingOverlap(XElement container)
+    {
+        XElement[] children = container.Elements()
+            .Where(static child => child.Name.LocalName != "column")
+            .ToArray();
+        for (int i = 0; i < children.Length; i++)
+        {
+            for (int j = i + 1; j < children.Length; j++)
+            {
+                XElement a = children[i], b = children[j];
+                if (a.Name.LocalName == "group" && b.Name.LocalName == "group")
+                    continue;
+                Assert.True(
+                    !RectanglesOverlap(a, b),
+                    $"<{a.Name}> text='{(string?)a.Attribute("text")}' @ "
+                    + $"({Number(a, "x")},{Number(a, "y")},{Number(a, "w")},{Number(a, "h")}) "
+                    + $"overlaps sibling <{b.Name}> text='{(string?)b.Attribute("text")}' @ "
+                    + $"({Number(b, "x")},{Number(b, "y")},{Number(b, "w")},{Number(b, "h")}).");
+            }
+        }
+        foreach (XElement child in children)
+            AssertNoSiblingOverlap(child);
+    }
+
+    private static bool RectanglesOverlap(XElement a, XElement b)
+    {
+        float aw = Number(a, "w"), ah = Number(a, "h");
+        float bw = Number(b, "w"), bh = Number(b, "h");
+        if (aw <= 0f || ah <= 0f || bw <= 0f || bh <= 0f)
+            return false; // an element with no declared size never "occupies" space
+        float ax = Number(a, "x"), ay = Number(a, "y");
+        float bx = Number(b, "x"), by = Number(b, "y");
+        return ax < bx + bw && bx < ax + aw && ay < by + bh && by < ay + ah;
+    }
+
     /// <summary>
     /// Fix round A (2026-09-07): the Advanced Options and Loot Editor popups
     /// moved out of mosstank.xml into their own plugin panel files. This