diff --git a/src/AcDream.App/Plugins/AppAutomationSurface.cs b/src/AcDream.App/Plugins/AppAutomationSurface.cs
index a4f87d0b..9ae412f7 100644
--- a/src/AcDream.App/Plugins/AppAutomationSurface.cs
+++ b/src/AcDream.App/Plugins/AppAutomationSurface.cs
@@ -1170,9 +1170,12 @@ internal sealed class AppAutomationSurface
     }
 
     /// <summary>
-    /// Routed to retail's ClientLocal log type (0x1A) — the channel the client
-    /// uses for its own notices. Nothing reaches the server, so a plugin cannot
-    /// accidentally speak in the player's name.
+    /// Owner direction 2026-09-07 (register row AD-124): plugin-originated
+    /// text now lands in the chat window (retail <c>Default</c>/0x00),
+    /// matching Decal's own <c>AddChatText</c> behavior — not retail's
+    /// ClientLocal (0x1A) SpewBox-only channel this previously used.
+    /// Nothing reaches the server, so a plugin cannot accidentally speak in
+    /// the player's name.
     /// </summary>
     public void PostSystemMessage(string text)
     {
@@ -1181,7 +1184,7 @@ internal sealed class AppAutomationSurface
         RuntimeCommunicationState? communication;
         lock (_gate)
             communication = _communication;
-        communication?.AddText(text, RetailLogTextType.ClientLocal);
+        communication?.AddText(text, RetailLogTextType.Default);
     }
 
     public bool Submit(string text)
diff --git a/src/AcDream.Plugin.Abstractions/Automation.cs b/src/AcDream.Plugin.Abstractions/Automation.cs
index 894d062b..2e968d1e 100644
--- a/src/AcDream.Plugin.Abstractions/Automation.cs
+++ b/src/AcDream.Plugin.Abstractions/Automation.cs
@@ -302,10 +302,20 @@ public interface IPluginChat
         Array.Empty<PluginChatMessage>();
 
     /// <summary>
-    /// Post a client-local system line, the channel retail uses for the
-    /// client's own notices. It is local to this client: nothing is sent to the
-    /// server and no other player sees it.
+    /// Post a plugin-originated system line into the chat window. It is
+    /// local to this client: nothing is sent to the server and no other
+    /// player sees it.
     /// </summary>
+    /// <remarks>
+    /// Owner direction 2026-09-07 (register row AD-124): this used to route
+    /// through retail's <c>ClientLocal</c> (0x1A) channel — the SpewBox
+    /// overlay every <c>ChatInterface</c> window's default filter excludes.
+    /// The owner explicitly overrode that for plugin text, matching Decal's
+    /// own <c>AddChatText</c> behavior: plugin output now lands in the chat
+    /// transcript (retail <c>Default</c>/0x00) so it is actually visible and
+    /// scrolls back, never the transient overlay. See
+    /// <c>AppAutomationSurface.PostSystemMessage</c> for the implementation.
+    /// </remarks>
     void PostSystemMessage(string text);
 
     /// <summary>
diff --git a/tests/AcDream.App.Tests/Plugins/AppAutomationSurfaceTests.cs b/tests/AcDream.App.Tests/Plugins/AppAutomationSurfaceTests.cs
index 9982ace3..b3221fde 100644
--- a/tests/AcDream.App.Tests/Plugins/AppAutomationSurfaceTests.cs
+++ b/tests/AcDream.App.Tests/Plugins/AppAutomationSurfaceTests.cs
@@ -146,6 +146,31 @@ public sealed class AppAutomationSurfaceTests
         Assert.Equal(0, second.CommunicationOwner.SubscriberCount);
     }
 
+    /// <summary>
+    /// Owner-directed override 2026-09-07 (register row AD-124): plugin
+    /// output ("Unknown commands like /vt or stuff from plugins ... should
+    /// go to the chatbox") must land in the chat log, never the transient
+    /// SpewBox overlay retail's own ClientLocal (0x1A) typing used to send
+    /// it to — the same VTank-faithful destination Decal's own
+    /// <c>AddChatText</c> uses.
+    /// </summary>
+    [Fact]
+    public void PostSystemMessage_RoutesToChatLog_NeverSpewBox()
+    {
+        using var runtime = GameRuntimeTestFactory.Create();
+        using var surface = new AppAutomationSurface();
+        surface.Bind(runtime, runtime.CharacterOwner, runtime.ActionOwner.SpellCast);
+
+        surface.PostSystemMessage("MossTank: buffs applied.");
+
+        var entry = Assert.Single(runtime.CommunicationOwner.Chat.Snapshot());
+        Assert.Equal("MossTank: buffs applied.", entry.Text);
+        Assert.Equal((uint)RetailLogTextType.Default, entry.LogTextType);
+
+        runtime.CommunicationOwner.SpewBox.Tick(0d);
+        Assert.Equal(0, runtime.CommunicationOwner.SpewBox.Count);
+    }
+
     [Fact]
     public void InventoryCompletionProjectsTheCanonicalRequestReceipt()
     {
diff --git a/tests/AcDream.UI.Abstractions.Tests/ChatVMTests.cs b/tests/AcDream.UI.Abstractions.Tests/ChatVMTests.cs
index 15cb0cc5..770aae9c 100644
--- a/tests/AcDream.UI.Abstractions.Tests/ChatVMTests.cs
+++ b/tests/AcDream.UI.Abstractions.Tests/ChatVMTests.cs
@@ -194,4 +194,36 @@ public sealed class ChatVMTests
         // The stored body never carries the stamp in either state.
         Assert.Equal("hi", log.Snapshot()[0].Text);
     }
+
+    /// <summary>
+    /// Owner-directed override 2026-09-07 (register row AD-124): plugin
+    /// output (<c>AppAutomationSurface.PostSystemMessage</c>, the
+    /// production implementation of <c>IPluginChat.PostSystemMessage</c>)
+    /// now funnels into <c>RuntimeCommunicationState.AddText(text,
+    /// RetailLogTextType.Default)</c>, which calls
+    /// <c>Chat.OnSystemMessage(text, (uint)Default)</c> — the exact call
+    /// this test performs directly on the shared <see cref="ChatLog"/>,
+    /// matching Decal's own <c>AddChatText</c> behavior for plugin text.
+    /// Any <see cref="ChatVM"/> bound to that log (the production chat
+    /// window) must show the line; it must never depend on the
+    /// <see cref="ChatVM.OnInterfaceText"/> SpewBox seam, which this call
+    /// never touches.
+    /// </summary>
+    [Fact]
+    public void RecentLines_ShowsPluginSystemMessage_TaggedDefault()
+    {
+        var log = new ChatLog();
+        var vm = new ChatVM(log, displayLimit: 50);
+
+        log.OnSystemMessage(
+            "MossTank: buffs applied.",
+            chatType: (uint)RetailLogTextType.Default);
+
+        Assert.Equal(
+            "MossTank: buffs applied.",
+            Assert.Single(vm.RecentLines()));
+        Assert.Equal(
+            (uint)RetailLogTextType.Default,
+            Assert.Single(log.Snapshot()).LogTextType);
+    }
 }