fix(chat): #363 — retail 0x1A typing for command refusals via the interface-text seam

ChatVM gains an OnInterfaceText hook + ShowInterfaceText(text), the
App-layer composition wires it to RuntimeCommunicationState.AddText,
and ChatCommandRouter routes every retail-0x1A command refusal through
it instead of the chat log's 0x00 sink. UI.Abstractions still never
references Runtime directly; unwired hosts (headless, tests) fall back
to the chat log tagged ClientLocal so no text is ever silently lost.

Reclassified per register row AP-183 (DoChannelList/On/Off, DoAllegiance,
DoHouseAvailableList — the last also corrected to retail's own bad-house-
type string instead of a synthesized "Usage:" line) and newly wired two
sites that previously showed nothing at all (DoStupidChannelHack's bare
legacy-channel-verb refusal, DoReply's message-but-no-last-teller
refusal). The generic bad-args fallback now resolves WeenieErrorMessages
0x026 ("That is not a valid command.", retail's HandleFailureEvent(0x26))
instead of synthesizing "Usage: {Usage}". DoSpeaker/DoEndurance/DoTitle
are untouched — already correct at 0x00.

Also closes #367 (DoHelp's "Unknown command" fallback and the degenerate-
prefix refusal now reach the SpewBox too) and retires register row
AP-186, whose own filing proposed exactly this seam shape.

Full Release suite: 12,542 passed / 4 skipped / 0 failed (baseline
12,466/4/0 at ff2784ea).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.App/Composition/InteractionRetainedUiComposition.cs

@@ -562,7 +562,15 @@ internal sealed class RetailInteractionRetainedUiCompositionFactory
             var chat = new ChatVM(
                 d.Communication.Chat,
                 displayLimit: 200,
-                commandTargets: d.Communication.CommandTargets);
+                commandTargets: d.Communication.CommandTargets)
+            {
+                // Issue #363 / #367: routes ChatCommandRouter's 0x1A
+                // (ClientLocal) command refusals to the same SpewBox
+                // chokepoint every other interface-text producer uses,
+                // instead of the chat scroll.
+                OnInterfaceText = text =>
+                    d.Communication.AddText(text, RetailLogTextType.ClientLocal),
+            };
             AcDream.UI.Abstractions.Panels.Settings.SettingsStore? layoutStore =
                 d.Settings.LayoutStore;
             RetailUiPersistenceBindings? persistence = layoutStore is null

src/AcDream.UI.Abstractions/Panels/Chat/ChatCommandRouter.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Linq;
+using AcDream.Core.Chat;
 
 namespace AcDream.UI.Abstractions.Panels.Chat;
 
@@ -51,8 +52,23 @@ public static class ChatCommandRouter
         {
             if (!clientCommand.HasValidArguments)
             {
-                vm.ShowSystemMessage(clientCommand.InvalidArgumentsText
-                    ?? $"Usage: {clientCommand.Usage}");
+                // #363 / register row AP-183: retail's bad-args refusal is
+                // ALWAYS 0x1A (ClientLocal / SpewBox-only) — verified
+                // against five decompiled handlers (DoDie, DoChannelList/
+                // On/Off, DoAllegiance, DoHouseAvailableList). A Definition
+                // with its own InvalidArgumentsText is the handler's own
+                // bespoke refusal string, printed before it returns
+                // "handled" (1) so retail's generic fallback never fires
+                // for it. A Definition with none falls to that generic
+                // fallback: ClientCommunicationSystem::DoCommand
+                // @0x0057E46D calls HandleFailureEvent(0x26) when a
+                // registered handler returns 0 (bad args) —
+                // "That is not a valid command." (WeenieErrorMessages
+                // [0x026]) — never the acdream-invented "Usage: {Usage}"
+                // line this branch used to synthesize.
+                vm.ShowInterfaceText(clientCommand.InvalidArgumentsText
+                    ?? WeenieErrorMessages.Resolve(0x026u, null).Text
+                    ?? "That is not a valid command.");
                 return SubmitOutcome.ClientHandled;
             }
 
@@ -66,10 +82,14 @@ public static class ChatCommandRouter
 
         // Command-shaped but no letter verb ("/", "//shrug", "@ x"):
         // refuse locally rather than putting junk on the wire or in speech.
+        // #363/#367: this is one of retail's DoHelp-family "Unknown
+        // command" fallbacks (0x1A ClientLocal, SpewBox-only) — routed
+        // through the interface-text seam now that one exists, instead of
+        // the chat scroll.
         if (trimmed[0] is '/' or '@'
             && (trimmed.Length == 1 || !char.IsLetter(trimmed[1])))
         {
-            vm.ShowSystemMessage(
+            vm.ShowInterfaceText(
                 $"Unknown command: {ChatInputParser.GetVerbToken(trimmed)}. Type /help for the list of supported commands.");
             return SubmitOutcome.UnknownCommand;
         }
@@ -97,6 +117,23 @@ public static class ChatCommandRouter
             return SubmitOutcome.Sent;
         }
 
+        // #363 / register row AP-183: retail's registered legacy-channel
+        // verbs (DoStupidChannelHack @0x0057B144) and /reply
+        // (DoReply @0x00577910) refuse locally at 0x1A instead of silently
+        // dropping the line the way ChatInputParser.Parse's pure "return
+        // null" shape does for these cases.
+        if (ChatInputParser.IsBareRegisteredChannelVerb(trimmed))
+        {
+            vm.ShowInterfaceText("You must specify the text you wish to say!");
+            return SubmitOutcome.ClientHandled;
+        }
+
+        if (ChatInputParser.IsReplyMissingLastTeller(trimmed, vm.LastIncomingTellSender))
+        {
+            vm.ShowInterfaceText("Someone must @tell you first!");
+            return SubmitOutcome.ClientHandled;
+        }
+
         var parsed = ChatInputParser.Parse(
             trimmed, defaultChannel, vm.LastIncomingTellSender, vm.LastOutgoingTellTarget);
         if (parsed is { } chat)
@@ -247,12 +284,10 @@ public static class ChatCommandRouter
             return;
         }
 
-        // Retail types this 0x1A (ClientLocal) -> SpewBox-only; ChatVM has
-        // no SpewBox routing capability yet, so this still renders via the
-        // chat scroll — a pre-existing gap, not new this round. See the
-        // class remarks on RetailCommandHelpTable.UnknownCommand and
-        // ISSUES.md #367.
-        vm.ShowSystemMessage(RetailCommandHelpTable.UnknownCommand);
+        // Retail types this 0x1A (ClientLocal) -> SpewBox-only. #363/#367:
+        // now routed through ChatVM.ShowInterfaceText instead of the chat
+        // scroll — see the class remarks on RetailCommandHelpTable.UnknownCommand.
+        vm.ShowInterfaceText(RetailCommandHelpTable.UnknownCommand);
     }
 
     private static bool EqAny(string value, params string[] options)

src/AcDream.UI.Abstractions/Panels/Chat/ChatInputParser.cs

@@ -124,6 +124,64 @@ public static class ChatInputParser
         ("/o",                ChatChannelKind.Olthoi),
     };
 
+    /// <summary>
+    /// The six retail channel groups whose registered-verb handler is
+    /// <c>ClientCommunicationSystem::DoStupidChannelHack @0x0057B144</c>
+    /// (command-registry doc §2.3) — the legacy 0x0147 channels. The
+    /// Turbine-only channels (General/Trade/Lfg/Roleplay/Society/Olthoi)
+    /// are never this handler's clients. <see cref="ChatChannelKind.Allegiance"/>
+    /// (retail's <c>@a</c>) still belongs here even though acdream always
+    /// sends it over Turbine once connected (<see cref="ChatChannelKind"/>'s
+    /// own doc comment) — DoStupidChannelHack dispatches on the REGISTERED
+    /// VERB, before Turbine send-time routing decides where the text goes;
+    /// retail's <c>"a"</c>/<c>"ab"</c> are one registered verb group.
+    /// </summary>
+    private static readonly HashSet<ChatChannelKind> LegacyChannelHackKinds =
+    [
+        ChatChannelKind.Fellowship,
+        ChatChannelKind.Allegiance,
+        ChatChannelKind.AllegianceBroadcast,
+        ChatChannelKind.Vassals,
+        ChatChannelKind.Patron,
+        ChatChannelKind.Monarch,
+        ChatChannelKind.CoVassals,
+    ];
+
+    /// <summary>
+    /// True when <paramref name="trimmed"/> is one of the
+    /// <see cref="LegacyChannelHackKinds"/> verbs with NO message — retail's
+    /// <c>DoStupidChannelHack</c> "You must specify the text you wish to
+    /// say!" refusal (<c>0x1A</c> ClientLocal,
+    /// acclient_2013_pseudo_c.txt:1030730, data_7da9b0). This parser stays
+    /// pure (no side effects — <see cref="Parse"/> just returns
+    /// <see langword="null"/> for this shape); <see cref="ChatCommandRouter"/>
+    /// owns the actual refusal text and routes it to the SpewBox.
+    /// </summary>
+    public static bool IsBareRegisteredChannelVerb(string trimmed)
+    {
+        foreach (var (verb, channel) in ChannelVerbs)
+        {
+            if (LegacyChannelHackKinds.Contains(channel) && IsBareVerb(trimmed, [verb]))
+                return true;
+        }
+
+        return false;
+    }
+
+    /// <summary>
+    /// True when <paramref name="trimmed"/> is <c>/reply</c>/<c>/r</c>/
+    /// <c>/rp</c> WITH a message but no prior incoming Tell — retail's
+    /// <c>ClientCommunicationSystem::DoReply @0x00577910</c> "Someone must
+    /// @tell you first!" refusal (<c>0x1A</c> ClientLocal,
+    /// acclient_2013_pseudo_c.txt:387538, data_7da974), the
+    /// <c>gmCCommunicationSystem::GetLastTeller() == 0</c> branch. Bare
+    /// <c>/r</c> with no message at all is a DIFFERENT retail branch (its
+    /// own copy of the "you must specify text" string) and is deliberately
+    /// out of scope here — not named by register row AP-183 / issue #363.
+    /// </summary>
+    public static bool IsReplyMissingLastTeller(string trimmed, string? lastTellSender) =>
+        string.IsNullOrEmpty(lastTellSender) && TryParseMessageOnly(trimmed, ReplyAliases, out _);
+
     /// <summary>
     /// Parse <paramref name="raw"/> into a <see cref="ParsedInput"/>
     /// triple, or <c>null</c> if the input is empty / whitespace /

src/AcDream.UI.Abstractions/Panels/Chat/ChatVM.cs

@@ -73,6 +73,21 @@ public sealed class ChatVM : IDisposable
     /// </summary>
     public Func<Vector3>? PositionProvider { get; init; }
 
+    /// <summary>
+    /// Optional hook routing retail-<c>0x1A</c> (<see
+    /// cref="RetailLogTextType.ClientLocal"/>) interface text — command
+    /// refusals and bad-argument usage lines — to the SpewBox instead of
+    /// the chat transcript. <c>AcDream.UI.Abstractions</c> must stay
+    /// Runtime-independent (Code Structure Rules), so it cannot call
+    /// <c>RuntimeCommunicationState.AddText</c> directly; the App-layer
+    /// composition host wires this the same way it wires
+    /// <see cref="FpsProvider"/>/<see cref="PositionProvider"/>. Closes
+    /// ISSUES.md #367 / register row AP-186 — <see cref="ChatCommandRouter"/>
+    /// no longer has to render every <c>0x1A</c> refusal through the chat
+    /// scroll.
+    /// </summary>
+    public Action<string>? OnInterfaceText { get; init; }
+
     /// <summary>Monotonic revision of the underlying transcript content.</summary>
     public long Revision => _log.Revision;
 
@@ -139,6 +154,33 @@ public sealed class ChatVM : IDisposable
     /// </remarks>
     public void ShowSystemMessage(string text) => _log.OnSystemMessage(text, chatType: 0x00u);
 
+    /// <summary>
+    /// Route a retail-<c>0x1A</c> (<see cref="RetailLogTextType.ClientLocal"/>)
+    /// command refusal / usage line to the SpewBox — retail's
+    /// <c>ClientSystem::AddTextToScroll(text, 0x1A, 1, windowId) @0x00563C50</c>
+    /// destination for this text type is the SpewBox exclusively, never a
+    /// chat window (<c>docs/research/2026-08-09-chat-retail-interface-text.md</c>
+    /// §2.1/§2.2).
+    /// </summary>
+    /// <remarks>
+    /// Prefers <see cref="OnInterfaceText"/> when the App-layer host wired
+    /// it (the production graphical client). When unwired — headless, the
+    /// automation probe runner, or a test fixture that only exercises the
+    /// pure UI.Abstractions layer — the text still needs to reach the
+    /// player somewhere, so it falls back to the ordinary chat transcript
+    /// tagged with the real <see cref="RetailLogTextType.ClientLocal"/>
+    /// color rather than being silently dropped. That fallback lands in
+    /// the wrong PANEL (chat instead of SpewBox) but keeps the right TYPE
+    /// and never loses the line — the safe default issue #363 requires.
+    /// </remarks>
+    public void ShowInterfaceText(string text)
+    {
+        if (OnInterfaceText is { } hook)
+            hook(text);
+        else
+            _log.OnSystemMessage(text, chatType: (uint)RetailLogTextType.ClientLocal);
+    }
+
     /// <summary>
     /// Drain the chat log. Used by the /clear client-side command.
     /// </summary>

src/AcDream.UI.Abstractions/Panels/Chat/RetailClientCommandCatalog.cs

@@ -346,11 +346,18 @@ public static class RetailClientCommandCatalog
 
     // ClientCommunicationSystem::DoHouseAvailableList @ 0x00570510. Exact
     // retail help: acclient_2013_pseudo_c.txt:1031049 (data_7dd9d0).
+    // #363 / register row AP-183: the bad-args refusal is retail's own
+    // specific string too, verified at acclient_2013_pseudo_c.txt:381481
+    // (AddTextToScroll(..., 0x1a, ...)), full text at
+    // acclient_2013_pseudo_c.txt:1029383 (data_7d0a98) — NOT the
+    // acdream-synthesized "Usage: /hslist <house type>" line this
+    // Definition used to fall back to.
     private static readonly Definition HouseAvailableList = new(
         ClientCommandId.HouseAvailableList,
         Usage: "/hslist <house type>",
         HelpText: "@hslist <house type> - Lists the number and, if appropriate, positions of houses currently available for purchase. Types include: Apartment, Cottage, Villa, Mansion",
-        ValidateArguments: static arguments => HouseTypes.ContainsKey(arguments.Trim()));
+        ValidateArguments: static arguments => HouseTypes.ContainsKey(arguments.Trim()),
+        InvalidArgumentsText: "Please see @help hslist for more information on how to use this command");
 
     // ClientCommunicationSystem::DoChannelIndex @ 0x0056E640. No help
     // string was extracted for the bare form; the verb is admin/advocate/

src/AcDream.UI.Abstractions/Panels/Chat/RetailCommandHelpTable.cs

@@ -91,14 +91,17 @@ namespace AcDream.UI.Abstractions.Panels.Chat;
 /// <see cref="UnknownCommand"/>, typed <c>0x1A</c> (<c>ClientLocal</c>) —
 /// retail routes that type to the SpewBox exclusively, never the chat
 /// window (<c>docs/research/2026-08-09-chat-retail-interface-text.md</c>
-/// §2.1/§2.2). <c>ChatCommandRouter</c> operates on <c>ChatVM</c>
-/// (<c>AcDream.UI.Abstractions</c>), which has no SpewBox routing
-/// capability — wiring that would mean threading a
-/// <c>RuntimeCommunicationState</c>-shaped dependency down into a layer
-/// that must stay presentation/Runtime-independent, out of this round's
-/// scope. The unknown-verb fallback therefore still renders via the chat
-/// scroll, a pre-existing (not newly introduced) gap now tracked at
-/// ISSUES.md #367 instead of silently continuing unregistered.
+/// §2.1/§2.2).
+/// </para>
+///
+/// <para>
+/// <b>Issue #363 (2026-08-10):</b> <c>ChatCommandRouter</c> now routes this
+/// fallback (and every other <c>0x1A</c> command-refusal call site) through
+/// <c>ChatVM.ShowInterfaceText</c> — an optional hook the App-layer host
+/// wires to <c>RuntimeCommunicationState.AddText</c>, the same SpewBox
+/// chokepoint every other producer of interface text uses. UI.Abstractions
+/// still never references Runtime directly (Code Structure Rules); the hook
+/// is the seam. Closes ISSUES.md #367 and retires register row AP-186.
 /// </para>
 /// </summary>
 public static class RetailCommandHelpTable
@@ -147,9 +150,9 @@ public static class RetailCommandHelpTable
     // acclient_2013_pseudo_c.txt:395052 (u"Unknown command", UTF-16LE) --
     // DoHelp's fallback when the verb hash lookup fails, or resolves to an
     // entry with no registered help callback. Retail types this 0x1A
-    // (ClientLocal) -- SpewBox-only; see the class remarks' routing note
-    // and ISSUES.md #367 for why ChatCommandRouter still shows it in the
-    // chat scroll.
+    // (ClientLocal) -- SpewBox-only; see the class remarks' routing note --
+    // ChatCommandRouter now routes it through ChatVM.ShowInterfaceText
+    // (issue #363), closing #367.
     public const string UnknownCommand = "Unknown command";
 
     // @mr/@pr are registered with a NULL function pointer in the 2013