fix(chat): / and @ are equivalent command prefixes (retail parity)

Retail treats / and @ interchangeably for commands, but two client-side
layers broke the / spelling for server commands:

- ChatCommandRouter refused ANY unknown /verb with a local "Unknown
  command" guess — so /tele, /ci, /acehelp never reached ACE even
  though ACE supports them. The guard is gone; the server is now the
  single authority on what's a valid command (ACE replies "Unknown
  command: x" itself).
- ChatInputParser passed unknown /verbs through as literal speech.
  ACE's GameActionTalk only intercepts the @ form on the wire (the /
  acceptance in CommandManager is the server CONSOLE path), so the
  parser now rewrites unknown /xyz -> @xyz.

Both command pass-throughs (@ and rewritten /) now also force the Say
channel: GameActionTalk (0x0015) is the only wire action ACE parses
commands on — previously a command typed with a chat channel active
would broadcast as channel speech.

Phase J Tier 4 ("/-text must never broadcast as speech") still holds:
letter-verbed input goes out as an @command (never speech), and
command-shaped-but-verbless input ("/", "//shrug") is refused locally
by a narrow router guard.

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

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

@@ -2,7 +2,11 @@ using System;
 
 namespace AcDream.UI.Abstractions.Panels.Chat;
 
-/// <summary>What a submit did, so the caller can clear its input + give feedback.</summary>
+/// <summary>What a submit did, so the caller can clear its input + give feedback.
+/// <c>UnknownCommand</c> is now produced only for command-SHAPED but verbless
+/// input ("/", "//x", "@ x"); real unknown verbs route to the server (retail
+/// treats / and @ as equivalent command prefixes, and ACE answers unknown
+/// commands itself).</summary>
 public enum SubmitOutcome { Empty, ClientHandled, UnknownCommand, Sent, Dropped }
 
 /// <summary>
@@ -10,9 +14,15 @@ public enum SubmitOutcome { Empty, ClientHandled, UnknownCommand, Sent, Dropped
 /// analogue). Both the ImGui devtools <see cref="ChatPanel"/> and the retail
 /// chat window route through here so command handling stays in one place.
 ///
-/// Order mirrors the prior inline <see cref="ChatPanel"/> flow:
-/// client-command intercept → unknown-slash-verb guard → <see cref="ChatInputParser.Parse"/>
-/// → <c>Publish(SendChatCmd)</c>.
+/// Flow: client-command intercept → degenerate-prefix guard →
+/// <see cref="ChatInputParser.Parse"/> → <c>Publish(SendChatCmd)</c>.
+/// Unknown slash/at verbs pass through the parser to the server (the parser
+/// rewrites <c>/xyz</c> → <c>@xyz</c> and forces the Say action, the only
+/// wire path ACE parses commands on); ACE replies "Unknown command: xyz"
+/// for verbs it doesn't know, so the server stays the single authority on
+/// what's a valid command. Prefix text with no letter verb is refused
+/// locally — /-prefixed input must NEVER broadcast as speech (Phase J
+/// Tier 4, from the 2026-04-25 "/ls echoed as speech" trace).
 /// </summary>
 public static class ChatCommandRouter
 {
@@ -26,15 +36,15 @@ public static class ChatCommandRouter
 
         if (TryHandleClientCommand(trimmed, vm)) return SubmitOutcome.ClientHandled;
 
-        if (trimmed[0] == '/')
+        // Command-shaped but no letter verb ("/", "//shrug", "@ x"): refuse
+        // locally. Rewriting to @ would put junk on the wire, and letting it
+        // fall through would broadcast /-text as speech (Tier-4 violation).
+        if (trimmed[0] is '/' or '@'
+            && (trimmed.Length == 1 || !char.IsLetter(trimmed[1])))
         {
-            var verb = ChatInputParser.GetVerbToken(trimmed);
-            if (!ChatInputParser.IsKnownVerb(verb))
-            {
-                vm.ShowSystemMessage(
-                    $"Unknown command: {verb}. Type /help for the list of supported commands.");
-                return SubmitOutcome.UnknownCommand;
-            }
+            vm.ShowSystemMessage(
+                $"Unknown command: {ChatInputParser.GetVerbToken(trimmed)}. Type /help for the list of supported commands.");
+            return SubmitOutcome.UnknownCommand;
         }
 
         var parsed = ChatInputParser.Parse(

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

@@ -16,11 +16,12 @@ namespace AcDream.UI.Abstractions.Panels.Chat;
 /// <item><c>/say</c> with no message → <c>null</c></item>
 /// <item><c>/t</c> with no target / no message → <c>null</c></item>
 /// <item><c>/r</c> with no <c>lastTellSender</c> → <c>null</c></item>
-/// <item>unknown <c>/xyz</c> verb → fall through to default channel
-///       carrying the literal text (matches holtburger
-///       <c>handle_slash_command</c> default arm at line ~744 — they
-///       send <c>ClientCommand::Talk(command)</c> with the original
-///       slash-prefixed string)</item>
+/// <item>unknown <c>/xyz</c> verb → rewritten to <c>@xyz</c> and passed
+///       through on the default channel. Retail treats / and @ as
+///       equivalent command prefixes; ACE's <c>GameActionTalk</c> only
+///       intercepts the <c>@</c> form on the wire. Deliberate divergence
+///       from holtburger's literal fall-through (which would SAY the
+///       command text out loud).</item>
 /// <item>multi-word <c>/t</c> target: first whitespace token is target,
 ///       rest is message (matches Rust <c>split_once</c> semantics)</item>
 /// </list>
@@ -122,8 +123,12 @@ public static class ChatInputParser
                 return Parse(substituted, defaultChannel, lastTellSender, lastOutgoingTellTarget);
             }
             // Unknown @-verb — keep the original @ so ACE recognizes
-            // it server-side when the message arrives via Talk.
-            return new ParsedInput(defaultChannel, null, trimmed);
+            // it server-side. Always emit as Say: ACE's GameActionTalk
+            // (the 0x0015 Talk action) is the ONLY wire path that parses
+            // @commands — on a chat channel the text would broadcast as
+            // ordinary channel speech. Retail likewise resolves commands
+            // before channel routing.
+            return new ParsedInput(ChatChannelKind.Say, null, trimmed);
         }
 
         // /say <msg>
@@ -165,11 +170,18 @@ public static class ChatInputParser
                 return null;
         }
 
-        // Unknown slash command: holtburger falls back to Talk(literal).
-        // We mirror that — emit on the default channel with the
-        // slash-prefixed text intact so the server treats it as speech.
-        // No special-case for known-but-unimplemented verbs; the user's
-        // text round-trips so their intent isn't silently dropped.
+        // Unknown slash verb: retail treats / and @ as equivalent command
+        // prefixes, but ACE's GameActionTalk only intercepts the @ form on
+        // the wire (a /-prefixed Talk is plain speech server-side). Rewrite
+        // to @ and emit as Say — same reasoning as the unknown-@ branch at
+        // the top: only the Talk action parses commands. (Deliberate
+        // divergence from holtburger's literal fall-through, which would
+        // SAY "/ci 629" out loud.)
+        if (trimmed.Length > 1 && trimmed[0] == '/' && char.IsLetter(trimmed[1]))
+            return new ParsedInput(ChatChannelKind.Say, null, "@" + trimmed.Substring(1));
+
+        // Plain speech (no recognized verb): emit on the default channel
+        // so the user's text round-trips instead of being silently dropped.
         return new ParsedInput(defaultChannel, null, trimmed);
     }
 

tests/AcDream.UI.Abstractions.Tests/Panels/Chat/ChatCommandRouterTests.cs

@@ -54,13 +54,31 @@ public class ChatCommandRouterTests
     }
 
     [Fact]
-    public void UnknownSlashVerb_ShowsSystemMessage_DoesNotPublish()
+    public void UnknownSlashVerb_RoutesToServerInAtForm()
     {
+        // Retail / ≡ @: unknown verbs are the server's to judge. The
+        // parser rewrites /-form to @-form (ACE's GameActionTalk only
+        // intercepts @ on the wire); ACE answers "Unknown command: x"
+        // for verbs it doesn't know — no local guess.
         var (vm, log, bus) = Fixture();
         var outcome = ChatCommandRouter.Submit("/notacommand", vm, bus, ChatChannelKind.Say);
-        Assert.Equal(SubmitOutcome.UnknownCommand, outcome);
-        Assert.Null(bus.Last);
-        Assert.Contains(log.Snapshot(), e => e.Text.Contains("Unknown command"));
+        Assert.Equal(SubmitOutcome.Sent, outcome);
+        Assert.NotNull(bus.Last);
+        Assert.Equal("@notacommand", bus.Last!.Text);
+        Assert.DoesNotContain(log.Snapshot(), e => e.Text.Contains("Unknown command"));
+    }
+
+    [Fact]
+    public void ServerCommandWithArgs_PublishesAtFormAsSay_EvenOnChannelDefault()
+    {
+        // Commands resolve before channel routing (retail behavior):
+        // even with Fellowship as the active input channel, a command
+        // goes out as Say/Talk — the only wire action ACE parses @ on.
+        var (vm, _, bus) = Fixture();
+        var outcome = ChatCommandRouter.Submit("/ci 629 5", vm, bus, ChatChannelKind.Fellowship);
+        Assert.Equal(SubmitOutcome.Sent, outcome);
+        Assert.Equal(ChatChannelKind.Say, bus.Last!.Channel);
+        Assert.Equal("@ci 629 5", bus.Last.Text);
     }
 
     [Fact]

tests/AcDream.UI.Abstractions.Tests/Panels/Chat/ChatInputParserTests.cs

@@ -191,18 +191,46 @@ public sealed class ChatInputParserTests
         Assert.Null(ChatInputParser.Parse("/a", ChatChannelKind.Say, lastTellSender: null));
     }
 
-    // -- Unknown slash command: holtburger fall-through to Talk(literal)
-    // ("/wave hello" → Talk("/wave hello") + treat-as-Say). See
-    // chat.rs::handle_slash_command default arm at line ~744.
+    // -- Unknown slash command: retail / ≡ @ equivalence. ACE's
+    // GameActionTalk only intercepts @-prefixed Talk on the wire, so
+    // the parser rewrites the unknown /-verb to its @ form for the
+    // server's CommandManager. (Deliberate divergence from holtburger's
+    // literal fall-through, which would speak the command out loud.)
     [Fact]
-    public void UnknownSlashCommand_FallsBackToDefaultChannelWithLiteralText()
+    public void UnknownSlashCommand_IsRewrittenToAtFormForServer()
     {
         var parsed = ChatInputParser.Parse("/xyz hello", ChatChannelKind.Say, lastTellSender: null);
 
         Assert.NotNull(parsed);
         Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
         Assert.Null(parsed.Value.TargetName);
-        Assert.Equal("/xyz hello", parsed.Value.Text);
+        Assert.Equal("@xyz hello", parsed.Value.Text);
+    }
+
+    [Theory]
+    [InlineData("/ci 629",       "@ci 629")]        // ACE admin: create inventory item
+    [InlineData("/tele holtburg", "@tele holtburg")] // ACE admin: teleport
+    [InlineData("@ci 629",       "@ci 629")]        // @ form already server-ready — untouched
+    [InlineData("@acehelp",      "@acehelp")]
+    public void ServerCommandVerbs_ReachTheWireInAtForm(string input, string expectedText)
+    {
+        var parsed = ChatInputParser.Parse(input, ChatChannelKind.Say, lastTellSender: null);
+
+        Assert.NotNull(parsed);
+        Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
+        Assert.Equal(expectedText, parsed.Value.Text);
+    }
+
+    [Fact]
+    public void SlashWithoutLetterVerb_StaysLiteralAtParseLevel()
+    {
+        // "/ hello" and "//shrug" have no letter verb after the slash, so
+        // the pure Parse function leaves them untouched. In the real
+        // submit flows they never reach the wire: ChatCommandRouter's
+        // degenerate-prefix guard refuses them locally (Phase J Tier 4 —
+        // /-prefixed text must never broadcast as speech).
+        Assert.Equal("/ hello", ChatInputParser.Parse("/ hello", ChatChannelKind.Say, lastTellSender: null)!.Value.Text);
+        Assert.Equal("//shrug", ChatInputParser.Parse("//shrug", ChatChannelKind.Say, lastTellSender: null)!.Value.Text);
     }
 
     // -- Default-channel parameter is honoured when no prefix is given --
@@ -227,17 +255,14 @@ public sealed class ChatInputParserTests
     {
         // Phase J added long-form aliases (/general, /allegiance,
         // /patron, etc.). The exact-token rule still applies — a
-        // verb prefix that ISN'T one of the listed aliases falls
-        // through. The Parse-level behaviour for unknown /-verbs is
-        // still "Say with the literal text" (matches holtburger);
-        // the ChatPanel layer is what catches unknowns and shows the
-        // local "Unknown command" line. ChatPanelInputTests cover
-        // that end-to-end behaviour.
+        // verb prefix that ISN'T one of the listed aliases is NOT a
+        // client verb; it routes to the server in @ form like any
+        // other unknown verb (retail / ≡ @).
         var parsed = ChatInputParser.Parse("/genio public", ChatChannelKind.Say, lastTellSender: null);
 
         Assert.NotNull(parsed);
         Assert.Equal(ChatChannelKind.Say, parsed!.Value.Channel);
-        Assert.Equal("/genio public", parsed.Value.Text);
+        Assert.Equal("@genio public", parsed.Value.Text);
     }
 
     [Theory]

tests/AcDream.UI.Abstractions.Tests/Panels/Chat/ChatPanelInputTests.cs

@@ -113,18 +113,43 @@ public sealed class ChatPanelInputTests
     }
 
     [Theory]
-    [InlineData("/foo")]
-    [InlineData("/ls")]
-    [InlineData("/mp /tools/script.py")]
-    [InlineData("/genio public")]
-    [InlineData("/")]
-    public void Submit_UnknownSlashCommand_ShowsUnknownAndDoesNotPublish(string raw)
+    [InlineData("/foo",                 "@foo")]
+    [InlineData("/ls",                  "@ls")]
+    [InlineData("/mp /tools/script.py", "@mp /tools/script.py")]
+    [InlineData("/genio public",        "@genio public")]
+    public void Submit_UnknownSlashCommand_RoutesToServerAsAtCommand(string raw, string expectedText)
     {
-        // Phase J Tier 4: /-prefixed text is NEVER broadcast as plain
-        // speech. Filed after a 2026-04-25 trace where typing /ls (a
-        // command-style request the user wanted) was getting echoed by
-        // the server as "You say, \"/ls\"". Now we intercept and show
-        // a local "Unknown command" line; nothing goes on the wire.
+        // Phase J Tier 4 held: /-prefixed text is still NEVER broadcast
+        // as plain speech. Retail treats / and @ as equivalent command
+        // prefixes, so unknown verbs now go to the SERVER as @commands
+        // (ACE's GameActionTalk intercepts @ on the Say action and
+        // answers "Unknown command: x" itself) instead of a local guess.
+        var log = new ChatLog();
+        var vm  = new ChatVM(log);
+        var panel = new ChatPanel(vm);
+        var bus = new RecordingBus();
+        var renderer = new FakePanelRenderer
+        {
+            InputTextSubmitNextSubmitted = raw,
+            InputTextSubmitNextBufferAfter = "",
+        };
+
+        panel.Render(new PanelContext(0.016f, bus), renderer);
+
+        var sendCmd = Assert.IsType<SendChatCmd>(Assert.Single(bus.Published));
+        Assert.Equal(ChatChannelKind.Say, sendCmd.Channel);
+        Assert.Equal(expectedText, sendCmd.Text);
+        Assert.Empty(log.Snapshot());   // no local "Unknown command" guess
+    }
+
+    [Theory]
+    [InlineData("/")]
+    [InlineData("//shrug")]
+    public void Submit_CommandShapedWithoutVerb_ShowsUnknownAndDoesNotPublish(string raw)
+    {
+        // Command-shaped but no letter verb: refused locally — this is
+        // the remaining Tier-4 guard (never broadcast /-text as speech,
+        // and don't put junk @-rewrites on the wire either).
         var log = new ChatLog();
         var vm  = new ChatVM(log);
         var panel = new ChatPanel(vm);