feat(cli): TUI slash command parsing + local commands (P8-009) (#176)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/cli/src/tui/app.tsx

@@ -1,5 +1,6 @@
 import React, { useState, useCallback, useEffect, useMemo } from 'react';
 import { Box, useApp, useInput } from 'ink';
+import type { ParsedCommand } from '@mosaic/types';
 import { TopBar } from './components/top-bar.js';
 import { BottomBar } from './components/bottom-bar.js';
 import { MessageList } from './components/message-list.js';
@@ -12,6 +13,7 @@ import { useViewport } from './hooks/use-viewport.js';
 import { useAppMode } from './hooks/use-app-mode.js';
 import { useConversations } from './hooks/use-conversations.js';
 import { useSearch } from './hooks/use-search.js';
+import { executeHelp, executeStatus } from './commands/index.js';
 
 export interface TuiAppProps {
   gatewayUrl: string;
@@ -71,6 +73,63 @@ export function TuiApp({
 
   const [sidebarSelectedIndex, setSidebarSelectedIndex] = useState(0);
 
+  const handleLocalCommand = useCallback(
+    (parsed: ParsedCommand) => {
+      switch (parsed.command) {
+        case 'help':
+        case 'h': {
+          const result = executeHelp(parsed);
+          socket.addSystemMessage(result);
+          break;
+        }
+        case 'status':
+        case 's': {
+          const result = executeStatus(parsed, {
+            connected: socket.connected,
+            model: socket.modelName,
+            provider: socket.providerName,
+            sessionId: socket.conversationId ?? null,
+            tokenCount: socket.tokenUsage.total,
+          });
+          socket.addSystemMessage(result);
+          break;
+        }
+        case 'clear':
+          socket.clearMessages();
+          break;
+        case 'stop':
+          // Currently no stop mechanism exposed — show feedback
+          socket.addSystemMessage('Stop is not available for the current session.');
+          break;
+        case 'cost': {
+          const u = socket.tokenUsage;
+          socket.addSystemMessage(
+            `Tokens — input: ${u.input}, output: ${u.output}, total: ${u.total}\nCost: $${u.cost.toFixed(6)}`,
+          );
+          break;
+        }
+        default:
+          socket.addSystemMessage(`Local command not implemented: /${parsed.command}`);
+      }
+    },
+    [socket],
+  );
+
+  const handleGatewayCommand = useCallback(
+    (parsed: ParsedCommand) => {
+      if (!socket.socketRef.current?.connected || !socket.conversationId) {
+        socket.addSystemMessage('Not connected to gateway. Command cannot be executed.');
+        return;
+      }
+      socket.socketRef.current.emit('command:execute', {
+        conversationId: socket.conversationId,
+        command: parsed.command,
+        args: parsed.args ?? undefined,
+      });
+    },
+    [socket],
+  );
+
   const handleSwitchConversation = useCallback(
     (id: string) => {
       socket.switchConversation(id);
@@ -202,6 +261,9 @@ export function TuiApp({
 
       <InputBar
         onSubmit={socket.sendMessage}
+        onSystemMessage={socket.addSystemMessage}
+        onLocalCommand={handleLocalCommand}
+        onGatewayCommand={handleGatewayCommand}
         isStreaming={socket.isStreaming}
         connected={socket.connected}
         placeholder={inputPlaceholder}