feat(tui): display tool execution status in minimal TUI

TUI now creates a NativeAgent with tool registry/executor and uses
agent.process() for message handling. Tool calls display status lines
showing tool name, args, and success/error result. Falls back to
direct model client when agent is not configured.

src/frontends/tui/minimal.ts

@@ -2,6 +2,7 @@ import * as readline from 'node:readline';
 import type { ManagedSession } from '../../session/index.js';
 import type { ModelClient, TokenUsage } from '../../models/types.js';
 import type { ModelRouter, ModelTier } from '../../models/router.js';
+import type { NativeAgent } from '../../backends/native/agent.js';
 import { parseCommand, getHelpText, resolveModelAlias, getCommandCompletions, getCommandTooltip, type Command } from './commands.js';
 import { renderMarkdown } from './markdown.js';
 import type { ModelConfig } from '../../config/schema.js';
@@ -32,6 +33,7 @@ export interface MinimalTuiConfig {
   modelClient: ModelClient;
   modelRouter?: ModelRouter;
   systemPrompt: string;
+  agent?: NativeAgent;
   onFullscreen?: () => void;
   onTransfer?: (target: string) => void;
   localProviders?: Record<string, ModelConfig>;
@@ -285,12 +287,22 @@ export class MinimalTui {
   }
 
   private async handleMessage(content: string): Promise<void> {
-    this.config.session.addMessage({ role: 'user', content });
-
     // Print Flynn label before response
     process.stdout.write(`\n${colors.orange}${colors.bold}Flynn:${colors.reset}\n`);
 
     try {
+      // Use agent if available (supports tool loop)
+      if (this.config.agent) {
+        const response = await this.config.agent.process(content);
+        const rendered = renderMarkdown(response);
+        console.log(rendered);
+        console.log();
+        return;
+      }
+
+      // Fallback: direct model client (no tool support)
+      this.config.session.addMessage({ role: 'user', content });
+
       // Try streaming if available
       if (this.config.modelClient.chatStream) {
         let fullContent = '';