fix: sync agent tier when /model command switches model

The /model command was only updating the router's currentTier but not
the agent's currentTier. Since NativeAgent.chatWithRouter() passes its
own tier to router.chat(), switching to 'local' still sent requests
through the default (Anthropic) client first.

src/frontends/tui/minimal.test.ts

@@ -77,4 +77,43 @@ describe('MinimalTui backend command', () => {
 
     expect(mockRouter.setLocalClient).toHaveBeenCalled();
   });
+
+  it('syncs agent tier when /model command switches tier', () => {
+    const mockSession = {
+      id: 'test',
+      getHistory: () => [],
+      addMessage: vi.fn(),
+      clear: vi.fn(),
+    };
+
+    const mockRouter = {
+      getTier: () => 'default' as const,
+      getAvailableTiers: () => ['default', 'local'],
+      setTier: vi.fn(() => true),
+      getLocalProviderName: () => 'ollama',
+      setLocalClient: vi.fn(),
+      chat: vi.fn(),
+      getClient: vi.fn(),
+    };
+
+    const mockAgent = {
+      setModelTier: vi.fn(),
+      getModelTier: vi.fn(() => 'default'),
+      process: vi.fn(),
+    };
+
+    const tui = new MinimalTui({
+      session: mockSession as any,
+      modelClient: mockRouter as any,
+      modelRouter: mockRouter as any,
+      agent: mockAgent as any,
+      systemPrompt: 'test',
+    });
+
+    // Call private handleModelCommand to switch to local
+    (tui as any).handleModelCommand('local');
+
+    expect(mockRouter.setTier).toHaveBeenCalledWith('local');
+    expect(mockAgent.setModelTier).toHaveBeenCalledWith('local');
+  });
 });

src/frontends/tui/minimal.ts

@@ -213,6 +213,10 @@ export class MinimalTui {
 
     const tier = resolveModelAlias(name);
     if (router.setTier(tier)) {
+      // Also update the agent tier so chatWithRouter uses the correct client
+      if (this.config.agent) {
+        this.config.agent.setModelTier(tier);
+      }
       console.log(`${colors.gray}Switched to model:${colors.reset} ${tier}\n`);
     } else {
       console.log(`${colors.gray}Model not available:${colors.reset} ${name}\n`);