feat: add /backend command handler to MinimalTui

src/frontends/tui/minimal.test.ts

@@ -1,5 +1,7 @@
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, vi } from 'vitest';
 import { formatPrompt, parseCommand } from './minimal.js';
+import type { ModelConfig } from '../../config/schema.js';
+import { MinimalTui } from './minimal.js';
 
 describe('formatPrompt', () => {
   it('formats default prompt', () => {
@@ -34,3 +36,45 @@ describe('parseCommand (re-exported)', () => {
     expect(result).toBeNull();
   });
 });
+
+describe('MinimalTui backend command', () => {
+  it('switches local backend when provider is configured', async () => {
+    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 localProviders: Record<string, ModelConfig> = {
+      llamacpp: {
+        provider: 'llamacpp',
+        model: '',
+        endpoint: 'http://localhost:8080',
+      },
+    };
+
+    const tui = new MinimalTui({
+      session: mockSession as any,
+      modelClient: mockRouter as any,
+      modelRouter: mockRouter as any,
+      systemPrompt: 'test',
+      localProviders,
+    });
+
+    // Access private method for testing
+    await (tui as any).handleBackendCommand('llamacpp');
+
+    expect(mockRouter.setLocalClient).toHaveBeenCalled();
+  });
+});