diff --git a/src/cli/tui.ts b/src/cli/tui.ts
index ec34b69..6dbc930 100644
--- a/src/cli/tui.ts
+++ b/src/cli/tui.ts
@@ -1,4 +1,31 @@
 import type { Command } from 'commander';
+import type { Config } from '../config/index.js';
+import { loadConfigSafe, getConfigPath } from './shared.js';
+import { existsSync, mkdirSync, readFileSync } from 'fs';
+import { resolve } from 'path';
+import { homedir } from 'os';
+
+// ANSI color codes for tool status display
+const toolColors = {
+  reset: '\x1b[0m',
+  dim: '\x1b[2m',
+  cyan: '\x1b[36m',
+  green: '\x1b[32m',
+  red: '\x1b[31m',
+};
+
+function loadSystemPrompt(): string {
+  const paths = [
+    resolve(process.cwd(), 'SOUL.md'),
+    resolve(import.meta.dirname, '../../SOUL.md'),
+  ];
+  for (const soulPath of paths) {
+    if (existsSync(soulPath)) {
+      return readFileSync(soulPath, 'utf-8');
+    }
+  }
+  return 'You are Flynn, a helpful personal AI assistant. Be direct, concise, and helpful. Use markdown when it improves readability.';
+}
 
 export function registerTuiCommand(program: Command): void {
   program
@@ -6,8 +33,180 @@ export function registerTuiCommand(program: Command): void {
     .description('Launch the interactive TUI')
     .option('-f, --fullscreen', 'Start in fullscreen mode')
     .option('-c, --config <path>', 'Config file path')
-    .action(async (_opts: { fullscreen?: boolean; config?: string }) => {
-      console.error('Not yet implemented');
-      process.exit(1);
+    .action(async (opts: { fullscreen?: boolean; config?: string }) => {
+      const configPath = opts.config ?? getConfigPath();
+      const { config, error } = loadConfigSafe(configPath);
+      if (!config) {
+        console.error(error);
+        process.exit(1);
+      }
+
+      // Dynamic imports to keep CLI startup fast
+      const { SessionStore, SessionManager } = await import('../session/index.js');
+      const { AnthropicClient, OpenAIClient, OllamaClient, LlamaCppClient, ModelRouter } = await import('../models/index.js');
+      const { MinimalTui, startFullscreenTui } = await import('../frontends/tui/index.js');
+      const { NativeAgent } = await import('../backends/index.js');
+      const { ToolRegistry, ToolExecutor, allBuiltinTools } = await import('../tools/index.js');
+      const { HookEngine } = await import('../hooks/index.js');
+
+      const dataDir = resolve(homedir(), '.local/share/flynn');
+      mkdirSync(dataDir, { recursive: true });
+
+      const sessionStore = new SessionStore(resolve(dataDir, 'sessions.db'));
+      const sessionManager = new SessionManager(sessionStore);
+      const models = config.models;
+
+      // Build model router
+      const defaultClient = new AnthropicClient({
+        model: models.default.model,
+        apiKey: models.default.api_key,
+        authToken: models.default.auth_token,
+      });
+
+      let fastClient;
+      let complexClient;
+      let localClient;
+
+      if (models.fast) {
+        fastClient = new AnthropicClient({
+          model: models.fast.model,
+          apiKey: models.fast.api_key,
+          authToken: models.fast.auth_token,
+        });
+      }
+
+      if (models.complex) {
+        complexClient = new AnthropicClient({
+          model: models.complex.model,
+          apiKey: models.complex.api_key,
+          authToken: models.complex.auth_token,
+        });
+      }
+
+      if (models.local) {
+        if (models.local.provider === 'ollama') {
+          localClient = new OllamaClient({
+            model: models.local.model,
+            host: models.local.endpoint,
+            numGpu: models.local.num_gpu,
+          });
+        } else if (models.local.provider === 'llamacpp') {
+          localClient = new LlamaCppClient({
+            endpoint: models.local.endpoint ?? 'http://localhost:8080',
+            model: models.local.model,
+            authToken: models.local.auth_token,
+          });
+        }
+      }
+
+      const fallbackChain = [];
+      for (const providerName of models.fallback_chain) {
+        if (providerName === 'openai') {
+          fallbackChain.push(new OpenAIClient({ model: 'gpt-4o' }));
+        } else if (providerName === 'local' && localClient) {
+          fallbackChain.push(localClient);
+        }
+      }
+
+      const modelRouter = new ModelRouter({
+        default: defaultClient,
+        fast: fastClient,
+        complex: complexClient,
+        local: localClient,
+        fallbackChain,
+      });
+
+      const systemPrompt = loadSystemPrompt();
+
+      const hookEngine = new HookEngine(config.hooks);
+      const toolRegistry = new ToolRegistry();
+      for (const tool of allBuiltinTools) {
+        toolRegistry.register(tool);
+      }
+      const toolExecutor = new ToolExecutor(toolRegistry, hookEngine);
+
+      const session = sessionManager.getSession('tui', 'local');
+
+      const agent = new NativeAgent({
+        modelClient: modelRouter,
+        systemPrompt,
+        session,
+        toolRegistry,
+        toolExecutor,
+        onToolUse: (event) => {
+          if (event.type === 'start') {
+            const argsStr = event.args ? ` ${toolColors.dim}${JSON.stringify(event.args)}${toolColors.reset}` : '';
+            process.stdout.write(`${toolColors.cyan}> ${event.tool}${toolColors.reset}${argsStr}\n`);
+          } else if (event.type === 'end' && event.result) {
+            const icon = event.result.success ? `${toolColors.green}done` : `${toolColors.red}error`;
+            const detail = event.result.success
+              ? `${toolColors.dim}(${event.result.output.split('\n').length} lines)${toolColors.reset}`
+              : `${toolColors.dim}${event.result.error ?? 'unknown error'}${toolColors.reset}`;
+            process.stdout.write(`  ${icon}${toolColors.reset} ${detail}\n`);
+          }
+        },
+      });
+
+      const cleanup = () => {
+        sessionStore.close();
+      };
+
+      process.on('SIGINT', () => {
+        cleanup();
+        process.exit(0);
+      });
+
+      if (opts.fullscreen) {
+        await startFullscreenTui({
+          session,
+          modelClient: modelRouter,
+          modelRouter,
+          systemPrompt,
+          model: config.models.default.model,
+          onExit: cleanup,
+        });
+      } else {
+        let switchingToFullscreen = false;
+
+        const tui = new MinimalTui({
+          session,
+          modelClient: modelRouter,
+          modelRouter,
+          systemPrompt,
+          agent,
+          localProviders: config.models.local_providers,
+          currentLocalProvider: config.models.local?.provider,
+          onTransfer: (target) => {
+            if (target === 'telegram') {
+              const telegramUserId = String(config.telegram.allowed_chat_ids[0]);
+              sessionManager.transferSession('tui', 'local', 'telegram', telegramUserId);
+              console.log(`Session transferred to Telegram (${telegramUserId})\n`);
+            } else {
+              console.log(`Unknown transfer target: ${target}\n`);
+            }
+          },
+          onFullscreen: () => {
+            switchingToFullscreen = true;
+            tui.stop(true);
+          },
+        });
+
+        await tui.start();
+
+        if (switchingToFullscreen) {
+          console.clear();
+          await startFullscreenTui({
+            session,
+            modelClient: modelRouter,
+            modelRouter,
+            systemPrompt,
+            model: config.models.default.model,
+            onExit: cleanup,
+          });
+          return;
+        }
+      }
+
+      cleanup();
     });
 }