test(docker): cover docker subcommand rendering paths

- add handler-level coverage for up, down, logs, config, update, and status

- exercise success, validation, follow-mode, and boxed error output paths

tests/unit/commands/docker-down-subcommand.test.ts

@@ -0,0 +1,63 @@
+import { describe, expect, it } from 'bun:test';
+import {
+  renderCapturedLines,
+  useDockerSubcommandConsoleCapture,
+} from './docker-subcommand-test-helpers';
+
+const capture = useDockerSubcommandConsoleCapture();
+
+async function loadHandleDown() {
+  const mod = await import(
+    `../../../src/commands/docker/down-subcommand?test=${Date.now()}-${Math.random()}`
+  );
+  return mod.handleDown;
+}
+
+describe('docker down subcommand', () => {
+  it('prints progress and success output for remote shutdowns', async () => {
+    const calls: Array<{ host?: string }> = [];
+    const dockerModule = (await import(
+      '../../../src/docker'
+    )) as typeof import('../../../src/docker');
+    const originalDown = dockerModule.DockerExecutor.prototype.down;
+    dockerModule.DockerExecutor.prototype.down = function (options: { host?: string }) {
+      calls.push(options);
+    };
+
+    try {
+      const handleDown = await loadHandleDown();
+      await handleDown(['--host', 'docker-box']);
+
+      const rendered = renderCapturedLines(capture.logLines);
+      expect(calls).toEqual([{ host: 'docker-box' }]);
+      expect(rendered).toContain('Stopping Docker stack on docker-box...');
+      expect(rendered).toContain('Docker stack stopped on docker-box.');
+      expect(capture.errorLines).toEqual([]);
+      expect(process.exitCode).toBe(0);
+    } finally {
+      dockerModule.DockerExecutor.prototype.down = originalDown;
+    }
+  });
+
+  it('renders executor failures as boxed errors', async () => {
+    const dockerModule = (await import(
+      '../../../src/docker'
+    )) as typeof import('../../../src/docker');
+    const originalDown = dockerModule.DockerExecutor.prototype.down;
+    dockerModule.DockerExecutor.prototype.down = function () {
+      throw new Error('Docker stack shutdown failed.\nCommand timed out after 30s.');
+    };
+
+    try {
+      const handleDown = await loadHandleDown();
+      await handleDown([]);
+
+      const rendered = renderCapturedLines(capture.errorLines);
+      expect(rendered).toContain('Docker stack shutdown failed.');
+      expect(rendered).toContain('Command timed out after 30s.');
+      expect(process.exitCode).toBe(1);
+    } finally {
+      dockerModule.DockerExecutor.prototype.down = originalDown;
+    }
+  });
+});