diff --git a/README.md b/README.md
index 9db852f..edd100b 100644
--- a/README.md
+++ b/README.md
@@ -20,6 +20,7 @@ ensemble pull
 ensemble release
 ensemble add
 ensemble enable
+ensemble test
 ensemble update
 ```
 
@@ -36,6 +37,7 @@ ensemble update
 | `ensemble release` | Manage releases (snapshots) of your app (interactive menu or subcommands)     |
 | `ensemble add`     | Add a new screen, widget, script, action, translation, or asset               |
 | `ensemble enable`  | Enable starter modules (camera, location, google_maps, etc.) in a Flutter app |
+| `ensemble test`    | Run declarative YAML tests in a Flutter starter project                       |
 | `ensemble update`  | Update the CLI to the latest version                                          |
 
 ### Options
@@ -91,6 +93,10 @@ ensemble update
   - After `pubspec.yaml` changes, run `flutter pub get`
   - Team architecture notes: [docs/ensemble-enable.md](docs/ensemble-enable.md)
 
+### `ensemble test`
+
+Run YAML tests in a Flutter starter project (starter root or `ensemble/apps/<app>`). Other flags pass through to the runner. See [docs/ensemble-test.md](docs/ensemble-test.md).
+
 ### `ensemble add`
 
 `ensemble add` scaffolds common app artifacts in your project and updates `.manifest.json` when needed.
diff --git a/docs/ensemble-test.md b/docs/ensemble-test.md
new file mode 100644
index 0000000..f5f07b0
--- /dev/null
+++ b/docs/ensemble-test.md
@@ -0,0 +1,43 @@
+# `ensemble test`
+
+Thin wrapper around [`ensemble_test_runner`](https://github.com/EnsembleUI/ensemble/tree/support-test-cases/packages/ensemble_test_runner). Splices a temporary dev dependency, runs tests, restores `pubspec.yaml`.
+
+```bash
+ensemble test [--project <path>] [runner flags...]
+```
+
+- Run from **starter root** or **`ensemble/apps/<app>`** (not subdirs). From an app dir, starter root is 2 parents up (`apps` → `ensemble` → starter).
+- `--project` sets starter root explicitly. All other flags pass through (`--timeout=`, `--verbose`, `--doctor`, etc.).
+- Uses `fvm dart` when `.fvmrc` exists. Requires Flutter **≥ 3.35**.
+
+---
+
+## Architecture
+
+```
+test.ts
+  ├── starterProject.ts       starter root or ensemble/apps/<app>
+  ├── pubspecTestRunner.ts    splice/restore ensemble_test_runner dev_dep
+  └── dartToolchain.ts        fvm dart when .fvmrc exists
+```
+
+```mermaid
+sequenceDiagram
+  participant CLI
+  participant Runner as ensemble_test_runner
+
+  CLI->>CLI: resolve starter root
+  CLI->>CLI: backup pubspec, splice dev_dep if missing
+  CLI->>Runner: dart run ensemble_test_runner:ensemble_test [flags]
+  Note over Runner: resolves deps if needed
+  Runner-->>CLI: exit code
+  CLI->>CLI: restore pubspec in finally
+```
+
+| Module                 | Role                                                                     |
+| ---------------------- | ------------------------------------------------------------------------ |
+| `starterProject.ts`    | Resolve starter root from cwd or 2 parents up from `ensemble/apps/<app>` |
+| `pubspecTestRunner.ts` | Insert fixed git dev_dep block; restore in `finally`                     |
+| `dartToolchain.ts`     | `fvm dart` vs `dart`                                                     |
+
+**Not duplicated in CLI:** test discovery, asset patching, `flutter test`, doctor/validate — owned by the runtime package.
diff --git a/src/commands/test.ts b/src/commands/test.ts
new file mode 100644
index 0000000..f32d643
--- /dev/null
+++ b/src/commands/test.ts
@@ -0,0 +1,31 @@
+import { assertDartAvailable, resolveDartInvocation } from '../core/dartToolchain.js';
+import { runDartWithExitCode, withTemporaryTestRunnerDep } from '../core/pubspecTestRunner.js';
+import { resolveStarterProjectRootWithWalkUp } from '../core/starterProject.js';
+
+function collectPassthroughArgs(argv: readonly string[] = process.argv): string[] {
+  const testIndex = argv.indexOf('test');
+  if (testIndex === -1) return [];
+
+  const passthrough: string[] = [];
+  for (let i = testIndex + 1; i < argv.length; i++) {
+    const arg = argv[i];
+    if (arg === '--project') {
+      i += 1;
+      continue;
+    }
+    if (!arg.startsWith('--project=')) passthrough.push(arg);
+  }
+  return passthrough;
+}
+
+export async function testCommand(options: { project?: string } = {}): Promise<void> {
+  const projectRoot = await resolveStarterProjectRootWithWalkUp(options.project);
+  const dart = await resolveDartInvocation(projectRoot);
+  await assertDartAvailable(dart);
+
+  const dartArgs = ['run', 'ensemble_test_runner:ensemble_test', ...collectPassthroughArgs()];
+
+  await withTemporaryTestRunnerDep(projectRoot, async () => {
+    process.exitCode = await runDartWithExitCode(dart, dartArgs, projectRoot);
+  });
+}
diff --git a/src/core/pubspecTestRunner.ts b/src/core/pubspecTestRunner.ts
new file mode 100644
index 0000000..e2c8bc0
--- /dev/null
+++ b/src/core/pubspecTestRunner.ts
@@ -0,0 +1,73 @@
+import fs from 'fs/promises';
+import path from 'path';
+import { spawn } from 'node:child_process';
+
+import { type DartInvocation } from './dartToolchain.js';
+import { ui } from './ui.js';
+
+const ENSEMBLE_GIT_URL = 'https://github.com/EnsembleUI/ensemble.git';
+const ENSEMBLE_TEST_RUNNER_REF = 'support-test-cases';
+const ENSEMBLE_TEST_RUNNER_PATH = 'packages/ensemble_test_runner';
+
+const TEST_RUNNER_DEV_DEP_BLOCK = `  ensemble_test_runner:
+    git:
+      url: ${ENSEMBLE_GIT_URL}
+      ref: ${ENSEMBLE_TEST_RUNNER_REF}
+      path: ${ENSEMBLE_TEST_RUNNER_PATH}
+`;
+
+function hasEnsembleTestRunnerDep(pubspecContent: string): boolean {
+  return /^\s*ensemble_test_runner\s*:/m.test(pubspecContent);
+}
+
+export function spliceTestRunnerDevDependency(pubspecContent: string): string {
+  if (hasEnsembleTestRunnerDep(pubspecContent)) return pubspecContent;
+
+  const match = pubspecContent.match(/^dev_dependencies:\s*$/m);
+  if (!match || match.index === undefined) {
+    throw new Error('pubspec.yaml has no dev_dependencies section.');
+  }
+
+  const insertAt = match.index + match[0].length;
+  return `${pubspecContent.slice(0, insertAt)}\n${TEST_RUNNER_DEV_DEP_BLOCK}${pubspecContent.slice(insertAt)}`;
+}
+
+export async function runDartWithExitCode(
+  dart: DartInvocation,
+  args: string[],
+  cwd: string
+): Promise<number> {
+  return new Promise((resolve, reject) => {
+    const child = spawn(dart.command, [...dart.prefixArgs, ...args], { cwd, stdio: 'inherit' });
+    child.on('error', reject);
+    child.on('close', (code) => resolve(code ?? 1));
+  });
+}
+
+export async function withTemporaryTestRunnerDep<T>(
+  projectRoot: string,
+  fn: () => Promise<T>
+): Promise<T> {
+  const pubspecPath = path.join(projectRoot, 'pubspec.yaml');
+  const original = await fs.readFile(pubspecPath, 'utf8');
+  let modified = false;
+
+  try {
+    if (!hasEnsembleTestRunnerDep(original)) {
+      await fs.writeFile(pubspecPath, spliceTestRunnerDevDependency(original), 'utf8');
+      modified = true;
+    }
+
+    return await fn();
+  } finally {
+    if (modified) {
+      try {
+        await fs.writeFile(pubspecPath, original, 'utf8');
+      } catch (error) {
+        ui.warn(
+          `Failed to restore pubspec.yaml after tests: ${error instanceof Error ? error.message : String(error)}`
+        );
+      }
+    }
+  }
+}
diff --git a/src/core/starterProject.ts b/src/core/starterProject.ts
index 7fc1909..a77a907 100644
--- a/src/core/starterProject.ts
+++ b/src/core/starterProject.ts
@@ -17,6 +17,12 @@ async function isStarterProjectRoot(dir: string): Promise<boolean> {
   );
 }
 
+function isEnsembleAppRoot(dir: string): boolean {
+  const parent = path.dirname(path.resolve(dir));
+  const grandparent = path.dirname(parent);
+  return path.basename(parent) === 'apps' && path.basename(grandparent) === 'ensemble';
+}
+
 export async function resolveStarterProjectRoot(explicitPath?: string): Promise<string> {
   const root = path.resolve(explicitPath ?? process.cwd());
 
@@ -28,3 +34,20 @@ export async function resolveStarterProjectRoot(explicitPath?: string): Promise<
 
   return root;
 }
+
+const TEST_CWD_HINT =
+  'Run ensemble test from the starter root or an ensemble app directory (ensemble/apps/<app>). Or pass --project <path>.';
+
+export async function resolveStarterProjectRootWithWalkUp(explicitPath?: string): Promise<string> {
+  if (explicitPath) return resolveStarterProjectRoot(explicitPath);
+
+  const cwd = path.resolve(process.cwd());
+  if (await isStarterProjectRoot(cwd)) return cwd;
+
+  if (!isEnsembleAppRoot(cwd)) throw new Error(TEST_CWD_HINT);
+
+  const starterRoot = path.resolve(cwd, '..', '..', '..');
+  if (await isStarterProjectRoot(starterRoot)) return starterRoot;
+
+  throw new Error(TEST_CWD_HINT);
+}
diff --git a/src/index.ts b/src/index.ts
index b6a3d9d..4c5b9c9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -22,6 +22,7 @@ import {
 } from './commands/release.js';
 import { updateCommand } from './commands/update.js';
 import { enableCommand } from './commands/enable.js';
+import { testCommand } from './commands/test.js';
 import { isUpdateCommand } from './core/cliArgs.js';
 import { printCliError, resolveDebugFlag } from './core/cliError.js';
 import { ui } from './core/ui.js';
@@ -238,6 +239,15 @@ program
     });
   });
 
+program
+  .command('test')
+  .description('Run declarative YAML tests from the app tests directory.')
+  .option('--project <path>', 'Starter project root (default: starter root or ensemble/apps/<app>)')
+  .allowUnknownOption()
+  .action(async (options: { project?: string }) => {
+    await testCommand({ project: options.project });
+  });
+
 function checkForUpdates(): void {
   // Skip update checks in CI or when explicitly disabled.
   const ci = process.env.CI;
diff --git a/tests/core/pubspecTestRunner.test.ts b/tests/core/pubspecTestRunner.test.ts
new file mode 100644
index 0000000..86288fb
--- /dev/null
+++ b/tests/core/pubspecTestRunner.test.ts
@@ -0,0 +1,68 @@
+import fs from 'fs/promises';
+import os from 'os';
+import path from 'path';
+
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+
+import {
+  spliceTestRunnerDevDependency,
+  withTemporaryTestRunnerDep,
+} from '../../src/core/pubspecTestRunner.js';
+
+const SAMPLE_PUBSPEC = `name: demo
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+`;
+
+describe('pubspecTestRunner', () => {
+  let tmpDir: string;
+
+  beforeEach(async () => {
+    tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'ensemble-pubspec-test-runner-'));
+  });
+
+  afterEach(async () => {
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+
+  it('splices test runner under dev_dependencies', () => {
+    const updated = spliceTestRunnerDevDependency(SAMPLE_PUBSPEC);
+    expect(updated).toContain('ensemble_test_runner:');
+    expect(updated).toContain('ref: support-test-cases');
+  });
+
+  it('restores pubspec after callback', async () => {
+    await fs.writeFile(path.join(tmpDir, 'pubspec.yaml'), SAMPLE_PUBSPEC, 'utf8');
+
+    await withTemporaryTestRunnerDep(tmpDir, async () => undefined);
+
+    expect(await fs.readFile(path.join(tmpDir, 'pubspec.yaml'), 'utf8')).toBe(SAMPLE_PUBSPEC);
+  });
+
+  it('restores pubspec when callback throws', async () => {
+    await fs.writeFile(path.join(tmpDir, 'pubspec.yaml'), SAMPLE_PUBSPEC, 'utf8');
+
+    await expect(
+      withTemporaryTestRunnerDep(tmpDir, async () => {
+        throw new Error('test failed');
+      })
+    ).rejects.toThrow(/test failed/i);
+
+    expect(await fs.readFile(path.join(tmpDir, 'pubspec.yaml'), 'utf8')).toBe(SAMPLE_PUBSPEC);
+  });
+
+  it('skips splice when ensemble_test_runner is already in pubspec', async () => {
+    const pubspec = `${SAMPLE_PUBSPEC}  ensemble_test_runner:
+    git:
+      url: https://github.com/EnsembleUI/ensemble.git
+      ref: support-test-cases
+      path: packages/ensemble_test_runner
+`;
+    await fs.writeFile(path.join(tmpDir, 'pubspec.yaml'), pubspec, 'utf8');
+
+    await withTemporaryTestRunnerDep(tmpDir, async () => undefined);
+
+    expect(await fs.readFile(path.join(tmpDir, 'pubspec.yaml'), 'utf8')).toBe(pubspec);
+  });
+});
diff --git a/tests/core/starterProject.test.ts b/tests/core/starterProject.test.ts
index a5c5129..112d887 100644
--- a/tests/core/starterProject.test.ts
+++ b/tests/core/starterProject.test.ts
@@ -4,7 +4,10 @@ import path from 'path';
 
 import { afterEach, beforeEach, describe, expect, it } from 'vitest';
 
-import { resolveStarterProjectRoot } from '../../src/core/starterProject.js';
+import {
+  resolveStarterProjectRoot,
+  resolveStarterProjectRootWithWalkUp,
+} from '../../src/core/starterProject.js';
 
 describe('starterProject', () => {
   let tmpDir: string;
@@ -67,4 +70,25 @@ describe('starterProject', () => {
     const root = await resolveStarterProjectRoot(tmpDir);
     expect(await fs.realpath(root)).toBe(await fs.realpath(tmpDir));
   });
+
+  it('resolves starter root from ensemble/apps/<app>', async () => {
+    await writeStarterLayout(tmpDir);
+    const appRoot = path.join(tmpDir, 'ensemble', 'apps', 'kpnApp');
+    await fs.mkdir(appRoot, { recursive: true });
+    process.chdir(appRoot);
+
+    const root = await resolveStarterProjectRootWithWalkUp();
+    expect(await fs.realpath(root)).toBe(await fs.realpath(tmpDir));
+  });
+
+  it('rejects nested paths inside an ensemble app', async () => {
+    await writeStarterLayout(tmpDir);
+    const nested = path.join(tmpDir, 'ensemble', 'apps', 'kpnApp', 'tests');
+    await fs.mkdir(nested, { recursive: true });
+    process.chdir(nested);
+
+    await expect(resolveStarterProjectRootWithWalkUp()).rejects.toThrow(
+      /starter root or an ensemble app directory/i
+    );
+  });
 });