diff --git a/api/tests/unit/test_app.py b/api/tests/unit/test_app.py
index 48e34c3..77e214e 100644
--- a/api/tests/unit/test_app.py
+++ b/api/tests/unit/test_app.py
@@ -143,6 +143,20 @@ async def test_nats_disabled_starts_nothing_and_healthcheck_reports_off(
     assert events == ["s3.close"]
 
 
+async def test_minimal_environment_starts_and_healthcheck_answers(
+    patched_app: Any, monkeypatch: pytest.MonkeyPatch, minimal_settings: Callable[..., Any]
+) -> None:
+    """Старт с минимальным окружением: только MinIO, адрес NATS и DEBUG (без seed/jwt, БД и SMB)."""
+    monkeypatch.setattr(patched_app, "settings", minimal_settings())
+    assert patched_app.settings.NATS_ENABLED is True
+
+    async with running_app(patched_app) as client:
+        response = await client.get("/healthcheck")
+
+    assert response.status_code == 200  # noqa: PLR2004 - HTTP 200
+    assert set(response.json()) == {"uptime", "version", "nats"}
+
+
 async def test_nats_enabled_subscribes_worker_and_reports_ok(
     patched_app: Any, monkeypatch: pytest.MonkeyPatch, events: list[str]
 ) -> None:
diff --git a/api/tests/unit/test_layout.py b/api/tests/unit/test_layout.py
new file mode 100644
index 0000000..6a60a4b
--- /dev/null
+++ b/api/tests/unit/test_layout.py
@@ -0,0 +1,32 @@
+"""Страж spec «Сервис не зависит от БД и фронта» (DECISION-4): ни зависимостей БД/SMB/шаблонной авторизации, ни
+каталогов фронта, миграций, моделей и репозиториев."""
+
+import re
+from pathlib import Path
+
+import pytest
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+REQUIREMENTS = REPO_ROOT / "api" / "requirements.txt"
+FORBIDDEN_PACKAGES = (
+    "asyncpg",
+    "sqlalchemy",
+    "alembic",
+    "smbprotocol",
+    "argon2-cffi",
+    "raisa_fastapi_protected_api",
+)
+FORBIDDEN_DIRS = ("web", "api/alembic", "api/src/db", "api/src/models", "api/src/repositories")
+
+
+@pytest.mark.parametrize("package", FORBIDDEN_PACKAGES)
+def test_requirements_have_no_database_or_template_auth_packages(package: str) -> None:
+    name = re.sub(r"[-_.]", "[-_.]", package)  # имена пакетов сравниваются по PEP 503: -, _ и . равнозначны
+    pattern = re.compile(rf"^\s*{name}\s*(?:[=<>!~;\[]|$)", re.IGNORECASE)
+    lines = REQUIREMENTS.read_text(encoding="utf-8").splitlines()
+    assert not [line for line in lines if pattern.match(line)]
+
+
+@pytest.mark.parametrize("directory", FORBIDDEN_DIRS)
+def test_no_frontend_or_database_directories(directory: str) -> None:
+    assert not (REPO_ROOT / directory).exists()