feat(check): make check fails when a service imports another service's sdk at startup

template/{{ part_dir }}/{% if layout == 'part' %}CLAUDE.md{% endif %}

@@ -5,3 +5,9 @@ ruff format
 ruff check --fix
 ty check
 ```
+
+## Imports
+Every service imports only what it needs to start. `make check` runs `scripts/check_imports.py`, which fails when a service loads a heavy package it is not allowed; `SERVICES` there is the contract, extend it on purpose.
+- Package `__init__` files don't re-export clients or SDKs.
+- An SDK used by one function is imported inside it. On an async path load it first with `await preload("<module>")` from `utils.imports`, so the event loop never waits on the import.
+- Types used in Dishka provider signatures and `FromDishka[...]` stay real top-level imports.