diff --git a/backend/llm.txt b/backend/llm.txt
index 2b2a8e1..8df481d 100644
--- a/backend/llm.txt
+++ b/backend/llm.txt
@@ -10,6 +10,8 @@ This file condenses `backend/docs/dev/http_api.md` + `backend/docs/dev/model.md`
 - MUST: HTTP module folder name MUST be `snake_case` (e.g. `tenant_public`), not `camelCase`/`mixedCase`.
 - DO keep controller methods thin: parse/bind → call `services.*` → return result/error.
 - DO regenerate code after changes (routes/docs/models).
+- MUST: after adding/removing/renaming any files under `backend/app/services/`, run `atomctl gen service --path ./app/services` to regenerate `backend/app/services/services.gen.go`; DO NOT edit `services.gen.go` manually.
+- MUST: a single service's methods MUST live in a single file; do NOT split one service across multiple files (e.g. `type user struct{}` in `user.go` but methods in `user_admin.go`), because `atomctl gen service` uses filenames to infer services and will generate incorrect `services.gen.go`.
 - DO add `// @provider` above every controller/service `struct` declaration.
 - DO keep HTTP middlewares in `backend/app/middlewares/` only.
 - DO keep all `const` declarations in `backend/pkg/consts/` only (do not declare constants elsewhere).