diff --git a/backend/CLAUDE.md b/backend/CLAUDE.md
index 5a0e281a..249221cc 100644
--- a/backend/CLAUDE.md
+++ b/backend/CLAUDE.md
@@ -97,7 +97,10 @@ public class MyEntity {
 
 - Annotated with `@Service`, `@RequiredArgsConstructor`, optionally `@Slf4j`.
 - Write methods: `@Transactional`.
-- Read methods: no annotation (default non-transactional).
+- Read methods: no annotation (default non-transactional) — **except** when the method returns
+  an entity whose lazy associations must remain accessible to the caller after the method
+  returns. In that case, use `@Transactional(readOnly = true)` to keep the Hibernate session
+  open. Removing this annotation causes `LazyInitializationException` in production. See ADR-022.
 - Cross-domain access goes through the other domain's service, never its repository.
 
 ## Error Handling