spring-modulith

# Spring Modulith ## Spring Boot 3 baseline Use the Spring Modulith 1.4 line with Boot 3.5; check the official compatibility matrix for older Boot 3 minors. ## Apply within the existing architecture Inspect the application root package, module boundaries and current dependency graph. Use direct subpackages as modules; keep their API at the module root and implementation in internal subpackages. Expose a named interface only for an intentional shared API. Use allowedDependencies when the architecture needs explicit dependency constraints. Avoid creating a generic shared module that every feature depends on. ## Verify boundaries Add spring-modulith-starter-test with test scope and run ApplicationModules.of(Application.class).verify() in CI. It checks cycles and access to module internals. Add ApplicationModuleTest for behavior confined to a module. A passing structure check does not prove transactional or delivery correctness. See [good module verification](examples/good-module-test.java) and [bad cross-module dependency](examples/bad-module-dependency.java). ## Reliable events Publish immutable event payloads containing IDs and necessary facts, not managed JPA entities. Use ApplicationModuleListener for asynchronous transactional listeners when that timing fits. For delivery that must survive a process crash, configure a persistent event publication registry using the chosen JDBC/JPA starter and manage its schema through migrations. An in-memory registry and a plain a...