upgrade to Spring Boot 4.2.1

docs/adrs/0003-2026-06-09.spring-boot-version.md

@@ -2,11 +2,11 @@
 
 **Status:**
 - proposed: 2026-06-09
-- accepted: -
+- accepted: 2026-06-09
 - rejected: -
 - superseded: -
 
-**Decision [proposed]:** Spring Boot 4.0 — only actively-supported version; springmockk workaround via @TestConfiguration until a compatible release is published.
+**Decision [accepted]:** Spring Boot 4.0.6 — only actively-supported version; springmockk 5.0.1 provides @MockkBean for Spring Boot 4.0.
 
 ## Context and Problem Statement
 
@@ -34,12 +34,12 @@ Spring Boot 4.0 moves to Spring Framework 7 and Jakarta EE 11.
 
 The key ecosystem dependencies and their Spring Boot 4.0 compatibility status:
 
-| Dependency | Role | Spring Boot 4.0 status |
-|---|---|---|
-| [picocli-spring-boot-starter](https://picocli.info/) | CLI wiring | Untested; last documented target is Spring Boot 3.1. The integration is minimal (one `IFactory` bean), so it likely works in practice. |
-| [springmockk](https://github.com/Ninja-Squad/springmockk) | `@MockkBean` in tests | **Incompatible** — confirmed Spring Boot 3.x only. |
-| [kotest-extensions-spring](https://github.com/kotest/kotest-extensions-spring) | Kotest + `@SpringBootTest` | Compatibility unconfirmed. |
-| [wiremock-spring-boot](https://wiremock.org/docs/spring-boot/) | HTTP stubbing in tests | **Compatible** — Spring Boot 4.0 explicitly supported since January 2026. |
+| Dependency | Version | Role | Spring Boot 4.0 status |
+|---|---|---|---|
+| [picocli-spring-boot-starter](https://picocli.info/) | 4.7.6 | CLI wiring | **Compatible** — `ApplicationContextTest` confirms context wiring works. |
+| [springmockk](https://github.com/Ninja-Squad/springmockk) | 5.0.1 | `@MockkBean` in tests | **Compatible** — 5.x released specifically for Spring Boot 4.0; `@MockkBean` verified. |
+| [kotest-extensions-spring](https://github.com/kotest/kotest-extensions-spring) | 6.1.5 | Kotest + `@SpringBootTest` | **Compatible** — 6.x (new groupId `io.kotest`) required; config moved to `io.kotest.provided.ProjectConfig`. |
+| [wiremock-spring-boot](https://wiremock.org/docs/spring-boot/) | 4.2.1 | HTTP stubbing in tests | **Compatible** — Spring Boot 4.0 explicitly supported since January 2026. |
 
 ## Considered Options
 
@@ -76,12 +76,9 @@ The current and only actively-supported major release.
 
 #### Disadvantages
 
-- **springmockk is incompatible.** The `@MockkBean` / `@SpykBean` annotations are not available.
-  This matters in particular for `@WebMvcTest` (controller error-behaviour) and
-  `@DataJpaTest`-adjacent tests where collaborators need to be mocked in the Spring context.
-  The workaround is to register MockK mocks as Spring beans via `@TestConfiguration`,
-  which preserves full MockK syntax (`every { }`, `verify { }`) at the cost of one
-  inner configuration class per test file and an explicit `clearMocks()` call in `beforeEach`:
+- **springmockk 5.x is required.** Version 4.x is Spring Boot 3.x only. Version 5.0.1 adds
+  Spring Boot 4.0 support; `@MockkBean` / `@SpykBean` work as expected.
+  As an alternative, register MockK mocks via `@TestConfiguration` without the springmockk dependency:
   ```kotlin
   @WebMvcTest(SomeController::class)
   @Import(SomeControllerTest.Mocks::class)
@@ -93,17 +90,12 @@ The current and only actively-supported major release.
       @Autowired lateinit var someService: SomeService
       init {
           beforeEach { clearMocks(someService) }
-          // full MockK syntax available
       }
   }
   ```
-  This is more verbose than `@MockkBean` but avoids mixing Mockito and MockK.
-  Revisit once springmockk publishes a Spring Boot 4.0-compatible release.
-- **picocli-spring-boot-starter is untested against Spring Boot 4.0.**
-  The risk is low (the auto-configuration is a single `IFactory` bean with no framework-version-specific API),
-  but it cannot be assumed safe until verified by a running context test.
-- **kotest-extensions-spring** compatibility needs verification before the first
-  `@SpringBootTest` test is written.
+- **picocli-spring-boot-starter** context wiring confirmed via `ApplicationContextTest`.
+- **kotest-extensions-spring 6.x** (groupId `io.kotest`) is required for Spring Boot 4.0.
+  The project config must be placed at `io.kotest.provided.ProjectConfig` (Kotest 6 discovery requirement).
 - Relatively new GA; fewer community examples for the 4.0 generation.
 
 ## Decision Outcome
@@ -124,9 +116,4 @@ The main reasons:
   - kotest-extensions-spring compatibility must be verified before the
     first `@SpringBootTest` test is written.
 
-Open items before the code is upgraded:
-1. Bump Spring Boot to 4.0.6 and verify `ApplicationContextTest` still passes.
-2. Confirm picocli-spring-boot-starter works under the new context.
-3. Confirm kotest-extensions-spring works with Spring Boot 4.0.
-4. Replace `@MockkBean` usages with the `@TestConfiguration` + `mockk()` pattern
-   until springmockk publishes a compatible release.
+All ecosystem blockers are resolved. The codebase runs Spring Boot 4.0.6.