Improve agent and code review guidance

.github/skills/code-review/SKILL.md

@@ -129,6 +129,13 @@ not claims that every subsystem exists or must be redesigned.
 - For dependency/build changes, inspect scopes, Java release requirements,
   annotation processing, shaded relocations, packaged resources, and classpath
   conflicts. Re-read the current POM rather than assuming another project's setup.
+- Preserve the current single-project layout. Review the packaged full and `shared`
+  JARs: neutral classes must not link platform APIs through signatures, annotations,
+  superclasses, initializers, services, or reflection, and legacy compatibility
+  facades must remain source/binary compatible unless a migration is authorized.
+- For configuration changes, test case-insensitive and literal-key traversal,
+  supported-value classification, nested raw maps, copy isolation, bounds/cycles,
+  and null-safe detached or rootless sections across neutral and Bukkit adapters.
 
 ### Concurrency, resources, and lifecycle
 

AGENTS.md

@@ -0,0 +1,56 @@
+# Maintainer and AI-agent guide
+
+SimpleAPI is a shared library consumed by AdvancedCore and other plugins. The repository now uses one Maven project and one source tree with platform-neutral and platform-specific packages; do not recreate the removed experimental submodule build.
+
+## Build and verification
+
+Requirements: JDK 21+ and Maven. The Maven project is in `SimpleAPI/`.
+
+```shell
+mvn -B -f SimpleAPI/pom.xml test
+mvn -B -f SimpleAPI/pom.xml package
+```
+
+Confirm current CI and POM settings before relying on these commands. Verify that the package invocation produced both the legacy/full artifact and every configured classifier, especially the `shared` JAR. Run `git diff --check` and confirm tests actually ran.
+
+## Packaging boundaries
+
+- `com.bencodez.simpleapi.core` contains platform-independent implementations.
+- Platform adapters belong under packages such as `com.bencodez.simpleapi.bukkit`; future Forge/Fabric/other adapters must remain isolated from core.
+- The full `simpleapi` artifact preserves existing consumers and public package names.
+- The `shared` classifier JAR contains only the explicitly selected neutral API. Because a classifier shares the project's ordinary POM, native consumers must exclude its transitives and explicitly declare the neutral dependencies they use, as documented in `docs/shared-libraries.md`.
+- Compatibility facades in older package names are intentional. Do not remove, relocate, or narrow them without an explicit migration and downstream verification.
+- Previously removed experimental coordinates such as `simpleapi-parent`, `simpleapi-core`, `simpleapi-configurate`, and `simpleapi-sql` are not current build modules.
+
+Core and the shared artifact must not link Bukkit, BungeeCord, Velocity, Minecraft, Forge, Fabric, NeoForge, or other loader-specific classes. Test the packaged JAR, not only source imports: signatures, annotations, superclass references, static initializers, service descriptors, and reflective loading can leak platform dependencies.
+
+## API and configuration compatibility
+
+Treat public signatures, constructors, overloads, generic types, return values, exceptions, callback threading, configuration shapes, and serialized data as compatibility surfaces.
+
+- Preserve legacy YAML key lookup, casing, literal-key behavior, defaults, numeric values, empty/missing distinctions, and copy isolation.
+- Keep structured/plain configuration views bounded and cycle-safe.
+- Shared configuration paths must reject or adapt native platform objects according to their documented contract; Bukkit adapters may preserve native `ConfigurationSection` behavior where promised.
+- Annotation binding must preserve inherited fields, supported value classification, nested traversal, and detached/rootless-section safety.
+- Database abstractions must keep connection ownership, transaction boundaries, timeouts, null/closed-connection handling, and shutdown behavior explicit.
+- Do not introduce hidden user extraction or Bukkit-only behavior into neutral APIs merely for a storage mode that is scheduled for removal.
+
+## Concurrency, lifecycle, and resources
+
+- Avoid blocking I/O on Bukkit, region, proxy, networking, or event threads.
+- Define callback execution context and preserve it across adapters.
+- Bound queues, caches, payloads, recursion, retries, and diagnostic output.
+- Handle cancellation, interruption, executor rejection, partial initialization, reload, and shutdown without leaked work.
+- Optional integrations must not cause class-loading failures when absent.
+
+## Change and PR workflow
+
+Keep changes focused and avoid unrelated formatting. Before any commit, push, PR update, review reply, or other remote change:
+
+1. run relevant focused tests;
+2. run the full Maven package build;
+3. inspect the newly produced full and shared artifacts;
+4. run `git diff --check`;
+5. inspect the complete base-to-HEAD diff and affected AdvancedCore/downstream contracts.
+
+For substantive changes, obtain a fresh source-read-only review. The implementation agent verifies and fixes accepted findings, reruns all required checks, and obtains a new review of the updated snapshot. Do not reuse an earlier clean verdict after changes, and do not merge without explicit authorization.