Extract shared executor runtime with a Bukkit lifecycle adapter

[BenCodez]

Summary

Second requested platform-preparation PR. Extract the existing executor/lifecycle implementation into core/runtime and the Bukkit-specific cleanup hooks into bukkit/runtime, in the current single Maven project.

• Introduce RuntimePlatform with JDK-only executor and cleanup contracts.
• Move creation of the three background executor owners and shutdown sequencing into AdvancedCoreRuntime.
• Keep AdvancedCoreLifecycle as the public compatibility facade. AdvancedCorePlugin already uses it, so the Bukkit path uses the extracted implementation immediately.
• Preserve scheduler/executor identity, separate executor ownership, cleanup order, 2/2/2/1-second grace periods, reward shutdown position, interruption handling and warning/debug callbacks.
• Retain existing lifecycle tests and add six tests for exact ordering, failure handling, identity and a real JDK-only runtime fixture.

Compatibility and scope

One POM, no submodules, no new workflows, no dependency/version changes, and no AdvancedCorePlugin public API changes. The existing BukkitScheduler/Folia behavior is untouched. This does not redirect entity/region work to a global executor.

This is the executor/lifecycle slice, not a complete native AdvancedCore service graph. User/storage/reward services and final native artifact packaging remain separate steps. There is no duplicate user cache or second service registry. Existing lifecycle serialization and synchronous cleanup behavior remain; the executor grace periods are not a global timeout for arbitrary cleanup callbacks.

Verified build

Existing Java CI with Maven — run 530 passed on Java 21. Inspected build job 101919368836 and its actual Maven log:

• mvn -B -f AdvancedCore/pom.xml package — BUILD SUCCESS.
• 284 tests, zero failures/errors/skips, including all six new tests and both original lifecycle tests.
• The headless fixture passed with Bukkit and JUnit absent from its isolated runtime.
• AdvancedCore.jar was generated and normal shading/minimization completed.
• Tested PR merge ref dc303c9aeea529f58e9a6c1a950830e7f2602c34 for head 50eb4bec1a0e0c42c757d428fa3ce778af3e7cb2 and base 5fe205bca26236a92ee2fda1634f056639b307a3.

Local Java 21 compilation of the two shared production classes also passed. A local JDK-only smoke program ran a real task, checked independent executor owners and cleanup order, verified termination, and verified rejection after shutdown.

The editing container has no Maven/dependency network access. The full Maven result is from GitHub Actions, not a local Maven run. No current downstream VotingPlugin build, live-server test or live-database matrix was run. Source inspection was same-context; no independent reviewer execution is claimed.

Related work

• Add structured reward configuration reads with Bukkit compatibility SimpleAPI#78: structured reward configuration boundary.
• Extract shared user-data reads while preserving caches and storage hooks #314: shared scalar user-data reads preserving existing caches and storage hooks.

These initial AdvancedCore PRs have disjoint production changes and independently target master. This lifecycle slice does not require SimpleAPI#78 to be published or merged.

Nothing is merged, deployed or published by this PR.

AI disclosure: This implementation and pull-request description were prepared with assistance from ChatGPT.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-08T02:57:26.196460Z	50eb4be	Draft marked ready
🔒 Security Review	✅ Completed 2026-09-08T03:00:19.381889Z	50eb4be	Draft marked ready

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