[Aionw]

Description

Implements another Phase 2 increment from #3534 by moving lightweight Store-facing Python utilities into the unified root Python package.

• move mooncake.buffer_pool and mooncake.mooncake_config into python/mooncake as their single authoritative source;
• move their tests under python/tests;
• preserve the existing public import paths;
• update direct CMake installation and the temporary legacy wheel staging path;
• add source-location and installed-wheel checks;
• update ownership and labeling for the migrated paths.

This migration is independent of #3585. The branch is based directly on main and contains no Reshard migration changes.

Module

• Transfer Engine (mooncake-transfer-engine)
• Mooncake Store (mooncake-store)
• Reshard (mooncake-reshard)
• Mooncake EP (mooncake-ep)
• Mooncake PG (mooncake-pg)
• Integration (mooncake-integration)
• P2P Store (mooncake-p2p-store)
• Python Wheel (mooncake-wheel)
• Common (mooncake-common)
• Mooncake RL (mooncake-rl)
• CI/CD
• Docs
• Other

Type of Change

• Bug fix
• New feature
• Refactor
• Breaking change
• Documentation update
• Performance improvement
• Other

How Has This Been Tested?

Test commands:

PYTHONPATH="$PWD/python" python -S python/tests/unit/test_mooncake_config.py
python -m pytest -q python/tests/packaging/test_project.py
CMAKE_BUILD_PARALLEL_LEVEL=128 python -m build --wheel
MOONCAKE_TEST_WHEEL="$PWD/dist/mooncake_transfer_engine-0.3.12.post1-cp310-cp310-linux_x86_64.whl" python -m pytest -q python/tests/packaging/test_installed_wheel.py
python -m twine check dist/mooncake_transfer_engine-0.3.12.post1-cp310-cp310-linux_x86_64.whl
python -m pre_commit run --files <files changed against main>

Test results:

• Unit tests pass (35 configuration tests and 5 packaging contract tests)
• Integration tests pass (isolated installed-wheel smoke test)
• Manual testing done (wheel manifest contains both migrated modules and twine check passes)

Checklist

• I have performed a self-review of my own code
• I have formatted my code using ./scripts/code_format.sh (no C/C++ source changes; Python and CMake formatting passed through pre-commit)
• I have run pre-commit on the files changed in this PR and all hooks pass
• I have updated the documentation (not applicable: public APIs and behavior are unchanged)
• I have added tests to prove my changes are effective
• For changes >500 LOC: I have filed RFC issue [RFC]: Unify Mooncake's Python package, build, and release architecture #3534

AI Assistance Disclosure

• No AI tools were used
• AI tools were used (specified below)

OpenAI Codex assisted with migration selection, implementation, packaging validation, and PR preparation. The human submitter remains responsible for reviewing and defending every changed line.

[Icedcoco]

Could you please confirm whether the direct CMake installation path also needs to install buffer_pool.py?

Since the module was moved from mooncake-wheel/mooncake to python/mooncake, the install(DIRECTORY ...) rule in python/CMakeLists.txt will no longer include it. However, mooncake/init.py still imports mooncake.buffer_pool, so users installing through the direct CMake path may encounter ModuleNotFoundError.

The wheel staging path appears to handle this module correctly. Would it make sense to add buffer_pool.py to the direct CMake install list and include a corresponding installation test?

[Icedcoco]

LGTM pending CI

[ShangmingCai]

Looks good, just some harmless test file migration and clean up.