Plan: Add cuda_mppi as git submodule

Status: Completed

Overview

Extract the CUDA MPPI implementation from src/cuda_mppi/ into a separate git repository and integrate it as a submodule at third_party/cuda_mppi.

Decisions Made

• New repository: riccardo-enr/cuda_mppi
• Submodule path: third_party/cuda_mppi
• Feature branch: feat/cuda-mppi-submodule
• Track branch: main (in submodule)

Implementation Steps

1. Create New cuda_mppi Repository

• Use gh repo create to create riccardo-enr/cuda_mppi
• Set appropriate description and visibility
• Initialize with README.md

2. Initialize cuda_mppi Repository

• Clone the new repository locally
• Copy contents from src/cuda_mppi/ to repository root
• Create proper repository structure:
  • CMakeLists.txt (standalone build)
  • README.md (usage and build instructions)
  • LICENSE (MIT, matching main project)
  • .gitignore
• Commit and push initial code

3. Create Feature Branch in jax_mppi

• Create branch: feat/cuda-mppi-submodule
• Checkout the new branch

4. Add Submodule to jax_mppi

• Create third_party/ directory
• Run: git submodule add https://github.com/riccardo-enr/cuda_mppi.git third_party/cuda_mppi
• Remove old src/cuda_mppi/ directory
• Commit submodule addition

5. Update Build System

• Update root CMakeLists.txt:
  • Change add_subdirectory(src/cuda_mppi) to add_subdirectory(third_party/cuda_mppi)
• Verify pyproject.toml (should work via scikit-build-core automatically)
• Check for any hardcoded paths in:
  • Python source files
  • CMake files
  • Documentation

6. Test Build

• Clean build: rm -rf build/ _skbuild/
• Test clone from scratch with submodules
• Build and install package: uv pip install -e .
• Run test: python examples/test_cuda_mppi.py
• Verify JIT examples work

7. Update Documentation

• Add submodule instructions to README.md:

  # Clone with submodules
  git clone --recursive https://github.com/riccardo-enr/jax_mppi.git
  
  # Or if already cloned
  git submodule update --init --recursive

• Document build requirements in both repositories

• Update any relevant documentation links

8. Create Pull Request

• Commit all changes with conventional commits
• Push feature branch
• Create PR referencing issue #23
• Move this plan to completed/ directory

Rollback Plan

If issues arise, we can:

1. Remove submodule: git submodule deinit -f third_party/cuda_mppi
2. Delete from git: git rm -f third_party/cuda_mppi
3. Remove from .gitmodules
4. Restore original src/cuda_mppi from git history