blosc/python-blosc2/wasm32-pyodide-dev

Use When

• You are developing python-blosc2 for wasm32/Pyodide and need a fast local edit-build-test loop.
• You need repeatable commands to build a cp313 Pyodide wheel and run targeted tests.

Assumptions

• OS is Linux.
• Repository root is python-blosc2.
• uv is installed and available.
• You have a host venv for pyodide-build tooling (example: .venv-pyodide-host).

Core Workflow

1. Install host tooling with uv and pin wheel if needed for pyodide xbuildenv.
2. Install xbuildenv for the target Pyodide version.
3. Create or reuse a Pyodide runtime venv.
4. Build a wasm32 wheel with cibuildwheel --platform pyodide.
5. Reinstall the freshly built wheel into the Pyodide runtime venv.
6. Run focused pytest modules first, then expand coverage.

Fast Commands

See references/commands.md for copy/paste one-liners.

Troubleshooting

• ModuleNotFoundError: No module named 'wheel.cli': pin wheel==0.45.1 in host tooling venv.
• Missing runtime deps inside Pyodide venv: install numpy msgpack ndindex requests there.
• Pure-Python file tweaks without full rebuild: copy updated module files from src/blosc2/ into installed site-packages/blosc2/.

Notes

• Keep wasm32 runs deterministic by preferring single-thread settings in tests where needed.
• For DSL/JIT benchmarks, compare --mode off|on|auto|all to separate JIT benefit from baseline runtime.