CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

Unreleased

Added

• When the target Python is a pre-release, the PYO3_USE_ABI3_FORWARD_COMPATIBILITY environment variable is now set for all builds so that PyO3 packages will build against the unstable CPython version.

Fixed

• The wrapper scripts written into a Pyodide virtual environment now quote every interpolated path, so pyodide venv works when the host Python, the cross-build environment, or PATH contains a space. This previously broke uv-managed Pythons on macOS, which live under Library/Application Support. #409

• Pyodide virtual environments on Windows now include the python.exe shim that Pyodide ships, and console scripts installed into them point at it. The venv previously had no .exe interpreter at all, and the launcher that pip puts in front of a console script refuses to invoke anything else, so no installed script could be run. This needs a cross-build environment from Pyodide 0.29.3 or later, which is when the shim was first shipped. #409

Changed

• Replaced the pydantic dependency with attrs + cattrs for recipe (meta.yaml) and cross-build environment metadata parsing/validation. Recipe validation errors now raise pyodide_build.recipe.spec.SpecValidationError instead of pydantic.ValidationError.

• The rustflags config is now applied via the target-specific CARGO_TARGET_WASM32_UNKNOWN_EMSCRIPTEN_RUSTFLAGS environment variable instead of the global RUSTFLAGS, so the flags only affect the wasm32-unknown-emscripten target and no longer leak into host builds of build-dependencies and proc-macros.

[0.37.0] - 2026/07/24

Changed

• Unvendored tests that are generated from the package recipes are now compressed as a .zip file instead of a .tar file. This should not affect any user-facing functionality. #401

[0.36.0] - 2026/06/30

Fixed

• Fixed several bugs in the cross-build-environment (xbuildenv) lifecycle #378:

  • A Python-version marker mismatch on an already-installed xbuildenv will now refresh the host packages.
  • Installing via DEFAULT_CROSS_BUILD_ENV_URL is now treated like an explicit --url install, so it no longer bakes a mangled, URL-derived version into the generated package index.
  • pyodide xbuildenv use no longer raises FileExistsError when the xbuildenv symlink is dangling (its target was removed); the stale symlink is now cleaned up first.
  • A failure during a later installation step no longer deletes a pre-existing, valid cached xbuildenv.

• Fixed a hang when a recipe build/script or build/post ends by exiting the shell itself (e.g. exit 0). The build no longer blocks forever waiting for an environment dump that never runs; the previous environment is kept instead. #383

• Fixed per-package build variables (PKGDIR, PKG_VERSION, DISTDIR, ...) leaking into the cached build-environment dict, which caused later packages in a sequential build-recipes run to see the previous package's values. #383

• Fixed find_matching_wheel raising RuntimeError("Found multiple matching wheels") for a single file. #381

• Fixed pyodide clean recipes incorrectly cleaning packages tagged always. #381

• Fixed a bug where boolean and non-string values in pyproject.toml crashes pyodide CLI when loading config values #381

• Sanitize Content-Disposition: filename=... header values to prevent path traversal. #382

• Fixed build constraints not being applied when using uv as the installer by setting UV_BUILD_CONSTRAINT alongside PIP_CONSTRAINT and PIP_BUILD_CONSTRAINT. #389

• Fixed a dead-code control flow in pyodide skeleton pypi where a package whose new release ships only wheels (while the recipe used an sdist) would raise an exception rather than updating to the wheel. #384

• skeleton: fixed incorrect predictable URLs sdists for .zip-style sdists and packages with non-normalised names (such as ruamel.yaml). #384

• Fixed three bugs in pyodide venv: pyodide venv --no-download / --never-download being silently ignored, versioned pip scripts (e.g., pip3.12) being renamed to pip3, and a failed pyodide venv invocation deleting a pre-existing destination directory. #377

Changed

• Fixed build-time scripts of unisolated packages (like f2py and numpy-config from NumPy) not being available on PATH during builds. #21

• oldest-supported-numpy is now explicitly rejected when encountered as a build-time dependency. It is deprecated since NumPy 2.0, and packages that still list it should migrate to a direct numpy dependency. #392

[0.35.1] - 2026/06/13

Fixed

• Fixed an include path issue on macOS when homebrew Python is installed: if sys.prefix contains a symlink (as is the case with homebrew), resolve it so that host include paths are still replaced by the cross-compile ones #375

[0.35.0] - 2026/06/09

Added

• CrossBuildEnvReleaseSpec now has a published_at field containing the UTC timestamp when the release was published on GitHub (ISO 8601 format). This is exposed in pyodide xbuildenv search --all and pyodide xbuildenv search --all --json. #349

• pyodide xbuildenv search and pyodide xbuildenv install now support --nightly and --debug flags to search and install stable-debug, nightly, and nightly-debug cross-build environments respectively. #350, #354

• pyodide build now accepts -v/--verbose flags (stackable twice up to -vv) to increase build verbosity. At -v, installer commands and backend hook invocations are shown. At -vv, the package installers (uv/pip) additionally receive a -v flag for detailed package resolution output. #363

[0.34.4] - 2026/05/15

Added

• We now show better error message when pyodide build fails to install build dependencies. #346

[0.34.3] - 2026/04/30

Fixed

• Fixed compatibility issue with newer pypa/build >= 1.4.4 #345

[0.34.2] - 2026/04/29

Fixed

• Fixed error when undefined environment variables are used in meta.yaml. #331

• pyodide venv now works with new pip 26.1. #341

[0.34.1] - 2026/04/03

Added

• pyodide config exposes variables emsdk_dir and emscripten_dir that point to the Emscripten SDK installation directory and Emscripten installation directory respectively in the xbuildenv (these are only available after Emscripten gets installed into the xbuildenv via the pyodide xbuildenv install-emscripten command). #321, #326

Changed

• Platform name for the Pyodide wheel is now pyemscripten instead of pyodide, following the PEP 783 standard. If you want to use the old platform name, you can set the USE_LEGACY_PLATFORM environment variable to 1. #319

[0.34.0] - 2026/03/31

Added

• pyodide xbuildenv install can skip eager installation, and cross-build packages are installed on first build-time use.

Changed

• vendor_sharedlib option is now enabled by default. #304

• By default, -Oz flag is used for C/C++ compilation instead of -O2, to reduce binary size. This can be overridden by setting cflags and cxxflags in pyproject.toml. #306

Fixed

• --enable-new-dtags linker flag is now filtered out. #317

[0.33.0] - 2026/02/26

Changed

• Emscripten will now be auto installed when running pyodide build and pyodide build-recipes if the host system does not have emscripten installed. #293

Fixed

• Fixed pyodide venv not working in Windows + Python 3.14. #299

[0.32.1] - 2026/02/20

Added

• Added --skip-cross-build-packages flag (and PYODIDE_SKIP_CROSS_BUILD_PACKAGES env var) to pyodide xbuildenv install, allowing users to skip installing cross-build packages (numpy, scipy, cffi, pycparser) into the host site-packages. This is useful in locked-down environments where packages need to be pre-approved, and the user is building packages that don't depend on these at cross-compile time.
• Added support for PIP_BUILD_CONSTRAINT environment variable for pip 26.2+ compatibility. The build system now prioritizes PIP_BUILD_CONSTRAINT over PIP_CONSTRAINT when determining build-time constraints, while maintaining backward compatibility.

Changed

• The feature to build packages with dependencies is now opt-in feature. It needs to be enabled by installing pyodide-build with pip install pyodide-build[resolve]. #277

Fixed

• Fixed pyodide venv not working in Windows with virtualenv 20.38. #298

[0.32.0] - 2026/01/27

Changed

• Dropped typer dependency in favor of click. #287

[0.31.2] - 2026/01/26

Added

• Added --clean option to clean up temporary build files after building a package with pyodide build-recipes. #282

[0.31.1] - 2026/01/05

Fixed

• Fixed an issue where pip inside the Pyodide venv would not correctly handle the arguments with spaces. #281

[0.31.0] - 2026/01/05

Added

• pyodide venv now works in Windows. It only works with Pyodide 0.29.1 and later. #274

Removed

• Removed pyodide create-zipfile subcommand. This command is was used only for building pyodide runtime and not for building packages. #276

Fixed

• Fixed an issue where the compiler flags such as cflags, cxxflags, and ldflags from the meta.yaml were being overridden by those from the default build arguments. #270

• Default cxxflags are not equal to the cflags #255

[0.30.9] - 2025/11/11

Added

• Added pyodide clean recipes, a CLI command that deletes build files for chosen packages or tags. #254

[0.30.8] - 2025/10/22

• pyodide config now exposes dist_dir variable. #236

• The CMake toolchain file for Pyodide now sets CMAKE_SHARED_LINKER_FLAGS_INIT and CMAKE_MODULE_LINKER_FLAGS_INIT and unset CMAKE_SHARED_LINKER_FLAGS to avoid conflicts with the user's settings. #247

[0.30.7] - 2025/08/18

[0.30.6] - 2025/08/16

• pyodide config now exposes rust_emscripten_target_url. #225

[0.30.5] - 2025/06/04

• Fixed a regression in quoting of pip arguments introduced in #185. #209

[0.30.4] - 2025/05/20

• Fixed compatibility with virtualenv 20.31 and later. The Pyodide virtual environment via pyodide venv no longer seeds wheel, i.e., the --wheel/--no-wheel options are not available anymore. #208

• The default cross-build metadata URL was changed to https://pyodide.github.io/pyodide/api/pyodide-cross-build-environments.json to circumvent rate limits imposed by GitHub. It remains overridable by setting the PYODIDE_CROSS_BUILD_ENV_METADATA_URL environment variable. #206

[0.30.3] - 2025/05/17

• Added interpreter and pacakge_index to the variables available via pyodide config get. #199

[0.30.2] - 2025/05/05

• Fixed a regression in pyodide venv installation of shell entryppints introduced in #185 #197

[0.30.1] - 2025/04/25

Added

• pyodide config exposes new variables: pyodide_root, pyodide_abi_version, and python_include_dir, and ignored_build_requirements. #186 and #187

Fixed

• pyodide venv now works in uv-managed environments. See issue #143. #185

[0.30.0] - 2025/04/08

Added

• Added basic support for uv. uv tool install pyodide-cli --with pyodide-build, or uvx --from pyodide-cli --with pyodide-build pyodide --help, or using pyodide-build in uv-managed virtual environments will now work. #132

• pyodide build now takes an additional --xbuildenv-path argument and corresponding equivalent PYODIDE_XBUILDENV_PATH environment variable to either use an existing cross-build environment or create one at the specified path. This means that users can use pyodide xbuildenv install <...> --path to install a cross-build environment somewhere and reuse this with pyodide build. #158

• Added a new config variable xbuildenv_path that can be left in the [tool.pyodide.build] section in pyproject.toml and retrieved through pyodide config get xbuildenv_path. The pyodide xbuildenv and pyodide build commands will setup/use cross-build environments at this path if one isn't specified as a CLI argument or unless overridden through the PYODIDE_XBUILDENV_PATH environment variable. #158

• Added support for building without a wheel without build isolation: pyodide build no accepts the --no-isolation/-n and/or --skip-dependency-check/-x flags to customise the wheel building behaviour, similar to pypa/build. #152

Changed

• The Rust toolchain version has been updated to nightly-2025-01-18. #103

• Pyodide cross-build environments will now be installed in the user cache directory by default, which is <home>/.cache or XDG cache in Linux systems, and /Users/<user>/Library/Caches in macOS. #148

• Removed cmake dependency from the package. The Pyodide build system now uses the cmake package specified in the pyproject.toml file of the target package. #141

Fixed

• Fixed Pyodide venv sys_platform marker evaluation with pip >= 25. #108

[0.29.3] - 2025/02/04

Added

• Added new configuration variable default_cross_build_env_url. #85

• Added a new recipe key requirement.constraint to set the package-level constraints. #97

• The pyodide venv command now supports more virtualenv command-line flags to customise the virtual environment creation behaviour (experimental) #117

[0.29.2] - 2024/11/29

Fixed

• Fixed pyodide venv command not loading the shared libraries correctly, resulting in the package load failure. This bug was introduced in version 0.28. #67

[0.29.1] - 2024/11/27

Added

• Add skip_emscripten_version_check flag and SKIP_EMSCRIPTEN_VERSION_CHECK environment variable to skip emscripten version check. #53
• Set the EM_PKG_CONFIG_PATH environment variable used by emscripten/pkg-config to discover dependencies #52

Changed

• Source tar files are now extracted with python's data filter #52

• The pyodide build command will now raise an error if the local Python version has been changed, after the cross-build environment has been set up. #62

[0.29.0] - 2024/09/19

Added

• The pyodide xbuildenv search command now accepts a --json flag to output the search results in JSON format that is machine-readable. The design for the regular tabular output has been improved. #28

Changed

• The pyodide skeleton pypi --update command and the --update-patched variant now validate the version and the source checksum when updating a package's recipe. #27

• pyo3_config_file is no longer available in pyodide config command. Pyodide now sets PYO3_CROSS_PYTHON_VERSION, PYO3_CROSS_LIB_DIR to specify the cross compilation environment for PyO3. #19

[0.28.0] - 2024/08/14

• pyodide xbuildenv subcommand is now publicly available. #15

[0.27.3] - 2024/07/17

• It is now possible to override _f2c_fixes.py file, with _f2c_fixes_wrapper variable. #8

[0.27.2] - 2024/07/11

Changed

• pyodide py-compile command now accepts excludes flag. #9

• cpython_module type recipes now should output wheels #10

[0.27.1] - 2024/06/28

Changed

• ported f2c_fixes patch from pyodide/pyodide#4822

[0.27.0] - 2024/06/18

• pyodide-build is now developed under https://github.com/pyodide/pyodide-build.