Official UMF Python support

umf-core provides the umf import namespace for the current UMF language. The authored spec/metamodel/umf.yaml generates the packaged JSON Schemas, portable constraint programs and Python shape data. Pydantic provides access models; it does not define a competing format. Consumer extensions and execution policies remain in consumer repositories.

Install the qualified release wheel:

pip install https://github.com/DocumentDrivenDX/umf/releases/download/umf-v0.5.1/umf_core-0.10.0-py3-none-any.whl

The release URL above identifies the existing published Python artifact. The development source builds a platform-specific native Rust extension instead:

rustup toolchain install 1.90.0
pip install ./python

Building from a checkout or source distribution requires Cargo/Rust 1.90.0 and the locked Cargo dependencies. An installed native wheel does not require Cargo, Node, Bun or V8. Native import failures are explicit; there is no semantic fallback. Pydantic remains the Python access-model dependency. This development change does not publish or replace the release linked above.

The GitHub release and its checksums identify the distributed wheel. PyPI publication is not configured. The separately distributed experimental umf_access host adapter is not required to read or validate UMF documents.

Development candidate distribution version 0.10.2 is distinct from the UMF document/core version 0.10.0. The existing 0.10.0 pure-Python wheel linked above is metadata-only for native execution and does not provide the single-SET action runtime. The source package now exposes create_action_engine, prepare_single_set_action, admit_generated_action_invocation, and admit_generated_record_values; their bounded admission profile is specified by CONTRACT-906. No installation URL for the 0.10.2 candidate native wheel is listed until its platform-specific release assets are published and qualified.

from umf import read_document, validate_document, write_document

document = read_document('''
umf: "0.10.0"
id: orders
vocabularies: {}
modules: []
''', format="yaml")
result = validate_document(document)
assert result.valid and result.complete
# Unknown or unregistered extension meaning can instead make complete false.
text = write_document(document, format="yaml")
assert read_document(text, format="yaml").to_dict() == document.to_dict()

Use canonical camelCase property names when constructing models. to_dict() preserves unknown content and field presence; checked_copy() revalidates mutable model state. Current APIs accept core 0.10.0; retired core dispatch and upgrade/rollback paths are removed. Structural checks and ordered core semantic constraints use generated data through bounded generic interpreters. Installed Python and TypeScript share 139 frozen conformance vectors; this is not a claim of parity for every TypeScript adapter or native execution API.

Unknown vocabulary versions, labels and qualifiers remain serializable and make interpretation incomplete. Consumers must refuse execution when their binding cannot interpret required semantics. Exact numeric token carriers, UUID/128-bit carriers, explicit null and omission retain their separate meanings.

Extensions register explicitly through Registry and Extension with exact versions, permitted scopes, a JSON Schema and optional semantic callback. Callbacks receive copies; schema references must be local. Documents never authorize loading code or fetching schemas. schema_validator() is reusable for consumer-owned schemas and honors their declared dialect.

The R2 Rust-backed production hosts and their resource controls are described in bindings/core/README.md. Ordinary UMF values retain the portable safe-number/UTF-16 profile. Standalone Python consumer-schema validation uses a separate native Python value profile; exact tested runtime versions and compatibility limits belong to the R2 qualification evidence.

The additive R3 compiler is available as from umf.rust_codegen import CodegenEngine. Construct it with the nine explicit trusted resources described in the binding README. Its snake_case convenience methods cover both generators, access diffing, table deployment/migration compilation and verification, change discovery and row-scope normalization. call() retains the complete semantic result envelope; convenience methods raise UmfCodegenError for semantic failures. Cooperative controls use the same operation context through admission, Rust and result copies. The existing umf_codegen default CLI and its MiniRacer dependency remain until R4.

Run python -m pytest python/tests from the repository root. Build with uv build --project python. The source distribution includes the current generated resources and supports building a wheel without the repository. Release checks install the actual wheel in an isolated environment, compare its packaged resource bytes and replay the shared core conformance corpus.