fast-mdurl-rs

Opt-in Rust-backed, behavior-compatible replacement for mdurl==0.1.2. It keeps the same mdurl import, public functions and URL NamedTuple while accelerating encode, decode and parse hot paths.

The frozen contract, reuse decision and evidence are in UPSTREAM-CONTRACT.md, REUSE-AUDIT.md, COMPATIBILITY.md, and FULL-RELEASE-REPORT.md. Release claims remain acceptance-gated: a source checkout or successful build alone is not evidence of a public PyPI release.

Latest exact-wheel evidence on macOS arm64: the complete upstream and candidate suites pass, a deterministic 10,000-case oracle differential has zero mismatches, and encode/decode/parse each outperform the frozen Python oracle. Exact raw samples, medians and p95 are in benchmark.json and COMPATIBILITY.md. The trivial Python formatter remains Python because the first Rust crossing measured only 0.63x; removing it is part of the design, not an omitted feature.

Real-consumer validation against markdown-it-py==4.2.0 passed its complete 981-test suite. Interleaved end-to-end measurements show a modest benefit on link-dense Markdown, while a real README and a no-link control show no consistent gain. Exact raw samples, medians, artifact hash and environment are generated after the immutable wheel in external consumer-benchmark.json; they are workload-specific evidence, not a blanket speed claim.

Installation limitation

The distribution is named fast-mdurl-rs, while consumers declare a dependency on the separate mdurl distribution. Python package resolvers do not treat one distribution as satisfying the other even though both provide the mdurl namespace. Therefore this is an API/import drop-in, not a resolver-transparent replacement. It supports Python >=3.9; the frozen upstream also supports 3.7 and 3.8, which are outside this package's compatibility range. A controlled opt-in install on Python 3.9+ is:

python -m pip install markdown-it-py
python -m pip uninstall -y mdurl
python -m pip install fast-mdurl-rs
python -c "from markdown_it import MarkdownIt; print(MarkdownIt().render('[x](https://example.com)'))"

pip check will still report that markdown-it-py requires mdurl; do not install both distributions together because they own the same import namespace. Rollback with python -m pip uninstall -y fast-mdurl-rs && python -m pip install 'mdurl~=0.1'. The lowest-friction ecosystem path is an optional backend accepted by upstream mdurl/markdown-it-py; no such upstream acceptance is claimed yet.

Local development:

uv venv
uv pip install maturin pytest pytest-randomly pytest-cov
uv run maturin develop
uv run pytest -q

Verification and release assets

• Complete frozen upstream and candidate suites plus a deterministic 10,000-case differential.
• Five-platform abi3 release-wheel matrix, sdist rebuild, artifact metadata/RECORD audit, and public reinstall gates.
• Exact-artifact benchmark evidence attached to the formal GitHub Release created last.
• Truthful limitations and workload-specific results in COMPATIBILITY.md and BENCHMARK.md.

License

MIT. The frozen upstream implementation is also MIT; attribution and dependency license metadata are retained in THIRD_PARTY_NOTICES.md.