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Changelog

2026.07.11

This release drops Python 3.9 and brings a batch of performance improvements, like caching uv detection and interpreter discovery, plus lazy module imports on Python 3.15. Various bugs were fixed as well.

We'd like to thank the following folks who contributed to this release:

• @​henryiii
• @​davidhewitt
• @​SAY-5 (first contribution)
• @​Himanshuagrawal4 (first contribution)
• @​TejasAmle (first contribution)
• @​felixfontein (first contribution)

Features:

• Drop Python 3.9 by @​henryiii in wntrblm/nox#1049
• Add return_code property to CommandFailed exception by @​felixfontein in wntrblm/nox#1129

Performance:

• Cache session-name normalization, uv detection, interpreter discovery, and metadata reads by @​henryiii in wntrblm/nox#1113
• Lazy modules on Python 3.15 by @​henryiii in wntrblm/nox#1115

Fixes:

• Script-mode pip resolution on Windows and --download-python fallback by @​henryiii in wntrblm/nox#1110
• Don't crash when a parametrized session has an empty parameter list by @​henryiii in wntrblm/nox#1109
• Hash fully non-ASCII session names instead of returning the envdir by @​henryiii in wntrblm/nox#1108
• Interpreter-resolution edge cases in virtualenv.py by @​henryiii in wntrblm/nox#1111
• Create missing parent directories for the session cache dir by @​henryiii in wntrblm/nox#1104
• Enforce --error-on-external-run even when log=False by @​henryiii in wntrblm/nox#1107
• Handle = in set_env values and out-of-tree change_dir in tox-to-nox by @​henryiii in wntrblm/nox#1105
• Return empty dict from load_toml when script file is missing by @​SAY-5 in wntrblm/nox#1096
• Show envvars in CLI help by @​henryiii in wntrblm/nox#1085

Documentation:

• Add PyO3 as a user by @​davidhewitt in wntrblm/nox#1123
• List micromamba in --default-venv-backend supported names by @​SAY-5 in wntrblm/nox#1092
• Clarify session.notify target docs by @​Himanshuagrawal4 in wntrblm/nox#1099
• Document venv backend for EOL Python by @​Himanshuagrawal4 in wntrblm/nox#1101
• Fix typo in README installation section by @​TejasAmle in wntrblm/nox#1097

Internal changes:

... (truncated)

• 3284968 chore: prepare release 2026.07.11 (#1132)
• d73f96a ci: add Python 3.15 to the test matrix and classifiers (#1133)
• 5391985 test: isolate run_nox envdir to fix flaky test_main_requires (#1134)
• 390d817 feat: add return_code to CommandFailed. (#1129)
• f1d5210 chore(deps): bump the github-actions group with 2 updates (#1125)
• 0894b73 chore(deps): bump the pre-commit group with 4 updates (#1126)
• 9b747ed ci: experimental MSYS2/MinGW test run (#1122)
• 8a44270 docs: add PyO3 as a user (#1123)
• 5bd0f83 perf: lazy modules on Python 3.15 (#1115)
• 982fcfa chore(deps): bump dependency-groups in the pre-commit group (#1121)
• Additional commits viewable in compare view

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