#10283 feat: Support `.python-version` file for plugin installs Pull request opened by nanjeshramesh Description Meltano already lets you pin the Python version for plugin venvs with a plugin-level

python

setting or the project-level

python

setting, falling back to whatever Python is running Meltano itself. This adds a third fallback in between: a

.python-version

file in the project root, following the same one-version-per-first-line convention as pyenv and uv. Precedence is plugin setting, then project setting, then the file, then the system Python, matching the ordering suggested in the issue, so a

.python-version

file some teams already keep around for other tools won't override anything explicitly configured in meltano.yml. Added a

python_version

property on

Project

, modeled on the existing

dotenv

handling in the same class, wired it into the one place

VenvBackend

resolves which Python to use, and extended the existing precedence test plus a dedicated test for the property itself. Also updated the settings docs where this fallback chain is explained to users. Ran the full pre-commit, typing (mypy + ty), and pytest sessions locally, all green. Checklist • I have read the contribution guide Was generative AI tooling used to co-author this PR? • Yes (please specify the tool below) Generated-by: Claude Code following the agentic coding guidelines Related Issues • Closes #9851 Summary by Sourcery Add

.python-version

support for selecting plugin virtual environment Python versions without overriding explicit Meltano settings. New Features: • Support using a project's

.python-version

file as a fallback Python version for plugin virtual environments. Enhancements: • Apply Python version precedence of plugin setting, project setting,

.python-version

file, then the system Python. • Expose the project's pinned Python version and document the supported first-line convention. Documentation: • Update settings documentation to describe

.python-version

fallback behavior and precedence. Tests: • Add coverage for

.python-version

parsing and Python version precedence during virtual environment creation. meltano/meltano