#10135 feat: use .python-version for plugin Python default Pull request opened by vku2018 on <!date^1783057351^{date_short}|2026-07-03T05:42:31Z> Description Adds project-level

.python-version

fallback support for the Meltano

python

setting used by plugin virtual environments. • reads the first non-empty, non-comment line from

.python-version

when the top-level

python

setting is otherwise unset • preserves existing precedence for

MELTANO_PYTHON

,

.env

,

meltano.yml

, and per-plugin

python

• documents the fallback in settings docs, bundled settings metadata, and the JSON schema • adds project settings tests for fallback and override behavior Checklist • I have read the contribution guide Was generative AI tooling used to co-author this PR? • Yes - Codex Generated-by: Codex following the agentic coding guidelines Validation •

git diff --check

•

uv run pytest tests/meltano/core/test_project_settings_service.py

•

uv run pytest tests/meltano/core/test_venv_service.py

•

uv run --with "ruff>=0.15.14" ruff check src/meltano/core/project_settings_service.py tests/meltano/core/test_project_settings_service.py

•

uv run ty check src/meltano/core/project_settings_service.py

Related Issues • Closes #9851 Summary by Sourcery Add project-level

.python-version

support as a default for the top-level

python

setting used by plugin environments while preserving existing precedence rules. New Features: • Use the first non-empty, non-comment line from a project

.python-version

file as the default value for the project

python

setting when no other value is configured. Enhancements: • Extend settings metadata and JSON schema to describe

.python-version

fallback behavior for the

python

setting. Documentation: • Update settings reference docs to document

.python-version

fallback for the project

python

setting and clarify that version numbers like

3.11

are accepted. Tests: • Add project settings tests to cover

.python-version

fallback behavior and ensure it does not override explicit configuration or environment variables. meltano/meltano