Summary

• raise the published Python floor from 3.9 to 3.11
• update the CI matrix, package classifiers, formatter/linter targets, and lockfile for Python 3.11+
• enable Ruff's pyupgrade rules
• adopt Python 3.11 union syntax, typing.Self, and slotted internal dataclasses without changing runtime behavior
• add a package metadata regression test for Requires-Python: >=3.11

This is intended to produce the v1.2.0 release. Python 3.9 and 3.10 environments will remain on the compatible v1.1 release because the v1.2 wheel metadata prevents installation on those runtimes. No library/API breaking changes are included beyond the supported-runtime floor.

Stack

This draft is intentionally based on codex/v1.1-hec-delivery / #3 so both PRs can be reviewed before v1.1 is merged. After #3 is merged and released, retarget this PR to main.

Validation

• Python 3.11: 38 unit tests passed
• Python 3.14: 38 unit tests passed
• lint, import sorting, and formatting checks passed
• source distribution and wheel build passed
• wheel metadata reports Requires-Python: >=3.11
• an isolated Python 3.10 install was rejected specifically because the wheel requires Python 3.11+

Draft readiness gate

Keep this PR in draft until #3 has passed the live HEC smoke suite and is merged/released. Retarget to main, rerun the full CI and smoke gates on the final stacked result, and then mark ready for review.