fix(pr-review): use both UV_PYTHON and UV_PYTHON_PREFERENCE

[xingyaoww]

Problem

PR #203 replaced UV_PYTHON_PREFERENCE=only-system with UV_PYTHON=3.12. This fixed repos with newer Python (e.g. .python-version: 3.13) but re-broke repos with older Python (e.g. .python-version: 3.11) — UV_PYTHON alone doesn't prevent uv from downloading the version specified in .python-version.

Evidence: MizzenAI/Personality (which has .python-version: 3.11) started failing again after #203:

Downloading cpython-3.11.15-linux-x86_64-gnu (download) (29.9MiB)
× No solution found when resolving `--with` dependencies:
╰─▶ Because the current Python version (3.11.15) does not satisfy Python>=3.12
    and all versions of openhands-sdk depend on Python>=3.12, ...

Fix

Use both env vars:

• UV_PYTHON=3.12 — tells uv which version to request (fixes .python-version > 3.12)
• UV_PYTHON_PREFERENCE=only-system — blocks managed downloads (fixes .python-version < 3.12)

Together they handle .python-version in either direction.

This PR was created by an AI assistant (OpenHands) on behalf of a user.

[all-hands-bot]

🟢 Good taste — Elegant fix that uses both env vars complementarily to handle .python-version in either direction. Solves a real production problem with minimal, well-documented change.

[RISK ASSESSMENT]

[Overall PR] ⚠️ Risk Assessment: 🟢 LOW

Configuration-only change with limited blast radius. Restores working behavior for repos with older Python versions while maintaining the fix for newer versions. No security concerns, infrastructure changes, or architectural shifts.

✅ Worth merging

KEY INSIGHT: The combination of UV_PYTHON=3.12 (version preference) + UV_PYTHON_PREFERENCE=only-system (block downloads) elegantly eliminates both edge cases without conditional logic.

[xingyaoww]

Closing — tested locally and UV_PYTHON=3.12 alone (current main, PR #203) handles all three cases correctly:

• .python-version: 3.11 → ✅ uses 3.12
• .python-version: 3.13 → ✅ uses 3.12
• no .python-version → ✅ uses 3.12

The screenshot was from before #203 was merged. No additional fix needed.

This comment was posted by an AI assistant (OpenHands) on behalf of a user.