[Bug]: quickstart.sh fails at uv sync on Python 3.12-only systems despite passing Python 3.11+ check

[coollad49]

Describe the Bug

./quickstart.sh reports Python as valid in Step 1 (e.g., Python 3.12), but fails in Step 2 when running uv sync with a generic workspace installation failed message.
This happens on systems where Python 3.12 is installed but Python 3.11 is not.
Root cause appears to be that quickstart validates a compatible interpreter (3.11+) but does not force uv to use that detected interpreter, so uv may still resolve against repo pinning (e.g., .python-version), causing an unexpected failure.

To Reproduce

1. Use a clean environment with Python 3.12 installed and no Python 3.11.
2. Clone the repository and run:
   ./quickstart.sh
3. Proceed through prompts.
4. Observe:
   • Step 1 succeeds (Python 3.12, uv detected)
   • Step 2 fails at Installing workspace packages... with workspace installation failed.

Expected Behavior

If Step 1 accepts Python 3.11+, quickstart should complete Step 2 successfully using the same validated interpreter, or provide a precise error message explaining interpreter mismatch and how to fix it.

Environment

• OS: Fedora 42
• Python version: 3.12

Configuration

Relevant parts of your agent configuration or environment setup (remove any sensitive data):

python:
  installed:
    - 3.12.x
  missing:
    - 3.11.x
uv:
  version: 0.8.11

Logs

Relevant log output:

⬢ Step 1: Checking Python...
⬢ Python 3.12
  ✓ uv detected: uv 0.8.11
  ✓ Node.js v22.20.0
⬢ Step 2: Installing packages...
This may take a minute...
  Installing workspace packages...   ✗ workspace installation failed

Additional Context

Installing Python 3.11 on the same machine made quickstart succeed, which suggests interpreter selection/pinning mismatch rather than a dependency or network issue.

[iamsanjaii]

Nice fix!! this makes sense, especially ensuring uv uses the same interpreter validated in Step 1.

One thing I was wondering: in environments with multiple Python versions installed, are we explicitly resolving and passing the interpreter path to uv (e.g., via UV_PYTHON or --python), or relying on PATH resolution?
Also, would it help to surface a clearer diagnostic if uv falls back to a different interpreter than the one validated?
Great catch on the mismatch here, this should improve onboarding reliability significantly.

[coollad49]

Spot on. It's relying on PATH right now, which is why the mismatch happens. I think forcing the path to uv is the right move to ensure Step 2 actually uses what Step 1 approved.

[Gilbertmax]

Hi! I'd like to work on this issue.

I reproduced the Python/uv mismatch locally and have a small fix ready that makes quickstart.sh pass the validated Python interpreter to uv sync.

Validation:

• Reproduced the failure with Python 3.12 and no Python 3.11 in uv's search path
• Verified the fix with uv sync --python <python3.12>
• Ran make test: 6067 passed, 283 skipped, 157 deselected