`pymanager -1` (`--one`) can contain unrelated output

[AA-Turner]

Install source and version

• Installed from the Windows Store

Version: 25.0

Describe the bug

Best demonstrated via an example:

PS> uv venv venv --python=$(pymanager list 3.14 -1 -f=exe)
error: Failed to inspect Python interpreter from provided path at `Python install manager was successfully updated to 25.0.  ...\AppData\Local\Python\pythoncore-3.14-64\python.exe`
  Caused by: Failed to query Python interpreter
  Caused by: failed to query metadata of file `...\{cwd}\Python install manager was successfully updated to 25.0.  ...\AppData\Local\Python\pythoncore-3.14-64\python.exe`: The filename, directory name,
 or volume label syntax is incorrect. (os error 123)

PS> uv venv venv --python=$(pymanager list 3.14 -1 -f=exe)
Using CPython 3.14.0 interpreter at: ...\AppData\Local\Python\pythoncore-3.14-64\python.exe
Creating virtual environment at: venv
Activate with: venv\Scripts\activate

To Reproduce

Have PyManager produce unrelated text, this case due to a version update

Expected behavior

When using -1, there should be no extra output.

Additional context

N/A

[zooba]

Hmm, that's a bit annoying to implement. Passing -q should guarantee no extra output already, but because -1/--one is specific to a certain command, I think we've already passed the welcome message.

I'll have a think and see if there's a nice way to plug it in. Possibly we want to always skip the welcome message if output is being captured anyway...

[AA-Turner]

Oh I see, that's not ideal. I'll add -q to my local invocations but I think -1 should attempt to avoid printing anything but the main output, in an ideal world.

A

[zooba]

You could reasonably argue that for all the commands, though. At which point, we then run into the problem of how we should display warnings relating to updates (as in, things the user isn't immediately responsible for causing, but has to do something to fix it up). With automatic updates, this matters more than it does for CPython - we can't expect people to read porting notes or choose not to update.

Unfortunately, it looks like we don't have an environment variable for setting "quiet", or even the log level (unless you want more output...). Putting "log_level": 30 in a config file will make -q the default, but that's not really the right place.

So we want:

• environment var for "quiet" (implemented as a config setting for "quiet" that reads from the env var by default)
• skip welcome message if output isn't going to a console
• ensure list --one doesn't include any other log.info() messages (which it presumably doesn't, the welcome message isn't part of that command)

[zooba]

Oh, I was wrong, the call to show the welcome message comes from the command itself after it's all parsed, so we can very easily suppress it for list -1 .... It's should also be easy to make it write through stderr instead of stdout, so that it's separate from actual output.