uv does not distinguish between 3.14 and 3.14t while creating virtual environment

[DhavalGojiya]

Description:
After changing the Python version from 3.14t (Free threaded python) to 3.14 using uv python pin, uv sync does not remove the old virtual environment or create a new one with the updated Python version.

Steps to Reproduce:

PS D:\Dhaval-WebDev\Test\venus> cat .python-version
3.14t

PS D:\Dhaval-WebDev\Test\venus> uv sync
Using CPython 3.14.0
Creating virtual environment at: .venv
Resolved 1 package in 83ms
Audited in 0.01ms

PS D:\Dhaval-WebDev\Test\venus> uv run python
Python 3.14.0 free-threading build (main, Oct 10 2025, 12:50:21) [MSC v.1944 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.base_prefix
'C:\\Users\\DHAVAL\\AppData\\Roaming\\uv\\python\\cpython-3.14.0+freethreaded-windows-x86_64-none'
>>> sys.prefix
'D:\\Dhaval-WebDev\\Test\\venus\\.venv'

PS D:\Dhaval-WebDev\Test\venus> uv python pin 3.14
Updated `.python-version` from `3.14t` -> `3.14`
PS D:\Dhaval-WebDev\Test\venus> cat .python-version
3.14

PS D:\Dhaval-WebDev\Test\venus> uv sync
Resolved 1 package in 2ms
Audited in 0.01ms

PS D:\Dhaval-WebDev\Test\venus> uv run python
Python 3.14.0 free-threading build (main, Oct 10 2025, 12:50:21) [MSC v.1944 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.base_prefix
'C:\\Users\\DHAVAL\\AppData\\Roaming\\uv\\python\\cpython-3.14.0+freethreaded-windows-x86_64-none'
>>> sys.prefix
'D:\\Dhaval-WebDev\\Test\\venus\\.venv'

Expected Behavior:
After changing the Python version from 3.14t (Free-threaded Python) to 3.14 using uv python pin, uv sync should:

1. Remove the old virtual environment created with 3.14t.
2. Create a new virtual environment .venv using Python 3.14.

Actual Behavior:
uv sync doesn't do anything; it thinks everything is up to date.

Extra Context:
If we manually delete the .venv and then run uv sync, it correctly creates a new virtual environment using the updated .python-version → 3.14.
At that time, there are no issues.

Platform

Microsoft Windows 11 Home Single Language

Version

uv 0.9.2 (141369c 2025-10-10)

Python version

Python 3.14.0

[DhavalGojiya]

Also noticed:

PS D:\Dhaval-WebDev\Test\venus> cat .python-version
3.14t

PS D:\Dhaval-WebDev\Test\venus> uv sync
Using CPython 3.14.0
Creating virtual environment at: .venv
Resolved 1 package in 83ms
Audited in 0.01ms

Here, uv sync says Using CPython 3.14.0 - shouldn't it say Using CPython 3.14t?

[zanieb]

A request for 3.14 is currently considered compatible with a 3.14 free-threaded interpreter.

[DhavalGojiya]

A request for 3.14 is currently considered compatible with a 3.14 free-threaded interpreter.

Ok, so this needs to be addressed, right? Since the runtime environments are different for both versions - especially when testing GitHub Actions with multiple Python versions locally - it’s unable to create the 3.14t environment, but that’s the one I actually want.

[zanieb]

it’s unable to create the 3.14t environment, but that’s the one I actually want.

What do you mean? In this case, you can just request 3.14t?

[DhavalGojiya]

it’s unable to create the 3.14t environment, but that’s the one I actually want.

What do you mean? In this case, you can just request 3.14t?

Uv is not removing old virtual environment and creating the new one.
This is what the issue was created for.

PS D:\Dhaval-WebDev\Test\venus> uv python pin 3.14
Updated `.python-version` from `3.14t` -> `3.14`
PS D:\Dhaval-WebDev\Test\venus> cat .python-version
3.14

PS D:\Dhaval-WebDev\Test\venus> uv sync
Resolved 1 package in 2ms
Audited in 0.01ms

[zanieb]

In that case you're going from 3.14t -> 3.14, but in your last message you said you could not create a 3.14t environment that you want?

[DhavalGojiya]

In that case you're going from 3.14t -> 3.14, but in your last message you said you could not create a 3.14t environment that you want?

What I mean is, I can create a virtual environment with any version I want using uv.
But if I already have a virtual environment with Python 3.14, and I want to create a new virtual environment for project using 3.14t, I first need to remove the .venv/ folder before reinstalling, and then run uv sync again - as you can see in the first message log.

If you see the first message ( long output written by me), I think you find the issue.
I am also not sure, that is it really an issue or is just uv behave like this.

Because as per my knowledge If you change .python-version file and then again run uv sync, uv will first delete .venv folder and re create a requested python versions virtual environment that satisfies (.python-version)

[zanieb]

#16537 would address this

[DhavalGojiya]

I think the following PRs:

• Include the Python variant suffix in "Using Python ..." messages #16536
• Allow Python requests to include +gil to require a GIL-enabled interpreter #16537

addressed this issue.

Here, uv sync says Using CPython 3.14.0 — shouldn't it say Using CPython 3.14t?

This one is also covered, right?
Can we close this issue, @zanieb?