Is pixi upgrade supposed to permanently loosen constraint bounds?

[matthewfeickert]

I had the Pixi manifest file

[workspace]
channels = ["conda-forge"]
name = "ml-example"
platforms = ["linux-64", "osx-arm64", "win-64"]
version = "0.1.0"

[tasks]

[dependencies]
python = ">=3.13.5,<3.14"

[feature.cpu.dependencies]
pytorch-cpu = ">=2.7.1,<3"
torchvision = ">=0.22.0,<0.23"

[feature.gpu.system-requirements]
cuda = "12"

[feature.gpu.target.linux-64.dependencies]
pytorch-gpu = ">=2.7.1,<3"
torchvision = ">=0.22.0,<0.23"

[feature.inference.dependencies]
matplotlib = ">=3.10.3,<4"

[environments]
cpu = ["cpu"]
gpu = ["gpu"]
inference = ["gpu", "inference"]

and when running pixi upgrade it loosens the lower bound on python in the default environment

$ pixi upgrade
$ git diff
diff --git a/paper/code/ml-example/pixi.toml b/paper/code/ml-example/pixi.toml
index 6c9763a..555e657 100644
--- a/paper/code/ml-example/pixi.toml
+++ b/paper/code/ml-example/pixi.toml
@@ -7,7 +7,7 @@ version = "0.1.0"
 [tasks]
 
 [dependencies]
-python = ">=3.13.5,<3.14"
+python = ">=3.10.18,<3.14"
 
 [feature.cpu.dependencies]
 pytorch-cpu = ">=2.7.1,<3"

Is this expected behavior for

$ pixi --version
pixi 0.50.2

?

pixi upgrade does mention that it loosens requirements

$ pixi upgrade --help | head -n 3
Checks if there are newer versions of the dependencies and upgrades them in the lockfile and manifest file.

`pixi upgrade` loosens the requirements for the given packages, updates the lock file and the adapts the manifest accordingly.

but I expected that loosening to not be permanent if those lower bounds existed.

I'll also note that I'm unable to reproduce this with a simpler example

$ pixi init /tmp/upgrade-example && cd /tmp/upgrade-example
✔ Created /tmp/upgrade-example/pixi.toml
$ pixi add "python >=3.13.5,<3.14"
✔ Added python >=3.13.5,<3.14
$ cat pixi.toml 
[workspace]
channels = ["conda-forge"]
name = "upgrade-example"
platforms = ["linux-64"]
version = "0.1.0"

[tasks]

[dependencies]
python = ">=3.13.5,<3.14"
$ pixi upgrade
$ cat pixi.toml 
[workspace]
channels = ["conda-forge"]
name = "upgrade-example"
platforms = ["linux-64"]
version = "0.1.0"

[tasks]

[dependencies]
python = ">=3.13.5,<3.14"

so I'm not sure if this is from a more complex interaction.