uv add should roll back changes to pyproject.toml if the automatic sync is cancelled #6818
Description
uv 0.4.0, macOS.
A minimal code snippet that reproduces the issue:
$ uv init foo
$ cd foo
$ uv add pyobjc
💭 oh crud, I don't need every single pyobjc framework! that's a lot of framework!
^C
$ uv add pyobjc-core
💭 oh crud, it's still downloading all frameworks! what's happening?!
^C
$ cat pyproject.toml
[...]
dependencies = [
"pyobjc",
"pyobjc-core",
]
$
IOW, I'd expect that if I cancel the uv add operation (even if it's made up of add and implicit sync afterwards), pyproject.toml was back to the state it was before uv add.