Request from for Protobuf version flexibility in cirq-google (Forschungszentrum Jülich)

[AlvaroHuanay]

Dear Cirq team,

We are currently installing Cirq as part of our Stages/2026 environment at Forschungszentrum Jülich. I noticed that the latest stable release includes a strict protobuf version constraint in cirq-google requirements.txt.

I would like to ask whether it would be possible to publish a stable release that includes the protobuf relaxation introduced in commit a0115b3a00b5411af6027cbd75048c6e957cb436, which makes the protobuf dependency more flexible. This would greatly help us integrate the latest Cirq version into our environment.

For better reproducibility, our current software stack contains:

Extension	Version
Python	3.13.5
Numpy	2.3.2
Scipy	1.16.1
Pybind11	3.0.0
Cython	3.1.2
binutils	2.44
poetry	2.1.3
maturin	1.9.1
hatchling	1.27.0
Rust	1.88.0
matplotlib	3.10.5
networkx	3.5
tqdm	4.67.1
ruamel.yaml	0.18.14
flit	3.12.0
protobuf	6.31.1

If any additional information is needed, I will be happy to provide it.

Kind regards.

[pavoljuhas]

Dear Álvaro, we intend to do a minor release by the end of the year. In the meantime you can install a pre-release version of cirq-google which would allow installation with protobuf-6.