Project-MONAI
Drop Zarr 2.x Support
Is your feature request related to a problem? Please describe. Zarr 3.x moved a number of types around and few other compatibility breaking changes. We currently try to support 2.x and 3.x in places like here but we should consider when to drop support for 2.x. This would help improve the typing of this module as well.
Zarr 3.0 requires Python 3.11 and newer. This is because they follow SPEC0 as seen in the PR that dropped Python 3.10 support in https://github.com/zarr-developers/zarr-python/commit/0e4cc7e6b1e11874197993b993d1a7834821f790.
As previously mentioned at https://github.com/Project-MONAI/MONAI/issues/8303#issuecomment-2601244571, MONAI could consider adopting SPEC0 as well which would mean bumping the minimum required Python version from 3.9 to 3.11 if it was done today. https://github.com/Project-MONAI/MONAI/blob/7c26e5af385eb5f7a813fa405c6f3fc87b7511fa/setup.cfg#L36
OME-NGFF file format specification is built on top of Zarr 2. Is this still true @joshmoore? What is the state of plans to move it to Zarr 3?
It would be good to keep support for Zarr 2 for longer.
NGFF 0.4 and before are Zarr v2 only. NGFF 0.5 is Zarr v3 only: https://forum.image.sc/t/ngff-0-5-release-with-support-for-zarr-v3-shards/107818
Without a pressing need to drop Zarr 2 support, we plan to stick to a two year time frame for supporting library versions as added in #8458.