Cannot read Zarr v2 data from SWIFT without consolidated metadata

What happened?

I'm trying to work with Zarr v2 data on a SWIFT store, with a fresh install of xarray and zarr in a virtual environment.

pip install swiftspec xarray "zarr[remote]"

If I open a dataset (which has been tested and used previously) without using the consolidated metadata, no variables are found:

import xarray as xr
botany_url="https://swift.dkrz.de/v1/dkrz_b42c6bc6-439f-4efb-9491-db3de70ad9ba/botany_1536_2D/botany_1536_2D.zarr"
ds_2D = xr.open_zarr(botany_url,consolidated=False)
print(ds_2D)

Changing to consolidated=True shows the variables. The dataset can be browsed here.

A possibly related issue:
When writing a Zarr v2 dataset to a SWIFT store, the consolidated metadata is written correctly if the dimension separator is the default, ., but not if it is changed to /. This means a v2 dataset with separator / written to SWIFT cannot be read back. This may be specific to SWIFT or more broadly to fsspec stores - writing to a local directory with a zarr.storage.DirectoryStore does write the consolidated metadata correctly (but this was tested with zarr 2.18.7 because in zarr 3 the DirectoryStore is gone).

Third issue: how do I write a Zarr v2 dataset with dimension_separator='/' using the current versions of everything, including zarr v3.x?

What did you expect to happen?

I expect to be able to read Zarr v2 from a SWIFT store with or without consolidated metadata.
I expect to be able to write Zarr v2 with dimension_separator='/' using the current versions of all the modules.

Minimal Complete Verifiable Example

import xarray as xr
botany_url="https://swift.dkrz.de/v1/dkrz_b42c6bc6-439f-4efb-9491-db3de70ad9ba/botany_1536_2D/botany_1536_2D.zarr"
ds_2D = xr.open_zarr(botany_url,consolidated=False)
print(ds_2D)

MVCE confirmation

• Minimal example — the example is as focused as reasonably possible to demonstrate the underlying issue in xarray.
• Complete example — the example is self-contained, including all data and the text of any traceback.
• Verifiable example — the example copy & pastes into an IPython prompt or Binder notebook, returning the result.
• New issue — a search of GitHub Issues suggests this is not a duplicate.
• Recent environment — the issue occurs with the latest version of xarray and its dependencies.

Relevant log output

Anything else we need to know?

No response

Environment

Start with the provided xr.open_zarr minimal example and trace how consolidated metadata, SWIFT access, and Zarr v2 dimension_separator='/' are handled. Reproduce the read and write cases against the linked SWIFT dataset; done means establishing whether both non-consolidated reads and slash-separated Zarr v2 writes work with the current dependency versions.