[vera-rubin]

Opening a dataset with decode_coords="all" moves grid_mapping from attrs to encoding. After that, .cf.grid_mappings raises AttributeError on DataArrays and returns empty coordinate associations on Datasets, although the API promises coordinate variable names.

import cf_xarray
import xarray as xr
from cf_xarray.datasets import rotds

decoded = xr.decode_cf(rotds, decode_coords="all")
decoded.cf.grid_mappings[0].coordinates  # Was (), should be ("rlon", "rlat")
decoded.temp.cf.grid_mappings  # Raised AttributeError

We now read associations from both metadata mappings, keeping attrs precedence and the declared order for multiple mappings.

The regression test covers both accessors with single and multiple mappings, and the accessor suite passes.

Tested: cf-xarray main at b0ecc0d and xarray 2026.9.0.

— ChipLab