Packaging: arviz floor 'arviz>=0.17' is too low for the diagnostics DataTree (ArviZ 1.x) code

[aaronstevenwhite]

Summary

The diagnostics and formulas optional-dependency groups pin arviz>=0.17, but quivers.diagnostics is written against the ArviZ 1.x API. The 1.x rewrite replaced the legacy InferenceData with an xarray.DataTree. On any arviz in [0.17, 1.0) the diagnostics code returns/consumes the wrong container type.

Evidence

pyproject.toml:

diagnostics = [ "arviz>=0.17", "xarray>=2025.1", "netcdf4>=1.7" ]
formulas    = [ ..., "arviz>=0.17", "xarray>=2025.1", "netcdf4>=1.7", "formulae>=0.6" ]

src/quivers/diagnostics/arviz_io.py returns xr.DataTree and its docstring states it is "the ArviZ 1.x replacement for the legacy InferenceData container"; comparison.py / predictive_checks.py call az.compare, az.loo, az.loo_pit with the 1.x DataTree contract. On arviz 0.17-0.x, az.from_dict(...) returns InferenceData, not DataTree, and idata.children / DataTree group access does not exist.

Verified working version

The shipped Docker image has arviz 1.2.0, and the full path (to_datatree -> az.loo) works there. The problem is only the declared floor.

Expected

Bump the floor to the first ArviZ release that ships the DataTree API (arviz>=1.0, likely >=1.2), in both the diagnostics and formulas extras.