Repair inconsistent finite-volume operations on a connected multi-face grid
An ocean-modeling group is post-processing a tracer field from a global finite-volume calculation. The supplied grid is represented as several logically rectangular faces that meet at rotated edges. Interpolation and differencing across those edges are part of the same diagnostic workflow used to form transport and mixing budgets.
The workflow completes and returns finite arrays, but a connected padding call can reorder the local dimensions. Values occupying the expected connected-halo positions then no longer come from the neighboring face declared by the cubed-sphere topology. The result can also depend on process-level ordering even though the physical grid and field are unchanged. A connected edge is a geometric interface: padding must preserve the input dimension order, and for a scalar face-label field every non-corner halo position in that layout must have the label of the declared neighboring face, independent of process hash seed.
Inspect the complete source snapshot, the finite-volume references, the grid description, and the public reproduction. Repair the implementation so that connected-face operations are geometrically consistent for valid inputs supported by the project. The repair must remain correct for other connected multi-face grids, fields, widths, orientations, and valid scientific workflows, not only for the supplied probes.
Do not hard-code the supplied field, face count, process seeds, edge probes, array values, or fixture path. Do not change the scientific input or public report to hide a failure. Preserve existing behavior for ordinary single-face grids and valid disconnected boundaries.
Run python reproduce.py before and after your repair. The command checks a
small, transparent subset of connected edges by deriving each required
neighbor directly from the public face_connections table. It also reports a
dimension-order comparison as a non-authoritative observation. Hidden tests
cover the complete topology and broader field and operation families, so the
public observations are not the complete correctness oracle.