| # Repair inconsistent finite-volume operations on a connected multi-face grid |
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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| 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. |
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