Rank-asymmetric temporary variable names in _vector_stats/_tensor_stats (_temp_mag_{id(self)})

[lmoresi]

Found while building the #379 synchronised_array_update rework (PR #383).

_vector_stats and _tensor_stats (discretisation_mesh_variables.py) create temporary mesh variables named _temp_mag_{id(self)} / _temp_frob_{id(self)}. id() is a rank-local memory address, so these variable names differ across ranks. Variable creation and deletion perform collective DM operations keyed by field name, and the variables are written inside uw.synchronised_array_update — any code path that uses the NAME as a cross-rank key breaks on them. This is also why the #379 collective flush uses creation-order registration ids rather than names.

Fix direction: derive the suffix from something rank-symmetric (a per-mesh monotonically increasing counter, or the parent variable's clean_name).

Underworld development team with AI support from Claude Code

[lmoresi]

Fixed by PR #401 (stats temporaries use the rank-symmetric clean_name suffix, with a collision refusal guard), merged to development on 2026-07-23 after a public adversarial review round. (Manual close — PRs target development, so auto-close does not fire.)

Underworld development team with AI support from Claude Code