The persisted grid_data files contain atoms (:base_m, :top_m,
:thickness_m, :min_freq_ghz, :native_min_gradient, :ducts, etc.) that
live in modules which aren't eagerly loaded during application start.
warm_grid_cache_from_latest_profile runs in Application.start/2 before
those modules get pulled in by their first call sites, so [:safe] was
rejecting our own legitimate files at boot — every weather page hit
crashed with "invalid or unsafe external representation of a term".
The whole point of [:safe] is to refuse atoms from untrusted external
ETF input. ProfilesFile.write!/2 in this same module is the only writer
of these files, so the input is trusted by definition — drop the flag.
The test additions round-trip the production data shape including duct
fields as a regression guard.
Graham McIntire
26015ce8ea