issue with External field

[greytower]

Subject: Refactor Inquiry: ParmParse Variables Ignored in 26.03 (Build 342a92e18738)

Environment: > * Build: 26.03-50-g342a92e18738

Backend: CUDA (1 Device), MPI (1 Process)

Issue: > Several ParmParse variables for External Fields (B_mobius) and Tracers are being flagged as "Unused" despite being registered in warpx.external_fields and particles.species_names.

Evidence (TinyProfiler):

AddPlasma() calls match physical species count (8) but omit tracers.

B_mobius.type = ParserFunction is rejected as Unused.

Inquiry:
Has the 26.03 binary moved ExternalField and Tracer instantiation to a different namespace (e.g., fields. or warpx.tracers)? The LaserParticleContainer correctly initializes with lasers.names, suggesting a shift toward species-style registries for all objects.

[WeiqunZhang]

This seems to be a WarpX question. Maybe you can post it on WarpX's GitHub site.