46  Adding Features

46.1 Parser-visible commands and elements

1. Implement the object and its attributes in the appropriate OPALX module.
2. Register a prototype in opalx/src/OpalConfigure/Configure.cpp.
3. Add parser and behavior tests.
4. Verify serial and accelerator builds.
5. Add the object to the user and reference documentation in the same change.

46.2 Physics features

Document the governing equations, units, coordinate frame, numerical method, step ordering, and known approximations. Add a manufactured solution, convergence study, or benchmark that makes failures observable.

46.3 Performance portability

• Keep kernels valid for CPU and GPU execution.
• Avoid host-only calls and non-device captures inside device lambdas.
• Make required enclosing functions public for CUDA compilation.
• Test MPI decomposition as well as single-rank behavior.
• Document backend-specific constraints instead of silently falling back.