tracer_recon_support_status Function

   pure function tracer_recon_support_status(recon_code, is_ocean, &
                                             has_multilayer_tracers) result(status)
      !! Decide whether a parsed tracer_recon code is honoured on this
      !! config, independent of the multilayer nghost/use_ppm_tracer
      !! quality guards (those apply only once this returns OK for a weno
      !! rung).  Factored out as a pure predicate so the fail-loud
      !! decision is unit-testable without triggering error stop.
      !!
      !! `recon_code` is the parse_tracer_recon result (may be < 0).
      !! The coastal multilayer solver is the ONLY consumer, so a weno*
      !! rung is rejected fail-loud on every other config:
      !!   * "pqm"        → REJECT_PQM      (deferred on all configs)
      !!   * unrecognised → REJECT_UNKNOWN
      !!   * sim_type='ocean' → REJECT_OCEAN  (coastal-only in wave 1)
      !!   * coastal, not multilayer → REJECT_NO_ML (2D barotropic / NH)
      !! "ppm" is always OK (the default path; bit-identical).
      integer, intent(in) :: recon_code
         !! parse_tracer_recon(cfg%tracer_recon) result.
      logical, intent(in) :: is_ocean
         !! .true. when sim_type == 'ocean'.
      logical, intent(in) :: has_multilayer_tracers
         !! cfg%use_multilayer — the coastal multilayer tracer registry.
      integer :: status
      if (recon_code == -2) then
         status = TRACER_RECON_REJECT_PQM
      else if (recon_code < 0) then
         status = TRACER_RECON_REJECT_UNKNOWN
      else if (recon_code == TRACER_RECON_PPM) then
         status = TRACER_RECON_OK
      else if (is_ocean) then
         status = TRACER_RECON_REJECT_OCEAN
      else if (.not. has_multilayer_tracers) then
         status = TRACER_RECON_REJECT_NO_ML
      else
         status = TRACER_RECON_OK
      end if
   end function tracer_recon_support_status