complete_ocean_create Subroutine

   subroutine complete_ocean_create(c_handle, h, status)
      !! Shared tail of `rdb_ocean_create_from_string` AND
      !! `rdb_ocean_create_finalize` (P2.5): `engine_setup` ->
      !! resolved-`n_inner` check -> `engine_enter_data` -> finalize handle
      !! bookkeeping. Consumes whatever geometry `h%engine%staged_*` fields
      !! carry (empty/unset for the single-call path — byte-identical to
      !! before P2.5). On any failure, destroys the WHOLE handle (F9) and
      !! clears the single-live-handle guard; `c_handle` is `c_null_ptr` and
      !! `h` is null on return in that case, matching `rdb_ocean_destroy`'s
      !! out-null convention.
      type(c_ptr), intent(inout) :: c_handle
      type(ocean_handle_t), pointer, intent(inout) :: h
      integer(c_int), intent(out) :: status

      integer :: ierr

      call engine_setup(h%engine, h%cfg, ierr)
      if (ierr /= OCEAN_STATUS_OK) then
         status = int(ierr, c_int)
         call handle_destroy(c_handle)
         g_handle_live = .false.
         h => null()
         return
      end if

      if (h%engine%n_inner < 1) then
         call error_ring_push("rdb_ocean_create: barotropic substep count "// &
                              "n_inner is unresolved (< 1) — set &ocean_bt_nml auto_n_inner "// &
                              "= .true. or n_inner explicitly")
         status = int(OCEAN_STATUS_ERR_SETUP, c_int)
         call handle_destroy(c_handle)
         g_handle_live = .false.
         h => null()
         return
      end if
      h%n_inner = h%engine%n_inner

      ! ---- Device placement ----
      call engine_enter_data(h%engine, h%cfg)
      ! `h%grid`/`h%state` are views onto the engine (see `ocean_handle_t`'s
      ! docstring) so every existing P2 accessor body below (`h%grid%...`,
      ! `h%state%...`) keeps working unchanged.
      h%grid = h%engine%grid
      h%state => h%engine%state
      h%device_mapped = .true.

      h%is_initialised = .true.
      h%is_pending = .false.
      status = int(OCEAN_STATUS_OK, c_int)
   end subroutine complete_ocean_create