regrid! does not accept AbstractMatrix despite docstring claiming n-dimensional support

[ctessum-claude]

Description

In src/regridder/regrid.jl:21-47, all four regrid! method signatures restrict arguments to AbstractVector or DenseVector:

function regrid!(dst_field::DenseVector, regridder::Regridder, src_field::DenseVector)
function regrid!(dst_field::AbstractVector, regridder::Regridder, src_field::AbstractVector)
function regrid!(dst_field::DenseVector, regridder::Regridder, src_field::AbstractVector)
function regrid!(dst_field::AbstractVector, regridder::Regridder, src_field::DenseVector)

However, the docstring (lines 4-5) states:

src_field and dst_field can be any n-dimensional array in which case regridding of the 1st dimension is broadcast to additional dimensions.

Passing a matrix (e.g., for regridding multiple vertical levels at once) throws a MethodError.

MWE

using ConservativeRegridding
using GeoInterface
using GeometryOpsCore
using Extents

function make_grid(nx, ny)
    polys = Matrix{GeoInterface.Polygon}(undef, nx, ny)
    for j in 1:ny, i in 1:nx
        x0, x1 = (i-1)/nx, i/nx
        y0, y1 = (j-1)/ny, j/ny
        ring = GeoInterface.LinearRing([(x0,y0),(x1,y0),(x1,y1),(x0,y1),(x0,y0)])
        polys[i,j] = GeoInterface.Polygon([ring])
    end
    polys
end

src_grid = make_grid(2, 2)
dst_grid = make_grid(3, 3)

# Fix bug #65 to create a working regridder:
@eval function ConservativeRegridding.Trees.cell_range_extent(
    q::ConservativeRegridding.Trees.ExplicitPolygonGrid{<:GeometryOpsCore.Planar},
    irange::UnitRange{Int}, jrange::UnitRange{Int},
)
    return mapreduce(
        GeoInterface.extent, Extents.union,
        (ConservativeRegridding.Trees.getcell(q, i, j) for i in irange, j in jrange),
    )
end

r = ConservativeRegridding.Regridder(GeometryOpsCore.Planar(), dst_grid, src_grid; threaded=false)

# Vector inputs work fine:
src_vec = ones(Float64, 4)
dst_vec = zeros(Float64, 9)
ConservativeRegridding.regrid!(dst_vec, r, src_vec)  # works

# Matrix inputs fail:
src_mat = ones(Float64, 4, 3)    # 4 source cells × 3 levels
dst_mat = zeros(Float64, 9, 3)   # 9 destination cells × 3 levels
ConservativeRegridding.regrid!(dst_mat, r, src_mat)  # MethodError

Error

MethodError: no method matching regrid!(::Matrix{Float64}, ::Regridder{...}, ::Matrix{Float64})

Version

ConservativeRegridding v0.2.0