diff --git a/.claude/sweep-api-consistency-state.csv b/.claude/sweep-api-consistency-state.csv
index 3403bb13..3ff54bea 100644
--- a/.claude/sweep-api-consistency-state.csv
+++ b/.claude/sweep-api-consistency-state.csv
@@ -1,3 +1,3 @@
 module,last_inspected,issue,severity_max,categories_found,notes
-geotiff,2026-05-11,1605,HIGH,1;5,"Filed open_geotiff(gpu=True) silently dropping window/band (HIGH, #1605) and fix PR -- adds window+band kwargs to read_geotiff_gpu and forwards them through open_geotiff GPU dispatch. Prior issues 1560/1561/1562 from 2026-05-10 audit all CLOSED. MEDIUM: read_geotiff_dask VRT defensive fallback drops window/band/max_pixels at line 1463 (acceptable since open_geotiff routes earlier and direct callers can switch to read_vrt). write_vrt wrapper uses **kwargs instead of explicit signature -- docs list the args but inspect.signature does not; cosmetic."
+geotiff,2026-05-11,1631,MEDIUM,3,"Filed write_vrt and write_geotiff_gpu signature/docstring drift vs to_geotiff (MEDIUM, #1631). Fix in PR (TBD): explicit write_vrt(relative, crs_wkt, nodata) signature (was **kwargs); 'cubic' added to write_geotiff_gpu overview_resampling docstring; write_geotiff_gpu(data) typed xr.DataArray|cupy.ndarray to match to_geotiff. Prior 1605/1606/1611/1612/1613/1615/1623 all CLOSED."
 reproject,2026-05-10,1570,HIGH,2;5,"Filed cross-module attrs['vertical_crs'] type collision (string vs EPSG int) vs xrspatial.geotiff. Fixed in PR (TBD): reproject now writes EPSG int and preserves friendly token under vertical_datum. MEDIUM kwarg-order drift (transform_precision vs chunk_size) and missing type hints vs geotiff documented but not fixed (cosmetic, kwarg-only)."
diff --git a/xrspatial/geotiff/__init__.py b/xrspatial/geotiff/__init__.py
index a639637b..4ad1f2fd 100644
--- a/xrspatial/geotiff/__init__.py
+++ b/xrspatial/geotiff/__init__.py
@@ -2663,7 +2663,8 @@ def _read_once():
     return result
 
 
-def write_geotiff_gpu(data, path: str, *,
+def write_geotiff_gpu(data: xr.DataArray | cupy.ndarray | np.ndarray,
+                      path: str, *,
                       crs: int | str | None = None,
                       nodata=None,
                       compression: str = 'zstd',
@@ -2692,8 +2693,10 @@ def write_geotiff_gpu(data, path: str, *,
 
     Parameters
     ----------
-    data : xr.DataArray (CuPy-backed) or cupy.ndarray
-        2D raster on GPU.
+    data : xr.DataArray (CuPy- or NumPy-backed), cupy.ndarray, or np.ndarray
+        2D or 3D raster. CuPy-backed inputs stay on device; NumPy/Dask
+        inputs are uploaded via ``cupy.asarray(np.asarray(data))``
+        before compression (matches ``to_geotiff`` parity).
     path : str
         Output file path.
     crs : int, str, or None
@@ -2726,7 +2729,10 @@ def write_geotiff_gpu(data, path: str, *,
         halving until the smallest overview fits in a single tile.
     overview_resampling : str
         Resampling method for overviews: 'mean' (default), 'nearest',
-        'min', 'max', 'median', or 'mode'.
+        'min', 'max', 'median', 'mode', or 'cubic'. ``mode`` and
+        ``cubic`` fall back to the CPU implementation in
+        ``xrspatial.geotiff._writer`` so the GPU writer produces the
+        same overview bytes as the CPU writer.
     bigtiff : bool or None
         Force BigTIFF (64-bit offsets). None auto-promotes when the
         estimated file size would exceed the classic-TIFF 4 GB limit.
@@ -3187,7 +3193,10 @@ def _sentinel_for_dtype(nodata_val, dtype):
     return result
 
 
-def write_vrt(vrt_path: str, source_files: list[str], **kwargs) -> str:
+def write_vrt(vrt_path: str, source_files: list[str], *,
+              relative: bool = True,
+              crs_wkt: str | None = None,
+              nodata: float | None = None) -> str:
     """Generate a VRT file that mosaics multiple GeoTIFF tiles.
 
     Parameters
@@ -3208,14 +3217,18 @@ def write_vrt(vrt_path: str, source_files: list[str], **kwargs) -> str:
     -------
     str
         Path to the written VRT file.
-
-    Notes
-    -----
-    Only the keyword arguments listed above are accepted. Passing any
-    other keyword raises ``TypeError`` from the underlying writer.
     """
+    # Explicit signature (previously ``**kwargs``) so ``inspect.signature``,
+    # IDE autocomplete, and ``mypy --strict`` can see the accepted kwargs
+    # without parsing the docstring. Mirrors ``_vrt.write_vrt`` exactly; if
+    # that signature changes, this wrapper must be updated in lockstep.
     from ._vrt import write_vrt as _write_vrt_internal
-    return _write_vrt_internal(vrt_path, source_files, **kwargs)
+    return _write_vrt_internal(
+        vrt_path, source_files,
+        relative=relative,
+        crs_wkt=crs_wkt,
+        nodata=nodata,
+    )
 
 
 def plot_geotiff(da: xr.DataArray, **kwargs):
diff --git a/xrspatial/geotiff/tests/test_signature_parity_1631.py b/xrspatial/geotiff/tests/test_signature_parity_1631.py
new file mode 100644
index 00000000..2f7e0378
--- /dev/null
+++ b/xrspatial/geotiff/tests/test_signature_parity_1631.py
@@ -0,0 +1,167 @@
+"""Regression test for #1631: public write_vrt / write_geotiff_gpu
+signature and docstring parity vs to_geotiff.
+
+Three drifts were flagged by the api-consistency sweep on 2026-05-11:
+
+1. ``write_vrt(vrt_path, source_files, **kwargs)`` swallowed every kwarg
+   into ``**kwargs``. The docstring documented ``relative``, ``crs_wkt``,
+   ``nodata``, but ``inspect.signature`` and IDE autocomplete saw nothing.
+2. ``write_geotiff_gpu``'s ``overview_resampling`` docstring omitted
+   ``'cubic'``; ``to_geotiff`` lists it and ``make_overview_gpu`` accepts
+   it (falling back to CPU).
+3. ``write_geotiff_gpu(data, ...)`` lacked the type hint that
+   ``to_geotiff(data, ...)`` has.
+
+This module pins each of those three guarantees against future drift.
+"""
+from __future__ import annotations
+
+import importlib.util
+import inspect
+import os
+
+import numpy as np
+import pytest
+import xarray as xr
+
+from xrspatial.geotiff import (
+    open_geotiff,
+    to_geotiff,
+    write_geotiff_gpu,
+    write_vrt,
+)
+
+
+def _gpu_available() -> bool:
+    """True when cupy imports and CUDA is initialised."""
+    if importlib.util.find_spec("cupy") is None:
+        return False
+    try:
+        import cupy
+
+        return bool(cupy.cuda.is_available())
+    except Exception:
+        return False
+
+
+_HAS_GPU = _gpu_available()
+_gpu_only = pytest.mark.skipif(
+    not _HAS_GPU, reason="cupy + CUDA required",
+)
+
+
+def test_write_vrt_signature_exposes_documented_kwargs():
+    """``inspect.signature(write_vrt)`` reports the three accepted kwargs.
+
+    Prior to #1631 the public wrapper used ``**kwargs``, so
+    ``inspect.signature`` only saw ``vrt_path`` and ``source_files``.
+    """
+    sig = inspect.signature(write_vrt)
+    params = sig.parameters
+    assert 'relative' in params
+    assert 'crs_wkt' in params
+    assert 'nodata' in params
+    # Defaults must match _vrt.write_vrt
+    assert params['relative'].default is True
+    assert params['crs_wkt'].default is None
+    assert params['nodata'].default is None
+    # No more catch-all VAR_KEYWORD
+    kinds = {p.kind for p in params.values()}
+    assert inspect.Parameter.VAR_KEYWORD not in kinds
+
+
+def test_write_vrt_unknown_kwarg_rejected_at_public_level(tmp_path):
+    """A typo'd kwarg now raises ``TypeError`` from the public function
+    rather than from deep inside ``_vrt.write_vrt``.
+    """
+    arr = np.zeros((8, 8), dtype=np.float32)
+    da = xr.DataArray(
+        arr, dims=['y', 'x'],
+        coords={'y': np.arange(8.0, 0, -1), 'x': np.arange(8.0)},
+        attrs={'crs': 4326, 'transform': (1.0, 0, 0.0, 0, -1.0, 8.0)},
+    )
+    tif_path = str(tmp_path / 't.tif')
+    to_geotiff(da, tif_path)
+
+    with pytest.raises(TypeError, match='typo_kwarg'):
+        write_vrt(str(tmp_path / 't.vrt'), [tif_path], typo_kwarg=1)
+
+
+def test_write_vrt_accepts_documented_kwargs(tmp_path):
+    """Each documented kwarg round-trips through the explicit signature."""
+    arr = np.zeros((8, 8), dtype=np.float32)
+    da = xr.DataArray(
+        arr, dims=['y', 'x'],
+        coords={'y': np.arange(8.0, 0, -1), 'x': np.arange(8.0)},
+        attrs={'crs': 4326, 'transform': (1.0, 0, 0.0, 0, -1.0, 8.0)},
+    )
+    tif_path = str(tmp_path / 't.tif')
+    to_geotiff(da, tif_path)
+
+    vrt_path = str(tmp_path / 't.vrt')
+    out = write_vrt(
+        vrt_path, [tif_path],
+        relative=False, crs_wkt=None, nodata=-9999.0,
+    )
+    assert out == vrt_path
+    assert os.path.exists(vrt_path)
+
+
+def test_write_geotiff_gpu_docstring_lists_cubic():
+    """``overview_resampling`` docstring includes ``'cubic'`` so it
+    matches ``to_geotiff`` and the underlying ``make_overview_gpu``.
+    """
+    doc = write_geotiff_gpu.__doc__
+    assert doc is not None
+    # Find the overview_resampling block
+    assert 'overview_resampling' in doc
+    # The block must mention cubic
+    block_start = doc.index('overview_resampling')
+    block_end = doc.index('bigtiff', block_start)
+    block = doc[block_start:block_end]
+    assert 'cubic' in block
+
+
+def test_write_geotiff_gpu_data_has_type_hint():
+    """``data`` parameter is annotated, matching ``to_geotiff(data, ...)``.
+
+    The annotation also covers ``np.ndarray`` because the implementation
+    accepts numpy inputs (uploaded via ``cupy.asarray(np.asarray(data))``)
+    and the test suite exercises that path (e.g.
+    ``test_backend_kwarg_parity_1561.py`` passes a numpy ``dummy``).
+    """
+    sig = inspect.signature(write_geotiff_gpu)
+    data_param = sig.parameters['data']
+    assert data_param.annotation is not inspect.Parameter.empty
+    # The annotation is a forward reference under ``from __future__ import
+    # annotations``; just confirm it mentions the documented types.
+    ann_str = str(data_param.annotation)
+    assert 'DataArray' in ann_str
+    assert 'cupy' in ann_str
+    assert 'ndarray' in ann_str  # numpy parity vs to_geotiff
+
+
+@_gpu_only
+def test_write_geotiff_gpu_cubic_overview_round_trip(tmp_path):
+    """``overview_resampling='cubic'`` works on the GPU writer.
+
+    Sanity check that the docstring update is not advertising an
+    unsupported codec. ``make_overview_gpu`` falls back to the CPU
+    cubic implementation for parity with the CPU writer.
+    """
+    import cupy
+
+    arr_cpu = np.random.RandomState(0).rand(256, 256).astype(np.float32)
+    arr_gpu = cupy.asarray(arr_cpu)
+    da_gpu = xr.DataArray(
+        arr_gpu, dims=['y', 'x'],
+        coords={'y': np.arange(256.0, 0, -1), 'x': np.arange(256.0)},
+    )
+    path = str(tmp_path / 'cog.tif')
+    write_geotiff_gpu(
+        da_gpu, path,
+        cog=True, tile_size=64, overview_resampling='cubic',
+    )
+    # Overview level 1 = 1/2 resolution
+    ov = open_geotiff(path, overview_level=1)
+    assert ov.shape == (128, 128)