Address Copilot review on #1639: clarify prior coverage scope

- Fix "six" -> "seven" reductions count (mean, nearest, min, max,
  median, mode, cubic).
- Reword module docstring: CPU end-to-end paths for min/max/median
  were already covered by test_cog_overview_nodata_1613; the gap
  this file closes is GPU end-to-end + direct CPU/GPU block-reducer
  branches.
- Mirror the clarification in the sweep-test-coverage state CSV row.

Author: brendancol

.claude/sweep-test-coverage-state.csv

@@ -1,3 +1,3 @@
 module,last_inspected,issue,severity_max,categories_found,notes
-geotiff,2026-05-11,,HIGH,2;3;4,"Pass 6 (2026-05-11): added test_overview_resampling_min_max_median_2026_05_11.py covering Cat 4 HIGH parameter-coverage gap on overview_resampling=min/max/median. Both CPU (_block_reduce_2d) and GPU (_block_reduce_2d_gpu) reductions had branches with zero test coverage; an unnoticed regression in any of the three modes would ship undetected. 26 tests, all passing on GPU host: block-reducer unit tests (finite + partial-NaN), end-to-end COG writes for both to_geotiff and write_geotiff_gpu, CPU/GPU parity for to_geotiff(gpu=True), CPU nodata-sentinel regression check, and ValueError error-path tests for unknown method names on both backends. Pass 5 (2026-05-11): added test_degenerate_shapes_backends_2026_05_11.py covering Cat 3 HIGH geometric gaps (1x1 / 1xN / Nx1 reads on dask+numpy, GPU, dask+cupy backends; 1x1 / 1xN / Nx1 writes through write_geotiff_gpu) and Cat 2 MEDIUM NaN/Inf gaps (all-NaN read on GPU + dask+cupy, Inf / -Inf reads on all non-eager backends, NaN sentinel mask on dask read path including sentinel block split across chunk boundary). 23 tests, all passing on GPU host. Prior passes still hold: pass 4 (r4) closed read_geotiff_gpu/dask name= + max_pixels= kwargs (Cat 4), pass 3 (r3) closed read_vrt GPU/dask+GPU backend dispatch (Cat 1) and dtype/name kwargs (Cat 4)."
+geotiff,2026-05-11,,HIGH,2;3;4,"Pass 6 (2026-05-11): added test_overview_resampling_min_max_median_2026_05_11.py covering Cat 4 HIGH parameter-coverage gap on overview_resampling=min/max/median. CPU end-to-end paths were already covered by test_cog_overview_nodata_1613::test_cpu_cog_overview_aggregations_ignore_sentinel; the GPU end-to-end paths and the direct CPU+GPU block-reducer branches had no targeted tests, so a regression on those code paths would ship undetected. 26 tests, all passing on GPU host: block-reducer unit tests (finite + partial-NaN), end-to-end COG writes for both to_geotiff and write_geotiff_gpu, CPU/GPU parity for to_geotiff(gpu=True), CPU nodata-sentinel regression check, and ValueError error-path tests for unknown method names on both backends. Pass 5 (2026-05-11): added test_degenerate_shapes_backends_2026_05_11.py covering Cat 3 HIGH geometric gaps (1x1 / 1xN / Nx1 reads on dask+numpy, GPU, dask+cupy backends; 1x1 / 1xN / Nx1 writes through write_geotiff_gpu) and Cat 2 MEDIUM NaN/Inf gaps (all-NaN read on GPU + dask+cupy, Inf / -Inf reads on all non-eager backends, NaN sentinel mask on dask read path including sentinel block split across chunk boundary). 23 tests, all passing on GPU host. Prior passes still hold: pass 4 (r4) closed read_geotiff_gpu/dask name= + max_pixels= kwargs (Cat 4), pass 3 (r3) closed read_vrt GPU/dask+GPU backend dispatch (Cat 1) and dtype/name kwargs (Cat 4)."
 reproject,2026-05-10,,HIGH,1;4;5,"Added 39 tests: LiteCRS direct coverage, itrf_transform behaviour/roundtrip/array, itrf_frames, geoid_height numerical correctness + raster happy-path, vertical helpers (ellipsoidal<->orthometric/depth), reproject() lat/lon and latitude/longitude dim propagation. Note: _merge_arrays_cupy is imported but unused (no cupy merge dispatch in merge()); flagged as feature gap not test gap."

xrspatial/geotiff/tests/test_overview_resampling_min_max_median_2026_05_11.py

@@ -3,22 +3,23 @@
 
 The CPU writer (``xrspatial.geotiff._writer._block_reduce_2d``) and the
 GPU writer (``xrspatial.geotiff._gpu_decode._block_reduce_2d_gpu``) both
-implement six resampling reductions for COG overview generation:
+implement seven resampling reductions for COG overview generation:
 
 * ``mean`` -- covered by ``test_cog_overview_nodata_1613`` and
   ``test_features``.
 * ``nearest`` -- covered by ``test_features`` and the same suite.
 * ``mode`` -- covered by ``test_mode_overview_perf``.
 * ``cubic`` -- covered by ``test_cog_cubic_overview_nodata_1623``.
-* ``min`` -- NO coverage prior to this file.
-* ``max`` -- NO coverage prior to this file.
-* ``median`` -- NO coverage prior to this file.
+* ``min`` / ``max`` / ``median`` -- CPU end-to-end paths covered by
+  ``test_cog_overview_nodata_1613::test_cpu_cog_overview_aggregations_ignore_sentinel``,
+  but the GPU end-to-end paths and the direct CPU/GPU block-reducer
+  branches had no targeted tests prior to this file.
 
 Test coverage gap sweep 2026-05-11 (pass 6) closes a Cat 4 (parameter
-coverage) HIGH gap: three documented public modes of the
-``overview_resampling`` parameter on ``to_geotiff`` and
-``write_geotiff_gpu`` had implementations but no tests, so a regression
-in any of those reduction branches would ship undetected.
+coverage) HIGH gap: the GPU end-to-end paths and the direct CPU+GPU
+block-reducer branches for ``overview_resampling='min'/'max'/'median'``
+had no targeted tests, so a regression on those code paths would ship
+undetected.
 
 The tests cover: