style(pathfinding): drop unused has_dask_array import, fix isort ordering

.claude/sweep-style-state.csv

@@ -17,6 +17,7 @@ mahalanobis,2026-06-30,,HIGH,3;4,F401 unused is_dask_cupy import (Cat 3 HIGH) +
 mcda,2026-06-10,3143,HIGH,3;4,F401 dead function-local warnings import in standardize.py; isort drift in weights.py combine.py __init__.py; flake8 otherwise clean; Cat 5 greps clean; fixed via PR for #3143
 morphology,2026-06-20,3400,HIGH,3;4,"F401 xr/has_cuda_and_cupy/not_implemented_func + F841 size (dead); isort ordering. /rockout PR off issue 3400. flake8+isort clean, 74 tests pass."
 multispectral,2026-06-20,3428,HIGH,3;4,F401 unused not_implemented_func (Cat3 HIGH); isort dataset_support before utils (Cat4 MEDIUM); Cat1/2/5 clean; fixed via #3428
+pathfinding,2026-07-08,3650,HIGH,3;4;5,"flake8 baseline 1: F401 has_dask_array imported from xrspatial.utils but unused (refactor leftover, not re-exported anywhere; HIGH per Cat 3). Cat 4 isort drift: dask/dask.array order in try block, _heap_push/_heap_pop order, hand-wrapped utils block, missing blank line after function-local import cupy. Cat 5: mutable default barriers: list = [] on both public funcs, never mutated (rebound via np.asarray) -- duplicate of #3644 item 4 (api-consistency sweep, same day), excluded from this fix. Cat 1/2 clean. Fixed F401+isort via issue #3650."
 perlin,2026-06-23,,HIGH,3;4,"Cat3 F401: unused not_implemented_func import from xrspatial.utils (refactor leftover, not re-exported; __init__ exports only perlin). Cat4 isort: utils from-import reflowed to line_length=100 after the name was dropped. No Cat1/2/5 (grep clean: no bare except, mutable defaults, ==None/True, or shadowed builtins). flake8+isort clean after fix; import smoke test ok; 12 perlin tests pass (CUDA available). GitHub issues disabled on repo so no issue filed; fix on deep-sweep branch + PR."
 polygon_clip,2026-06-10,3184,HIGH,3;4,"Cat 3 F401: dropped unused typing imports Sequence/Tuple/Union (line 10, only Optional used) and the dead 'import cupy' inside the _apply_mask dask+cupy closure (line 245); the other 'import cupy' at line 261 is used (cupy.asarray) and kept. None re-exported (__init__ re-exports only clip_polygon). Cat 4 isort: reflowed the 5-name xrspatial.utils from-import block to line_length=100. Cat 1/2/5 grep clean (no E/W codes, no bare except, mutable defaults, ==None/True, or shadowed builtins). flake8+isort clean after fix; 23 test_polygon_clip tests pass. PR open."
 polygonize,2026-05-27,2534,HIGH,1;3;4,"F401 line 58 (is_cupy_array unused, not re-exported). E127 lines 83/88 (overload continuation indent in generated_jit). isort: 5-line .utils import block collapses to one line at 100-char limit. Cat 2 clean. Cat 5 grep clean."

xrspatial/pathfinding.py

@@ -8,19 +8,16 @@
 import xarray as xr
 
 try:
-    import dask.array as da
     import dask
+    import dask.array as da
 except ImportError:
     da = None
     dask = None
 
-from xrspatial.cost_distance import _heap_push, _heap_pop
+from xrspatial.cost_distance import _heap_pop, _heap_push
 from xrspatial.dataset_support import supports_dataset
-from xrspatial.utils import (
-    _validate_raster,
-    get_dataarray_resolution, ngjit,
-    has_cuda_and_cupy, is_cupy_array, is_dask_cupy, has_dask_array,
-)
+from xrspatial.utils import (_validate_raster, get_dataarray_resolution, has_cuda_and_cupy,
+                             is_cupy_array, is_dask_cupy, ngjit)
 
 NONE = -1
 
@@ -1060,6 +1057,7 @@ def a_star_search(surface: xr.DataArray,
 
     elif _is_cupy_backend:
         import cupy
+
         # Transfer to CPU, run numpy kernel, transfer back
         if 'surface_np' not in dir():
             surface_np = surface_data.get()