From 14060b91caca9e7a1af1394d90b9925e2378ae32 Mon Sep 17 00:00:00 2001
From: Sam Evans <47793072+Sevans711@users.noreply.github.com>
Date: Wed, 23 Sep 2026 08:10:54 -0400
Subject: [PATCH 1/3] pin cartopy<0.26; fix relevant regression test

---
 ci/asv.yml         |  2 +-
 ci/docs.yml        |  2 +-
 ci/environment.yml |  2 +-
 pyproject.toml     |  4 ++--
 test/test_plot.py  | 19 ++++++++++++++-----
 5 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/ci/asv.yml b/ci/asv.yml
index 7062c7e33..b3ad61f1d 100644
--- a/ci/asv.yml
+++ b/ci/asv.yml
@@ -3,7 +3,7 @@ channels:
   - conda-forge
 dependencies:
   - python=3.11
-  - cartopy
+  - cartopy<0.26   # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
   - dask
   - datashader
   - geoviews
diff --git a/ci/docs.yml b/ci/docs.yml
index 07172c0d2..8eddd92dd 100644
--- a/ci/docs.yml
+++ b/ci/docs.yml
@@ -34,7 +34,7 @@ dependencies:
     - hvplot
     - holoviews
     - geoviews
-    - cartopy
+    - cartopy<0.26   # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
     - pandas
     - geocat-datafiles
     - spatialpandas
diff --git a/ci/environment.yml b/ci/environment.yml
index 938470f61..af96fd886 100644
--- a/ci/environment.yml
+++ b/ci/environment.yml
@@ -4,7 +4,7 @@ channels:
   - nodefaults
 dependencies:
   - antimeridian
-  - cartopy
+  - cartopy   # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
   - dask
   - datashader
   - geoviews
diff --git a/pyproject.toml b/pyproject.toml
index 510d81717..c894a440f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -54,10 +54,10 @@ geo = [
     "spatialpandas",
 ]
 viz = [
-    "cartopy",
+    "cartopy<0.26",  # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
     "datashader",
     "matplotlib<3.11",  # matplotlib 3.11.0 breaks some plots but <3.11 is fine; see issue #1542.
-    "geoviews",
+    "geoviews",  # no version pin; newer should support any cartopy; see holoviz/geoviews#884.
     "holoviews",
     "hvplot",
 ]
diff --git a/test/test_plot.py b/test/test_plot.py
index 26836f8ee..bdaca1fd8 100644
--- a/test/test_plot.py
+++ b/test/test_plot.py
@@ -361,9 +361,18 @@ def __init__(self, params):
 
 def test_plot_topology_with_explicit_projection(gridpath):
     """`plot.edges` with an explicit projection exercises the central-longitude
-    lookup that regressed under cartopy 0.26."""
-    import cartopy.crs as ccrs
-
+    lookup that regressed under cartopy 0.26.
+    Regression test for issue #1780.
+    """
     uxgrid = ux.open_grid(gridpath("mpas", "QU", "oQU480.231010.nc"))
-    uxgrid.plot.edges(backend="matplotlib", projection=ccrs.PlateCarree())
-    uxgrid.plot.edges(backend="matplotlib", projection=ccrs.Robinson())
+    plot0 = uxgrid.plot.edges(backend="matplotlib", projection=ccrs.PlateCarree())
+    plot1 = uxgrid.plot.edges(backend="matplotlib", projection=ccrs.Robinson())
+    plot2 = uxgrid.plot.edges(backend="matplotlib", projection=ccrs.Orthographic())
+
+    # the crash associated with issue #1780 only occurs when actually trying to render,
+    # and only for some projections, but definitely for at least one of the above,
+    # so, try to render all three of them.
+    renderer = hv.renderer("matplotlib")
+    renderer.get_plot(plot0)
+    renderer.get_plot(plot1)
+    renderer.get_plot(plot2)

From 17bbf01e470b9d38f91826191eb775a932e39668 Mon Sep 17 00:00:00 2001
From: Sam Evans <47793072+Sevans711@users.noreply.github.com>
Date: Wed, 23 Sep 2026 08:38:13 -0400
Subject: [PATCH 2/3] fix typo (forgot cartopy pin in one spot)

---
 ci/environment.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/environment.yml b/ci/environment.yml
index af96fd886..cce05047e 100644
--- a/ci/environment.yml
+++ b/ci/environment.yml
@@ -4,7 +4,7 @@ channels:
   - nodefaults
 dependencies:
   - antimeridian
-  - cartopy   # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
+  - cartopy<0.26   # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
   - dask
   - datashader
   - geoviews

From f42df5ae169e24b450cc6a5408077f0729744205 Mon Sep 17 00:00:00 2001
From: Sam Evans <47793072+Sevans711@users.noreply.github.com>
Date: Wed, 23 Sep 2026 14:08:11 -0400
Subject: [PATCH 3/3] comment to say why no cartopy pin in geo extras

---
 pyproject.toml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pyproject.toml b/pyproject.toml
index c894a440f..fc15f2fb4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -55,6 +55,7 @@ geo = [
 ]
 viz = [
     "cartopy<0.26",  # cartopy 0.26.0 breaks some geoviews plots; see issue #1780.
+    # (cartopy pin intentionally here but not in "geo" extras because geoviews is only in "viz".)
     "datashader",
     "matplotlib<3.11",  # matplotlib 3.11.0 breaks some plots but <3.11 is fine; see issue #1542.
     "geoviews",  # no version pin; newer should support any cartopy; see holoviz/geoviews#884.