From 21ed4569326b5ab56a9d7def99cf77db835705ce Mon Sep 17 00:00:00 2001
From: Ben Karl <bkarl@tonkintaylor.co.nz>
Date: Mon, 10 Nov 2025 16:11:33 +1300
Subject: [PATCH 1/3] write failing test

---
 .../geopins/drivers/gdf/filetypes/test_gpkg.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/geopins/drivers/gdf/filetypes/test_gpkg.py b/tests/geopins/drivers/gdf/filetypes/test_gpkg.py
index bdf1d31..2a5b13d 100644
--- a/tests/geopins/drivers/gdf/filetypes/test_gpkg.py
+++ b/tests/geopins/drivers/gdf/filetypes/test_gpkg.py
@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from time import sleep
 from typing import TYPE_CHECKING
 
 import geopandas as gpd
@@ -27,3 +28,20 @@ def test_round_trip(tmp_geoboard: GeoBaseBoard):
     # Assert
     assert gdf.equals(retrieved)
     assert gdf.crs == retrieved.crs
+
+
+def test_hash_is_not_dependent_on_file_write_time(tmp_geoboard: GeoBaseBoard):
+    # Arrange
+    gdf = gpd.GeoDataFrame(
+        {"id": [1, 2, 3]},
+        geometry=gpd.points_from_xy([0, 1, 2], [0, 1, 2]),
+        crs="EPSG:2193",  # NZGD2000 / New Zealand Transverse Mercator 2000
+    )
+
+    # Act
+    meta1 = tmp_geoboard.pin_write(gdf, name="test-gdf-hash", type="gpkg")
+    sleep(1)
+    meta2 = tmp_geoboard.pin_write(gdf, name="test-gdf-hash", type="gpkg")
+
+    # Assert
+    assert meta1.pin_hash == meta2.pin_hash

From df6470ea2cc1847673405b7d30565fbdbbbf9c5e Mon Sep 17 00:00:00 2001
From: Ben Karl <bkarl@tonkintaylor.co.nz>
Date: Mon, 10 Nov 2025 16:28:44 +1300
Subject: [PATCH 2/3] freeze last_modified

---
 src/geopins/drivers/gdf/filetypes/gpkg.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/geopins/drivers/gdf/filetypes/gpkg.py b/src/geopins/drivers/gdf/filetypes/gpkg.py
index c35416d..4b16f59 100644
--- a/src/geopins/drivers/gdf/filetypes/gpkg.py
+++ b/src/geopins/drivers/gdf/filetypes/gpkg.py
@@ -3,6 +3,7 @@
 import tempfile
 import warnings
 from pathlib import Path
+from sqlite3 import connect
 from typing import TYPE_CHECKING
 
 import geopandas as gpd
@@ -112,6 +113,9 @@ def pin_write_gdf_gpkg(  # noqa: PLR0913
         path = Path(tmpdir_path) / f"{name}.gpkg"
         x.to_file(path, driver="GPKG")
 
+        # Overwrite the modification time to keep hashing stable and release locks.
+        _snapshot_last_change(path=path)
+
         with warnings.catch_warnings():
             # Upstream issue relating to opening files without context managers
             warnings.simplefilter("ignore", category=ResourceWarning)
@@ -123,3 +127,19 @@ def pin_write_gdf_gpkg(  # noqa: PLR0913
                 description=description,
                 metadata=metadata,
             )
+
+
+def _snapshot_last_change(path: Path) -> None:
+    """Set the last_change timestamp to Unix epoch to keep GeoPackage hashing stable."""
+
+    conn = connect(path.as_posix())
+    try:
+        conn.execute(
+            """
+            UPDATE gpkg_contents
+            SET last_change = '1970-01-01T00:00:00Z';
+            """
+        )
+        conn.commit()
+    finally:
+        conn.close()

From be6de49bf65c9f99f682b98d66fa68eee36d66cf Mon Sep 17 00:00:00 2001
From: Ben Karl <bkarl@tonkintaylor.co.nz>
Date: Mon, 10 Nov 2025 16:38:05 +1300
Subject: [PATCH 3/3] add comment explaining not using a context manager

---
 src/geopins/drivers/gdf/filetypes/gpkg.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/geopins/drivers/gdf/filetypes/gpkg.py b/src/geopins/drivers/gdf/filetypes/gpkg.py
index 4b16f59..5ef9d55 100644
--- a/src/geopins/drivers/gdf/filetypes/gpkg.py
+++ b/src/geopins/drivers/gdf/filetypes/gpkg.py
@@ -132,6 +132,8 @@ def pin_write_gdf_gpkg(  # noqa: PLR0913
 def _snapshot_last_change(path: Path) -> None:
     """Set the last_change timestamp to Unix epoch to keep GeoPackage hashing stable."""
 
+    # Avoid `with connect(...)` because the context manager delays handle release on
+    # Windows, which keeps the temporary GeoPackage locked during cleanup.
     conn = connect(path.as_posix())
     try:
         conn.execute(