From 7a27a256988839811430597615a485c8e2ddb5b5 Mon Sep 17 00:00:00 2001
From: Wouter Deconinck <wdconinc@gmail.com>
Date: Mon, 29 Dec 2025 14:23:44 -0600
Subject: [PATCH 1/2] fix: support free-threaded python3.14t/site-packages
 prefixes

---
 cmake/podioBuild.cmake | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/cmake/podioBuild.cmake b/cmake/podioBuild.cmake
index e20470b7e..0f434a7e6 100644
--- a/cmake/podioBuild.cmake
+++ b/cmake/podioBuild.cmake
@@ -214,13 +214,27 @@ endif()
 # Setup the python install dir. See the discussion in
 # https://github.com/AIDASoft/podio/pull/599 for more details on why this is
 # done the way it is
+#
+# For Python 3.13+ with free-threading (PEP 703), the site-packages directory
+# includes a 't' suffix (e.g., python3.14t/site-packages). We use Python's
+# own SITEARCH to get the correct path including any ABI suffixes.
+#
 set(podio_python_lib_dir lib)
 if("${Python3_SITEARCH}" MATCHES "/lib64/")
   set(podio_python_lib_dir lib64)
 endif()
 
+# Extract the python-specific part of the path (e.g., python3.14t/site-packages)
+# from Python3_SITEARCH
+string(REGEX MATCH "python[0-9]+\\.[0-9]+[a-z]*/site-packages" _python_site_subdir "${Python3_SITEARCH}")
+if(NOT _python_site_subdir)
+  # Fallback to manual construction if regex fails
+  set(_python_site_subdir "python${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}/site-packages")
+  message(WARNING "Could not extract site-packages path from Python3_SITEARCH (${Python3_SITEARCH}), using fallback: ${_python_site_subdir}")
+endif()
+
 set(podio_PYTHON_INSTALLDIR
-  "${CMAKE_INSTALL_PREFIX}/${podio_python_lib_dir}/python${Python3_VERSION_MAJOR}.${Python3_VERSION_MINOR}/site-packages"
+  "${CMAKE_INSTALL_PREFIX}/${podio_python_lib_dir}/${_python_site_subdir}"
   CACHE STRING
   "The install prefix for the python bindings and the generator and templates"
 )

From 5415b2920c698d574725b787f3bab1e27d4a084e Mon Sep 17 00:00:00 2001
From: Wouter Deconinck <wdconinc@gmail.com>
Date: Mon, 29 Dec 2025 14:59:24 -0600
Subject: [PATCH 2/2] fix: append sys.abiflags to e.g. python3.14 in env.sh

---
 env.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/env.sh b/env.sh
index 1c0f250a7..34e90d58e 100644
--- a/env.sh
+++ b/env.sh
@@ -25,7 +25,7 @@ elif [[ "$unamestr" = 'Darwin' ]]; then
     fi
 fi
 
-python_stem=python3.$(python -c 'import sys; print(sys.version_info[1])')/site-packages
+python_stem=python3.$(python -c 'import sys; print(str(sys.version_info[1]) + sys.abiflags )')/site-packages
 if [ -d $PODIO/lib64/${python_stem} ]; then
   if ! echo $PYTHONPATH | grep -o $PODIO/lib64/${python_stem} > /dev/null 2>&1; then
     export PYTHONPATH=$PODIO/lib64/${python_stem}:$PYTHONPATH