From bcd1f59d797a11f48348edaf53fd4b9b7d28e2ee Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Thu, 8 Oct 2026 22:31:34 +0200
Subject: [PATCH 01/10] Close remaining issues identified in #254

---
 atom/src/atomdict.cpp | 6 +++++-
 atom/src/atomlist.cpp | 4 ++++
 atom/src/atomset.cpp  | 2 ++
 atom/src/catom.cpp    | 4 +++-
 atom/src/member.cpp   | 4 +++-
 5 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/atom/src/atomdict.cpp b/atom/src/atomdict.cpp
index 1c321f5c..ef5ffacd 100644
--- a/atom/src/atomdict.cpp
+++ b/atom/src/atomdict.cpp
@@ -110,12 +110,14 @@ int AtomDict_traverse( AtomDict* self, visitproc visit, void* arg )
 
 void AtomDict_dealloc( AtomDict* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
 	PyObject_GC_UnTrack( self );
 	cppy::clear( &self->m_key_validator );
 	cppy::clear( &self->m_value_validator );
     delete atomdict_cast( self )->pointer;
     atomdict_cast( self )->pointer = 0;
 	PyDict_Type.tp_dealloc( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 
@@ -458,8 +460,10 @@ bool DefaultAtomDict::Ready()
 	// This will work only if we create this type after the standard AtomDict
     // The reference will be handled by the module to which we will add the type
 	cppy::ptr bases( PyTuple_New( 1 ) );
-	if ( !bases )
+	if ( !bases ) {
 		return false; // LCOV_EXCL_LINE (failed tuple creation)
+	}
+	Py_INCREF( pyobject_cast( AtomDict::TypeObject ) );
 	PyTuple_SET_ITEM( bases.get(), 0, cppy::incref( pyobject_cast( AtomDict::TypeObject ) ) );
 	TypeObject = pytype_cast(
 		PyType_FromSpecWithBases( &TypeObject_Spec, bases.get() )
diff --git a/atom/src/atomlist.cpp b/atom/src/atomlist.cpp
index f22a461e..030ef923 100644
--- a/atom/src/atomlist.cpp
+++ b/atom/src/atomlist.cpp
@@ -296,11 +296,13 @@ int AtomList_traverse( AtomList* self, visitproc visit, void* arg )
 void
 AtomList_dealloc( AtomList* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
     PyObject_GC_UnTrack( self );
     cppy::clear( &self->validator );
     delete self->pointer;
     self->pointer = 0;
     PyList_Type.tp_dealloc( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 
@@ -1034,12 +1036,14 @@ int AtomCList_traverse( AtomCList* self, visitproc visit, void* arg )
 void
 AtomCList_dealloc( AtomCList* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
     PyObject_GC_UnTrack( self );
     cppy::clear( &self->member );
     cppy::clear( &atomlist_cast( self )->validator );
     delete atomlist_cast( self )->pointer;
     atomlist_cast( self )->pointer = 0;
     PyList_Type.tp_dealloc( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 
diff --git a/atom/src/atomset.cpp b/atom/src/atomset.cpp
index fb09bf45..7869b94c 100644
--- a/atom/src/atomset.cpp
+++ b/atom/src/atomset.cpp
@@ -122,11 +122,13 @@ int AtomSet_traverse( AtomSet* self, visitproc visit, void* arg )
 
 void AtomSet_dealloc( AtomSet* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
 	PyObject_GC_UnTrack( self );
 	cppy::clear( &self->m_value_validator );
 	delete atomset_cast( self )->pointer;
     atomset_cast( self )->pointer = 0;
 	PySet_Type.tp_dealloc( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 
diff --git a/atom/src/catom.cpp b/atom/src/catom.cpp
index 539ea2ab..50ef0a0d 100644
--- a/atom/src/catom.cpp
+++ b/atom/src/catom.cpp
@@ -130,6 +130,7 @@ CAtom_traverse( CAtom* self, visitproc visit, void* arg )
 void
 CAtom_dealloc( CAtom* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
     if( self->has_guards() )
     {
         CAtom::clear_guards( self );
@@ -146,7 +147,8 @@ CAtom_dealloc( CAtom* self )
     }
     delete self->observers;
     self->observers = 0;
-    Py_TYPE(self)->tp_free( pyobject_cast( self ) );
+    tp->tp_free( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 
diff --git a/atom/src/member.cpp b/atom/src/member.cpp
index fca66907..468ca416 100644
--- a/atom/src/member.cpp
+++ b/atom/src/member.cpp
@@ -94,11 +94,13 @@ Member_traverse( Member* self, visitproc visit, void* arg )
 void
 Member_dealloc( Member* self )
 {
+    PyTypeObject* tp = Py_TYPE( self );
     PyObject_GC_UnTrack( self );
     Member_clear( self );
     delete self->static_observers;
     self->static_observers = 0;
-    Py_TYPE(self)->tp_free( pyobject_cast( self ) );
+    tp->tp_free( pyobject_cast( self ) );
+    Py_DECREF( tp );
 }
 
 

From 8a85f275adc269ebf33567eb221dfa2b6ea90d89 Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Thu, 8 Oct 2026 23:23:43 +0200
Subject: [PATCH 02/10] complete closing of #256

---
 atom/src/utils.h              | 5 ++++-
 atom/src/validatebehavior.cpp | 2 ++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/atom/src/utils.h b/atom/src/utils.h
index f02c926f..fb0d5951 100644
--- a/atom/src/utils.h
+++ b/atom/src/utils.h
@@ -109,8 +109,11 @@ inline bool safe_richcompare( PyObject* first, PyObject* second, int opid )
 
     // Clear the error if one happened because we attempted an invalid
     // comparison.
-    if( PyErr_Occurred() )
+    if( PyErr_Occurred() ) {
+        if( !PyErr_ExceptionMatches( PyExc_TypeError ) )
+            return false;  // or propagate somehow
         PyErr_Clear();
+    }
 
     // Fallback to the Python 2 default 3 way compare.
     int c = fallback_3way_compare( first, second );
diff --git a/atom/src/validatebehavior.cpp b/atom/src/validatebehavior.cpp
index e6da684b..19d9f74a 100644
--- a/atom/src/validatebehavior.cpp
+++ b/atom/src/validatebehavior.cpp
@@ -893,6 +893,7 @@ range_handler( Member* member, CAtom* atom, PyObject* oldvalue, PyObject* newval
                 Py_TYPE( pyobject_cast( atom ) )->tp_name
             );
         default:
+            // Exception occurred during comparison
             return 0;
         }
     }
@@ -910,6 +911,7 @@ range_handler( Member* member, CAtom* atom, PyObject* oldvalue, PyObject* newval
                 Py_TYPE( pyobject_cast( atom ) )->tp_name
             );
         default:
+            // Exception occurred during comparison
             return 0;
         }
     }

From f4be55300aa0fd8dbf198f88a21b2a865996b105 Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 13:13:10 +0200
Subject: [PATCH 03/10] close 257

---
 atom/src/enumtypes.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/atom/src/enumtypes.cpp b/atom/src/enumtypes.cpp
index adf658fb..449c3407 100644
--- a/atom/src/enumtypes.cpp
+++ b/atom/src/enumtypes.cpp
@@ -38,11 +38,12 @@ add_long( cppy::ptr& dict_ptr, const char* name, T value )
     {
         return false;  // LCOV_EXCL_LINE (failed long creation, impossible)
     }
+    // PyDict_SetItemString does not steal a reference so cppy::ptr
+    // must decref the pyint reference after insertion.
     if( PyDict_SetItemString( dict_ptr.get(), name, pyint.get() ) != 0 )
     {
         return false;  // LCOV_EXCL_LINE (failed dict insertion, impossible)
     }
-    pyint.release(); // Release the reference since the operation succeeded
     return true;
 }
 

From fff548cef2e0d4b1ecfe6210cde9a74fbdf44124 Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 13:18:48 +0200
Subject: [PATCH 04/10] close #258

---
 atom/src/atomset.cpp   | 3 ++-
 atom/src/catom.cpp     | 4 ++++
 atom/src/sortedmap.cpp | 3 ++-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/atom/src/atomset.cpp b/atom/src/atomset.cpp
index 7869b94c..a609a413 100644
--- a/atom/src/atomset.cpp
+++ b/atom/src/atomset.cpp
@@ -87,8 +87,9 @@ PyObject* validate_set( AtomSet* set, PyObject* value )
             return 0;
         }
 	}
-	if ( PyErr_Occurred() )
+	if ( PyErr_Occurred() ) {
 		return 0;
+	}
 	return val_set.release();
 }
 
diff --git a/atom/src/catom.cpp b/atom/src/catom.cpp
index 50ef0a0d..5e2c414b 100644
--- a/atom/src/catom.cpp
+++ b/atom/src/catom.cpp
@@ -403,6 +403,7 @@ CAtom_getstate( CAtom* self )
             if (!value ) {
                 // Following CPython impl it is not an error if the attribute is
                 // not present.
+                PyErr_Clear();
                 continue;
             }
             else if ( PyDict_SetItem(stateptr.get(), name, value.get()) ) {
@@ -476,6 +477,9 @@ CAtom_setstate( CAtom* self, PyObject* state )
         if ( PyObject_SetAttr( pyobject_cast(self), key.get(), value.get() ) )
             return 0;
     }
+    if ( PyErr_Occurred() ) {
+        return 0;
+    }
 
     if ( frozen )
         self->set_frozen(true);
diff --git a/atom/src/sortedmap.cpp b/atom/src/sortedmap.cpp
index 518fb2db..616ad151 100644
--- a/atom/src/sortedmap.cpp
+++ b/atom/src/sortedmap.cpp
@@ -170,8 +170,9 @@ struct SortedMap
                     self->setitem( PySequence_Fast_GET_ITEM( pair.get(), 0 ),
                                    PySequence_Fast_GET_ITEM( pair.get(), 1 ) );
                 }
-                if ( PyErr_Occurred() )
+                if ( PyErr_Occurred() ) {
                     return 0; // error during iteration
+                }
             }
         }
 

From cb589c740dec924dc3a90ebd517c7925626bffdf Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 13:25:42 +0200
Subject: [PATCH 05/10] completely close #261

---
 atom/src/catommodule.cpp     | 30 ++++++++++++++++++++----------
 atom/src/getattrbehavior.cpp |  2 ++
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/atom/src/catommodule.cpp b/atom/src/catommodule.cpp
index 147b4ce6..9c52c91c 100644
--- a/atom/src/catommodule.cpp
+++ b/atom/src/catommodule.cpp
@@ -148,16 +148,26 @@ bool add_objects( PyObject* mod )
     cppy::incref( PyPostValidate );
     cppy::incref( PyGetState );
     cppy::incref( PyChangeType );
-    PyModule_AddObject( mod, "GetAttr", PyGetAttr );
-    PyModule_AddObject( mod, "SetAttr", PySetAttr );
-    PyModule_AddObject( mod, "DelAttr", PyDelAttr );
-    PyModule_AddObject( mod, "PostGetAttr", PyPostGetAttr );
-    PyModule_AddObject( mod, "PostSetAttr", PyPostSetAttr );
-    PyModule_AddObject( mod, "DefaultValue", PyDefaultValue );
-    PyModule_AddObject( mod, "Validate", PyValidate );
-    PyModule_AddObject( mod, "PostValidate", PyPostValidate );
-    PyModule_AddObject( mod, "GetState", PyGetState );
-    PyModule_AddObject( mod, "ChangeType", PyChangeType );
+    if (PyModule_AddObject( mod, "GetAttr", PyGetAttr ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "SetAttr", PySetAttr ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "DelAttr", PyDelAttr ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "PostGetAttr", PyPostGetAttr ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "PostSetAttr", PyPostSetAttr ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "DefaultValue", PyDefaultValue ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "Validate", PyValidate ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "PostValidate", PyPostValidate ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "GetState", PyGetState ) < 0)
+        return false;
+    if (PyModule_AddObject( mod, "ChangeType", PyChangeType ) < 0)
+        return false;
 
 	return true;
 }
diff --git a/atom/src/getattrbehavior.cpp b/atom/src/getattrbehavior.cpp
index 809724bb..36a344a6 100644
--- a/atom/src/getattrbehavior.cpp
+++ b/atom/src/getattrbehavior.cpp
@@ -183,6 +183,8 @@ cached_property_handler( Member* member, CAtom* atom )
     if( value )
         return value.release();
     value = property_handler( member, atom );
+    if( !value )
+        return 0;
     atom->set_slot( member->index, value.get() );  // exception-safe
     return value.release();
 }

From 28d64211d1979dbecb40ffa2aed7f3c54b4d28fc Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 13:43:51 +0200
Subject: [PATCH 06/10] close part of #262

---
 atom/src/atomdict.cpp      |  6 ++--
 atom/src/catommodule.cpp   | 56 +++++++++++++-------------------------
 atom/src/member.cpp        |  2 --
 atom/src/methodwrapper.cpp |  6 ++--
 atom/src/modifyguard.h     | 14 +++++++++-
 5 files changed, 37 insertions(+), 47 deletions(-)

diff --git a/atom/src/atomdict.cpp b/atom/src/atomdict.cpp
index ef5ffacd..cbec90dd 100644
--- a/atom/src/atomdict.cpp
+++ b/atom/src/atomdict.cpp
@@ -347,8 +347,7 @@ PyType_Spec AtomDict::TypeObject_Spec = {
 	0,                                          /* tp_itemsize */
 	Py_TPFLAGS_DEFAULT
 	| Py_TPFLAGS_BASETYPE
-	| Py_TPFLAGS_HAVE_GC
-	| Py_TPFLAGS_HAVE_VERSION_TAG,              /* tp_flags */
+	| Py_TPFLAGS_HAVE_GC,              /* tp_flags */
     AtomDict_Type_slots                         /* slots */
 };
 
@@ -430,8 +429,7 @@ PyType_Spec DefaultAtomDict::TypeObject_Spec = {
 	0,                                          /* tp_itemsize */
 	Py_TPFLAGS_DEFAULT
 	| Py_TPFLAGS_BASETYPE
-	| Py_TPFLAGS_HAVE_GC
-	| Py_TPFLAGS_HAVE_VERSION_TAG,              /* tp_flags */
+	| Py_TPFLAGS_HAVE_GC,              /* tp_flags */
     DefaultAtomDict_Type_slots                  /* slots */
 };
 
diff --git a/atom/src/catommodule.cpp b/atom/src/catommodule.cpp
index 9c52c91c..c98779e6 100644
--- a/atom/src/catommodule.cpp
+++ b/atom/src/catommodule.cpp
@@ -76,97 +76,79 @@ bool add_objects( PyObject* mod )
 
     // atomlist
     cppy::ptr atom_list( pyobject_cast( AtomList::TypeObject ) );
-	if( PyModule_AddObject( mod, "atomlist", atom_list.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "atomlist", atom_list.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    atom_list.release();
 
     // atomclist
     cppy::ptr atom_clist( pyobject_cast( AtomCList::TypeObject ) );
-	if( PyModule_AddObject( mod, "atomclist", atom_clist.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "atomclist", atom_clist.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    atom_clist.release();
 
     // atomdict
     cppy::ptr atom_dict( pyobject_cast( AtomDict::TypeObject ) );
-	if( PyModule_AddObject( mod, "atomdict", atom_dict.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "atomdict", atom_dict.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    atom_dict.release();
 
     // defaultatomdict
     cppy::ptr defaultatom_dict( pyobject_cast( DefaultAtomDict::TypeObject ) );
-	if( PyModule_AddObject( mod, "defaultatomdict", defaultatom_dict.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "defaultatomdict", defaultatom_dict.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    defaultatom_dict.release();
 
     // atomset
     cppy::ptr atom_set( pyobject_cast( AtomSet::TypeObject ) );
-	if( PyModule_AddObject( mod, "atomset", atom_set.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "atomset", atom_set.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    atom_set.release();
 
     // atomref
     cppy::ptr atom_ref( pyobject_cast( AtomRef::TypeObject ) );
-	if( PyModule_AddObject( mod, "atomref", atom_ref.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "atomref", atom_ref.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    atom_ref.release();
 
     // Member
     cppy::ptr member( pyobject_cast( Member::TypeObject ) );
-	if( PyModule_AddObject( mod, "Member", member.get() ) < 0 )  // LCOV_EXCL_BR_LINE
+	if( PyModule_AddObjectRef( mod, "Member", member.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    member.release();
 
     // CAtom
     cppy::ptr catom( pyobject_cast( CAtom::TypeObject ) );
-	if( PyModule_AddObject( mod, "CAtom", catom.get() ) < 0 )
+	if( PyModule_AddObjectRef( mod, "CAtom", catom.get() ) < 0 )  // LCOV_EXCL_BR_LINE
 	{
 		return false;  // LCOV_EXCL_LINE (failed type addition to module)
 	}
-    catom.release();
-
-    cppy::incref( PyGetAttr );
-    cppy::incref( PySetAttr );
-    cppy::incref( PyDelAttr );
-    cppy::incref( PyPostGetAttr );
-    cppy::incref( PyPostSetAttr );
-    cppy::incref( PyDefaultValue );
-    cppy::incref( PyValidate );
-    cppy::incref( PyPostValidate );
-    cppy::incref( PyGetState );
-    cppy::incref( PyChangeType );
-    if (PyModule_AddObject( mod, "GetAttr", PyGetAttr ) < 0)
+
+    if (PyModule_AddObjectRef( mod, "GetAttr", PyGetAttr ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "SetAttr", PySetAttr ) < 0)
+    if (PyModule_AddObjectRef( mod, "SetAttr", PySetAttr ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "DelAttr", PyDelAttr ) < 0)
+    if (PyModule_AddObjectRef( mod, "DelAttr", PyDelAttr ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "PostGetAttr", PyPostGetAttr ) < 0)
+    if (PyModule_AddObjectRef( mod, "PostGetAttr", PyPostGetAttr ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "PostSetAttr", PyPostSetAttr ) < 0)
+    if (PyModule_AddObjectRef( mod, "PostSetAttr", PyPostSetAttr ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "DefaultValue", PyDefaultValue ) < 0)
+    if (PyModule_AddObjectRef( mod, "DefaultValue", PyDefaultValue ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "Validate", PyValidate ) < 0)
+    if (PyModule_AddObjectRef( mod, "Validate", PyValidate ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "PostValidate", PyPostValidate ) < 0)
+    if (PyModule_AddObjectRef( mod, "PostValidate", PyPostValidate ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "GetState", PyGetState ) < 0)
+    if (PyModule_AddObjectRef( mod, "GetState", PyGetState ) < 0)
         return false;
-    if (PyModule_AddObject( mod, "ChangeType", PyChangeType ) < 0)
+    if (PyModule_AddObjectRef( mod, "ChangeType", PyChangeType ) < 0)
         return false;
 
 	return true;
diff --git a/atom/src/member.cpp b/atom/src/member.cpp
index 468ca416..ae6ecb92 100644
--- a/atom/src/member.cpp
+++ b/atom/src/member.cpp
@@ -919,12 +919,10 @@ Member_methods[] = {
       "Notify the static observers for the given member and atom." },
     { "tag", ( PyCFunction )Member_tag, METH_VARARGS | METH_KEYWORDS,
       "Tag the member with metatdata. " },
-#if PY_VERSION_HEX >= 0x03090000
     // Generic aliases have been added in 3.9 and allow to index types
     // This removes the need to quote explicit member type annotations
     { "__class_getitem__", (PyCFunction)Py_GenericAlias, METH_O|METH_CLASS,
       "See PEP 585"},
-#endif
     { 0 } // sentinel
 };
 
diff --git a/atom/src/methodwrapper.cpp b/atom/src/methodwrapper.cpp
index 6a4ec38d..7c41b5bd 100644
--- a/atom/src/methodwrapper.cpp
+++ b/atom/src/methodwrapper.cpp
@@ -234,9 +234,9 @@ PyTypeObject* AtomMethodWrapper::TypeObject = NULL;
 PyType_Spec AtomMethodWrapper::TypeObject_Spec = {
 	PACKAGE_TYPENAME( "AtomMethodWrapper" ),             /* tp_name */
 	sizeof( AtomMethodWrapper ),                         /* tp_basicsize */
-	0,                                               /* tp_itemsize */
-	Py_TPFLAGS_DEFAULT,                              /* tp_flags */
-    AtomMethodWrapper_Type_slots                           /* slots */
+	0,                                                   /* tp_itemsize */
+	Py_TPFLAGS_DEFAULT,                                  /* tp_flags */
+    AtomMethodWrapper_Type_slots                         /* slots */
 };
 
 
diff --git a/atom/src/modifyguard.h b/atom/src/modifyguard.h
index a1d0c2d7..cfdb1e07 100644
--- a/atom/src/modifyguard.h
+++ b/atom/src/modifyguard.h
@@ -37,11 +37,18 @@ class ModifyGuard
         // modification have been done as otherwise it can (Python 3) cause
         // boolean tests (PyObject_IsTrue) to fail for wrong reasons.
         bool exception_set = false;
+#if PY_VERSION_HEX >= 0x030D0000
+        PyObject *exc = PyErr_GetRaisedException();
+        if( PyErr_Occurred() ){
+            exception_set = true;
+        }
+#else
         PyObject *type, *value, *traceback;
         if( PyErr_Occurred() ){
             PyErr_Fetch(&type, &value, &traceback);
             exception_set = true;
         }
+#endif
 
         if( m_owner.get_modify_guard() == this )
         {
@@ -56,8 +63,13 @@ class ModifyGuard
         }
 
         // Restore previous exception if one was set.
-        if( exception_set )
+        if( exception_set ) {
+#if PY_VERSION_HEX >= 0x030D0000
+            PyErr_SetRaisedException(exc);
+#else
             PyErr_Restore(type, value, traceback);
+#endif
+        }
     }
 
     void add_task( ModifyTask* task ) { m_tasks.push_back( task ); }

From 2f83a5d4dd057edff3010301b46af61fc5ba7f5b Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 15:31:50 +0200
Subject: [PATCH 07/10] narrower fix for #256

---
 atom/src/utils.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/atom/src/utils.h b/atom/src/utils.h
index fb0d5951..acb0b858 100644
--- a/atom/src/utils.h
+++ b/atom/src/utils.h
@@ -110,7 +110,8 @@ inline bool safe_richcompare( PyObject* first, PyObject* second, int opid )
     // Clear the error if one happened because we attempted an invalid
     // comparison.
     if( PyErr_Occurred() ) {
-        if( !PyErr_ExceptionMatches( PyExc_TypeError ) )
+        // Do not swallow KeyboardInterrupt or SystemExit
+        if( !PyErr_ExceptionMatches( PyExc_Exception ) )
             return false;  // or propagate somehow
         PyErr_Clear();
     }

From 40f7e4194cc7800a41dd22451fa0ae6f4f65feb2 Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 15:45:10 +0200
Subject: [PATCH 08/10] proper use of PyErr_GetRaisedException in modifyguard

---
 atom/src/modifyguard.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/atom/src/modifyguard.h b/atom/src/modifyguard.h
index cfdb1e07..40c7a691 100644
--- a/atom/src/modifyguard.h
+++ b/atom/src/modifyguard.h
@@ -38,8 +38,9 @@ class ModifyGuard
         // boolean tests (PyObject_IsTrue) to fail for wrong reasons.
         bool exception_set = false;
 #if PY_VERSION_HEX >= 0x030D0000
-        PyObject *exc = PyErr_GetRaisedException();
+        PyObject *exc;
         if( PyErr_Occurred() ){
+            exc = PyErr_GetRaisedException();
             exception_set = true;
         }
 #else

From d5e7a02876109bfd84f778d27776bafb0dc9a421 Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 15:57:22 +0200
Subject: [PATCH 09/10] remove double incref

---
 atom/src/atomdict.cpp | 1 -
 1 file changed, 1 deletion(-)

diff --git a/atom/src/atomdict.cpp b/atom/src/atomdict.cpp
index cbec90dd..df754119 100644
--- a/atom/src/atomdict.cpp
+++ b/atom/src/atomdict.cpp
@@ -461,7 +461,6 @@ bool DefaultAtomDict::Ready()
 	if ( !bases ) {
 		return false; // LCOV_EXCL_LINE (failed tuple creation)
 	}
-	Py_INCREF( pyobject_cast( AtomDict::TypeObject ) );
 	PyTuple_SET_ITEM( bases.get(), 0, cppy::incref( pyobject_cast( AtomDict::TypeObject ) ) );
 	TypeObject = pytype_cast(
 		PyType_FromSpecWithBases( &TypeObject_Spec, bases.get() )

From 0470aa031bb36b24e2d6f294fc79dbb9657e216a Mon Sep 17 00:00:00 2001
From: mdartiailh <m.dartiailh@gmail.com>
Date: Fri, 9 Oct 2026 16:05:01 +0200
Subject: [PATCH 10/10] update release notes

---
 releasenotes.rst | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/releasenotes.rst b/releasenotes.rst
index 749ddaab..d1978978 100644
--- a/releasenotes.rst
+++ b/releasenotes.rst
@@ -1,6 +1,13 @@
 Atom Release Notes
 ==================
 
+0.13.0 - unreleased
+-------------------
+
+- add support for Python 3.15 PR #273
+- improve type stubs and checks them against mypy, pyrefly and ty PR #274
+- C API improvements
+
 0.12.1 - 02/10/2025
 -------------------