diff --git a/crates/vm/src/builtins/bool.rs b/crates/vm/src/builtins/bool.rs
index 3dabdbae717..24ded08ab10 100644
--- a/crates/vm/src/builtins/bool.rs
+++ b/crates/vm/src/builtins/bool.rs
@@ -9,7 +9,6 @@ use crate::{
     types::{AsNumber, Constructor, Representable},
 };
 use core::fmt::{Debug, Formatter};
-use malachite_bigint::Sign;
 use num_traits::Zero;
 
 impl ToPyObject for bool {
@@ -42,46 +41,28 @@ impl PyObjectRef {
         if self.is(&vm.ctx.false_value) {
             return Ok(false);
         }
-        let rs_bool = if let Some(nb_bool) = self.class().slots.as_number.boolean.load() {
-            nb_bool(self.as_object().number(), vm)?
-        } else {
-            // TODO: Fully implement AsNumber and remove this block
-            match vm.get_method(self.clone(), identifier!(vm, __bool__)) {
-                Some(method_or_err) => {
-                    // If descriptor returns Error, propagate it further
-                    let method = method_or_err?;
-                    let bool_obj = method.call((), vm)?;
-                    if !bool_obj.fast_isinstance(vm.ctx.types.bool_type) {
-                        return Err(vm.new_type_error(format!(
-                            "__bool__ should return bool, returned type {}",
-                            bool_obj.class().name()
-                        )));
-                    }
-
-                    get_value(&bool_obj)
-                }
-                None => match vm.get_method(self, identifier!(vm, __len__)) {
-                    Some(method_or_err) => {
-                        let method = method_or_err?;
-                        let bool_obj = method.call((), vm)?;
-                        let int_obj = bool_obj.downcast_ref::<PyInt>().ok_or_else(|| {
-                            vm.new_type_error(format!(
-                                "'{}' object cannot be interpreted as an integer",
-                                bool_obj.class().name()
-                            ))
-                        })?;
-
-                        let len_val = int_obj.as_bigint();
-                        if len_val.sign() == Sign::Minus {
-                            return Err(vm.new_value_error("__len__() should return >= 0"));
-                        }
-                        !len_val.is_zero()
-                    }
-                    None => true,
-                },
-            }
-        };
-        Ok(rs_bool)
+
+        let slots = &self.class().slots;
+
+        // 1. Try nb_bool slot first
+        if let Some(nb_bool) = slots.as_number.boolean.load() {
+            return nb_bool(self.as_object().number(), vm);
+        }
+
+        // 2. Try mp_length slot (mapping protocol)
+        if let Some(mp_length) = slots.as_mapping.length.load() {
+            let len = mp_length(self.as_object().mapping_unchecked(), vm)?;
+            return Ok(len != 0);
+        }
+
+        // 3. Try sq_length slot (sequence protocol)
+        if let Some(sq_length) = slots.as_sequence.length.load() {
+            let len = sq_length(self.as_object().sequence_unchecked(), vm)?;
+            return Ok(len != 0);
+        }
+
+        // 4. Default: objects without __bool__ or __len__ are truthy
+        Ok(true)
     }
 }
 
diff --git a/crates/vm/src/builtins/bytearray.rs b/crates/vm/src/builtins/bytearray.rs
index 212e4604ec9..dc5ee100acf 100644
--- a/crates/vm/src/builtins/bytearray.rs
+++ b/crates/vm/src/builtins/bytearray.rs
@@ -206,7 +206,6 @@ impl PyByteArray {
         self.inner().capacity()
     }
 
-    #[pymethod]
     fn __len__(&self) -> usize {
         self.borrow_buf().len()
     }
diff --git a/crates/vm/src/builtins/bytes.rs b/crates/vm/src/builtins/bytes.rs
index b3feac8ac97..7e5b98b1ece 100644
--- a/crates/vm/src/builtins/bytes.rs
+++ b/crates/vm/src/builtins/bytes.rs
@@ -205,7 +205,6 @@ impl PyRef<PyBytes> {
 )]
 impl PyBytes {
     #[inline]
-    #[pymethod]
     pub const fn __len__(&self) -> usize {
         self.inner.len()
     }
diff --git a/crates/vm/src/builtins/dict.rs b/crates/vm/src/builtins/dict.rs
index 358685fcdc4..693505b1f82 100644
--- a/crates/vm/src/builtins/dict.rs
+++ b/crates/vm/src/builtins/dict.rs
@@ -212,7 +212,6 @@ impl PyDict {
         }
     }
 
-    #[pymethod]
     pub fn __len__(&self) -> usize {
         self.entries.len()
     }
@@ -764,7 +763,6 @@ trait DictView: PyPayload + PyClassDef + Iterable + Representable {
     fn dict(&self) -> &Py<PyDict>;
     fn item(vm: &VirtualMachine, key: PyObjectRef, value: PyObjectRef) -> PyObjectRef;
 
-    #[pymethod]
     fn __len__(&self) -> usize {
         self.dict().__len__()
     }
diff --git a/crates/vm/src/builtins/list.rs b/crates/vm/src/builtins/list.rs
index 46145b339cf..52df0756498 100644
--- a/crates/vm/src/builtins/list.rs
+++ b/crates/vm/src/builtins/list.rs
@@ -182,7 +182,6 @@ impl PyList {
     }
 
     #[allow(clippy::len_without_is_empty)]
-    #[pymethod]
     pub fn __len__(&self) -> usize {
         self.borrow_vec().len()
     }
diff --git a/crates/vm/src/builtins/mappingproxy.rs b/crates/vm/src/builtins/mappingproxy.rs
index 475f36cb5a9..34a598b03e0 100644
--- a/crates/vm/src/builtins/mappingproxy.rs
+++ b/crates/vm/src/builtins/mappingproxy.rs
@@ -173,7 +173,6 @@ impl PyMappingProxy {
         PyGenericAlias::from_args(cls, args, vm)
     }
 
-    #[pymethod]
     fn __len__(&self, vm: &VirtualMachine) -> PyResult<usize> {
         let obj = self.to_object(vm)?;
         obj.length(vm)
@@ -235,6 +234,7 @@ impl AsMapping for PyMappingProxy {
 impl AsSequence for PyMappingProxy {
     fn as_sequence() -> &'static PySequenceMethods {
         static AS_SEQUENCE: LazyLock<PySequenceMethods> = LazyLock::new(|| PySequenceMethods {
+            length: atomic_func!(|seq, vm| PyMappingProxy::sequence_downcast(seq).__len__(vm)),
             contains: atomic_func!(
                 |seq, target, vm| PyMappingProxy::sequence_downcast(seq)._contains(target, vm)
             ),
diff --git a/crates/vm/src/builtins/memory.rs b/crates/vm/src/builtins/memory.rs
index ff5df031c42..5ca4257cded 100644
--- a/crates/vm/src/builtins/memory.rs
+++ b/crates/vm/src/builtins/memory.rs
@@ -690,7 +690,6 @@ impl PyMemoryView {
         Err(vm.new_type_error("cannot delete memory"))
     }
 
-    #[pymethod]
     fn __len__(&self, vm: &VirtualMachine) -> PyResult<usize> {
         self.try_not_released(vm)?;
         if self.desc.ndim() == 0 {
diff --git a/crates/vm/src/builtins/set.rs b/crates/vm/src/builtins/set.rs
index b1236e44e93..1c0268e2ed7 100644
--- a/crates/vm/src/builtins/set.rs
+++ b/crates/vm/src/builtins/set.rs
@@ -533,11 +533,14 @@ fn reduce_set(
     flags(BASETYPE, _MATCH_SELF)
 )]
 impl PySet {
-    #[pymethod]
     fn __len__(&self) -> usize {
         self.inner.len()
     }
 
+    fn __contains__(&self, needle: &PyObject, vm: &VirtualMachine) -> PyResult<bool> {
+        self.inner.contains(needle, vm)
+    }
+
     #[pymethod]
     fn __sizeof__(&self) -> usize {
         core::mem::size_of::<Self>() + self.inner.sizeof()
@@ -550,11 +553,6 @@ impl PySet {
         }
     }
 
-    #[pymethod]
-    fn __contains__(&self, needle: PyObjectRef, vm: &VirtualMachine) -> PyResult<bool> {
-        self.inner.contains(&needle, vm)
-    }
-
     #[pymethod]
     fn union(&self, others: PosArgs<ArgIterable>, vm: &VirtualMachine) -> PyResult<Self> {
         self.fold_op(others.into_iter(), PySetInner::union, vm)
@@ -594,8 +592,6 @@ impl PySet {
         self.inner.isdisjoint(other, vm)
     }
 
-    #[pymethod(name = "__ror__")]
-    #[pymethod]
     fn __or__(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyArithmeticValue<Self>> {
         if let Ok(other) = AnySet::try_from_object(vm, other) {
             Ok(PyArithmeticValue::Implemented(self.op(
@@ -608,8 +604,6 @@ impl PySet {
         }
     }
 
-    #[pymethod(name = "__rand__")]
-    #[pymethod]
     fn __and__(
         &self,
         other: PyObjectRef,
@@ -626,7 +620,6 @@ impl PySet {
         }
     }
 
-    #[pymethod]
     fn __sub__(
         &self,
         other: PyObjectRef,
@@ -643,7 +636,6 @@ impl PySet {
         }
     }
 
-    #[pymethod]
     fn __rsub__(
         zelf: PyRef<Self>,
         other: PyObjectRef,
@@ -660,8 +652,6 @@ impl PySet {
         }
     }
 
-    #[pymethod(name = "__rxor__")]
-    #[pymethod]
     fn __xor__(
         &self,
         other: PyObjectRef,
@@ -705,7 +695,6 @@ impl PySet {
         self.inner.pop(vm)
     }
 
-    #[pymethod]
     fn __ior__(zelf: PyRef<Self>, set: AnySet, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
         zelf.inner.update(set.into_iterable_iter(vm)?, vm)?;
         Ok(zelf)
@@ -729,7 +718,6 @@ impl PySet {
         Ok(())
     }
 
-    #[pymethod]
     fn __iand__(zelf: PyRef<Self>, set: AnySet, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
         zelf.inner
             .intersection_update(core::iter::once(set.into_iterable(vm)?), vm)?;
@@ -742,7 +730,6 @@ impl PySet {
         Ok(())
     }
 
-    #[pymethod]
     fn __isub__(zelf: PyRef<Self>, set: AnySet, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
         zelf.inner
             .difference_update(set.into_iterable_iter(vm)?, vm)?;
@@ -760,7 +747,6 @@ impl PySet {
         Ok(())
     }
 
-    #[pymethod]
     fn __ixor__(zelf: PyRef<Self>, set: AnySet, vm: &VirtualMachine) -> PyResult<PyRef<Self>> {
         zelf.inner
             .symmetric_difference_update(set.into_iterable_iter(vm)?, vm)?;
@@ -799,9 +785,9 @@ impl AsSequence for PySet {
     fn as_sequence() -> &'static PySequenceMethods {
         static AS_SEQUENCE: LazyLock<PySequenceMethods> = LazyLock::new(|| PySequenceMethods {
             length: atomic_func!(|seq, _vm| Ok(PySet::sequence_downcast(seq).__len__())),
-            contains: atomic_func!(|seq, needle, vm| PySet::sequence_downcast(seq)
-                .inner
-                .contains(needle, vm)),
+            contains: atomic_func!(
+                |seq, needle, vm| PySet::sequence_downcast(seq).__contains__(needle, vm)
+            ),
             ..PySequenceMethods::NOT_IMPLEMENTED
         });
         &AS_SEQUENCE
@@ -830,30 +816,77 @@ impl Iterable for PySet {
 impl AsNumber for PySet {
     fn as_number() -> &'static PyNumberMethods {
         static AS_NUMBER: PyNumberMethods = PyNumberMethods {
+            // Binary ops check both operands are sets (like CPython's set_sub, etc.)
+            // This is needed because __rsub__ swaps operands: a.__rsub__(b) calls subtract(b, a)
             subtract: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PySet>() {
                     a.__sub__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
+                    // When called via __rsub__, a might be PyFrozenSet
+                    a.__sub__(b.to_owned(), vm)
+                        .map(|r| {
+                            r.map(|s| PySet {
+                                inner: s.inner.clone(),
+                            })
+                        })
+                        .to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             and: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PySet>() {
                     a.__and__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
+                    a.__and__(b.to_owned(), vm)
+                        .map(|r| {
+                            r.map(|s| PySet {
+                                inner: s.inner.clone(),
+                            })
+                        })
+                        .to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             xor: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PySet>() {
                     a.__xor__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
+                    a.__xor__(b.to_owned(), vm)
+                        .map(|r| {
+                            r.map(|s| PySet {
+                                inner: s.inner.clone(),
+                            })
+                        })
+                        .to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             or: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PySet>() {
                     a.__or__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
+                    a.__or__(b.to_owned(), vm)
+                        .map(|r| {
+                            r.map(|s| PySet {
+                                inner: s.inner.clone(),
+                            })
+                        })
+                        .to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
@@ -972,11 +1005,14 @@ impl Constructor for PyFrozenSet {
     )
 )]
 impl PyFrozenSet {
-    #[pymethod]
     fn __len__(&self) -> usize {
         self.inner.len()
     }
 
+    fn __contains__(&self, needle: &PyObject, vm: &VirtualMachine) -> PyResult<bool> {
+        self.inner.contains(needle, vm)
+    }
+
     #[pymethod]
     fn __sizeof__(&self) -> usize {
         core::mem::size_of::<Self>() + self.inner.sizeof()
@@ -995,11 +1031,6 @@ impl PyFrozenSet {
         }
     }
 
-    #[pymethod]
-    fn __contains__(&self, needle: PyObjectRef, vm: &VirtualMachine) -> PyResult<bool> {
-        self.inner.contains(&needle, vm)
-    }
-
     #[pymethod]
     fn union(&self, others: PosArgs<ArgIterable>, vm: &VirtualMachine) -> PyResult<Self> {
         self.fold_op(others.into_iter(), PySetInner::union, vm)
@@ -1039,8 +1070,6 @@ impl PyFrozenSet {
         self.inner.isdisjoint(other, vm)
     }
 
-    #[pymethod(name = "__ror__")]
-    #[pymethod]
     fn __or__(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<PyArithmeticValue<Self>> {
         if let Ok(set) = AnySet::try_from_object(vm, other) {
             Ok(PyArithmeticValue::Implemented(self.op(
@@ -1053,8 +1082,6 @@ impl PyFrozenSet {
         }
     }
 
-    #[pymethod(name = "__rand__")]
-    #[pymethod]
     fn __and__(
         &self,
         other: PyObjectRef,
@@ -1071,7 +1098,6 @@ impl PyFrozenSet {
         }
     }
 
-    #[pymethod]
     fn __sub__(
         &self,
         other: PyObjectRef,
@@ -1088,7 +1114,6 @@ impl PyFrozenSet {
         }
     }
 
-    #[pymethod]
     fn __rsub__(
         zelf: PyRef<Self>,
         other: PyObjectRef,
@@ -1106,8 +1131,6 @@ impl PyFrozenSet {
         }
     }
 
-    #[pymethod(name = "__rxor__")]
-    #[pymethod]
     fn __xor__(
         &self,
         other: PyObjectRef,
@@ -1142,9 +1165,9 @@ impl AsSequence for PyFrozenSet {
     fn as_sequence() -> &'static PySequenceMethods {
         static AS_SEQUENCE: LazyLock<PySequenceMethods> = LazyLock::new(|| PySequenceMethods {
             length: atomic_func!(|seq, _vm| Ok(PyFrozenSet::sequence_downcast(seq).__len__())),
-            contains: atomic_func!(|seq, needle, vm| PyFrozenSet::sequence_downcast(seq)
-                .inner
-                .contains(needle, vm)),
+            contains: atomic_func!(
+                |seq, needle, vm| PyFrozenSet::sequence_downcast(seq).__contains__(needle, vm)
+            ),
             ..PySequenceMethods::NOT_IMPLEMENTED
         });
         &AS_SEQUENCE
@@ -1196,30 +1219,53 @@ impl Iterable for PyFrozenSet {
 impl AsNumber for PyFrozenSet {
     fn as_number() -> &'static PyNumberMethods {
         static AS_NUMBER: PyNumberMethods = PyNumberMethods {
+            // Binary ops check both operands are sets (like CPython's set_sub, etc.)
+            // __rsub__ swaps operands. Result type follows first operand's type.
             subtract: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
                     a.__sub__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PySet>() {
+                    // When called via __rsub__, a might be PySet - return set (not frozenset)
+                    a.__sub__(b.to_owned(), vm).to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             and: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
                     a.__and__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PySet>() {
+                    a.__and__(b.to_owned(), vm).to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             xor: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
                     a.__xor__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PySet>() {
+                    a.__xor__(b.to_owned(), vm).to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
             }),
             or: Some(|a, b, vm| {
+                if !AnySet::check(a, vm) || !AnySet::check(b, vm) {
+                    return Ok(vm.ctx.not_implemented());
+                }
                 if let Some(a) = a.downcast_ref::<PyFrozenSet>() {
                     a.__or__(b.to_owned(), vm).to_pyresult(vm)
+                } else if let Some(a) = a.downcast_ref::<PySet>() {
+                    a.__or__(b.to_owned(), vm).to_pyresult(vm)
                 } else {
                     Ok(vm.ctx.not_implemented())
                 }
@@ -1252,6 +1298,13 @@ struct AnySet {
 }
 
 impl AnySet {
+    /// Check if object is a set or frozenset (including subclasses)
+    /// Equivalent to CPython's PyAnySet_Check
+    fn check(obj: &PyObject, vm: &VirtualMachine) -> bool {
+        let ctx = &vm.ctx;
+        obj.fast_isinstance(ctx.types.set_type) || obj.fast_isinstance(ctx.types.frozenset_type)
+    }
+
     fn into_iterable(self, vm: &VirtualMachine) -> PyResult<ArgIterable> {
         self.object.try_into_value(vm)
     }
diff --git a/crates/vm/src/builtins/tuple.rs b/crates/vm/src/builtins/tuple.rs
index e0b8009e892..910b0c8a204 100644
--- a/crates/vm/src/builtins/tuple.rs
+++ b/crates/vm/src/builtins/tuple.rs
@@ -298,7 +298,6 @@ impl PyTuple {
     }
 
     #[inline]
-    #[pymethod]
     pub const fn __len__(&self) -> usize {
         self.elements.len()
     }
diff --git a/crates/vm/src/protocol/number.rs b/crates/vm/src/protocol/number.rs
index 58891d1d710..542afce2c6c 100644
--- a/crates/vm/src/protocol/number.rs
+++ b/crates/vm/src/protocol/number.rs
@@ -356,21 +356,27 @@ impl PyNumberSlots {
     pub fn copy_from(&self, methods: &PyNumberMethods) {
         if let Some(f) = methods.add {
             self.add.store(Some(f));
+            self.right_add.store(Some(f));
         }
         if let Some(f) = methods.subtract {
             self.subtract.store(Some(f));
+            self.right_subtract.store(Some(f));
         }
         if let Some(f) = methods.multiply {
             self.multiply.store(Some(f));
+            self.right_multiply.store(Some(f));
         }
         if let Some(f) = methods.remainder {
             self.remainder.store(Some(f));
+            self.right_remainder.store(Some(f));
         }
         if let Some(f) = methods.divmod {
             self.divmod.store(Some(f));
+            self.right_divmod.store(Some(f));
         }
         if let Some(f) = methods.power {
             self.power.store(Some(f));
+            self.right_power.store(Some(f));
         }
         if let Some(f) = methods.negative {
             self.negative.store(Some(f));
@@ -389,18 +395,23 @@ impl PyNumberSlots {
         }
         if let Some(f) = methods.lshift {
             self.lshift.store(Some(f));
+            self.right_lshift.store(Some(f));
         }
         if let Some(f) = methods.rshift {
             self.rshift.store(Some(f));
+            self.right_rshift.store(Some(f));
         }
         if let Some(f) = methods.and {
             self.and.store(Some(f));
+            self.right_and.store(Some(f));
         }
         if let Some(f) = methods.xor {
             self.xor.store(Some(f));
+            self.right_xor.store(Some(f));
         }
         if let Some(f) = methods.or {
             self.or.store(Some(f));
+            self.right_or.store(Some(f));
         }
         if let Some(f) = methods.int {
             self.int.store(Some(f));
@@ -440,9 +451,11 @@ impl PyNumberSlots {
         }
         if let Some(f) = methods.floor_divide {
             self.floor_divide.store(Some(f));
+            self.right_floor_divide.store(Some(f));
         }
         if let Some(f) = methods.true_divide {
             self.true_divide.store(Some(f));
+            self.right_true_divide.store(Some(f));
         }
         if let Some(f) = methods.inplace_floor_divide {
             self.inplace_floor_divide.store(Some(f));
@@ -455,6 +468,7 @@ impl PyNumberSlots {
         }
         if let Some(f) = methods.matrix_multiply {
             self.matrix_multiply.store(Some(f));
+            self.right_matrix_multiply.store(Some(f));
         }
         if let Some(f) = methods.inplace_matrix_multiply {
             self.inplace_matrix_multiply.store(Some(f));
diff --git a/crates/vm/src/stdlib/collections.rs b/crates/vm/src/stdlib/collections.rs
index 67e8e1f2734..9b7a78f7237 100644
--- a/crates/vm/src/stdlib/collections.rs
+++ b/crates/vm/src/stdlib/collections.rs
@@ -350,16 +350,10 @@ mod _collections {
             Ok(zelf)
         }
 
-        #[pymethod]
         fn __len__(&self) -> usize {
             self.borrow_deque().len()
         }
 
-        #[pymethod]
-        fn __add__(&self, other: PyObjectRef, vm: &VirtualMachine) -> PyResult<Self> {
-            self.concat(&other, vm)
-        }
-
         fn concat(&self, other: &PyObject, vm: &VirtualMachine) -> PyResult<Self> {
             if let Some(o) = other.downcast_ref::<Self>() {
                 let mut deque = self.borrow_deque().clone();
diff --git a/crates/vm/src/stdlib/ctypes/array.rs b/crates/vm/src/stdlib/ctypes/array.rs
index 5c298d26a56..63594879878 100644
--- a/crates/vm/src/stdlib/ctypes/array.rs
+++ b/crates/vm/src/stdlib/ctypes/array.rs
@@ -1087,7 +1087,6 @@ impl PyCArray {
         Ok(())
     }
 
-    #[pymethod]
     fn __len__(zelf: &Py<Self>, _vm: &VirtualMachine) -> usize {
         zelf.class().stg_info_opt().map_or(0, |i| i.length)
     }
diff --git a/crates/vm/src/stdlib/winreg.rs b/crates/vm/src/stdlib/winreg.rs
index 400cab44210..28fa2e9b74c 100644
--- a/crates/vm/src/stdlib/winreg.rs
+++ b/crates/vm/src/stdlib/winreg.rs
@@ -222,7 +222,6 @@ mod winreg {
             zelf.Close(vm)
         }
 
-        #[pymethod]
         fn __int__(&self) -> usize {
             self.hkey.load() as usize
         }
diff --git a/crates/vm/src/types/slot.rs b/crates/vm/src/types/slot.rs
index d7ead562063..17b2b4e2f8a 100644
--- a/crates/vm/src/types/slot.rs
+++ b/crates/vm/src/types/slot.rs
@@ -607,7 +607,9 @@ impl PyType {
         debug_assert!(name.as_str().ends_with("__"));
 
         // Find all slot_defs matching this name and update each
-        for def in find_slot_defs_by_name(name.as_str()) {
+        // NOTE: Collect into Vec first to avoid issues during iteration
+        let defs: Vec<_> = find_slot_defs_by_name(name.as_str()).collect();
+        for def in defs {
             self.update_one_slot::<ADD>(&def.accessor, name, ctx);
         }
 
@@ -676,7 +678,29 @@ impl PyType {
         macro_rules! update_sub_slot {
             ($group:ident, $slot:ident, $wrapper:expr, $variant:ident) => {{
                 if ADD {
-                    if let Some(func) = self.lookup_slot_in_mro(name, ctx, |sf| {
+                    // Check if this type defines any method that maps to this slot.
+                    // Some slots like SqAssItem/MpAssSubscript are shared by multiple
+                    // methods (__setitem__ and __delitem__). If any of those methods
+                    // is defined, we must use the wrapper to ensure Python method calls.
+                    let has_own = {
+                        let guard = self.attributes.read();
+                        // Check the current method name
+                        let mut result = guard.contains_key(name);
+                        // For ass_item/ass_subscript slots, also check the paired method
+                        // (__setitem__ and __delitem__ share the same slot)
+                        if !result
+                            && (stringify!($slot) == "ass_item"
+                                || stringify!($slot) == "ass_subscript")
+                        {
+                            let setitem = ctx.intern_str("__setitem__");
+                            let delitem = ctx.intern_str("__delitem__");
+                            result = guard.contains_key(setitem) || guard.contains_key(delitem);
+                        }
+                        result
+                    };
+                    if has_own {
+                        self.slots.$group.$slot.store(Some($wrapper));
+                    } else if let Some(func) = self.lookup_slot_in_mro(name, ctx, |sf| {
                         if let SlotFunc::$variant(f) = sf {
                             Some(*f)
                         } else {