Reviewing files that changed from the base of the PR and between d3e2fa4 and 9dfc029.

• crates/stdlib/src/array.rs
• crates/vm/src/builtins/bytearray.rs
• crates/vm/src/builtins/bytes.rs
• crates/vm/src/builtins/descriptor.rs
• crates/vm/src/builtins/dict.rs
• crates/vm/src/builtins/genericalias.rs
• crates/vm/src/builtins/list.rs
• crates/vm/src/builtins/mappingproxy.rs
• crates/vm/src/builtins/str.rs
• crates/vm/src/builtins/tuple.rs
• crates/vm/src/builtins/type.rs
• crates/vm/src/builtins/union.rs
• crates/vm/src/stdlib/collections.rs
• crates/vm/src/stdlib/ctypes/pointer.rs
• crates/vm/src/stdlib/ctypes/simple.rs
• crates/vm/src/stdlib/ctypes/structure.rs
• crates/vm/src/types/slot.rs

• crates/vm/src/builtins/genericalias.rs
• crates/vm/src/stdlib/ctypes/structure.rs
• crates/vm/src/stdlib/ctypes/simple.rs
• crates/vm/src/builtins/dict.rs
• crates/vm/src/builtins/type.rs
• crates/vm/src/builtins/tuple.rs
• crates/vm/src/builtins/list.rs
• crates/stdlib/src/array.rs
• crates/vm/src/builtins/union.rs
• crates/vm/src/builtins/mappingproxy.rs
• crates/vm/src/stdlib/collections.rs
• crates/vm/src/stdlib/ctypes/pointer.rs

crates/vm/src/builtins/bytearray.rs (1)

534-537: Remainder (mod) wiring for PyByteArray looks correct

__mod__ simply wraps inner().cformat and AsNumber::remainder now delegates to it via to_pyresult(vm), matching the pattern used for bytes/str and keeping formatting logic centralized. No issues from a correctness or API-consistency standpoint.

Also applies to: 812-819

crates/vm/src/builtins/bytes.rs (1)

518-521: Bytes mod implementation and numeric remainder slot are consistent

The new __mod__ wrapper around inner.cformat plus AsNumber::remainder delegating to it mirrors the bytearray/str setup and keeps %-formatting behavior in one place. The conversion through into() and to_pyresult(vm) is type-safe and idiomatic here.

Also applies to: 669-675

crates/vm/src/builtins/str.rs (1)

947-949: String % formatting routed through mod and AsNumber cleanly

Renaming the helper to __mod__ and having AsNumber::remainder call it centralizes %-formatting via cformat_string while keeping the return as Wtf8Buf converted through to_pyresult(vm). This aligns string behavior with bytes/bytearray and looks semantically correct.

Also applies to: 1556-1562

crates/vm/src/builtins/descriptor.rs (2)

8-8: SeqRepeat now uses ArgSize for count – consistent with size/index semantics

Switching SlotFunc::SeqRepeat to bind (ArgSize,) and pass n.into() to the SeqRepeatFunc aligns sequence repeat with other ArgSize-based sites (e.g., str/bytearray __mul__), improving bounds/overflow handling without changing call sites of the slot itself.

Also applies to: 595-598

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776-785: Type-compatibility check in PyMethodWrapper.call matches CPython’s descriptor rules

The added fast_isinstance guard before invoking the wrapped slot prevents calling a method-wrapper on an incompatible instance and produces a clear TypeError, mirroring CPython’s behavior for wrappers bound to the wrong class. This is a good safety improvement with no downside.

crates/vm/src/types/slot.rs (2)

441-449: Sequence repeat slots correctly delegate to __mul__ / __imul__ wrappers

sequence_repeat_wrapper and sequence_inplace_repeat_wrapper now forward to __mul__ / __imul__ via call_special_method, and SqRepeat / SqInplaceRepeat are wired through them with update_sub_slot. This keeps the C-API-style sequence slots in sync with Python-level dunder methods and respects existing type-specific SeqRepeat functions when present.

Also applies to: 1307-1316

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1365-1368: MRO-based slot lookup now honors wrapper.typ compatibility

The new is_subclass_of + try_extract logic ensures a wrapper_descriptor’s slot is only reused when the target class’s MRO actually contains wrapper.typ, and it stops once a real method (non-wrapper) is found. Using appropriate MRO slices (&mro, &mro[i+1..]) keeps the subclass relationship checks accurate across the hierarchy. This tightens correctness around slot reuse without affecting existing valid cases.

Also applies to: 1371-1374, 1388-1402