Measured 2026-10-03 (frankuser)

def fin(a):
    yield a
    yield a + 1
d = {"a": fin(3)}
print(next(d["a"]))        # pxx at pin v452: 11    CPython: 3
class K:
    ctr = None
K.ctr = fin(5)
print(next(K.ctr))         # 11
g = [fin(3)]
print(next(g[0]))          # 3 -- a list subscript happened to work

Same on main before this session. list(d["a"]) was right; only next().

Fix

PyNextOverListAhead (the token-level gate of the next arm) now claims every argument except a NAME already typed TPyIter/TPyCounter and a direct call of a stackless generator, which keep the TPyIter overload. pynext_v dispatches on the run-time value (cursor, list, user next).

Census over subscript, attribute, default, list element, iter(list), a user next class, a fresh generator, a named one, iter(str): 3000/10000/30000 rounds live 28/42/42, flat. test_nilpy_classvar_counter (a dataclass field factory calling next() on a ClassVar counter) is the existing fixture that caught it once count became a generator.