int/int8 and int/uint8 conversion saturates for packed widths but wraps for width 1

Which component has the problem?

CUTLASS C++ - include/cutlass/numeric_conversion.h, NumericArrayConverter<int8_t, int, N> / NumericArrayConverter<uint8_t, int, N> family

Describe the bug

Saturation behavior differs by array width within the same converter family:

• N == 1 (numeric_conversion.h ~1194 and ~1317) routes through NumericConverter<int8_t, int, Round> / NumericConverter<uint8_t, int, Round>. No such specialization exists anywhere under include/ (the existing scalar specializations cover float and half_t sources only), so the primary template's static_cast applies and out-of-range values wrap modulo 256.
• N == 2 / 4 / generic packed widths (~1213, ~1242, ~1336, ~1365) use cvt.pack.sat.s8.s32.b32 / cvt.pack.sat.u8.s32 PTX, which saturate to [-128, 127] / [0, 255].

Concrete device-side divergence:

Array<int, 1> a{200};
Array<int8_t, 1> r1 = convert(a);   // -56   (wrap)
Array<int, 2> b{200, 0};
Array<int8_t, 2> r2 = convert(b);   // {127, 0}  (saturate)

The same asymmetry surfaces through NumericArrayFP32ToIntConverter<T, N> (~5031): when N is not a multiple of the packed width the remainder elements take the wrapping element-wise path while the packed bulk takes the saturating asm path, so one array can contain both saturated and wrapped results. Relatedly, scalar float -> int4b_t/uint4b_t via integer_subbyte has no saturation either (asserts in debug, wraps in release), unlike the packed int4 paths.

Not covered by test/unit/core/numeric_conversion.cu: there is no <int8_t, int> / <uint8_t, int> pair in it.

Expected behavior

Consistent treatment across widths of the same source/destination pair - either all widths saturate (matching the cvt.pack.sat contract used by the packed paths), or the divergence is documented. A saturating scalar path would be trivially expressible with min/max clamping on host and device.

Environment details

• Current main, header-only observation; the wrap path also reproduces in host compilation since the generic converter is plain static_cast
• Found during an audit of numeric_conversion.h; the packed PTX blocks themselves were verified correct

Start in include/cutlass/numeric_conversion.h at the NumericArrayConverter<int8_t, int, N> and NumericArrayConverter<uint8_t, int, N> paths, then inspect NumericArrayFP32ToIntConverter<T, N> and the integer_subbyte conversions. Run test/unit/core/numeric_conversion.cu and extend coverage for the missing conversion pairs and widths; done means the selected behavior is consistent across scalar, packed, and remainder paths.