# masked-mha-runtime

FlashRT native SM110 masked FP16/BF16 MHA for fixed-shape CUDA Graph runtimes.
It masks padded logits during softmax, supports fused-QKV token strides, and
keeps caller-owned logits/output buffers stable across graph replay.

```python
from kernels import get_kernel
import torch

ops = get_kernel("flashrt/masked-mha-runtime", version=1)
logits = ops.allocate_workspace(q, k)
out = torch.empty_like(q, memory_format=torch.contiguous_format)
ops.forward_static(q, k, v, logits=logits, out=out)
```

Public functions are `allocate_workspace`, `forward_static`, and `forward`.
Inputs use `(sequence, heads, head_dim)`. The production GROOT gate covers
DiT `(41, 32, 48)`, ViT/LLM sequence lengths `277/1024`, padded boundaries
`1025/2048`, FP16 and BF16, fused strides, and bitwise CUDA Graph replay.

See [CARD.md](CARD.md) for the complete contract. Source provenance is FlashRT
commit `24df793f4fa2d50780aea03b644208c6e0cb4162`.