* studio: skip flash-attn install on Blackwell GPUs (sm_100+)
Dao-AILab does not publish prebuilt flash-attn wheels for sm_100, sm_120,
or sm_121, and the older-arch wheels fail to load on Blackwell. Add a
shared has_blackwell_gpu() helper and gate both the install-time
(install_python_stack._ensure_flash_attn) and runtime
(worker._ensure_flash_attn_for_long_context) paths on it. Detection uses
nvidia-smi --query-gpu=compute_cap, which works on Linux and Windows.
* test: stub has_blackwell_gpu in pre-existing runtime flash-attn tests
prefers_prebuilt_wheel and falls_back_to_pypi exercise the install
paths that the Blackwell guard now short-circuits. Make them explicit
about non-Blackwell so they pass on real Blackwell hosts.
* studio: cache has_blackwell_gpu, skip Blackwell warning under NO_TORCH
- Wrap has_blackwell_gpu in functools.lru_cache so repeated calls in a
single process avoid redundant nvidia-smi spawns. Tests clear the
cache via setup_method/teardown_method.
- In _ensure_flash_attn, run the NO_TORCH short-circuit before the
Blackwell check so GGUF-only users (who never install torch anyway)
do not see a Blackwell warning. Blackwell check still runs above the
IS_WINDOWS / IS_MACOS gates so Blackwell-on-Windows users still see
the explicit reason rather than a silent OS skip.
* [pre-commit.ci] auto fixes from pre-commit.com hooks
for more information, see https://pre-commit.ci
* test: add has_blackwell_gpu to mlx worker test wheel_utils stub
test_mlx_training_worker_config loads worker.py against a hand-rolled
utils.wheel_utils stub. Adding has_blackwell_gpu to the stub symbol
list so worker's import line resolves.
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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