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Studio diffusion (Phase 16) review fixes: native engine robustness

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- sd_cpp_backend: stop truncating explicit seeds to 53 bits (mask to int64);
  a large requested seed was silently collapsed (2**53 -> 0) and distinct seeds
  aliased to the same image. Random seeds stay 53-bit (JS-safe).
- sd_cpp_backend: sanitize empty/whitespace hf_token to None so HfApi/hf_hub
  fall back to anonymous instead of failing auth on a blank token.
- sd_cpp_backend: a superseding load now cancels the in-flight generation, so the
  old sd-cli can no longer return/persist an image from the previous model.
- diffusion_engine_router: run the previous engine's unload() OUTSIDE the lock so a
  slow 10+ GB free / CUDA sync does not block engine selection.
- diffusion_engine_router: probe sd-cli runnability (version()) before committing to
  native, so a present-but-unrunnable binary falls back to diffusers at selection.
- diffusion_device: resolve a torch-free CPU target when torch is unavailable, so a
  CPU-only install can still reach the native sd.cpp engine instead of failing load.
- tests updated for the runnability probe + a not-runnable fallback case.
This commit is contained in:
Daniel Han 2026-06-29 05:19:25 +00:00
commit 656d11c731
5 changed files with 84 additions and 10 deletions
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19
studio/backend/tests/test_diffusion_engine_router.py
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@ -47,6 +47,12 @@ def _set_binary(monkeypatch, path):
monkeypatch.setattr(r, "ensure_sd_cpp_binary", lambda **_: path)
def _set_runnable(monkeypatch, version = "sd-cli v0"):
"""Stub the runnability probe so a stubbed binary path is treated as executable
(the router now probes ``SdCppEngine(...).version()`` before committing to native)."""
monkeypatch.setattr(r, "SdCppEngine", lambda **_: SimpleNamespace(version = lambda: version))
def _select(fam_name = "z-image"):
"""Activate the engine for a family and return which engine was chosen."""
r.select_and_activate_engine(detect_family(fam_name))
@ -59,10 +65,21 @@ def _select(fam_name = "z-image"):
def test_cpu_with_binary_and_supported_family_picks_sd_cpp(monkeypatch):
_set_device(monkeypatch, "cpu")
_set_binary(monkeypatch, "/usr/bin/sd-cli")
_set_runnable(monkeypatch)
assert _select() == ENGINE_SD_CPP
assert r.active_engine_name() == ENGINE_SD_CPP
def test_present_but_not_runnable_binary_falls_back(monkeypatch):
# A binary that exists but cannot run (version() -> None) must fall back to
# diffusers at selection, not commit native and fail inside the load.
_set_device(monkeypatch, "cpu")
_set_binary(monkeypatch, "/usr/bin/sd-cli")
monkeypatch.setattr(r, "SdCppEngine", lambda **_: SimpleNamespace(version = lambda: None))
assert _select() == ENGINE_DIFFUSERS
assert "binary unavailable" in (r.active_status()["fallback_reason"] or "")
@pytest.mark.parametrize("gpu", ["cuda", "rocm", "xpu"])
def test_gpu_backends_use_diffusers(monkeypatch, gpu):
_set_device(monkeypatch, gpu)
@ -90,6 +107,7 @@ def test_sd_cpp_disabled_uses_diffusers(monkeypatch):
def test_mps_default_diffusers_but_optin_sd_cpp(monkeypatch):
_set_device(monkeypatch, "mps")
_set_binary(monkeypatch, "/usr/bin/sd-cli")
_set_runnable(monkeypatch)
# Default: MPS is not native-eligible -> diffusers.
assert _select() == ENGINE_DIFFUSERS
# Opt in: MPS routes to sd.cpp.
@ -115,6 +133,7 @@ def test_missing_binary_falls_back(monkeypatch):
def test_force_sd_cpp_on_gpu_when_binary_present(monkeypatch):
_set_device(monkeypatch, "cuda")
_set_binary(monkeypatch, "/usr/bin/sd-cli")
_set_runnable(monkeypatch)
monkeypatch.setenv("UNSLOTH_DIFFUSION_ENGINE", "sd_cpp")
assert _select() == ENGINE_SD_CPP