ci: stage reviewed HC backend patch

Author: TheHiddenObserver

dev/benchmarks/_pr126_apply_hc_backend_fix.py

@@ -0,0 +1,50 @@
+from pathlib import Path
+
+path = Path("statgpu/panel/_covariance.py")
+text = path.read_text(encoding="utf-8")
+old = '''    leverage_np = np.asarray(_to_numpy(leverage), dtype=np.float64).ravel()
+    tol = 256.0 * np.finfo(np.float64).eps
+    if leverage_np.size and float(np.min(leverage_np)) < -tol:
+        raise ValueError("HC2/HC3 leverage is materially negative")
+    if leverage_np.size and float(np.max(leverage_np)) > 1.0 + tol:
+        raise ValueError("HC2/HC3 leverage is materially greater than one")
+    leverage_np = np.clip(leverage_np, 0.0, 1.0)
+    denominator_np = 1.0 - leverage_np
+    if denominator_np.size and float(np.min(denominator_np)) <= tol:
+        raise ValueError("HC2/HC3 covariance is undefined when leverage is numerically one")
+    denominator = xp_asarray(
+        denominator_np,
+        dtype=xp.float64,
+        xp=xp,
+        ref_arr=X,
+    )
+'''
+new = '''    leverage_min = _to_float_scalar(xp.min(leverage))
+    leverage_max = _to_float_scalar(xp.max(leverage))
+    tol = 256.0 * np.finfo(np.float64).eps
+    if leverage_min < -tol:
+        raise ValueError("HC2/HC3 leverage is materially negative")
+    if leverage_max > 1.0 + tol:
+        raise ValueError("HC2/HC3 leverage is materially greater than one")
+    if _is_torch(xp):
+        leverage = xp.clamp(leverage, min=0.0, max=1.0)
+    else:
+        leverage = xp.clip(leverage, 0.0, 1.0)
+    denominator = 1.0 - leverage
+    denominator_min = _to_float_scalar(xp.min(denominator))
+    if denominator_min <= tol:
+        raise ValueError("HC2/HC3 covariance is undefined when leverage is numerically one")
+'''
+if old not in text:
+    raise SystemExit("expected HC leverage block not found")
+text = text.replace(old, new, 1)
+old_meta = '''                "leverage_min": float(leverage_np.min()) if leverage_np.size else None,
+                "leverage_max": float(leverage_np.max()) if leverage_np.size else None,
+'''
+new_meta = '''                "leverage_min": float(leverage_min),
+                "leverage_max": float(leverage_max),
+'''
+if old_meta not in text:
+    raise SystemExit("expected HC leverage metadata block not found")
+text = text.replace(old_meta, new_meta, 1)
+path.write_text(text, encoding="utf-8")