test: harden CP HiCache metadata invariants

python/sglang/srt/mem_cache/hiradix_cache.py

@@ -64,8 +64,12 @@ class CpHiCacheNodeMetadata:
     def __post_init__(self):
         if self.logical_len < 0:
             raise ValueError(f"logical_len must be non-negative, got {self.logical_len}")
-        self.owned_positions = self.owned_positions.to(device="cpu", dtype=torch.int64)
-        self.host_indices = self.host_indices.to(device="cpu", dtype=torch.int64)
+        self.owned_positions = self.owned_positions.to(
+            device="cpu", dtype=torch.int64
+        ).detach().clone()
+        self.host_indices = self.host_indices.to(
+            device="cpu", dtype=torch.int64
+        ).detach().clone()
         if self.owned_positions.numel() != self.host_indices.numel():
             raise ValueError(
                 "owned_positions and host_indices must have same length, got "
@@ -76,8 +80,10 @@ class CpHiCacheNodeMetadata:
                 self.owned_positions >= self.logical_len
             ):
                 raise ValueError("owned_positions must be in [0, logical_len)")
-            if torch.any(self.owned_positions[1:] < self.owned_positions[:-1]):
-                raise ValueError("owned_positions must be sorted")
+            if torch.any(self.owned_positions[1:] <= self.owned_positions[:-1]):
+                raise ValueError(
+                    "owned_positions must be sorted and strictly increasing"
+                )
 
     def split(
         self, split_len: int