[fix] fixed request to request error.

nanovllm/kvcache/hybrid_manager.py

@@ -231,6 +231,11 @@ class HybridKVCacheManager(KVCacheManager):
         seq.num_cached_tokens = 0
         seq.block_table.clear()
 
+        # Reset OffloadEngine state to prevent request-to-request contamination
+        # This clears all KV buffers and pending async events
+        if self.offload_engine is not None:
+            self.offload_engine.reset()
+
     def can_append(self, seq: Sequence) -> bool:
         """Check if we can append a token."""
         need_new_block = (len(seq) % self._block_size == 1)

nanovllm/kvcache/offload_engine.py

@@ -278,6 +278,42 @@ class OffloadEngine:
         """
         return self.k_cache_gpu, self.v_cache_gpu
 
+    def reset(self) -> None:
+        """
+        Reset all KV cache buffers to zero.
+
+        This clears all GPU and CPU-side KV cache storage, preventing
+        request-to-request contamination. Must be called between generate()
+        calls when reusing the same OffloadEngine instance.
+
+        Clears:
+        - GPU ring buffer slots (k_cache_gpu, v_cache_gpu)
+        - Per-layer decode buffers (decode_k_buffer, decode_v_buffer)
+        - Cross-layer pipeline buffers (layer_k/v_buffer_a/b)
+        - Per-layer prefill buffers (prefill_k/v_buffer)
+        - All pending async transfer events
+        """
+        # Clear GPU ring buffer slots
+        self.k_cache_gpu.zero_()
+        self.v_cache_gpu.zero_()
+
+        # Clear per-layer decode buffers
+        self.decode_k_buffer.zero_()
+        self.decode_v_buffer.zero_()
+
+        # Clear cross-layer pipeline buffers
+        self.layer_k_buffer_a.zero_()
+        self.layer_v_buffer_a.zero_()
+        self.layer_k_buffer_b.zero_()
+        self.layer_v_buffer_b.zero_()
+
+        # Clear per-layer prefill buffers
+        self.prefill_k_buffer.zero_()
+        self.prefill_v_buffer.zero_()
+
+        # Clear all pending async transfer events
+        self.pending_events.clear()
+
     # ========== Memory info ==========
 
     def gpu_memory_bytes(self) -> int: