From 01e3f4682e2071ae110a593a219685a3ef7e201f Mon Sep 17 00:00:00 2001
From: ishandhanani <82981111+ishandhanani@users.noreply.github.com>
Date: Mon, 9 Feb 2026 14:39:15 -0600
Subject: [PATCH] feat(kv-events): Add medium field to KV event types for
 storage tier tracking (#18205)

---
 python/sglang/srt/disaggregation/kv_events.py | 7 +++++++
 python/sglang/srt/mem_cache/radix_cache.py    | 6 +++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/python/sglang/srt/disaggregation/kv_events.py b/python/sglang/srt/disaggregation/kv_events.py
index 22c7aeeb3..b8048ee6b 100644
--- a/python/sglang/srt/disaggregation/kv_events.py
+++ b/python/sglang/srt/disaggregation/kv_events.py
@@ -56,16 +56,23 @@ class KVCacheEvent(
     """Base class for all KV cache-related events"""
 
 
+# Medium values for hicache storage tiers 
+MEDIUM_GPU = "GPU"
+MEDIUM_CPU = "CPU_PINNED"
+
+
 class BlockStored(KVCacheEvent):
     block_hashes: list[int]
     parent_block_hash: Optional[int]
     token_ids: list[int]
     block_size: int
     lora_id: Optional[int]
+    medium: Optional[str] = None
 
 
 class BlockRemoved(KVCacheEvent):
     block_hashes: list[int]
+    medium: Optional[str] = None
 
 
 class AllBlocksCleared(KVCacheEvent):
diff --git a/python/sglang/srt/mem_cache/radix_cache.py b/python/sglang/srt/mem_cache/radix_cache.py
index fcec2c9ac..9dba0b349 100644
--- a/python/sglang/srt/mem_cache/radix_cache.py
+++ b/python/sglang/srt/mem_cache/radix_cache.py
@@ -35,6 +35,7 @@ import torch
 logger = logging.getLogger(__name__)
 
 from sglang.srt.disaggregation.kv_events import (
+    MEDIUM_GPU,
     AllBlocksCleared,
     BlockRemoved,
     BlockStored,
@@ -822,6 +823,7 @@ class RadixCache(BasePrefixCache):
                         token_ids=page_tokens,
                         block_size=len(page_tokens),
                         lora_id=None,
+                        medium=MEDIUM_GPU,
                     )
                 )
 
@@ -843,7 +845,9 @@ class RadixCache(BasePrefixCache):
 
                 block_hash = hash_str_to_int64(node.hash_value[page_index])
 
-                self.kv_event_queue.append(BlockRemoved(block_hashes=[block_hash]))
+                self.kv_event_queue.append(
+                    BlockRemoved(block_hashes=[block_hash], medium=MEDIUM_GPU)
+                )
 
                 page_index += 1