[Feature] Add process-local in-memory KV indexer and Router integration (#33370)

Co-authored-by: Wu, Yutong <yutong.wu@amd.com>
Co-authored-by: TianDi101 <ditian12@amd.com>
Co-authored-by: Zhangheng <hzh0425@apache.org>

experimental/sgl-router/sgl-kv-indexer/tests/common/kv.rs

@@ -0,0 +1,57 @@
+// SPDX-FileCopyrightText: Copyright (c) 2026 The SGLang Authors
+// SPDX-License-Identifier: Apache-2.0
+
+use sgl_kv_indexer::pb::{
+    ApplyExternalKvBatchRequest, ExternalKvAction, ExternalKvActionType, TierType,
+};
+
+pub fn hbm() -> i32 {
+    TierType::TierHbm as i32
+}
+
+pub fn dram() -> i32 {
+    TierType::TierDram as i32
+}
+
+pub fn action(kind: ExternalKvActionType, tier: i32, hashes: &[i64]) -> ExternalKvAction {
+    ExternalKvAction {
+        r#type: kind as i32,
+        tier,
+        hashes: hashes.to_vec(),
+        component_masks: Vec::new(),
+        block_sizes: Vec::new(),
+    }
+}
+
+/// A component-aware REPORT action: each hash carries its component bitmask and
+/// token count, index-aligned with `hashes`.
+#[allow(dead_code)] // used by memory_integration, not grpc_contract
+pub fn component_report(
+    tier: i32,
+    hashes: &[i64],
+    masks: &[u32],
+    block_sizes: &[u32],
+) -> ExternalKvAction {
+    ExternalKvAction {
+        r#type: ExternalKvActionType::ActionReport as i32,
+        tier,
+        hashes: hashes.to_vec(),
+        component_masks: masks.to_vec(),
+        block_sizes: block_sizes.to_vec(),
+    }
+}
+
+pub fn apply_request(
+    worker: &str,
+    address: &str,
+    seq: u64,
+    actions: Vec<ExternalKvAction>,
+) -> ApplyExternalKvBatchRequest {
+    ApplyExternalKvBatchRequest {
+        worker_id: worker.to_string(),
+        seq,
+        actions,
+        worker_address: address.to_string(),
+        cache_spec: None,
+    }
+}