[MLX] Support Qwen3.5 (dense) Model (#25754)

Signed-off-by: Xiaodong Ye <yeahdongcn@gmail.com>
Co-authored-by: Alex Nails <alex.nails@radixark.ai>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.isort.cfg

@@ -1,3 +1,4 @@
 [settings]
 profile=black
 known_first_party=sglang
+known_third_party=mlx,mlx_lm

python/pyproject_other.toml

@@ -19,6 +19,7 @@ dependencies = ["aiohttp", "requests", "tqdm", "numpy", "IPython", "setproctitle
 runtime_common = [
   "IPython",
   "aiohttp",
+  "apache-tvm-ffi",
   "anthropic>=0.20.0",
   "blobfile==3.0.0",
   "av",

python/sglang/bench_one_batch.py

@@ -536,7 +536,7 @@ class _MlxBenchRunner:
         if server_args.max_total_tokens is not None:
             init_kwargs["pool_size"] = server_args.max_total_tokens
         self.mlx_runner = MlxModelRunner(**init_kwargs)
-        self.mlx_runner.init_kv_pool(req_to_token_pool=None)
+        self.mlx_runner.init_cache_pools(req_to_token_pool=None)
         self.fake_torch_runner = model_runner
 
     def clear(self):

python/sglang/srt/entrypoints/http_server.py

@@ -164,6 +164,7 @@ from sglang.srt.utils import (
     add_prometheus_track_response_middleware,
     delete_directory,
     get_bool_env_var,
+    is_mps,
     kill_process_tree,
     set_uvicorn_logging_configs,
 )
@@ -1903,8 +1904,8 @@ def _execute_server_warmup(server_args: ServerArgs):
 
     model_info = res.json()
 
-    # Construct a warmup request
+    # Construct a warmup request (MLX: text warmup for VLM-advertising models; TODO: enable image warmup).
-    is_vlm = bool(model_info.get("has_image_understanding", False))
+    is_vlm = bool(model_info.get("has_image_understanding", False)) and not is_mps()
     if model_info["is_generation"]:
         if is_vlm and not server_args.skip_tokenizer_init:
             request_name = "/v1/chat/completions"

python/sglang/srt/hardware_backend/mlx/aot.py

@@ -13,8 +13,8 @@ from sglang.srt.environ import envs
 logger = logging.getLogger(__name__)
 
 if TYPE_CHECKING:
-    from sglang.srt.hardware_backend.mlx.kv_cache.contiguous_cache import (
+    from sglang.srt.hardware_backend.mlx.kv_cache.attention_kv_cache import (
-        ContiguousKVCache,
+        ContiguousAttentionKVCache,
     )
 
 
@@ -123,6 +123,10 @@ class MlxAOTKernelRegistry:
 
 
 def _build_rope_kernel(inputs: MlxAOTKernelBuildInputs) -> MlxAOTRoPEKernel:
+    from sglang.srt.hardware_backend.mlx.kv_cache.attention_contract import (
+        get_num_heads,
+    )
+
     sample_attn = getattr(inputs.sample_attn, "_inner", inputs.sample_attn)
     rope = getattr(sample_attn, "rope", None)
     if rope is None or getattr(rope, "traditional", False):
@@ -136,10 +140,13 @@ def _build_rope_kernel(inputs: MlxAOTKernelBuildInputs) -> MlxAOTRoPEKernel:
         return MlxAOTRoPEKernel()
 
     base = float(getattr(rope, "base", 10000.0))
+    num_qo_heads = get_num_heads(sample_attn)
+    if num_qo_heads is None:
+        return MlxAOTRoPEKernel()
     config = {
         "head_dim": int(inputs.head_dim),
         "rope_dim": rope_dim,
-        "num_qo_heads": int(sample_attn.n_heads),
+        "num_qo_heads": int(num_qo_heads),
         "num_kv_heads": int(inputs.n_kv_heads),
     }
     try:
@@ -196,7 +203,7 @@ class MlxAOTKernelContext:
         req_ids: list[str],
         req_pool_idx: dict[str, int],
         req_to_token_pool: Any | None,
-        layer_caches: list[list[ContiguousKVCache]],
+        layer_caches: list[list[ContiguousAttentionKVCache]],
     ) -> "MlxAOTKernelContext":
         """Build optional AOT context for one batched decode step."""
         if not aot_kernels.rope.enabled or kv_pool is None:

python/sglang/srt/hardware_backend/mlx/kv_cache/__init__.py

@@ -1,5 +1,20 @@
-"""KV cache components for the MLX backend."""
+"""Cache components for the MLX backend."""
 
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_contract import (
+    get_head_dim,
+    get_num_heads,
+    get_num_kv_heads,
+    is_attention_module,
+    uses_sliding_window_attention,
+)
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_kv_cache import (
+    AttentionOffsetCache,
+    ContiguousAttentionKVCache,
+    PoolBackedAttentionKVCache,
+)
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_kv_pool import (
+    MlxAttentionKVPool,
+)
 from sglang.srt.hardware_backend.mlx.kv_cache.attention_wrapper import (
     BatchedDecodeContext,
     MLXAttentionWrapper,
@@ -7,12 +22,12 @@ from sglang.srt.hardware_backend.mlx.kv_cache.attention_wrapper import (
     get_context,
     set_context,
 )
-from sglang.srt.hardware_backend.mlx.kv_cache.contiguous_cache import (
+from sglang.srt.hardware_backend.mlx.kv_cache.auxiliary_state import (
-    ContiguousKVCache,
+    MlxAuxiliaryStateComponent,
-    OffsetCache,
+    MlxAuxiliaryStatePool,
-    PoolBackedCache,
+    MlxAuxiliaryStateReqToTokenPool,
 )
-from sglang.srt.hardware_backend.mlx.kv_cache.kv_pool import MlxKVPool
+from sglang.srt.hardware_backend.mlx.kv_cache.layout import MlxModelCacheLayout
 from sglang.srt.hardware_backend.mlx.kv_cache.model_patching import (
     find_attention_layers,
     get_num_layers,
@@ -22,14 +37,23 @@ from sglang.srt.hardware_backend.mlx.kv_cache.model_patching import (
 __all__ = [
     "BatchedDecodeContext",
     "clear_context",
-    "ContiguousKVCache",
+    "AttentionOffsetCache",
+    "ContiguousAttentionKVCache",
     "find_attention_layers",
+    "get_head_dim",
     "get_context",
     "get_num_layers",
+    "get_num_heads",
+    "get_num_kv_heads",
+    "is_attention_module",
     "MLXAttentionWrapper",
-    "MlxKVPool",
+    "MlxAttentionKVPool",
-    "OffsetCache",
+    "MlxAuxiliaryStateComponent",
+    "MlxAuxiliaryStatePool",
+    "MlxAuxiliaryStateReqToTokenPool",
+    "MlxModelCacheLayout",
     "patch_model_attention",
-    "PoolBackedCache",
+    "PoolBackedAttentionKVCache",
     "set_context",
+    "uses_sliding_window_attention",
 ]

python/sglang/srt/hardware_backend/mlx/kv_cache/attention_contract.py

@@ -0,0 +1,66 @@
+"""Attention helpers based on duck typing for the MLX backend."""
+
+from __future__ import annotations
+
+from typing import Any, Iterable
+
+# ``rope`` and ``scale`` are required by MLXAttentionWrapper. Keeping them in
+# the contract also prevents recurrent mixers such as DeltaNet from being
+# mistaken for softmax attention just because they expose projection layers.
+ATTENTION_API_ATTRS = ("q_proj", "k_proj", "v_proj", "o_proj", "rope", "scale")
+NUM_HEAD_ATTRS = ("n_heads", "num_heads", "num_attention_heads")
+NUM_KV_HEAD_ATTRS = ("n_kv_heads", "num_k_heads", "num_kv_heads", "num_key_value_heads")
+SLIDING_ATTENTION_ATTRS = (
+    "is_sliding",
+    "use_sliding",
+    "is_sliding_window",
+    "use_sliding_window",
+    "is_swa",
+)
+
+
+def first_present_attr(module: Any, names: Iterable[str]) -> Any | None:
+    """Return the first present attribute value without treating 0 as absent."""
+    for name in names:
+        if hasattr(module, name):
+            return getattr(module, name)
+    return None
+
+
+def get_num_heads(module: Any) -> int | None:
+    return first_present_attr(module, NUM_HEAD_ATTRS)
+
+
+def get_num_kv_heads(module: Any) -> int | None:
+    return first_present_attr(module, NUM_KV_HEAD_ATTRS)
+
+
+def get_head_dim(module: Any) -> int | None:
+    head_dim = first_present_attr(module, ("head_dim",))
+    if head_dim is not None:
+        return head_dim
+
+    n_kv_heads = get_num_kv_heads(module)
+    if n_kv_heads is None:
+        return None
+    if hasattr(module, "hidden_size") and hasattr(module, "num_k_heads"):
+        return module.hidden_size // module.num_k_heads
+    if hasattr(module, "k_proj") and hasattr(module.k_proj, "weight"):
+        return module.k_proj.weight.shape[0] // n_kv_heads
+    return None
+
+
+def is_attention_module(module: Any) -> bool:
+    return (
+        all(hasattr(module, attr) for attr in ATTENTION_API_ATTRS)
+        and get_num_heads(module) is not None
+        and get_num_kv_heads(module) is not None
+    )
+
+
+def uses_sliding_window_attention(*modules: Any) -> bool:
+    return any(
+        bool(getattr(module, attr, False))
+        for module in modules
+        for attr in SLIDING_ATTENTION_ATTRS
+    )

python/sglang/srt/hardware_backend/mlx/kv_cache/attention_kv_cache.py

@@ -1,4 +1,4 @@
-"""ContiguousKVCache, PoolBackedCache and OffsetCache for MLX backend."""
+"""Attention KV cache adapters for the MLX backend."""
 
 from __future__ import annotations
 
@@ -7,10 +7,12 @@ from typing import TYPE_CHECKING
 import mlx.core as mx
 
 if TYPE_CHECKING:
-    from sglang.srt.hardware_backend.mlx.kv_cache.kv_pool import MlxKVPool
+    from sglang.srt.hardware_backend.mlx.kv_cache.attention_kv_pool import (
+        MlxAttentionKVPool,
+    )
 
 
-class OffsetCache:
+class AttentionOffsetCache:
     """Data-free shim satisfying mlx-lm's cache protocol.
 
     Provides ``make_mask`` and ``state`` without storing actual K/V.
@@ -27,14 +29,14 @@ class OffsetCache:
         return None if N == 1 else "causal"
 
     def update_and_fetch(self, keys, values):
-        raise RuntimeError("OffsetCache should not store data")
+        raise RuntimeError("AttentionOffsetCache should not store data")
 
 
 _DEFAULT_MAX_SEQ_LEN = 4096
 
 
-class ContiguousKVCache:
+class ContiguousAttentionKVCache:
-    """Pre-allocated KV buffer for one request × one layer.
+    """Pre-allocated attention KV buffer for one request and one layer.
 
     Shape ``(1, n_kv_heads, max_seq_len, head_dim)``.  Slice assignment
     instead of ``mx.concatenate``.  Lazy-allocated on first write.
@@ -119,12 +121,12 @@ class ContiguousKVCache:
         return self.keys[:, :, : self.offset, :], self.values[:, :, : self.offset, :]
 
 
-class PoolBackedCache:
+class PoolBackedAttentionKVCache:
-    """Lazily gathers cached KV from the shared pool during forward pass.
+    """Lazily gathers cached attention KV from the shared pool during forward.
 
     Each ``update_and_fetch`` gathers this layer's prefix from the pool
     on demand, keeping operations in the lazy compute graph.  Convert to
-    ``ContiguousKVCache`` via ``to_contiguous`` after the forward pass.
+    ``ContiguousAttentionKVCache`` via ``to_contiguous`` after the forward pass.
     """
 
     __slots__ = (
@@ -140,7 +142,7 @@ class PoolBackedCache:
 
     def __init__(
         self,
-        pool: MlxKVPool,
+        pool: MlxAttentionKVPool,
         layer_idx: int,
         slots: mx.array,
         prefix_len: int,
@@ -197,9 +199,9 @@ class PoolBackedCache:
         self._new_values = values
         return k_all, v_all
 
-    def to_contiguous(self, max_seq_len: int = 4096) -> ContiguousKVCache:
+    def to_contiguous(self, max_seq_len: int = 4096) -> ContiguousAttentionKVCache:
-        """Convert to ContiguousKVCache reusing forward-pass arrays."""
+        """Convert to contiguous attention KV reusing forward-pass arrays."""
-        cache = ContiguousKVCache(max_seq_len=max_seq_len)
+        cache = ContiguousAttentionKVCache(max_seq_len=max_seq_len)
         if self._full_keys is not None:
             cache.update_and_fetch(self._full_keys, self._full_values)
         return cache

python/sglang/srt/hardware_backend/mlx/kv_cache/attention_kv_pool.py

@@ -1,4 +1,10 @@
-"""Flat KV pool with per-layer buffers of shape (pool_size, n_kv_heads, head_dim).
+"""Flat attention KV pool for the MLX backend.
+
+Each layer buffer has shape ``(pool_size, n_kv_heads, head_dim)``.
+This v1 pool is intentionally uniform: every wrapped softmax-attention
+layer must share the same KV shape and full-context KV semantics.
+Heterogeneous KV shapes and sliding-window KV need per-layer/window-aware
+pools before they can use MLX radix reuse.
 
 Slot 0 is reserved as padding (1-based indexing).
 """
@@ -10,8 +16,8 @@ import mlx.core as mx
 logger = logging.getLogger(__name__)
 
 
-class MlxKVPool:
+class MlxAttentionKVPool:
-    """Pre-allocated KV pool indexed by integer slot IDs."""
+    """Pre-allocated attention KV pool indexed by integer slot IDs."""
 
     def __init__(
         self,
@@ -27,7 +33,7 @@ class MlxKVPool:
         self.head_dim = head_dim
         self.dtype = dtype
 
-        # Per-layer buffers: (pool_size, n_kv_heads, head_dim)
+        # Per-attention-layer buffers: (pool_size, n_kv_heads, head_dim)
         self.k_buffer: list[mx.array] = [
             mx.zeros((pool_size, n_kv_heads, head_dim), dtype=dtype)
             for _ in range(num_layers)
@@ -41,8 +47,8 @@ class MlxKVPool:
             1024 * 1024
         )
         logger.info(
-            f"MlxKVPool: {pool_size} slots × {num_layers} layers "
+            f"MlxAttentionKVPool: {pool_size} slots x {num_layers} layers "
-            f"× {n_kv_heads} heads × {head_dim} dim, "
+            f"x {n_kv_heads} heads x {head_dim} dim, "
             f"dtype={dtype}, ~{mem_mb:.1f} MB"
         )
 

python/sglang/srt/hardware_backend/mlx/kv_cache/attention_wrapper.py

@@ -14,7 +14,14 @@ from sglang.srt.hardware_backend.mlx.aot import (
     MlxAOTKernelSet,
     MlxAOTRoPEContext,
 )
-from sglang.srt.hardware_backend.mlx.kv_cache.contiguous_cache import ContiguousKVCache
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_contract import (
+    get_head_dim,
+    get_num_heads,
+    get_num_kv_heads,
+)
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_kv_cache import (
+    ContiguousAttentionKVCache,
+)
 
 _thread_local = threading.local()
 
@@ -26,8 +33,9 @@ class BatchedDecodeContext:
 
     batch_size: int
     seq_lens: list[int]  # per-request token count before the new token
-    # layer_caches[layer_idx][req_idx] = ContiguousKVCache
+    # attention_layer_caches[attention_pool_idx][req_idx] = ContiguousAttentionKVCache
-    layer_caches: list[list[ContiguousKVCache]]
+    attention_layer_caches: list[list[ContiguousAttentionKVCache]]
+    attention_pool_index_by_layer: dict[int, int] = field(default_factory=dict)
 
     # Optional AOT kernel state. Keep kernel-specific fields out of the regular
     # MLX decode path so future AOT kernels can be added without growing this
@@ -51,36 +59,46 @@ class BatchedDecodeContext:
         self.needs_padding = min(seq_lens) < max_seq_len
         self.pad_sizes = [max_seq_len - s for s in seq_lens]
         self.positions = mx.arange(self.max_len) if self.needs_padding else None
+        if not self.attention_pool_index_by_layer:
+            self.attention_pool_index_by_layer = {
+                idx: idx for idx in range(len(self.attention_layer_caches))
+            }
 
     @classmethod
     def from_decode(
         cls,
         *,
-        caches: list[list[ContiguousKVCache]],
+        caches: list[list[Any]],
-        num_layers: int,
         req_ids: list[str],
         aot_kernels: MlxAOTKernelSet,
         kv_pool: Any | None,
         req_pool_idx: dict[str, int],
         req_to_token_pool: Any | None,
+        attention_layer_indices: list[int] | None = None,
+        attention_pool_index_by_layer: dict[int, int] | None = None,
     ) -> "BatchedDecodeContext":
         batch_size = len(req_ids)
-        seq_lens = [caches[i][0].offset for i in range(batch_size)]
+        if attention_layer_indices is None:
-        layer_caches = [
+            attention_layer_indices = list(range(len(caches[0])))
+        seq_lens = [
+            caches[i][attention_layer_indices[0]].offset for i in range(batch_size)
+        ]
+        attention_layer_caches = [
             [caches[i][layer_idx] for i in range(batch_size)]
-            for layer_idx in range(num_layers)
+            for layer_idx in attention_layer_indices
         ]
         return cls(
             batch_size=batch_size,
             seq_lens=seq_lens,
-            layer_caches=layer_caches,
+            attention_layer_caches=attention_layer_caches,
+            attention_pool_index_by_layer=attention_pool_index_by_layer or {},
             aot=MlxAOTKernelContext.from_decode(
                 aot_kernels=aot_kernels,
                 kv_pool=kv_pool,
                 req_ids=req_ids,
                 req_pool_idx=req_pool_idx,
                 req_to_token_pool=req_to_token_pool,
-                layer_caches=layer_caches,
+                layer_caches=attention_layer_caches,
             ),
         )
 
@@ -119,15 +137,38 @@ class MLXAttentionWrapper(nn.Module):
         inner = self._inner
         layer_idx = self._layer_idx
         B = ctx.batch_size
+        n_heads = get_num_heads(inner)
+        n_kv_heads = get_num_kv_heads(inner)
+        if n_heads is None or n_kv_heads is None:
+            raise RuntimeError(
+                f"Cannot determine attention head counts for {type(inner).__name__}"
+            )
 
-        queries = inner.q_proj(x)
+        q_proj_output = inner.q_proj(x)
         keys = inner.k_proj(x)
         values = inner.v_proj(x)
 
-        head_dim = queries.shape[-1] // inner.n_heads
+        head_dim = get_head_dim(inner)
-        queries = queries.reshape(B, 1, inner.n_heads, head_dim)
+        if head_dim is None:
-        keys = keys.reshape(B, 1, inner.n_kv_heads, head_dim)
+            head_dim = keys.shape[-1] // n_kv_heads
-        values = values.reshape(B, 1, inner.n_kv_heads, head_dim)
+
+        q_width = n_heads * head_dim
+        gate = None
+        if q_proj_output.shape[-1] == q_width:
+            queries = q_proj_output.reshape(B, 1, n_heads, head_dim)
+        elif q_proj_output.shape[-1] == 2 * q_width:
+            queries, gate = mx.split(
+                q_proj_output.reshape(B, 1, n_heads, 2 * head_dim), 2, axis=-1
+            )
+            gate = gate.reshape(B, 1, q_width)
+        else:
+            raise RuntimeError(
+                f"Unexpected q_proj output shape {q_proj_output.shape} for "
+                f"{type(inner).__name__}"
+            )
+
+        keys = keys.reshape(B, 1, n_kv_heads, head_dim)
+        values = values.reshape(B, 1, n_kv_heads, head_dim)
 
         if hasattr(inner, "q_norm"):
             queries = inner.q_norm(queries)
@@ -140,6 +181,7 @@ class MLXAttentionWrapper(nn.Module):
 
         # Vectorized RoPE with per-batch offsets (cached on the context).
         offsets = ctx.offsets
+        attention_pool_idx = ctx.attention_pool_index_by_layer[layer_idx]
 
         if ctx.aot.rope is not None:
             # AOT path: real .metallib RoPE + fused KV pool scatter.
@@ -148,7 +190,7 @@ class MLXAttentionWrapper(nn.Module):
                 keys,
                 values,
                 offsets,
-                layer_idx,
+                attention_pool_idx,
                 ctx.aot.rope,
             )
         else:
@@ -157,7 +199,7 @@ class MLXAttentionWrapper(nn.Module):
             queries = inner.rope(queries, offset=offsets)
             keys = inner.rope(keys, offset=offsets)
 
-        layer_caches = ctx.layer_caches[layer_idx]
+        layer_caches = ctx.attention_layer_caches[attention_pool_idx]
         pad_sizes = ctx.pad_sizes
 
         # TODO: replace per-request loop with native batched/ragged
@@ -173,12 +215,8 @@ class MLXAttentionWrapper(nn.Module):
 
             pad = pad_sizes[i]
             if pad > 0:
-                k_pad = mx.zeros(
+                k_pad = mx.zeros((1, n_kv_heads, pad, head_dim), dtype=k_all.dtype)
-                    (1, inner.n_kv_heads, pad, head_dim), dtype=k_all.dtype
+                v_pad = mx.zeros((1, n_kv_heads, pad, head_dim), dtype=v_all.dtype)
-                )
-                v_pad = mx.zeros(
-                    (1, inner.n_kv_heads, pad, head_dim), dtype=v_all.dtype
-                )
                 k_all = mx.concatenate([k_all, k_pad], axis=2)
                 v_all = mx.concatenate([v_all, v_pad], axis=2)
 
@@ -202,6 +240,8 @@ class MLXAttentionWrapper(nn.Module):
         )
 
         output = output.transpose(0, 2, 1, 3).reshape(B, 1, -1)
+        if gate is not None:
+            output = output * mx.sigmoid(gate)
         return inner.o_proj(output)
 
     @staticmethod
@@ -210,7 +250,7 @@ class MLXAttentionWrapper(nn.Module):
         keys: mx.array,
         values: mx.array,
         positions: mx.array,
-        layer_idx: int,
+        attention_pool_idx: int,
         rope_ctx: MlxAOTRoPEContext,
     ) -> tuple[mx.array, mx.array]:
         """AOT path: rotate Q/K and scatter K/V into the shared pool.
@@ -234,8 +274,8 @@ class MLXAttentionWrapper(nn.Module):
         else:
             slots = rope_ctx.new_token_slots.astype(mx.int32)
 
-        k_pool = rope_ctx.kv_pool.k_buffer[layer_idx]
+        k_pool = rope_ctx.kv_pool.k_buffer[attention_pool_idx]
-        v_pool = rope_ctx.kv_pool.v_buffer[layer_idx]
+        v_pool = rope_ctx.kv_pool.v_buffer[attention_pool_idx]
 
         q_rot, k_rot, k_pool_new, v_pool_new = rope_ctx.kernel.rope_pool_fused(
             q_flat,
@@ -251,8 +291,8 @@ class MLXAttentionWrapper(nn.Module):
             rope_base=rope_ctx.kernel.base,
         )
         # Rebind pool buffers (zero-copy donation result).
-        rope_ctx.kv_pool.k_buffer[layer_idx] = k_pool_new
+        rope_ctx.kv_pool.k_buffer[attention_pool_idx] = k_pool_new
-        rope_ctx.kv_pool.v_buffer[layer_idx] = v_pool_new
+        rope_ctx.kv_pool.v_buffer[attention_pool_idx] = v_pool_new
 
         # (B, n_heads, head_dim) -> (B, n_heads, 1, head_dim) for SDPA path
         return q_rot[:, :, None, :], k_rot[:, :, None, :]

python/sglang/srt/hardware_backend/mlx/kv_cache/auxiliary_state.py

@@ -0,0 +1,390 @@
+"""MLX auxiliary-state snapshots for unified radix cache.
+
+Hybrid MLX models may include non-softmax-attention layers whose native
+``mlx-lm`` cache state cannot be reconstructed from the attention KV pool.
+The global scheduler exposes that state through its existing MAMBA component
+contract, so this MLX adapter keeps those scheduler-facing field names while
+storing model-agnostic native cache snapshots.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any, Iterable, Optional
+
+import mlx.core as mx
+import torch
+
+from sglang.srt.mem_cache.base_prefix_cache import EvictParams, InsertResult
+from sglang.srt.mem_cache.memory_pool import ReqToTokenPool
+from sglang.srt.mem_cache.unified_cache_components.mamba_component import (
+    MambaComponent,
+)
+from sglang.srt.mem_cache.unified_cache_components.tree_component import TreeComponent
+
+_CACHE_ATTRS = ("offset", "lengths", "left_padding")
+_MISSING = object()
+
+
+def _clone_tree(value: Any) -> Any:
+    if isinstance(value, mx.array):
+        return mx.array(value)
+    if isinstance(value, list):
+        return [_clone_tree(item) for item in value]
+    if isinstance(value, tuple):
+        return tuple(_clone_tree(item) for item in value)
+    if isinstance(value, dict):
+        return {key: _clone_tree(item) for key, item in value.items()}
+    return value
+
+
+def _arrays_in_tree(value: Any) -> list[mx.array]:
+    arrays: list[mx.array] = []
+
+    def collect(item: Any) -> None:
+        if isinstance(item, mx.array):
+            arrays.append(item)
+        elif isinstance(item, (list, tuple)):
+            for child in item:
+                collect(child)
+        elif isinstance(item, dict):
+            for child in item.values():
+                collect(child)
+
+    collect(value)
+    return arrays
+
+
+@dataclass
+class _CacheSnapshot:
+    state: Any
+    meta_state: Any = _MISSING
+    attrs: dict[str, Any] | None = None
+
+
+def _snapshot_cache(cache: Any) -> _CacheSnapshot:
+    state = _clone_tree(getattr(cache, "state", ()))
+    meta_state = (
+        _clone_tree(cache.meta_state) if hasattr(cache, "meta_state") else _MISSING
+    )
+    attrs = {
+        name: _clone_tree(getattr(cache, name))
+        for name in _CACHE_ATTRS
+        if hasattr(cache, name)
+    }
+    arrays = _arrays_in_tree((state, meta_state, attrs))
+    if arrays:
+        mx.eval(*arrays)
+    return _CacheSnapshot(state=state, meta_state=meta_state, attrs=attrs)
+
+
+def _restore_cache(cache: Any, snapshot: _CacheSnapshot) -> None:
+    cache.state = _clone_tree(snapshot.state)
+    if snapshot.meta_state is not _MISSING and hasattr(cache, "meta_state"):
+        cache.meta_state = _clone_tree(snapshot.meta_state)
+    for name, value in (snapshot.attrs or {}).items():
+        setattr(cache, name, _clone_tree(value))
+
+
+class MlxAuxiliaryStatePool:
+    """Index-addressable snapshots of native MLX auxiliary cache state."""
+
+    def __init__(self, size: int, device: str):
+        self.size = size
+        self.device = device
+        self.mamba_cache = None
+        self.mem_usage = 0
+        self._snapshots: dict[int, dict[int, _CacheSnapshot]] = {}
+        self.clear()
+
+    def _tensor(self, indices: Any) -> torch.Tensor:
+        return torch.as_tensor(indices, dtype=torch.int64, device=self.device).view(-1)
+
+    def _index(self, index: Any) -> int:
+        flat = self._tensor(index)
+        assert flat.numel() == 1
+        return int(flat.item())
+
+    def available_size(self) -> int:
+        return int(self.free_slots.numel())
+
+    def alloc(self, need_size: int) -> Optional[torch.Tensor]:
+        if need_size > self.available_size():
+            return None
+        slots = self.free_slots[:need_size].clone()
+        self.free_slots = self.free_slots[need_size:]
+        for slot in slots.tolist():
+            self._snapshots.pop(int(slot), None)
+        return slots
+
+    def free(self, indices: Any) -> None:
+        if indices is None:
+            return
+        indices = self._tensor(indices)
+        if indices.numel() == 0:
+            return
+        for slot in indices.tolist():
+            self._snapshots.pop(int(slot), None)
+        self.free_slots = torch.cat([self.free_slots, indices])
+
+    def clear(self) -> None:
+        self.free_slots = torch.arange(
+            1, self.size + 1, dtype=torch.int64, device=self.device
+        )
+        self._snapshots.clear()
+
+    def copy_from(self, src: Any, dst: Any) -> None:
+        src_indices = self._tensor(src)
+        dst_indices = self._tensor(dst)
+        assert src_indices.numel() == dst_indices.numel()
+        for src_idx, dst_idx in zip(src_indices.tolist(), dst_indices.tolist()):
+            snapshot = self._snapshots.get(int(src_idx))
+            if snapshot is None:
+                self._snapshots.pop(int(dst_idx), None)
+            else:
+                self._snapshots[int(dst_idx)] = {
+                    layer_idx: _CacheSnapshot(
+                        state=_clone_tree(cache_snapshot.state),
+                        meta_state=_clone_tree(cache_snapshot.meta_state),
+                        attrs=_clone_tree(cache_snapshot.attrs),
+                    )
+                    for layer_idx, cache_snapshot in snapshot.items()
+                }
+
+    def fork_from(self, src: Any) -> Optional[torch.Tensor]:
+        src_indices = self._tensor(src)
+        dst = self.alloc(src_indices.numel())
+        if dst is None:
+            return None
+        self.copy_from(src_indices, dst)
+        return dst
+
+    def store_cache(
+        self,
+        index: Any,
+        cache: list[Any],
+        layer_indices: Iterable[int],
+    ) -> None:
+        self._snapshots[self._index(index)] = {
+            layer_idx: _snapshot_cache(cache[layer_idx]) for layer_idx in layer_indices
+        }
+
+    def restore_cache(
+        self,
+        index: Any,
+        cache: list[Any],
+        layer_indices: Iterable[int] | None = None,
+    ) -> bool:
+        snapshot = self._snapshots.get(self._index(index))
+        if snapshot is None:
+            return False
+        selected_layers = set(layer_indices) if layer_indices is not None else None
+        for layer_idx, cache_snapshot in snapshot.items():
+            if selected_layers is not None and layer_idx not in selected_layers:
+                continue
+            _restore_cache(cache[layer_idx], cache_snapshot)
+        return True
+
+    def has_snapshot(self, index: Any) -> bool:
+        return self._index(index) in self._snapshots
+
+
+class MlxAuxiliaryStateReqToTokenPool(ReqToTokenPool):
+    """Req-to-token pool with MLX auxiliary-state slot bookkeeping."""
+
+    def __init__(
+        self,
+        *,
+        size: int,
+        max_context_len: int,
+        device: str,
+        enable_memory_saver: bool,
+        auxiliary_state_size: int,
+    ):
+        super().__init__(
+            size=size,
+            max_context_len=max_context_len,
+            device=device,
+            enable_memory_saver=enable_memory_saver,
+        )
+        self.mamba_pool = MlxAuxiliaryStatePool(
+            size=auxiliary_state_size,
+            device=device,
+        )
+        # The unified radix base MAMBA component still reads ``mamba_pool``.
+        # Keep the MLX-owned name beside it so local code can avoid model-
+        # specific terminology.
+        self.auxiliary_state_pool = self.mamba_pool
+        self.enable_mamba_extra_buffer = False
+        self.req_index_to_auxiliary_state_index_mapping = torch.zeros(
+            self._alloc_size, dtype=torch.int32, device=device
+        )
+
+    def alloc(self, reqs):
+        select_index = super().alloc(reqs)
+        if select_index is None:
+            return None
+
+        auxiliary_state_indices = []
+        for req in reqs:
+            if getattr(req, "mamba_pool_idx", None) is not None:
+                mid = req.mamba_pool_idx
+            else:
+                allocated = self.auxiliary_state_pool.alloc(1)
+                assert allocated is not None, "Not enough MLX auxiliary state slots"
+                mid = allocated[0]
+                req.mamba_pool_idx = mid
+            auxiliary_state_indices.append(mid.to(dtype=torch.int32))
+        self.req_index_to_auxiliary_state_index_mapping[select_index] = torch.stack(
+            auxiliary_state_indices
+        )
+        return select_index
+
+    def get_auxiliary_state_indices(self, req_indices) -> torch.Tensor:
+        return self.req_index_to_auxiliary_state_index_mapping[req_indices]
+
+    def get_mamba_indices(self, req_indices) -> torch.Tensor:
+        return self.get_auxiliary_state_indices(req_indices)
+
+    def get_mamba_ping_pong_other_idx(self, mamba_next_track_idx: int) -> int:
+        return 0
+
+    def free_mamba_cache(self, req, mamba_ping_pong_track_buffer_to_keep=None):
+        if getattr(req, "mamba_pool_idx", None) is not None:
+            self.auxiliary_state_pool.free(req.mamba_pool_idx.unsqueeze(0))
+            req.mamba_pool_idx = None
+        track_buffer = getattr(req, "mamba_ping_pong_track_buffer", None)
+        if track_buffer is not None:
+            if mamba_ping_pong_track_buffer_to_keep is None:
+                self.auxiliary_state_pool.free(track_buffer)
+            req.mamba_ping_pong_track_buffer = None
+            req.mamba_next_track_idx = None
+
+    def free_auxiliary_state_cache(self, req, track_buffer_to_keep=None):
+        self.free_mamba_cache(
+            req,
+            mamba_ping_pong_track_buffer_to_keep=track_buffer_to_keep,
+        )
+
+    def free(self, req):
+        super().free(req)
+
+    def clear(self):
+        super().clear()
+        self.auxiliary_state_pool.clear()
+        self.req_index_to_auxiliary_state_index_mapping.zero_()
+
+
+class MlxAuxiliaryStateComponent(MambaComponent):
+    """Unified radix component for MLX native auxiliary-state snapshots."""
+
+    def __init__(self, cache, params):
+        if params.enable_mamba_extra_buffer:
+            raise NotImplementedError(
+                "MLX auxiliary-state radix cache does not support "
+                "enable_mamba_extra_buffer yet."
+            )
+        pool = getattr(cache.req_to_token_pool, "auxiliary_state_pool", None)
+        if not isinstance(pool, MlxAuxiliaryStatePool):
+            raise TypeError(
+                "MlxAuxiliaryStateComponent requires MlxAuxiliaryStatePool, "
+                f"got {type(pool)}"
+            )
+        TreeComponent.__init__(self, cache, params)
+        self.enable_mamba_extra_buffer = False
+        self._mamba_pool_host = None
+
+    @staticmethod
+    def _tracked_value(req) -> tuple[object | None, bool]:
+        track_buffer = getattr(req, "mamba_ping_pong_track_buffer", None)
+        track_len = getattr(req, "mamba_last_track_seqlen", None)
+        if track_buffer is not None and track_len is not None:
+            return track_buffer[0].unsqueeze(-1).clone(), True
+        if getattr(req, "mamba_pool_idx", None) is None:
+            return None, False
+        return req.mamba_pool_idx.unsqueeze(-1).clone(), False
+
+    def prepare_for_caching_req(
+        self,
+        req,
+        insert_params,
+        token_ids_len: int,
+        is_finished: bool,
+    ) -> int | None:
+        cache_len = getattr(req, "mamba_last_track_seqlen", None)
+        auxiliary_value, uses_track_slot = self._tracked_value(req)
+        setattr(insert_params, "mlx_auxiliary_state_uses_track_slot", uses_track_slot)
+
+        if auxiliary_value is None:
+            return 0 if is_finished else None
+
+        if cache_len is None:
+            cache_len = token_ids_len
+        if is_finished:
+            insert_params.mamba_value = auxiliary_value
+        else:
+            source_value = auxiliary_value
+            forked_value = self.cache.req_to_token_pool.auxiliary_state_pool.fork_from(
+                source_value
+            )
+            if forked_value is None:
+                self.cache.evict(EvictParams(num_tokens=0, mamba_num=1))
+                forked_value = (
+                    self.cache.req_to_token_pool.auxiliary_state_pool.fork_from(
+                        source_value
+                    )
+                )
+                assert forked_value is not None, "Can not alloc MLX auxiliary cache"
+            insert_params.mamba_value = forked_value
+        return cache_len
+
+    def cleanup_after_caching_req(
+        self,
+        req,
+        is_finished: bool,
+        insert_result: InsertResult | None = None,
+        insert_params=None,
+    ) -> None:
+        if not is_finished:
+            if (
+                insert_params is not None
+                and insert_params.mamba_value is not None
+                and (insert_result is None or insert_result.mamba_exist)
+            ):
+                self.cache.req_to_token_pool.auxiliary_state_pool.free(
+                    insert_params.mamba_value
+                )
+            if bool(
+                getattr(insert_params, "mlx_auxiliary_state_uses_track_slot", False)
+            ):
+                track_buffer = getattr(req, "mamba_ping_pong_track_buffer", None)
+                if track_buffer is not None:
+                    self.cache.req_to_token_pool.auxiliary_state_pool.free(track_buffer)
+                req.mamba_ping_pong_track_buffer = None
+                req.mamba_next_track_idx = None
+            req.mamba_last_track_seqlen = None
+            return
+
+        auxiliary_value_exists = (
+            insert_result.mamba_exist if insert_result is not None else True
+        )
+        uses_track_slot = bool(
+            getattr(insert_params, "mlx_auxiliary_state_uses_track_slot", False)
+        )
+        if uses_track_slot:
+            keep_track_slot = not auxiliary_value_exists
+            self.cache.req_to_token_pool.free_auxiliary_state_cache(
+                req,
+                track_buffer_to_keep=0 if keep_track_slot else None,
+            )
+        elif auxiliary_value_exists:
+            self.cache.req_to_token_pool.free_auxiliary_state_cache(req)
+        else:
+            # The radix tree now owns the live auxiliary-state slot.
+            track_buffer = getattr(req, "mamba_ping_pong_track_buffer", None)
+            if track_buffer is not None:
+                self.cache.req_to_token_pool.auxiliary_state_pool.free(track_buffer)
+                req.mamba_ping_pong_track_buffer = None
+                req.mamba_next_track_idx = None
+            req.mamba_pool_idx = None
+        req.mamba_last_track_seqlen = None

python/sglang/srt/hardware_backend/mlx/kv_cache/layout.py

@@ -0,0 +1,93 @@
+"""Model cache layout helpers for the MLX backend."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+from typing import Any, Sequence
+
+
+@dataclass(frozen=True)
+class MlxModelCacheLayout:
+    """Map model layers to MLX cache storage components.
+
+    Attention layers store softmax-attention KV in the MLX attention KV pool.
+    Auxiliary layers keep native ``mlx-lm`` cache state and are snapshotted by
+    the MLX auxiliary-state component.
+    """
+
+    layers: tuple[Any, ...]
+    attention_attrs: tuple[str | None, ...]
+    attention_layer_indices: tuple[int, ...]
+    auxiliary_layer_indices: tuple[int, ...]
+    attention_pool_index_by_layer: dict[int, int]
+
+    @classmethod
+    def from_attention_discovery(
+        cls,
+        layers: Sequence[Any],
+        attention_attrs: Sequence[str | None],
+    ) -> "MlxModelCacheLayout":
+        if len(layers) != len(attention_attrs):
+            raise ValueError(
+                "Layer count and attention attribute count differ: "
+                f"{len(layers)} != {len(attention_attrs)}"
+            )
+
+        attention_layer_indices = tuple(
+            idx for idx, attr in enumerate(attention_attrs) if attr is not None
+        )
+        auxiliary_layer_indices = tuple(
+            idx for idx, attr in enumerate(attention_attrs) if attr is None
+        )
+        attention_pool_index_by_layer = {
+            layer_idx: pool_idx
+            for pool_idx, layer_idx in enumerate(attention_layer_indices)
+        }
+
+        return cls(
+            layers=tuple(layers),
+            attention_attrs=tuple(attention_attrs),
+            attention_layer_indices=attention_layer_indices,
+            auxiliary_layer_indices=auxiliary_layer_indices,
+            attention_pool_index_by_layer=attention_pool_index_by_layer,
+        )
+
+    @property
+    def num_layers(self) -> int:
+        return len(self.layers)
+
+    @property
+    def num_attention_layers(self) -> int:
+        return len(self.attention_layer_indices)
+
+    @property
+    def has_auxiliary_state(self) -> bool:
+        return bool(self.auxiliary_layer_indices)
+
+    @property
+    def first_attention_layer_index(self) -> int:
+        if not self.attention_layer_indices:
+            raise RuntimeError("MLX model has no supported attention layers")
+        return self.attention_layer_indices[0]
+
+    def attention_pool_index(self, layer_idx: int) -> int:
+        try:
+            return self.attention_pool_index_by_layer[layer_idx]
+        except KeyError as exc:
+            raise KeyError(f"Layer {layer_idx} is not an attention layer") from exc
+
+    def attention_attr(self, layer_idx: int) -> str:
+        attr = self.attention_attrs[layer_idx]
+        if attr is None:
+            raise KeyError(f"Layer {layer_idx} is not an attention layer")
+        return attr
+
+    def attention_layer_caches(
+        self,
+        caches_by_request: list[list[Any]],
+    ) -> list[list[Any]]:
+        """Return layer-major attention caches for batched decode."""
+        return [
+            [request_cache[layer_idx] for request_cache in caches_by_request]
+            for layer_idx in self.attention_layer_indices
+        ]

python/sglang/srt/hardware_backend/mlx/kv_cache/model_patching.py

@@ -2,25 +2,38 @@
 
 from typing import Any
 
+import mlx.nn as nn
+
+from sglang.srt.hardware_backend.mlx.kv_cache.attention_contract import (
+    is_attention_module,
+)
 from sglang.srt.hardware_backend.mlx.kv_cache.attention_wrapper import (
     MLXAttentionWrapper,
 )
 
 
-def find_attention_layers(model: Any) -> tuple[list[Any], str]:
+def _find_attention_attr(layer: Any) -> str | None:
-    """Find transformer layers and the attention attribute name."""
+    """Return the direct child name that satisfies the attention contract."""
+    if not isinstance(layer, nn.Module):
+        raise TypeError(f"Expected mlx.nn.Module layer, got {type(layer)}")
+    for name, module in layer.children().items():
+        if isinstance(module, MLXAttentionWrapper) or is_attention_module(module):
+            return name
+    return None
+
+
+def find_attention_layers(model: Any) -> tuple[list[Any], list[str | None]]:
+    """Find transformer layers and per-layer attention attribute names."""
     root = getattr(model, "language_model", model)
     container = getattr(root, "model", root)
     layer_list = getattr(container, "layers", None) or getattr(root, "layers", [])
 
     if layer_list:
-        sample = layer_list[0]
+        attn_attrs = [_find_attention_attr(layer) for layer in layer_list]
-        if hasattr(sample, "self_attn"):
+        if any(attr is not None for attr in attn_attrs):
-            return layer_list, "self_attn"
+            return layer_list, attn_attrs
-        if hasattr(sample, "attention"):
+        raise ValueError(f"No attention attribute in layer type {type(layer_list[0])}")
-            return layer_list, "attention"
+    return layer_list, []
-        raise ValueError(f"No attention attribute in layer type {type(sample)}")
-    return layer_list, "self_attn"
 
 
 def patch_model_attention(model: Any) -> int:
@@ -29,9 +42,11 @@ def patch_model_attention(model: Any) -> int:
     The wrapper delegates to the inner module when no BatchedDecodeContext
     is set, so it is always installed and never removed.
     """
-    layer_list, attn_attr = find_attention_layers(model)
+    layer_list, attn_attrs = find_attention_layers(model)
     patched = 0
-    for idx, layer in enumerate(layer_list):
+    for idx, (layer, attn_attr) in enumerate(zip(layer_list, attn_attrs)):
+        if attn_attr is None:
+            continue
         attn = getattr(layer, attn_attr)
         if isinstance(attn, MLXAttentionWrapper):
             continue

python/sglang/srt/hardware_backend/mlx/model_runner_stub.py

@@ -9,6 +9,9 @@ from typing import Tuple
 
 import torch
 
+from sglang.srt.hardware_backend.mlx.kv_cache.auxiliary_state import (
+    MlxAuxiliaryStateReqToTokenPool,
+)
 from sglang.srt.mem_cache.allocator import TokenToKVPoolAllocator
 from sglang.srt.mem_cache.memory_pool import KVCache, ReqToTokenPool
 from sglang.srt.model_executor.model_runner import ModelRunner
@@ -17,11 +20,11 @@ logger = logging.getLogger(__name__)
 
 
 class _DummyKVCache(KVCache):
-    """A KV cache that allocates no GPU memory.
+    """Scheduler-facing KV cache that allocates no GPU memory.
 
     Satisfies the KVCache interface so that TokenToKVPoolAllocator can be
-    constructed, but every buffer access raises — the MLX backend manages
+    constructed, but every buffer access raises. The MLX backend manages
-    its own KV cache internally.
+    attention KV and auxiliary state internally.
     """
 
     def __init__(self, size: int, dtype: torch.dtype, device: str):
@@ -42,16 +45,16 @@ class _DummyKVCache(KVCache):
         self.custom_mem_pool = None
 
     def get_key_buffer(self, layer_id: int) -> torch.Tensor:
-        raise RuntimeError("_DummyKVCache has no key buffer (MLX manages KV cache)")
+        raise RuntimeError("_DummyKVCache has no key buffer (MLX manages cache)")
 
     def get_value_buffer(self, layer_id: int) -> torch.Tensor:
-        raise RuntimeError("_DummyKVCache has no value buffer (MLX manages KV cache)")
+        raise RuntimeError("_DummyKVCache has no value buffer (MLX manages cache)")
 
     def get_kv_buffer(self, layer_id: int) -> Tuple[torch.Tensor, torch.Tensor]:
-        raise RuntimeError("_DummyKVCache has no kv buffer (MLX manages KV cache)")
+        raise RuntimeError("_DummyKVCache has no kv buffer (MLX manages cache)")
 
     def set_kv_buffer(self, layer, loc, cache_k, cache_v) -> None:
-        raise RuntimeError("_DummyKVCache cannot set kv buffer (MLX manages KV cache)")
+        raise RuntimeError("_DummyKVCache cannot set kv buffer (MLX manages cache)")
 
     def get_kv_size_bytes(self):
         return 0, 0
@@ -141,6 +144,18 @@ class MlxModelRunnerStub(ModelRunner):
         self.is_hybrid_swa = False
 
         # Create minimal pools
+        if self.mambaish_config is not None:
+            auxiliary_state_size = self.server_args.max_mamba_cache_size
+            if auxiliary_state_size is None:
+                auxiliary_state_size = self.max_running_requests * 4
+            self.req_to_token_pool = MlxAuxiliaryStateReqToTokenPool(
+                size=self.max_running_requests,
+                max_context_len=self.model_config.context_len,
+                device="cpu",
+                enable_memory_saver=False,
+                auxiliary_state_size=auxiliary_state_size,
+            )
+        else:
             self.req_to_token_pool = ReqToTokenPool(
                 size=self.max_running_requests,
                 max_context_len=self.model_config.context_len,

python/sglang/srt/hardware_backend/mlx/scheduler_mixin.py

@@ -6,11 +6,11 @@ the scheduler runs its CPU-side bookkeeping on the tokens of the
 older one.  The lazy-graph primitives live in
 ``hardware_backend/mlx/tp_worker.py`` and ``model_runner.py``.
 
-Each request's KV lives ina set of per-request, per-layer ``ContiguousKVCache``
+Each request's attention KV lives in per-request, per-layer
-objects that the ``MLXAttentionWrapper`` mutates in place during the forward pass.
+``ContiguousAttentionKVCache`` objects that ``MLXAttentionWrapper`` mutates
-Chained decodes reuse the same cache objects: step N+1's graph reads
+in place during the forward pass. Chained decodes reuse the same cache objects:
-step N's lazy writes via MLX's dependency tracking, so the GPU runs
+step N+1's graph reads step N's lazy writes via MLX's dependency tracking, so
-both steps back-to-back with no idle gap.
+the GPU runs both steps back-to-back with no idle gap.
 """
 
 from __future__ import annotations
@@ -62,6 +62,9 @@ class MlxPendingJob:
             time.  Decoupled from the live batch so
             ``process_batch_result`` can update request state without
             racing against the next scheduling decision.
+        schedule_batch: The full scheduler batch.  Unlike ``batch_copy``,
+            this keeps allocator/cache fields needed when a prefill batch
+            becomes the next running decode batch.
         reqs: Snapshot of ``batch.reqs`` at launch time.  The overlap
             loop uses this to check ``req.finished()`` on the previous
             step's request list without holding a reference to the
@@ -74,12 +77,27 @@ class MlxPendingJob:
     decode: Optional["MlxPendingDecode"]
     mode: str
     batch_copy: "ScheduleBatch"
+    schedule_batch: "ScheduleBatch"
     reqs: List[Req]
 
 
 class SchedulerMlxOverlapMixin:
     """Mixin that adds MLX overlap scheduling to :class:`Scheduler`."""
 
+    def _finalize_mlx_pending_job(self: "Scheduler", pending: MlxPendingJob):
+        result = self.tp_worker.finalize_mlx_result(
+            pending.prefills,
+            pending.extends,
+            pending.decode,
+            pending.mode,
+            pending.reqs,
+        )
+        if result.next_token_ids is not None:
+            pending.batch_copy.input_ids = result.next_token_ids
+            pending.schedule_batch.input_ids = result.next_token_ids
+        self.last_batch = pending.schedule_batch
+        self.process_batch_result(pending.batch_copy, result)
+
     @DynamicGradMode()
     def event_loop_overlap_mlx(self: "Scheduler"):
         """MLX-specific overlap loop modelled on ``mlx_lm.generate.generate_step``.
@@ -123,18 +141,6 @@ class SchedulerMlxOverlapMixin:
         pending_curr: Optional[MlxPendingJob] = None
         pending_next: Optional[MlxPendingJob] = None
 
-        def _finalize(pending: MlxPendingJob):
-            result = self.tp_worker.finalize_mlx_result(
-                pending.prefills,
-                pending.extends,
-                pending.decode,
-                pending.mode,
-                pending.reqs,
-            )
-            if result.next_token_ids is not None:
-                pending.batch_copy.input_ids = result.next_token_ids
-            self.process_batch_result(pending.batch_copy, result)
-
         def _launch_fresh(batch: "ScheduleBatch") -> MlxPendingJob:
             lazy_tokens, prefills, extends, decode, mode = (
                 self.tp_worker.async_forward_batch_generation_mlx(batch)
@@ -146,6 +152,7 @@ class SchedulerMlxOverlapMixin:
                 decode=decode,
                 mode=mode,
                 batch_copy=batch.copy(),
+                schedule_batch=batch,
                 reqs=list(batch.reqs),
             )
 
@@ -164,6 +171,7 @@ class SchedulerMlxOverlapMixin:
                 decode=decode,
                 mode=mode,
                 batch_copy=prev.batch_copy.copy(),
+                schedule_batch=prev.schedule_batch,
                 reqs=prev.reqs,
             )
 
@@ -191,7 +199,7 @@ class SchedulerMlxOverlapMixin:
             # 2. Finalize/process on pending_curr's tokens.  (GPU is already
             #    executing pending_next at this point.)
             if pending_curr is not None:
-                _finalize(pending_curr)
+                self._finalize_mlx_pending_job(pending_curr)
                 self.result_queue.popleft()
                 pending_curr = None
 
@@ -208,8 +216,8 @@ class SchedulerMlxOverlapMixin:
             ):
                 pending_curr = pending_next
                 pending_next = None
-                self.cur_batch = pending_curr.batch_copy
+                self.cur_batch = pending_curr.schedule_batch
-                self.last_batch = pending_curr.batch_copy
+                self.last_batch = pending_curr.schedule_batch
                 if envs.SGLANG_ENABLE_STRICT_MEM_CHECK_DURING_BUSY.get():
                     self.invariant_checker.self_check_during_busy()
                 continue
@@ -217,7 +225,7 @@ class SchedulerMlxOverlapMixin:
             # 4. Chain is broken. Finalise pending_next (if any), then
             #    schedule fresh.
             if pending_next is not None:
-                _finalize(pending_next)
+                self._finalize_mlx_pending_job(pending_next)
                 self.result_queue.popleft()
                 pending_next = None
             next_batch = self.get_next_batch_to_run()

python/sglang/srt/hardware_backend/mlx/tp_worker.py

@@ -2,7 +2,7 @@
 
 Routes forward passes through the MLX model runner, bypassing PyTorch
 MPS.  A lightweight stub provides scheduler bookkeeping; the actual
-KV data lives in MlxKVPool.
+attention KV data lives in MlxAttentionKVPool.
 
 The worker also exposes an async (lazy-eval) surface used by the MLX
 overlap scheduler: ``async_forward_batch_generation_mlx`` launches a
@@ -87,9 +87,9 @@ class MlxTpModelWorker(TpModelWorker):
         return None
 
     def _ensure_mlx_pool_initialized(self):
-        """Lazily initialize the MlxKVPool after the stub's pools are ready."""
+        """Lazily initialize MLX cache pools after the stub pools are ready."""
         if not self._mlx_pool_initialized:
-            self._mlx_runner.init_kv_pool(self._model_runner.req_to_token_pool)
+            self._mlx_runner.init_cache_pools(self._model_runner.req_to_token_pool)
             self._mlx_pool_initialized = True
 
     def forward_batch_generation(
@@ -124,6 +124,14 @@ class MlxTpModelWorker(TpModelWorker):
         else:
             self._mlx_active_rids |= current_rids
 
+    def prepare_for_kv_cache_release(self, req) -> None:
+        """Snapshot MLX auxiliary state at the scheduler's radix insert point."""
+        if self._mlx_runner.has_request(req.rid):
+            self._mlx_runner.store_auxiliary_state_for_request(req.rid)
+            # Prefer the just-snapshotted live auxiliary state for the final
+            # insert. Any older tracked slot is released during component cleanup.
+            req.mamba_last_track_seqlen = None
+
     def _forward_batch_generation_mlx(
         self, batch: ScheduleBatch
     ) -> GenerationBatchResult:
@@ -144,7 +152,7 @@ class MlxTpModelWorker(TpModelWorker):
         next_token_ids_list: list[int] = []
 
         if forward_mode.is_extend():
-            # Ensure pool is up-to-date before PoolBackedCache reads it
+            # Ensure pool is up-to-date before pool-backed attention reads it
             # for prefix-cached prefills.  Only runs on extend batches.
             self._mlx_runner.flush_all_decode_kv()
             input_ids_cpu = batch.input_ids.cpu().tolist()
@@ -185,6 +193,7 @@ class MlxTpModelWorker(TpModelWorker):
                         prefix_slot_ids=prefix_slot_ids,
                         new_slot_ids=req_new_slots,
                         req_pool_idx=req.req_pool_idx,
+                        req=req,
                     )
                     prefill_rids.append((req.rid, next_token))
 
@@ -270,7 +279,7 @@ class MlxTpModelWorker(TpModelWorker):
 
         if forward_mode.is_extend():
             # TODO (changminbark): Implement per-batch flushing using prefix_slot_ids
-            # Ensure the pool is up-to-date before any PoolBackedCache
+            # Ensure the pool is up-to-date before pool-backed attention
             # reads it for prefix-cached prefills. Mirror the sync path.
             self._mlx_runner.flush_all_decode_kv()
             return self._async_extend_batch(batch)
@@ -330,6 +339,7 @@ class MlxTpModelWorker(TpModelWorker):
                         prefix_slot_ids=prefix_slot_ids,
                         new_slot_ids=req_new_slots,
                         req_pool_idx=req.req_pool_idx,
+                        req=req,
                     )
                 )
 
@@ -377,7 +387,23 @@ class MlxTpModelWorker(TpModelWorker):
     @staticmethod
     def _cache_state(cache_list) -> list[mx.array]:
         """Flatten a per-layer cache list to its ``state`` arrays."""
-        return [s for c in cache_list for s in c.state]
+        arrays: list[mx.array] = []
+
+        def collect(value):
+            if isinstance(value, mx.array):
+                arrays.append(value)
+            elif value is None:
+                return
+            elif isinstance(value, (list, tuple)):
+                for item in value:
+                    collect(item)
+            elif isinstance(value, dict):
+                for item in value.values():
+                    collect(item)
+
+        for cache in cache_list:
+            collect(getattr(cache, "state", ()))
+        return arrays
 
     def async_chained_decode_mlx(
         self,

python/sglang/srt/managers/scheduler_components/batch_result_processor.py

@@ -828,6 +828,11 @@ class SchedulerBatchResultProcessor:
             else:
                 if self.server_args.enable_hisparse:
                     self.hisparse_coordinator.request_finished(req)
+                prepare_release = getattr(
+                    self.model_worker, "prepare_for_kv_cache_release", None
+                )
+                if callable(prepare_release):
+                    prepare_release(req)
                 release_kv_cache(req, self.tree_cache)
 
             req.time_stats.set_completion_time()

python/sglang/srt/mem_cache/cache_init_params.py

@@ -9,6 +9,9 @@ if TYPE_CHECKING:
     from sglang.srt.mem_cache.allocator import BaseTokenToKVPoolAllocator
     from sglang.srt.mem_cache.memory_pool import ReqToTokenPool
     from sglang.srt.mem_cache.unified_cache_components import ComponentType
+    from sglang.srt.mem_cache.unified_cache_components.tree_component import (
+        TreeComponent,
+    )
 
 
 @dataclasses.dataclass
@@ -44,3 +47,6 @@ class CacheInitParams:
     cache_ttl_seconds: Optional[float] = None
 
     tree_components: Optional[tuple[ComponentType, ...]] = None
+    component_registry_override: Optional[dict[ComponentType, type[TreeComponent]]] = (
+        None
+    )

python/sglang/srt/mem_cache/registry.py

@@ -17,6 +17,7 @@ from typing import TYPE_CHECKING, Any, Callable, Optional
 from sglang.srt.environ import envs
 from sglang.srt.mem_cache.base_prefix_cache import BasePrefixCache
 from sglang.srt.mem_cache.cache_init_params import CacheInitParams
+from sglang.srt.utils.tensor_bridge import use_mlx
 
 if TYPE_CHECKING:
     from sglang.srt.configs.model_config import ModelConfig
@@ -94,7 +95,7 @@ def default_radix_cache_factory(ctx: TreeCacheBuildContext) -> BasePrefixCache:
         logger.info("Using experimental C++ radix tree implementation.")
         return RadixCacheCpp(params=params, server_args=server_args)
 
-    if envs.SGLANG_ENABLE_UNIFIED_RADIX_TREE.get():
+    if envs.SGLANG_ENABLE_UNIFIED_RADIX_TREE.get() or use_mlx():
         from sglang.srt.mem_cache.unified_cache_components import ComponentType
         from sglang.srt.mem_cache.unified_radix_cache import UnifiedRadixCache
 
@@ -104,6 +105,14 @@ def default_radix_cache_factory(ctx: TreeCacheBuildContext) -> BasePrefixCache:
                 ComponentType.SWA if ctx.is_hybrid_swa else ComponentType.MAMBA
             )
         params.tree_components = tuple(tree_components)
+        if use_mlx() and ctx.is_hybrid_ssm:
+            from sglang.srt.hardware_backend.mlx.kv_cache.auxiliary_state import (
+                MlxAuxiliaryStateComponent,
+            )
+
+            params.component_registry_override = {
+                ComponentType.MAMBA: MlxAuxiliaryStateComponent,
+            }
         cache = UnifiedRadixCache(params)
         if ctx.enable_hierarchical_cache:
             cache.init_hicache(server_args, params)

python/sglang/srt/mem_cache/unified_radix_cache.py

@@ -258,8 +258,14 @@ class UnifiedRadixCache(KVCacheEventMixin, BasePrefixCache):
 
         assert params.tree_components is not None
         self.tree_components = tuple(params.tree_components)
+        component_registry = COMPONENT_REGISTRY
+        if params.component_registry_override:
+            component_registry = {
+                **COMPONENT_REGISTRY,
+                **params.component_registry_override,
+            }
         self.components: dict[ComponentType, TreeComponent] = {
-            ct: COMPONENT_REGISTRY[ct](self, params) for ct in self.tree_components
+            ct: component_registry[ct](self, params) for ct in self.tree_components
         }
         self._components_tuple: tuple[TreeComponent, ...] = tuple(
             self.components.values()

test/registered/unit/mem_cache/test_unified_radix_cache_unittest.py

@@ -41,8 +41,11 @@ from sglang.srt.mem_cache.swa_memory_pool import SWAKVPool, SWATokenToKVPoolAllo
 from sglang.srt.mem_cache.unified_cache_components.tree_component import (
     CacheTransferPhase,
     ComponentType,
+    EvictLayer,
+    TreeComponent,
 )
 from sglang.srt.mem_cache.unified_radix_cache import (
+    COMPONENT_REGISTRY,
     UnifiedRadixCache,
     UnifiedTreeNode,
 )
@@ -119,6 +122,52 @@ class CacheConfig:
         return "_".join(parts)
 
 
+class _FakeFullComponent(TreeComponent):
+    component_type = ComponentType.FULL
+
+    def create_match_validator(self, match_device_only: bool = False):
+        return lambda node: True
+
+    def redistribute_on_node_split(self, new_parent, child):
+        return None
+
+    def evict_component(
+        self, node, target: EvictLayer = EvictLayer.DEVICE
+    ) -> tuple[int, int]:
+        return 0, 0
+
+    def drive_eviction(self, params: EvictParams, tracker: dict[ComponentType, int]):
+        return None
+
+    def acquire_component_lock(self, node, result):
+        return result
+
+    def release_component_lock(self, node, params):
+        return None
+
+
+class TestUnifiedRadixComponentRegistryOverride(CustomTestCase):
+    def test_component_registry_override_is_instance_local(self):
+        params = CacheInitParams(
+            req_to_token_pool=ReqToTokenPool(
+                size=2,
+                max_context_len=8,
+                device="cpu",
+                enable_memory_saver=False,
+            ),
+            token_to_kv_pool_allocator=None,
+            page_size=1,
+            disable=True,
+            tree_components=(ComponentType.FULL,),
+            component_registry_override={ComponentType.FULL: _FakeFullComponent},
+        )
+
+        tree = UnifiedRadixCache(params=params)
+
+        self.assertIsInstance(tree.components[ComponentType.FULL], _FakeFullComponent)
+        self.assertIsNot(COMPONENT_REGISTRY[ComponentType.FULL], _FakeFullComponent)
+
+
 def build_fixture(cfg: CacheConfig, *, enable_kv_cache_events: bool = False):
     """Create (tree, allocator, req_to_token_pool) from a CacheConfig."""
     server_args = ServerArgs(model_path="dummy", page_size=cfg.page_size)