# glm53-dflash-01-aux-hidden-states.patch — give the GLM trunk the EAGLE3 / DFlash2
# auxiliary-hidden-state interface.
#
# STATUS: WIP, and INDEPENDENT of the compile changelist (01-05). It patches the same
# file as glm53-compile-01-model-decorator.patch, so if both are ever applied, apply 01
# first. Not part of the deployed shape.
#
# WHY.  `--speculative-config '{"method":"dflash","model":"/path/to/drafter", ...}'` with
# incoai/GLM-5.3-Flash-DFlash2 is accepted -- the config parses, the drafter loads -- and
# then the worker dies at init with:
#
#     RuntimeError: Model does not support EAGLE3 interface
#
# raised by v1/worker/gpu/spec_decode/eagle/eagle3_utils.py:20 through
# `supports_eagle3(model)` == `isinstance(model, SupportsEagle3)` (a runtime-checkable
# Protocol).  Nothing about the drafter, the method name or the payload is wrong:
# `glm5next` implements neither half of the contract.
#
# THE CONTRACT (read out of this image, not assumed):
#   * interfaces.py:1663 -- `supports_eagle3: ClassVar[Literal[True]] = True`.  THE FLAG
#     IS A REQUIRED MEMBER FOR `isinstance`: satisfying the Protocol with methods alone
#     still raises the same RuntimeError -- v1 of this patch did exactly that and the boot
#     failed identically.  INHERIT the Protocol instead.  That is the idiom in this image
#     (LagunaForCausalLM, MiMoV2FlashForCausalLM and DFlashLagunaForCausalLM all list
#     SupportsEagle3 among their bases) and it brings the flag, SupportsEagleBase's
#     has_own_lm_head/has_own_embed_tokens, AND working non-stub defaults for both methods.
#   * interfaces.py:1673-1719 -- the inherited defaults unwrap
#     `holder = getattr(parent_ref, "model", parent_ref)`, assert
#     `isinstance(holder, EagleModelMixin)`, set `holder._set_aux_hidden_state_layers`, and
#     default to (2, L // 2, L - 3).  So the INNER trunk must inherit EagleModelMixin,
#     which supplies `aux_hidden_state_layers` and the slot helpers.
#   * eagle3_utils.py:26-31 -- layers come from the spec config when it carries them
#     (this drafter ships target_layer_ids [5, 14, 24, 33, 42]), else from the default.
#   * deepseek_v2.py:1551-1585 and v1/worker/gpu/cudagraph_utils.py:621 -- the trunk
#     appends one tensor per aux layer while looping and returns the TUPLE
#     (hidden_states, aux_hidden_states) only when that list is non-empty.
#
# WHAT IT ADDS for GLM: the mixin on Glm5NextModel; aux capture in the layer loop, where
# the aux state is the single-stream `hidden_states` ENTERING that layer (GLM's loop
# carries the already-summed single-stream state -- its non-mHC branch re-splits
# `residual = hidden_states` inside the layer -- so this is the equivalent of
# deepseek_v2's `hidden_states + residual`); the conditional tuple return; and
# SupportsEagle3 among Glm5NextForCausalLM's bases.
#
# HONEST SCOPE: this makes the interface PRESENT, which is exactly what the engine
# checks -- it does not make drafts GOOD, and per the measured profile it is not a
# decode-speed fix (a verification pass pays pointwise cost proportional to its token
# count, which is why MTP4 measured flat).  It is the prerequisite for driving DFlash2
# on this endpoint at all.
#
# TARGET: vllm/models/glm5next/common/model.py   (inside the pinned image)
#   base    sha256 008eeaa2a07e091465319f86900b5a321d921238723ccbe22e6b9e971e1d2b28
#   patched sha256 5eea89c51d4ab37ef823526286b5103e39996802ca08aa1934f6373fc4728062
#
# APPLY: `patch -p1` from the vllm package root, or bind-mount the patched file over
# site-packages (which is what a scratch-launcher DFLASH_PATCH=1 does).
--- a/vllm/models/glm5next/common/model.py
+++ b/vllm/models/glm5next/common/model.py
@@ -95,6 +95,12 @@
 logger = init_logger(__name__)
 
 
+from vllm.model_executor.models.interfaces import (
+    EagleModelMixin,
+    SupportsEagle3,
+)
+
+
 class Glm5NextMLP(nn.Module):
     def __init__(
         self,
@@ -623,7 +629,7 @@
         )
 
 
-class Glm5NextModel(nn.Module):
+class Glm5NextModel(nn.Module, EagleModelMixin):
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         super().__init__()
 
@@ -730,7 +736,14 @@
         if self.is_sequence_parallel:
             hidden_states = sp_shard(hidden_states)
 
-        for layer in self._active_layers:
+        aux_hidden_states: list[torch.Tensor] = []
+        for local_idx, layer in enumerate(self._active_layers):
+            if (getattr(self, "start_layer", 0) + local_idx) in self.aux_hidden_state_layers:
+                # Auxiliary hidden state for EAGLE-3 / DFlash2 drafts: the
+                # single-stream state ENTERING this layer, before its input norm --
+                # the same semantic deepseek_v2 implements by appending
+                # hidden_states + residual at this point in its loop.
+                aux_hidden_states.append(hidden_states)
             hidden_states, residual, post, comb = layer(
                 positions, hidden_states, residual, post, comb
             )
@@ -749,6 +762,8 @@
             hidden_states = sp_all_gather(hidden_states)[:full_num_tokens]
 
         hidden_states = self.norm(hidden_states)
+        if len(aux_hidden_states) > 0:
+            return hidden_states, aux_hidden_states
         return hidden_states
 
     def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
@@ -935,7 +950,12 @@
 
 
 class Glm5NextForCausalLM(
-    nn.Module, HasInnerState, SupportsPP, MixtureOfExperts, IsHybrid
+    nn.Module,
+    HasInnerState,
+    SupportsPP,
+    MixtureOfExperts,
+    IsHybrid,
+    SupportsEagle3,
 ):
     def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         super().__init__()