[TRTLLM-12500][feat] Add support for Qwen3.5 VL MoE (with the MTP fixes)

docs/source/models/supported-models.md

@@ -106,6 +106,7 @@ Note: Support for other models may vary. Features marked "N/A" are not applicabl
 | `Qwen3VLMoeForConditionalGeneration` | Yes               | Yes        | Yes             | Yes           | Yes              | Yes            | Yes                   | Yes                       | L + I + V |
 | `Step3p7ForConditionalGeneration`    | Yes               | Yes        | Untested        | Yes           | Untested         | Untested       | Untested              | Untested                  | L + I     |
 | `MiniMaxM3SparseForConditionalGeneration` [^11] | Yes               | Yes        | Untested        | Yes           | Untested         | No             | Untested              | Untested                  | L + I + V |
+| `Qwen3_5MoeForConditionalGeneration` | Yes               | Yes        | Untested        | Yes           | Yes              | No             | Untested              | Yes                       | L + I + V |
 
 Note:
 - L: Language

tensorrt_llm/_torch/models/__init__.py

@@ -42,7 +42,8 @@
                             Qwen2ForRewardModel)
 from .modeling_qwen2vl import Qwen2_5_VLModel, Qwen2VLModel
 from .modeling_qwen3 import Qwen3ForCausalLM
-from .modeling_qwen3_5 import Qwen3_5ForCausalLM, Qwen3_5MoeForCausalLM
+from .modeling_qwen3_5 import (Qwen3_5ForCausalLM, Qwen3_5MoeForCausalLM,
+                               Qwen3_5MoeVLModel)
 from .modeling_qwen3_moe import Qwen3MoeForCausalLM
 from .modeling_qwen3_next import Qwen3NextForCausalLM
 from .modeling_qwen3vl import Qwen3VLModel
@@ -102,6 +103,7 @@
     "Qwen3MoeForCausalLM",
     "Qwen3_5ForCausalLM",
     "Qwen3_5MoeForCausalLM",
+    "Qwen3_5MoeVLModel",
     "Qwen3NextForCausalLM",
     "Qwen3MoeVLModel",
     "GptOssForCausalLM",

tensorrt_llm/_torch/models/checkpoints/hf/qwen3_5_weight_mapper.py

@@ -16,6 +16,7 @@
 
 
 @register_mapper("HF", "Qwen3_5MoeForCausalLM")
+@register_mapper("HF", "Qwen3_5MoeForConditionalGeneration")
 @register_mapper("HF", "Qwen3_5ForCausalLM")
 class Qwen3_5MoeHfWeightMapper(Qwen3NextHfWeightMapper):
     """Weight mapper for Qwen3.5 MoE text checkpoints.

tensorrt_llm/_torch/models/modeling_qwen3_5.py

@@ -1,7 +1,29 @@
 import re
+from types import SimpleNamespace
+from typing import Dict, List
 
+import torch
+from transformers import PretrainedConfig
+
+from ...inputs import (
+    ContentFormat,
+    MultimodalPlaceholderMetadata,
+    MultimodalPlaceholderPlacement,
+    register_input_processor,
+    support_multimodal_disaggregated,
+)
+from ..pyexecutor.config_utils import get_qwen3_hybrid_layer_types
+from .checkpoints.base_weight_mapper import BaseWeightMapper
+from .checkpoints.hf.qwen3_5_weight_mapper import Qwen3_5MoeHfWeightMapper
+from .modeling_multimodal_utils import _is_mm_disagg
 from .modeling_qwen3_next import Qwen3NextForCausalLM
-from .modeling_utils import register_auto_model
+from .modeling_qwen3vl import (
+    Qwen3VisionModel,
+    Qwen3VisionModelBase,
+    Qwen3VLInputProcessorBase,
+    Qwen3VLModelBase,
+)
+from .modeling_utils import ModelConfig, register_auto_model, register_vision_encoder
 
 _LANG_PREFIX = "model.language_model."
 
@@ -51,6 +73,248 @@ def _translate_mtp_pattern(name, n_hidden_layers):
     return None
 
 
+# --- Config adapters --------------------------------------------------------
+#
+# These run from `load_pretrained_config` in
+# `tensorrt_llm/_torch/pyexecutor/config_utils.py` via lazy import — the
+# runtime layer asks the model module how to load its own config.
+#
+# There are two entry points:
+#   - `Qwen35ConfigCompat.normalize(config_dict)` — for text-only
+#     Qwen3.5 (MoE and dense). Returns a dict that
+#     `transformers.Qwen3NextConfig.from_dict(...)` can consume, so the
+#     existing Qwen3Next runtime is reused unchanged.
+#   - `_normalize_qwen35_moe_vl_config(model_config)` — for the
+#     Qwen3.5-MoE VLM. Mutates the HF-native `transformers.Qwen3_5MoeConfig`
+#     in place, attaching the runtime aliases the Qwen3Next-based LM expects
+#     while keeping `text_config` / `vision_config` composite.
+
+
+class Qwen35ConfigCompat:
+    """Temporary shim for flattening Qwen3.5 text configs into Qwen3NextConfig.
+
+    We normalize to `Qwen3NextConfig` (rather than to a Qwen3.5-native
+    schema) so the runtime can reuse the existing `Qwen3NextForCausalLM`
+    model implementation unchanged — Qwen3.5 text is structurally identical
+    to Qwen3Next, so matching the config schema lets the same code serve
+    both.
+
+    This is used for Qwen3.5 text-only configs and for shared helper logic such
+    as RoPE and quantization exclude-module normalization. Qwen3.5-MoE VLM
+    configs should stay composite and use transformers.Qwen3_5MoeConfig plus
+    _normalize_qwen35_moe_vl_config instead.
+
+    To remove: delete this class and the elif branch in
+    load_pretrained_config that flattens Qwen3.5 text configs.
+    """
+
+    @staticmethod
+    def normalize(config_dict: dict) -> dict:
+        """Entry point: raw config.json dict -> flat Qwen3NextConfig-compatible dict."""
+        text_config = Qwen35ConfigCompat._extract_text_config(config_dict)
+        text_config = Qwen35ConfigCompat._inherit_quantization_config(config_dict, text_config)
+        text_config = Qwen35ConfigCompat._flatten_rope(text_config)
+
+        # Detect dense vs MoE and set architecture + MoE defaults accordingly
+        is_moe = "num_experts" in text_config and text_config["num_experts"] > 0
+        if is_moe:
+            text_config["architectures"] = ["Qwen3_5MoeForCausalLM"]
+        else:
+            text_config["architectures"] = ["Qwen3_5ForCausalLM"]
+            # Ensure MoE fields are zeroed so Qwen3NextConfig defaults don't
+            # accidentally enable MoE for the dense model.
+            text_config.setdefault("num_experts", 0)
+            text_config.setdefault("num_experts_per_tok", 0)
+            text_config.setdefault("moe_intermediate_size", 0)
+            text_config.setdefault("shared_expert_intermediate_size", 0)
+        return text_config
+
+    _VLM_ARCHITECTURES = {
+        "Qwen3_5MoeForConditionalGeneration",
+        "Qwen3_5ForConditionalGeneration",
+    }
+
+    @staticmethod
+    def _extract_text_config(config_dict: dict) -> dict:
+        """Pull nested text_config from VLM checkpoints, or use dict as-is."""
+        architectures = config_dict.get("architectures") or []
+        if architectures and architectures[0] in Qwen35ConfigCompat._VLM_ARCHITECTURES:
+            text_config = dict(config_dict.get("text_config") or {})
+        else:
+            text_config = dict(config_dict)
+        if not text_config:
+            raise ValueError("Qwen3.5 config is missing a usable text_config")
+        return text_config
+
+    @staticmethod
+    def _inherit_quantization_config(config_dict: dict, text_config: dict) -> dict:
+        """Copy top-level quantization_config into text_config with name normalization.
+
+        Also adds a temporary workaround that keeps packed linear-attention
+        in_proj_qkvz on the bf16 path until FP8 block-scale TP loading is
+        fixed for that layout.
+        """
+        if "quantization_config" in text_config:
+            return text_config
+        if "quantization_config" not in config_dict:
+            return text_config
+
+        quantization_config = dict(config_dict["quantization_config"])
+        if "modules_to_not_convert" in quantization_config:
+            modules = Qwen35ConfigCompat._normalize_exclude_modules(
+                quantization_config["modules_to_not_convert"]
+            )
+            modules = Qwen35ConfigCompat._add_qkvz_bf16_workaround(text_config, modules)
+            quantization_config["modules_to_not_convert"] = sorted(set(modules))
+        text_config["quantization_config"] = quantization_config
+        return text_config
+
+    @staticmethod
+    def _normalize_exclude_modules(modules: list[str]) -> list[str]:
+        """Translate HF quantization exclude-module paths to TRT-LLM names.
+
+        - Strip model.language_model. prefix -> model.
+        - Drop model.visual.* and mtp.* entries
+        - Map split projection names to packed TRT-LLM names
+        """
+        normalized = set()
+        for name in modules:
+            if name.startswith("model.language_model."):
+                name = "model." + name[len("model.language_model.") :]
+            if name.startswith("model.visual.") or name.startswith("mtp."):
+                continue
+            name = re.sub(r"\.in_proj_[ab]$", ".in_proj_ba", name)
+            name = re.sub(r"\.in_proj_(q|k|v|z|qkv)$", ".in_proj_qkvz", name)
+            normalized.add(name)
+        return sorted(normalized)
+
+    @staticmethod
+    def _add_qkvz_bf16_workaround(text_config: dict, modules: list[str]) -> list[str]:
+        """Keep packed linear-attention qkvz on bf16 path for all linear-attention layers.
+
+        Temporary until FP8 block-scale TP loading is fixed for this layout.
+        """
+        try:
+            layer_types = get_qwen3_hybrid_layer_types(SimpleNamespace(**text_config))
+        except (ValueError, AttributeError):
+            return modules
+        for layer_idx, layer_type in enumerate(layer_types):
+            if layer_type == "linear_attention":
+                modules.append(f"model.layers.{layer_idx}.linear_attn.in_proj_qkvz")
+        return modules
+
+    @staticmethod
+    def _flatten_rope(text_config: dict) -> dict:
+        """Flatten rope_parameters into top-level rope_theta / partial_rotary_factor / rope_scaling.
+
+        Qwen3.5 nests these inside a rope_parameters dict and uses rope_type
+        instead of type in rope_scaling.  Qwen3NextConfig expects them as
+        top-level fields with rope_scaling.type.
+        """
+        rope_parameters = dict(text_config.pop("rope_parameters", {}) or {})
+        rope_scaling = dict(text_config.get("rope_scaling") or {})
+        if rope_parameters:
+            rope_theta = rope_parameters.pop("rope_theta", None)
+            if rope_theta is not None:
+                text_config.setdefault("rope_theta", rope_theta)
+            partial_rotary_factor = rope_parameters.pop("partial_rotary_factor", None)
+            if partial_rotary_factor is not None:
+                text_config.setdefault("partial_rotary_factor", partial_rotary_factor)
+            if rope_parameters:
+                rope_scaling = rope_parameters | rope_scaling
+        if rope_scaling:
+            has_mrope = "mrope_section" in rope_scaling or rope_scaling.get(
+                "mrope_interleaved", False
+            )
+            if has_mrope:
+                rope_scaling["type"] = "mrope"
+                rope_scaling.pop("rope_type", None)
+            elif "type" not in rope_scaling and "rope_type" in rope_scaling:
+                rope_type = rope_scaling.pop("rope_type")
+                # "default" means standard RoPE (no scaling) — don't set
+                # rope_scaling to avoid triggering scaling code paths.
+                if rope_type == "default":
+                    rope_scaling = {}
+                else:
+                    rope_scaling["type"] = rope_type
+            if rope_scaling:
+                text_config["rope_scaling"] = rope_scaling
+        return text_config
+
+
+def _normalize_qwen35_mrope_config(text_config) -> None:
+    """Materialize Qwen3.5 mRoPE aliases needed by the Qwen3-VL path.
+
+    HF stores RoPE metadata under `rope_parameters`; the shared Qwen3-VL
+    wrapper reads `rope_theta`, `partial_rotary_factor`, and
+    `rope_scaling` directly on the text config.
+    """
+    rope_parameters = getattr(text_config, "rope_parameters", None)
+    if not rope_parameters:
+        return
+    if hasattr(rope_parameters, "to_dict"):
+        rope_parameters = rope_parameters.to_dict()
+    flattened = Qwen35ConfigCompat._flatten_rope(
+        {
+            "rope_parameters": dict(rope_parameters),
+            "rope_scaling": dict(getattr(text_config, "rope_scaling", None) or {}),
+        }
+    )
+    for attr in ("rope_theta", "partial_rotary_factor", "rope_scaling"):
+        value = flattened.get(attr)
+        if value is not None:
+            setattr(text_config, attr, value)
+
+
+def _normalize_qwen35_qwen3next_text_aliases(text_config) -> None:
+    """Materialize Qwen3Next-style text aliases used by the shared runtime."""
+    if getattr(text_config, "intermediate_size", None) is None:
+        moe_intermediate_size = getattr(text_config, "moe_intermediate_size", None)
+        num_experts_per_tok = getattr(text_config, "num_experts_per_tok", None)
+        shared_expert_intermediate_size = (
+            getattr(text_config, "shared_expert_intermediate_size", 0) or 0
+        )
+        if moe_intermediate_size is not None and num_experts_per_tok is not None:
+            text_config.intermediate_size = (
+                num_experts_per_tok * moe_intermediate_size + shared_expert_intermediate_size
+            )
+
+
+def _normalize_qwen35_quantization_config(model_config) -> None:
+    quantization_config = getattr(model_config, "quantization_config", None)
+    if not isinstance(quantization_config, dict):
+        return
+
+    modules = quantization_config.get("modules_to_not_convert")
+    if modules is None:
+        return
+
+    text_config = getattr(model_config, "text_config", None)
+    normalized_modules = Qwen35ConfigCompat._normalize_exclude_modules(modules)
+    if text_config is not None:
+        normalized_modules = Qwen35ConfigCompat._add_qkvz_bf16_workaround(
+            text_config.to_dict(), normalized_modules
+        )
+    quantization_config["modules_to_not_convert"] = sorted(set(normalized_modules))
+
+
+def _normalize_qwen35_moe_vl_config(model_config) -> None:
+    """Adapt HF Qwen3.5-MoE VLM config to TRT-LLM runtime conventions."""
+    if not getattr(model_config, "architectures", None):
+        model_config.architectures = ["Qwen3_5MoeForConditionalGeneration"]
+
+    text_config = getattr(model_config, "text_config", None)
+    if text_config is None:
+        raise ValueError("Qwen3.5-MoE VLM config is missing text_config")
+
+    text_config.architectures = ["Qwen3_5MoeForCausalLM"]
+    _normalize_qwen35_qwen3next_text_aliases(text_config)
+    _normalize_qwen35_mrope_config(text_config)
+
+    model_config.get_text_config = lambda decoder=False: text_config
+    _normalize_qwen35_quantization_config(model_config)
+
+
 def _normalize_qwen35_exclude_modules(model_config):
     """Normalize NVFP4/FP8 exclude_modules from HF naming to TRT-LLM naming.
 
@@ -130,10 +394,58 @@ class Qwen3_5ForCausalLM(Qwen3NextForCausalLM):
 
     Same reuse pattern as Qwen3_5MoeForCausalLM, but for the dense 27B
     variant which uses GatedMLP instead of SparseMoeBlock.  The config
-    normalizer (_Qwen35ConfigCompat) sets num_experts=0 so that
+    normalizer (Qwen35ConfigCompat) sets num_experts=0 so that
     Qwen3NextModel selects GatedMLP for the feed-forward layers.
     """
 
     def __init__(self, model_config):
         _normalize_qwen35_exclude_modules(model_config)
         super().__init__(model_config)
+
+
+# TODO: Add tests for disaggregated support.
+@support_multimodal_disaggregated
+@register_vision_encoder(Qwen3VisionModelBase, vlm_base_model=Qwen3VisionModel)
+@register_auto_model("Qwen3_5MoeForConditionalGeneration")
+@register_input_processor(
+    Qwen3VLInputProcessorBase,
+    model_type="qwen3_5_moe",
+    placeholder_metadata=MultimodalPlaceholderMetadata(
+        placeholder_map={
+            "image": "<|vision_start|><|image_pad|><|vision_end|>",
+            "video": "<|vision_start|><|video_pad|><|vision_end|>",
+        },
+        placeholder_placement=MultimodalPlaceholderPlacement.BEFORE_TEXT,
+        placeholders_separator="",
+        content_format=ContentFormat.STRING,
+    ),
+)
+class Qwen3_5MoeVLModel(Qwen3VLModelBase):
+    """VLM wrapper composing Qwen3 vision encoder with Qwen3.5 MoE text decoder."""
+
+    def __init__(self, model_config: ModelConfig[PretrainedConfig], *args, **kwargs):
+        kwargs["vision_model_class"] = Qwen3VisionModel
+        kwargs["disable_fuse_rope"] = kwargs.get("disable_fuse_rope", False)
+        super().__init__(model_config, *args, **kwargs)
+
+    @property
+    def multimodal_data_device_paths(self) -> List[str]:
+        return [
+            "image.pixel_values",
+            "video.pixel_values_videos",
+            "multimodal_embedding",
+            "mrope_config.mrope_position_ids",
+            "mrope_config.mrope_position_deltas",
+        ]
+
+    def load_weights(self, weights: Dict[str, torch.Tensor], weight_mapper: BaseWeightMapper):
+        if not _is_mm_disagg():
+            self.mm_encoder.load_weights(weights)
+
+        weight_mapper = Qwen3_5MoeHfWeightMapper()
+        weight_mapper.init_model_and_config(self.llm, self.model_config)
+        filtered_weights = {k: v for k, v in weights.items() if not k.startswith("model.visual.")}
+        params_map = {
+            r"^model\.language_model\.(.*)$": r"model.\1",
+        }
+        self.llm.load_weights(filtered_weights, weight_mapper, params_map=params_map)

tensorrt_llm/_torch/models/modeling_qwen3_next.py

@@ -976,9 +976,18 @@ def get_model_defaults(cls, llm_args: 'TorchLlmArgs') -> dict:
         # is supported for Mamba/SSM-based models
         return {"kv_cache_config": {"enable_block_reuse": False}}
 
-    def load_weights(self, weights: dict, weight_mapper: BaseWeightMapper):
+    def load_weights(self,
+                     weights: dict,
+                     weight_mapper: BaseWeightMapper,
+                     params_map: Optional[Dict[str, str]] = None,
+                     allow_partial_loading: bool = False):
         new_weights = weight_mapper.preprocess_weights(weights)
-        super().load_weights(new_weights, weight_mapper)
+        super().load_weights(
+            new_weights,
+            weight_mapper=weight_mapper,
+            params_map=params_map,
+            allow_partial_loading=allow_partial_loading,
+        )
 
     def setup_aliases(self) -> None:
         for idx, layer in enumerate(