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# Copyright 2025 The Qwen Team and The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from collections.abc import Callable
from dataclasses import dataclass
from typing import Any, Optional, Union, List

import torch
import torch.nn.functional as F
from torch import nn

from transformers import initialization as init
from transformers.activations import ACT2FN
from transformers.cache_utils import Cache
from transformers.generation import GenerationMixin
from transformers.integrations import use_kernelized_func
from transformers.masking_utils import create_causal_mask
from transformers.modeling_flash_attention_utils import FlashAttentionKwargs
from transformers.modeling_layers import GradientCheckpointingLayer
from transformers.modeling_outputs import (
    BaseModelOutputWithPast,
    BaseModelOutputWithPooling,
    CausalLMOutputWithPast,
    ModelOutput,
)
from transformers.modeling_rope_utils import ROPE_INIT_FUNCTIONS, dynamic_rope_update
from transformers.modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from transformers.processing_utils import Unpack
from transformers.utils import TransformersKwargs, auto_docstring, can_return_tuple, logging, torch_compilable_check
from transformers.utils.generic import is_flash_attention_requested, maybe_autocast, merge_with_config_defaults
from transformers.utils.import_utils import is_causal_conv1d_available, is_flash_linear_attention_available
from transformers.utils.output_capturing import capture_outputs
from transformers.models.qwen3_5.configuration_qwen3_5 import Qwen3_5Config, Qwen3_5TextConfig, Qwen3_5VisionConfig

from mindspeed.fsdp.utils.log import print_rank
from mindspeed_mm.fsdp.utils.register import model_register
from mindspeed_mm.fsdp.utils.device import IS_NPU_AVAILABLE

if IS_NPU_AVAILABLE:
    import torch_npu

from mindspeed_mm.fsdp.distributed.context_parallel.communication import (
    split_forward_gather_backward,
    gather_forward_split_backward,
    split_forward_gather_backward_with_cp,
    gather_forward_split_backward_with_cp,
    packed_data_split_forward_gather_backward_with_cp,
    packed_data_gather_forward_split_backward_with_cp
)
from mindspeed_mm.fsdp.distributed.parallel_state import get_parallel_state
from mindspeed_mm.fsdp.distributed.context_parallel.utils import cal_split_sizes, cal_split_sizes_multi
from mindspeed_mm.fsdp.distributed.context_parallel.utils import generate_ulysses_cu_seqlen_params
from mindspeed_mm.fsdp.distributed.context_parallel.communication import all_to_all
from mindspeed_mm.fsdp.models.mtp import MultiTokenPredictionBlock

_TOTAL_SEQ_LEN = None
_VISUAL_SEQ_LEN = None
_VISUAL_PER_SEQ_LEN = None
IGNORE_INDEX = -100


def get_seq_len(seq_type: str = None) -> int:
    if seq_type == "total":
        global _TOTAL_SEQ_LEN
        return _TOTAL_SEQ_LEN
    elif seq_type == "visual":
        global _VISUAL_SEQ_LEN
        return _VISUAL_SEQ_LEN
    elif seq_type == "per_visual":
        global _VISUAL_PER_SEQ_LEN
        return _VISUAL_PER_SEQ_LEN
    else:
        raise ValueError(
            f"Invalid sequence type: '{seq_type}'. Expected 'total' or 'visual'."
        )


def set_seq_len(seq_type: str = None, seq_len: Optional[Union[int, List[int]]] = None) -> None:
    if seq_type == "total":
        global _TOTAL_SEQ_LEN
        _TOTAL_SEQ_LEN = seq_len
    elif seq_type == "visual":
        global _VISUAL_SEQ_LEN
        _VISUAL_SEQ_LEN = seq_len
    elif seq_type == "per_visual":
        global _VISUAL_PER_SEQ_LEN
        _VISUAL_PER_SEQ_LEN = seq_len
    else:
        raise ValueError(
            f"Invalid sequence type: '{seq_type}'. Expected 'total' or 'visual'."
        )


if is_causal_conv1d_available():
    from causal_conv1d import causal_conv1d_fn, causal_conv1d_update
else:
    causal_conv1d_update, causal_conv1d_fn = None, None

if is_flash_linear_attention_available():
    from fla.modules import FusedRMSNormGated
    from fla.ops.gated_delta_rule import chunk_gated_delta_rule as fla_chunk_gated_delta_rule, fused_recurrent_gated_delta_rule
else:
    fla_chunk_gated_delta_rule, fused_recurrent_gated_delta_rule = None, None
    FusedRMSNormGated = None

logger = logging.get_logger(__name__)


class Qwen3_5DynamicCache:
    """
    A dynamic cache that can handle both the attention cache (which has a seq_len dimension) and the linear attention
    cache (which has a constant shape regardless of seq_len).

    This cache has two sets of lists of tensors: `key_cache` and `value_cache` for attention cache and `conv_states`
    and `ssm_states` for gated deltanet cache. Each of these lists has `num_layers` tensors. The expected shape for each tensor
    For attention layers, `key_cache` and `value_cache` have a shape of `(batch_size, num_heads, seq_len, head_dim)`,
    while `conv_states` and `ssm_states` have a shape of `(batch_size, 0)` (empty tensors).
    For linear attention layers, `key_cache` and `value_cache` have a shape of `(batch_size, 0)` (empty tensors),
    while `conv_states` represents the convolution state and has a shape of `(batch_size, d_inner, d_conv)`,
    and `recurrent_states` represents the recurrent state and has a shape of `(batch_size, d_inner, d_state)`.
    """

    is_compileable = False

    def __init__(self, config: Qwen3_5Config):
        super().__init__()
        self.layer_types = config.layer_types
        self.transformer_layers = [
            i for i in range(config.num_hidden_layers) if self.layer_types[i] == "full_attention"
        ]
        self.last_linear_layer = len(self.layer_types) - 1 - self.layer_types[::-1].index("linear_attention")

        # Initialize everything to None -> will be lazy initialized to allow multi-gpu (device_map) inference
        self.conv_states = [None for _ in range(config.num_hidden_layers)]
        self.recurrent_states = [None for _ in range(config.num_hidden_layers)]
        self.key_cache = [None for _ in range(config.num_hidden_layers)]
        self.value_cache = [None for _ in range(config.num_hidden_layers)]

    def __len__(self):
        return len(self.layer_types)

    def update(
        self,
        key_states: torch.Tensor,
        value_states: torch.Tensor,
        layer_idx: int,
        cache_kwargs: dict[str, Any] | None = None,
    ) -> tuple[torch.Tensor, torch.Tensor]:
        if self.key_cache[layer_idx] is None:
            self.key_cache[layer_idx] = key_states
            self.value_cache[layer_idx] = value_states
        else:
            self.key_cache[layer_idx] = torch.cat([self.key_cache[layer_idx], key_states], dim=2)
            self.value_cache[layer_idx] = torch.cat([self.value_cache[layer_idx], value_states], dim=2)

        return self.key_cache[layer_idx], self.value_cache[layer_idx]

    def reorder_cache(self, beam_idx: torch.LongTensor):
        """Reorders the cache for beam search, given the selected beam indices."""
        for layer_idx in range(len(self.key_cache)):
            if self.key_cache[layer_idx] is not None:
                device = self.key_cache[layer_idx].device
                beam_idx = beam_idx.to(device)
                self.key_cache[layer_idx] = self.key_cache[layer_idx].index_select(0, beam_idx)
                self.value_cache[layer_idx] = self.value_cache[layer_idx].index_select(0, beam_idx)

            if self.conv_states[layer_idx] is not None:
                device = self.conv_states[layer_idx].device
                beam_idx = beam_idx.to(device)
                self.conv_states[layer_idx] = self.conv_states[layer_idx].index_select(0, beam_idx)
                self.recurrent_states[layer_idx] = self.recurrent_states[layer_idx].index_select(0, beam_idx)

    def get_seq_length(self, layer_idx: int | None = 0) -> int:
        """Returns the sequence length of the cached states. A layer index can be optionally passed."""
        # take any layer that contains cache and not empty tensor
        layer_idx = self.transformer_layers[0] if layer_idx not in self.transformer_layers else layer_idx
        if len(self.key_cache) <= layer_idx or self.key_cache[layer_idx] is None:
            return 0
        return self.key_cache[layer_idx].shape[-2]

    def get_mask_sizes(self, cache_position: torch.Tensor, layer_idx: int) -> tuple[int, int]:
        """
        Return a tuple (kv_length, kv_offset) corresponding to the length and offset that will be returned for
        the given layer at `layer_idx`.
        The masks are then prepared according to the given lengths (kv_length, kv_offset) and patterns for each layer.
        """
        kv_offset = 0
        query_length = cache_position.shape[0]
        past_seen_tokens = self.get_seq_length(layer_idx)
        kv_length = query_length + past_seen_tokens
        return kv_length, kv_offset

    @property
    def has_previous_state(self):
        """We have a previous state if the last linear (conv) layer was already updated."""
        return self.conv_states[self.last_linear_layer] is not None


class Qwen3_5VisionRotaryEmbedding(nn.Module):
    inv_freq: torch.Tensor  # fix linting for `register_buffer`

    def __init__(self, dim: int, theta: float = 10000.0) -> None:
        super().__init__()
        self.dim = dim
        self.theta = theta
        inv_freq = 1.0 / (theta ** (torch.arange(0, dim, 2, dtype=torch.float) / dim))
        self.register_buffer("inv_freq", inv_freq, persistent=False)

    def forward(self, seqlen: int) -> torch.Tensor:
        seq = torch.arange(seqlen, device=self.inv_freq.device, dtype=self.inv_freq.dtype)
        freqs = torch.outer(seq, self.inv_freq)
        return freqs


class Qwen3_5TextRotaryEmbedding(nn.Module):
    inv_freq: torch.Tensor  # fix linting for `register_buffer`

    def __init__(self, config: Qwen3_5TextConfig, device=None):
        super().__init__()
        self.max_seq_len_cached = config.max_position_embeddings
        self.original_max_seq_len = config.max_position_embeddings

        self.config = config

        self.rope_type = self.config.rope_parameters["rope_type"]
        rope_init_fn: Callable = self.compute_default_rope_parameters
        if self.rope_type != "default":
            rope_init_fn = ROPE_INIT_FUNCTIONS[self.rope_type]
        inv_freq, self.attention_scaling = rope_init_fn(self.config, device)

        self.register_buffer("inv_freq", inv_freq, persistent=False)
        self.register_buffer("original_inv_freq", inv_freq.clone(), persistent=False)
        self.mrope_section = config.rope_parameters.get("mrope_section", [11, 11, 10])

    @staticmethod
    def compute_default_rope_parameters(
        config: Qwen3_5TextConfig | None = None,
        device: Optional["torch.device"] = None,
        seq_len: int | None = None,
    ) -> tuple["torch.Tensor", float]:
        """
        Computes the inverse frequencies according to the original RoPE implementation
        Args:
            config ([`~transformers.PreTrainedConfig`]):
                The model configuration.
            device (`torch.device`):
                The device to use for initialization of the inverse frequencies.
            seq_len (`int`, *optional*):
                The current sequence length. Unused for this type of RoPE.
        Returns:
            Tuple of (`torch.Tensor`, `float`), containing the inverse frequencies for the RoPE embeddings and the
            post-processing scaling factor applied to the computed cos/sin (unused in this type of RoPE).
        """
        base = config.rope_parameters["rope_theta"]
        partial_rotary_factor = config.rope_parameters.get("partial_rotary_factor", 1.0)
        head_dim = getattr(config, "head_dim", None) or config.hidden_size // config.num_attention_heads
        dim = int(head_dim * partial_rotary_factor)

        attention_factor = 1.0  # Unused in this type of RoPE

        # Compute the inverse frequencies
        inv_freq = 1.0 / (
            base ** (torch.arange(0, dim, 2, dtype=torch.int64).to(device=device, dtype=torch.float) / dim)
        )
        return inv_freq, attention_factor

    @torch.no_grad()
    @dynamic_rope_update  # power user: used with advanced RoPE types (e.g. dynamic rope)
    def forward(self, x, position_ids):
        # In contrast to other models, Qwen3_5 has different position ids for the grids
        # So we expand the inv_freq to shape (3, ...)
        if position_ids.ndim == 2:
            position_ids = position_ids[None, ...].expand(3, position_ids.shape[0], -1)
        inv_freq_expanded = self.inv_freq[None, None, :, None].float().expand(3, position_ids.shape[1], -1, 1)
        position_ids_expanded = position_ids[:, :, None, :].float()  # shape (3, bs, 1, positions)

        device_type = x.device.type if isinstance(x.device.type, str) and x.device.type != "mps" else "cpu"
        with maybe_autocast(device_type=device_type, enabled=False):  # Force float32
            freqs = (inv_freq_expanded.float() @ position_ids_expanded.float()).transpose(2, 3)
            freqs = self.apply_interleaved_mrope(freqs, self.mrope_section)
            emb = torch.cat((freqs, freqs), dim=-1)
            cos = emb.cos() * self.attention_scaling
            sin = emb.sin() * self.attention_scaling

        return cos.to(dtype=x.dtype), sin.to(dtype=x.dtype)

    def apply_interleaved_mrope(self, freqs, mrope_section):
        """Apply interleaved MRoPE to 3D rotary embeddings.
        Reorganizes frequency layout from chunked [TTT...HHH...WWW] to
        interleaved [THWTHWTHW...TT], preserving frequency continuity.
        args:
            x: (3, bs, seq_len, head_dim // 2)
            mrope_section: (3,)
        returns:
            x_t: (bs, seq_len, head_dim // 2)
        """
        freqs_t = freqs[0]  # just overwrite the first dimension T
        for dim, offset in enumerate((1, 2), start=1):  # H, W
            length = mrope_section[dim] * 3
            idx = slice(offset, length, 3)
            freqs_t[..., idx] = freqs[dim, ..., idx]
        return freqs_t


class Qwen3_5RMSNormGated(nn.Module):
    def __init__(self, hidden_size, eps=1e-6, **kwargs):
        super().__init__()
        self.weight = nn.Parameter(torch.ones(hidden_size))
        self.variance_epsilon = eps

    def forward(self, hidden_states, gate=None):
        if IS_NPU_AVAILABLE:
            # NPU optimized: fused rms_norm + silu gate via npu_rms_norm
            hidden_states = torch_npu.npu_rms_norm(hidden_states, self.weight, self.variance_epsilon)[0]
            return hidden_states * F.silu(gate)
        input_dtype = hidden_states.dtype
        hidden_states = hidden_states.to(torch.float32)
        variance = hidden_states.pow(2).mean(-1, keepdim=True)
        # Norm before gate
        hidden_states = hidden_states * torch.rsqrt(variance + self.variance_epsilon)
        hidden_states = self.weight * hidden_states.to(input_dtype)
        hidden_states = hidden_states * F.silu(gate.to(torch.float32))

        return hidden_states.to(input_dtype)


def apply_mask_to_padding_states(hidden_states, attention_mask):
    """
    Tunes out the hidden states for padding tokens
    """
    # NOTE: attention mask is a 2D boolean tensor
    ps = get_parallel_state()
    if attention_mask is not None and attention_mask.shape[1] > 1 and attention_mask.shape[0] > 1:
        dtype = hidden_states.dtype
        if ps.is_ulysses_enable():
            split_sizes = cal_split_sizes(attention_mask.shape[1], world_size=ps.get_ulysses_group_size())
            attention_mask = torch.split(attention_mask, split_sizes, dim=1)[ps.get_ulysses_rank()]
        hidden_states = (hidden_states * attention_mask[:, :, None]).to(dtype)

    return hidden_states


is_fast_path_available = all(
    (causal_conv1d_fn, causal_conv1d_update, fla_chunk_gated_delta_rule, fused_recurrent_gated_delta_rule)
)


def torch_causal_conv1d_update(
    hidden_states,
    conv_state,
    weight,
    bias=None,
    activation=None,
):
    _, hidden_size, seq_len = hidden_states.shape
    state_len = conv_state.shape[-1]

    hidden_states_new = torch.cat([conv_state, hidden_states], dim=-1).to(weight.dtype)
    conv_state.copy_(hidden_states_new[:, :, -state_len:])
    out = F.conv1d(hidden_states_new, weight.unsqueeze(1), bias, padding=0, groups=hidden_size)
    out = F.silu(out[:, :, -seq_len:])
    out = out.to(hidden_states.dtype)
    return out


def l2norm(x: torch.FloatTensor, dim: int = -1, eps: float = 1e-6):
    """This function is intended to align with the l2norm implementation in the FLA library."""
    inv_norm = torch.rsqrt((x * x).sum(dim=dim, keepdim=True) + eps)
    return x * inv_norm


def torch_chunk_gated_delta_rule(
    query,
    key,
    value,
    g,
    beta,
    chunk_size=64,
    initial_state=None,
    output_final_state=False,
    use_qk_l2norm_in_kernel=False,
):
    initial_dtype = query.dtype
    if use_qk_l2norm_in_kernel:
        query = l2norm(query, dim=-1, eps=1e-6)
        key = l2norm(key, dim=-1, eps=1e-6)
    query, key, value, beta, g = [
        x.transpose(1, 2).contiguous().to(torch.float32) for x in (query, key, value, beta, g)
    ]

    batch_size, num_heads, sequence_length, k_head_dim = key.shape
    v_head_dim = value.shape[-1]
    pad_size = (chunk_size - sequence_length % chunk_size) % chunk_size
    query = F.pad(query, (0, 0, 0, pad_size))
    key = F.pad(key, (0, 0, 0, pad_size))
    value = F.pad(value, (0, 0, 0, pad_size))
    beta = F.pad(beta, (0, pad_size))
    g = F.pad(g, (0, pad_size))
    total_sequence_length = sequence_length + pad_size
    scale = 1 / (query.shape[-1] ** 0.5)
    query = query * scale

    v_beta = value * beta.unsqueeze(-1)
    k_beta = key * beta.unsqueeze(-1)
    # reshape to chunks
    query, key, value, k_beta, v_beta = [
        x.reshape(x.shape[0], x.shape[1], -1, chunk_size, x.shape[-1]) for x in (query, key, value, k_beta, v_beta)
    ]
    g = g.reshape(g.shape[0], g.shape[1], -1, chunk_size)
    mask = torch.triu(torch.ones(chunk_size, chunk_size, dtype=torch.bool, device=query.device), diagonal=0)

    # chunk decay
    g = g.cumsum(dim=-1)
    decay_mask = ((g.unsqueeze(-1) - g.unsqueeze(-2)).tril().exp().float()).tril()
    attn = -((k_beta @ key.transpose(-1, -2)) * decay_mask).masked_fill(mask, 0)
    for i in range(1, chunk_size):
        row = attn[..., i, :i].clone()
        sub = attn[..., :i, :i].clone()
        attn[..., i, :i] = row + (row.unsqueeze(-1) * sub).sum(-2)
    attn = attn + torch.eye(chunk_size, dtype=attn.dtype, device=attn.device)
    value = attn @ v_beta
    k_cumdecay = attn @ (k_beta * g.exp().unsqueeze(-1))
    last_recurrent_state = (
        torch.zeros(batch_size, num_heads, k_head_dim, v_head_dim).to(value)
        if initial_state is None
        else initial_state.to(value)
    )
    core_attn_out = torch.zeros_like(value)
    mask = torch.triu(torch.ones(chunk_size, chunk_size, dtype=torch.bool, device=query.device), diagonal=1)

    # for each chunk
    for i in range(0, total_sequence_length // chunk_size):
        q_i, k_i, v_i = query[:, :, i], key[:, :, i], value[:, :, i]
        attn = (q_i @ k_i.transpose(-1, -2) * decay_mask[:, :, i]).masked_fill_(mask, 0)
        v_prime = (k_cumdecay[:, :, i]) @ last_recurrent_state
        v_new = v_i - v_prime
        attn_inter = (q_i * g[:, :, i, :, None].exp()) @ last_recurrent_state
        core_attn_out[:, :, i] = attn_inter + attn @ v_new
        last_recurrent_state = (
            last_recurrent_state * g[:, :, i, -1, None, None].exp()
            + (k_i * (g[:, :, i, -1, None] - g[:, :, i]).exp()[..., None]).transpose(-1, -2) @ v_new
        )

    if not output_final_state:
        last_recurrent_state = None
    core_attn_out = core_attn_out.reshape(core_attn_out.shape[0], core_attn_out.shape[1], -1, core_attn_out.shape[-1])
    core_attn_out = core_attn_out[:, :, :sequence_length]
    core_attn_out = core_attn_out.transpose(1, 2).contiguous().to(initial_dtype)
    return core_attn_out, last_recurrent_state


def torch_recurrent_gated_delta_rule(
    query, key, value, g, beta, initial_state, output_final_state, use_qk_l2norm_in_kernel=False
):
    initial_dtype = query.dtype
    if use_qk_l2norm_in_kernel:
        query = l2norm(query, dim=-1, eps=1e-6)
        key = l2norm(key, dim=-1, eps=1e-6)
    query, key, value, beta, g = [
        x.transpose(1, 2).contiguous().to(torch.float32) for x in (query, key, value, beta, g)
    ]

    batch_size, num_heads, sequence_length, k_head_dim = key.shape
    v_head_dim = value.shape[-1]
    scale = 1 / (query.shape[-1] ** 0.5)
    query = query * scale

    core_attn_out = torch.zeros(batch_size, num_heads, sequence_length, v_head_dim).to(value)
    last_recurrent_state = (
        torch.zeros(batch_size, num_heads, k_head_dim, v_head_dim).to(value)
        if initial_state is None
        else initial_state.to(value)
    )

    for i in range(sequence_length):
        q_t = query[:, :, i]
        k_t = key[:, :, i]
        v_t = value[:, :, i]
        g_t = g[:, :, i].exp().unsqueeze(-1).unsqueeze(-1)
        beta_t = beta[:, :, i].unsqueeze(-1)

        last_recurrent_state = last_recurrent_state * g_t
        kv_mem = (last_recurrent_state * k_t.unsqueeze(-1)).sum(dim=-2)
        delta = (v_t - kv_mem) * beta_t
        last_recurrent_state = last_recurrent_state + k_t.unsqueeze(-1) * delta.unsqueeze(-2)
        core_attn_out[:, :, i] = (last_recurrent_state * q_t.unsqueeze(-1)).sum(dim=-2)

    if not output_final_state:
        last_recurrent_state = None
    core_attn_out = core_attn_out.transpose(1, 2).contiguous().to(initial_dtype)
    return core_attn_out, last_recurrent_state


class Qwen3_5GatedDeltaNet(nn.Module):
    def __init__(self, config: Qwen3_5Config, layer_idx: int):
        super().__init__()
        self.hidden_size = config.hidden_size
        self.num_v_heads = config.linear_num_value_heads
        self.num_k_heads = config.linear_num_key_heads
        self.head_k_dim = config.linear_key_head_dim
        self.head_v_dim = config.linear_value_head_dim
        self.key_dim = self.head_k_dim * self.num_k_heads
        self.value_dim = self.head_v_dim * self.num_v_heads

        self.conv_kernel_size = config.linear_conv_kernel_dim
        self.layer_idx = layer_idx
        self.activation = config.hidden_act
        self.act = ACT2FN[config.hidden_act]
        self.layer_norm_epsilon = config.rms_norm_eps

        # QKV
        self.conv_dim = self.key_dim * 2 + self.value_dim
        self.conv1d = nn.Conv1d(
            in_channels=self.conv_dim,
            out_channels=self.conv_dim,
            bias=False,
            kernel_size=self.conv_kernel_size,
            groups=self.conv_dim,
            padding=self.conv_kernel_size - 1,
        )

        # time step projection (discretization)
        # instantiate once and copy inv_dt in init_weights of PretrainedModel
        self.dt_bias = nn.Parameter(torch.ones(self.num_v_heads))

        A = torch.empty(self.num_v_heads).uniform_(0, 16)
        self.A_log = nn.Parameter(torch.log(A))

        self.norm = (
            Qwen3_5RMSNormGated(self.head_v_dim, eps=self.layer_norm_epsilon)
            if FusedRMSNormGated is None
            else FusedRMSNormGated(
                self.head_v_dim,
                eps=self.layer_norm_epsilon,
                activation=self.activation,
                device=torch.cuda.current_device(),
                dtype=config.dtype if config.dtype is not None else torch.get_default_dtype(),
            )
        )

        self.out_proj = nn.Linear(self.value_dim, self.hidden_size, bias=False)

        self.causal_conv1d_implementation = config.causal_conv1d_implementation
        if self.causal_conv1d_implementation == "triton" and IS_NPU_AVAILABLE:
            from mindspeed_mm.fsdp.models.qwen3_5.causal_conv1d import causal_conv1d
            print_rank(logger.info, "Qwen3_5Moe causal_conv1d use NPU triton ops")
            self.causal_conv1d_fn = causal_conv1d
        else:
            self.causal_conv1d_fn = causal_conv1d_fn
        self.causal_conv1d_update = causal_conv1d_update or torch_causal_conv1d_update

        self.gdn_implementation = config.gdn_implementation
        if self.gdn_implementation == "triton":
            if IS_NPU_AVAILABLE:
                from mindspeed_mm.fsdp.ops.gdn.chunk_gated_delta_rule import chunk_gated_delta_rule
                self.chunk_gated_delta_rule = chunk_gated_delta_rule
            elif is_flash_linear_attention_available():
                self.chunk_gated_delta_rule = fla_chunk_gated_delta_rule
            else:
                raise ValueError(
                    f"gdn_implementation='triton' requires NPU or flash_linear_attention, "
                    f"but neither is available. Please install the required dependency or use gdn_implementation='eager'."
                )
        elif self.gdn_implementation == "AscendC":
            if IS_NPU_AVAILABLE:
                from mindspeed_mm.fsdp.ops.gdn.flash_chunk_gated_delta_rule import chunk_gated_delta_rule
                self.chunk_gated_delta_rule = chunk_gated_delta_rule
            else:
                raise ValueError(
                    f"gdn_implementation='AscendC' requires NPU, but NPU is not available. "
                    f"Please use gdn_implementation='eager' or gdn_implementation='triton' instead."
                )
        elif self.gdn_implementation == "eager":
            self.chunk_gated_delta_rule = torch_chunk_gated_delta_rule
        else:
            raise ValueError(
                f"Invalid gdn_implementation='{self.gdn_implementation}'. Must be one of: 'eager', 'triton', 'AscendC'."
            )

        self.recurrent_gated_delta_rule = fused_recurrent_gated_delta_rule or torch_recurrent_gated_delta_rule

        if not is_fast_path_available:
            logger.warning_once(
                "The fast path is not available because one of the required library is not installed. Falling back to "
                "torch implementation."
            )

        self.in_proj_qkv = nn.Linear(self.hidden_size, self.key_dim * 2 + self.value_dim, bias=False)
        self.in_proj_z = nn.Linear(self.hidden_size, self.value_dim, bias=False)
        self.in_proj_b = nn.Linear(self.hidden_size, self.num_v_heads, bias=False)
        self.in_proj_a = nn.Linear(self.hidden_size, self.num_v_heads, bias=False)

    def _get_local_conv1d_weight(self, ulysses_rank: int, local_key_dim: int, local_value_dim: int) -> torch.Tensor:
        # Modification: shard depthwise conv1d weights to match head-sharded mixed_qkv channels.
        w_full = self.conv1d.weight
        if w_full.shape[0] != self.key_dim * 2 + self.value_dim:
            raise ValueError(
                f"conv1d weight dim ({w_full.shape[0]}) must match "
                f"(2 * key_dim + value_dim) ({self.key_dim * 2 + self.value_dim})"
            )
        k_off = ulysses_rank * local_key_dim
        v_off = ulysses_rank * local_value_dim
        w_q = w_full[k_off: k_off + local_key_dim]
        w_k = w_full[self.key_dim + k_off: self.key_dim + k_off + local_key_dim]
        w_v = w_full[2 * self.key_dim + v_off: 2 * self.key_dim + v_off + local_value_dim]
        return torch.cat([w_q, w_k, w_v], dim=0)

    def forward(
        self,
        hidden_states: torch.Tensor,
        cache_params: Qwen3_5DynamicCache | None = None,
        cache_position: torch.LongTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ):
        hidden_states = apply_mask_to_padding_states(hidden_states, attention_mask)

        # Set up dimensions for reshapes later
        batch_size, seq_len, _ = hidden_states.shape

        use_precomputed_states = (
            cache_params is not None
            and cache_params.has_previous_state
            and seq_len == 1
            and cache_position is not None
        )

        # getting projected states from cache if it exists
        if cache_params is not None:
            conv_state = cache_params.conv_states[self.layer_idx]
            recurrent_state = cache_params.recurrent_states[self.layer_idx]

        mixed_qkv = self.in_proj_qkv(hidden_states) # b s h
        # Modification(removed): No need to transpose here as it's handled later in conv path
        # mixed_qkv = mixed_qkv.transpose(1, 2)# b h s

        z = self.in_proj_z(hidden_states)
        z = z.reshape(batch_size, seq_len, -1, self.head_v_dim)

        b = self.in_proj_b(hidden_states)
        a = self.in_proj_a(hidden_states)

        # Modification: Ulysses SP all-to-all for linear attention heads.
        ps = get_parallel_state()
        if ps.is_ulysses_enable():
            ulysses_group = ps.get_ulysses_group()
            ulysses_size = ps.get_ulysses_group_size()
            ulysses_rank = ps.get_ulysses_rank()
            if self.num_k_heads % ulysses_size != 0 or self.num_v_heads % ulysses_size != 0:
                raise ValueError(
                    f"SP size ({ulysses_size}) must divide num_k_heads ({self.num_k_heads}) "
                    f"and num_v_heads ({self.num_v_heads}) for gated deltanet LASP"
                )

            local_num_k_heads = self.num_k_heads // ulysses_size
            local_num_v_heads = self.num_v_heads // ulysses_size
            local_key_dim = self.head_k_dim * local_num_k_heads
            local_value_dim = self.head_v_dim * local_num_v_heads

            # Reshape mixed_qkv to head layout for all-to-all: [B, S_local, D] -> split+reshape to heads
            q_proj, k_proj, v_proj = torch.split(mixed_qkv, [self.key_dim, self.key_dim, self.value_dim], dim=-1)

            # All-to-all: gather full sequence, scatter heads -> [B, S_full, local_dim]
            q_proj = all_to_all(q_proj, process_group=ulysses_group, scatter_dim=2, gather_dim=1, gather_size=get_seq_len("total"))
            k_proj = all_to_all(k_proj, process_group=ulysses_group, scatter_dim=2, gather_dim=1, gather_size=get_seq_len("total"))
            v_proj = all_to_all(v_proj, process_group=ulysses_group, scatter_dim=2, gather_dim=1, gather_size=get_seq_len("total"))

            b = b.reshape(batch_size, seq_len, self.num_v_heads)
            a = a.reshape(batch_size, seq_len, self.num_v_heads)
            b = all_to_all(b, process_group=ulysses_group, scatter_dim=2, gather_dim=1, gather_size=get_seq_len("total"))
            a = all_to_all(a, process_group=ulysses_group, scatter_dim=2, gather_dim=1, gather_size=get_seq_len("total"))

            # Concat for conv1d: [B, S_full, local_dim]
            mixed_qkv = torch.cat((q_proj, k_proj, v_proj), dim=-1)
        else:
            local_num_k_heads = self.num_k_heads
            local_num_v_heads = self.num_v_heads
            local_key_dim = self.key_dim
            local_value_dim = self.value_dim


        if use_precomputed_states:
            # 2. Convolution sequence transformation
            # NOTE: the conv state is updated in `causal_conv1d_update`
            mixed_qkv = self.causal_conv1d_update(
                mixed_qkv,
                conv_state,
                self.conv1d.weight.squeeze(1),
                self.conv1d.bias,
                self.activation,
            )
        else:
            if cache_params is not None:
                # Modification: Transpose for conv state padding and update cache
                mixed_qkv_t = mixed_qkv.transpose(1, 2)
                conv_state = F.pad(mixed_qkv_t, (self.conv_kernel_size - mixed_qkv_t.shape[-1], 0))
                cache_params.conv_states[self.layer_idx] = conv_state
            # Modification: shard conv1d weights per Ulysses rank to match head-sharded channels.
            if ps.is_ulysses_enable():
                conv_weight = self._get_local_conv1d_weight(
                    ulysses_rank=ulysses_rank,
                    local_key_dim=local_key_dim,
                    local_value_dim=local_value_dim,
                )
            else:
                conv_weight = self.conv1d.weight

            cu_seqlens = None
            if "cu_seqlens" in kwargs and kwargs.get("cu_seqlens") is not None:
                cu_seqlens = kwargs.get("cu_seq_lens_q").to(torch.int64)

            if self.causal_conv1d_implementation == "triton":
                conv_weight = conv_weight.squeeze(1)
                mixed_qkv, _ = self.causal_conv1d_fn(
                    x=mixed_qkv,
                    weight=conv_weight.transpose(-1, -2).contiguous(),
                    bias=self.conv1d.bias,
                    activation=self.activation,
                    cu_seqlens=cu_seqlens,
                )
            elif self.causal_conv1d_implementation == "eager" and self.causal_conv1d_fn is not None:  # for fla
                conv_weight = conv_weight.squeeze(1)
                mixed_qkv = self.causal_conv1d_fn(
                    x=mixed_qkv,
                    weight=conv_weight,
                    bias=self.conv1d.bias,
                    activation=self.activation,
                    seq_idx=None,
                )
                mixed_qkv = mixed_qkv.transpose(1, 2)
            else:
                mixed_qkv = mixed_qkv.transpose(1, 2)
                mixed_qkv = F.silu(F.conv1d(mixed_qkv, weight=conv_weight, bias=self.conv1d.bias, padding=self.conv_kernel_size - 1, groups=local_key_dim * 2 + local_value_dim)[:, :, :mixed_qkv.shape[-1]])
                mixed_qkv = mixed_qkv.transpose(1, 2)

        query, key, value = torch.split(
            mixed_qkv,
            [
                local_key_dim,
                local_key_dim,
                local_value_dim,
            ],
            dim=-1,
        )

        query = query.reshape(query.shape[0], query.shape[1], local_num_k_heads, self.head_k_dim)
        key = key.reshape(key.shape[0], key.shape[1], local_num_k_heads, self.head_k_dim)
        value = value.reshape(value.shape[0], value.shape[1], local_num_v_heads, self.head_v_dim)

        beta = b.sigmoid()
        # If the model is loaded in fp16, without the .float() here, A might be -inf
        # Modification: slice A_log/dt_bias for local V-heads under Ulysses SP.
        if ps.is_ulysses_enable():
            v_head_offset = ulysses_rank * local_num_v_heads
            v_head_slice = slice(v_head_offset, v_head_offset + local_num_v_heads)
            g = -self.A_log[v_head_slice].float().exp() * F.softplus(a.float() + self.dt_bias[v_head_slice])
        else:
            g = -self.A_log.float().exp() * F.softplus(a.float() + self.dt_bias)
        if self.num_v_heads // self.num_k_heads > 1:
            query = query.repeat_interleave(self.num_v_heads // self.num_k_heads, dim=2)
            key = key.repeat_interleave(self.num_v_heads // self.num_k_heads, dim=2)

        if not use_precomputed_states:
            if self.gdn_implementation == "triton" or self.gdn_implementation == "AscendC":
                core_attn_out, last_recurrent_state = self.chunk_gated_delta_rule(
                    query,
                    key,
                    value,
                    g=g,
                    beta=beta,
                    cu_seqlens=cu_seqlens,
                    initial_state=None,
                    output_final_state=cache_params is not None,
                    use_qk_l2norm_in_kernel=True,
                )
            else:
                core_attn_out, last_recurrent_state = self.chunk_gated_delta_rule(
                    query,
                    key,
                    value,
                    g=g,
                    beta=beta,
                    initial_state=None,
                    output_final_state=cache_params is not None,
                    use_qk_l2norm_in_kernel=True,
                )

        else:
            core_attn_out, last_recurrent_state = self.recurrent_gated_delta_rule(
                query,
                key,
                value,
                g=g,
                beta=beta,
                initial_state=recurrent_state,
                output_final_state=cache_params is not None,
                use_qk_l2norm_in_kernel=True,
            )

        # Update cache
        if cache_params is not None:
            cache_params.recurrent_states[self.layer_idx] = last_recurrent_state

        # Modification: gather attention output back to sequence-sharded layout before gated norm.
        if ps.is_ulysses_enable():
            core_attn_out = all_to_all(core_attn_out, process_group=ulysses_group, scatter_dim=1, gather_dim=2)

        # reshape input data into 2D tensor
        core_attn_out = core_attn_out.reshape(-1, self.head_v_dim)
        z = z.reshape(-1, self.head_v_dim)
        core_attn_out = self.norm(core_attn_out, z)
        core_attn_out = core_attn_out.reshape(batch_size, seq_len, -1)

        output = self.out_proj(core_attn_out)  # [b,s,h]
        return output


def rotate_half(x):
    """Rotates half the hidden dims of the input."""
    x1 = x[..., : x.shape[-1] // 2]
    x2 = x[..., x.shape[-1] // 2 :]
    return torch.cat((-x2, x1), dim=-1)


# Adapted from transformers.models.glm.modular_glm.apply_rotary_pos_emb
def apply_rotary_pos_emb(q, k, cos, sin, unsqueeze_dim=1):
    """Applies Rotary Position Embedding to the query and key tensors.

    Removes the interleaving of cos and sin from GLM

    Args:
        q (`torch.Tensor`): The query tensor.
        k (`torch.Tensor`): The key tensor.
        cos (`torch.Tensor`): The cosine part of the rotary embedding.
        sin (`torch.Tensor`): The sine part of the rotary embedding.
        unsqueeze_dim (`int`, *optional*, defaults to 1):
            The 'unsqueeze_dim' argument specifies the dimension along which to unsqueeze cos[position_ids] and
            sin[position_ids] so that they can be properly broadcasted to the dimensions of q and k. For example, note
            that cos[position_ids] and sin[position_ids] have the shape [batch_size, seq_len, head_dim]. Then, if q and
            k have the shape [batch_size, heads, seq_len, head_dim], then setting unsqueeze_dim=1 makes
            cos[position_ids] and sin[position_ids] broadcastable to the shapes of q and k. Similarly, if q and k have
            the shape [batch_size, seq_len, heads, head_dim], then set unsqueeze_dim=2.
    Returns:
        `tuple(torch.Tensor)` comprising of the query and key tensors rotated using the Rotary Position Embedding.
    """
    cos = cos.unsqueeze(unsqueeze_dim)
    sin = sin.unsqueeze(unsqueeze_dim)

    # Keep half or full tensor for later concatenation
    rotary_dim = cos.shape[-1]
    q_rot, q_pass = q[..., :rotary_dim], q[..., rotary_dim:]
    k_rot, k_pass = k[..., :rotary_dim], k[..., rotary_dim:]

    if IS_NPU_AVAILABLE:
        # NPU optimized: fused rotary mul instead of separate rotate_half + multiply
        q_embed = torch_npu.npu_rotary_mul(q_rot, cos, sin)
        k_embed = torch_npu.npu_rotary_mul(k_rot, cos, sin)
    else:
        # Apply rotary embeddings on the first half or full tensor
        q_embed = (q_rot * cos) + (rotate_half(q_rot) * sin)
        k_embed = (k_rot * cos) + (rotate_half(k_rot) * sin)

    # Concatenate back to full shape
    q_embed = torch.cat([q_embed, q_pass], dim=-1)
    k_embed = torch.cat([k_embed, k_pass], dim=-1)
    return q_embed, k_embed


def repeat_kv(hidden_states: torch.Tensor, n_rep: int) -> torch.Tensor:
    """
    This is the equivalent of torch.repeat_interleave(x, dim=1, repeats=n_rep). The hidden states go from (batch,
    num_key_value_heads, seqlen, head_dim) to (batch, num_attention_heads, seqlen, head_dim)
    """
    batch, num_key_value_heads, slen, head_dim = hidden_states.shape
    if n_rep == 1:
        return hidden_states
    hidden_states = hidden_states[:, :, None, :, :].expand(batch, num_key_value_heads, n_rep, slen, head_dim)
    return hidden_states.reshape(batch, num_key_value_heads * n_rep, slen, head_dim)


def eager_attention_forward(
    module: nn.Module,
    query: torch.Tensor,
    key: torch.Tensor,
    value: torch.Tensor,
    attention_mask: torch.Tensor | None,
    scaling: float,
    dropout: float = 0.0,
    **kwargs: Unpack[TransformersKwargs],
):
    key_states = repeat_kv(key, module.num_key_value_groups)
    value_states = repeat_kv(value, module.num_key_value_groups)

    attn_weights = torch.matmul(query, key_states.transpose(2, 3)) * scaling
    if attention_mask is not None:
        attn_weights = attn_weights + attention_mask

    attn_weights = nn.functional.softmax(attn_weights, dim=-1, dtype=torch.float32).to(query.dtype)
    attn_weights = nn.functional.dropout(attn_weights, p=dropout, training=module.training)
    attn_output = torch.matmul(attn_weights, value_states)
    attn_output = attn_output.transpose(1, 2).contiguous()

    return attn_output, attn_weights


@use_kernelized_func(apply_rotary_pos_emb)
class Qwen3_5Attention(nn.Module):
    """Multi-headed attention from 'Attention Is All You Need' paper"""

    def __init__(self, config: Qwen3_5Config, layer_idx: int):
        super().__init__()
        self.config = config
        self.layer_idx = layer_idx
        self.head_dim = getattr(config, "head_dim", config.hidden_size // config.num_attention_heads)
        self.num_key_value_groups = config.num_attention_heads // config.num_key_value_heads
        self.scaling = self.head_dim**-0.5
        self.attention_dropout = config.attention_dropout
        self.is_causal = True
        self.q_proj = nn.Linear(
            config.hidden_size, config.num_attention_heads * self.head_dim * 2, bias=config.attention_bias
        )
        self.k_proj = nn.Linear(
            config.hidden_size, config.num_key_value_heads * self.head_dim, bias=config.attention_bias
        )
        self.v_proj = nn.Linear(
            config.hidden_size, config.num_key_value_heads * self.head_dim, bias=config.attention_bias
        )
        self.o_proj = nn.Linear(
            config.num_attention_heads * self.head_dim, config.hidden_size, bias=config.attention_bias
        )
        self.q_norm = Qwen3_5RMSNorm(self.head_dim, eps=config.rms_norm_eps)  # unlike olmo, only on the head dim!
        self.k_norm = Qwen3_5RMSNorm(self.head_dim, eps=config.rms_norm_eps)  # thus post q_norm does not need reshape

    def forward(
        self,
        hidden_states: torch.Tensor,
        position_embeddings: tuple[torch.Tensor, torch.Tensor],
        attention_mask: torch.Tensor | None,
        past_key_values: Cache | None = None,
        cache_position: torch.LongTensor | None = None,
        **kwargs: Unpack[FlashAttentionKwargs],
    ) -> tuple[torch.Tensor, torch.Tensor | None]:
        input_shape = hidden_states.shape[:-1]
        hidden_shape = (*input_shape, -1, self.head_dim)

        query_states, gate = torch.chunk(
            self.q_proj(hidden_states).view(*input_shape, -1, self.head_dim * 2), 2, dim=-1
        )
        gate = gate.reshape(*input_shape, -1)

        query_states = self.q_norm(query_states.view(hidden_shape)).transpose(1, 2)
        key_states = self.k_norm(self.k_proj(hidden_states).view(hidden_shape)).transpose(1, 2)
        value_states = self.v_proj(hidden_states).view(hidden_shape).transpose(1, 2)

        cos, sin = position_embeddings
        query_states, key_states = apply_rotary_pos_emb(query_states, key_states, cos, sin)

        if past_key_values is not None:
            # sin and cos are specific to RoPE models; cache_position needed for the static cache
            cache_kwargs = {"sin": sin, "cos": cos, "cache_position": cache_position}
            key_states, value_states = past_key_values.update(key_states, value_states, self.layer_idx, cache_kwargs)

        attention_interface: Callable = ALL_ATTENTION_FUNCTIONS.get_interface(
            self.config._attn_implementation, eager_attention_forward
        )
        # CP Modification: add total_seq_len for Attention
        total_seq_len = get_seq_len("total")
        if get_parallel_state().get_ulysses_group_size() > self.config.num_key_value_heads:
            key_states = repeat_kv(key_states, self.num_key_value_groups)
            value_states = repeat_kv(value_states, self.num_key_value_groups)
        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask,
            dropout=0.0 if not self.training else self.attention_dropout,
            scaling=self.scaling,
            is_causal=True,
            total_seq_len=total_seq_len,
            seq_split_lens=None,
            **kwargs,
        )

        attn_output = attn_output.reshape(*input_shape, -1).contiguous()
        attn_output = attn_output * torch.sigmoid(gate)

        attn_output = self.o_proj(attn_output)
        return attn_output, attn_weights


class Qwen3_5MLP(nn.Module):
    def __init__(self, config: Qwen3_5Config, intermediate_size: int):
        super().__init__()
        self.config = config
        self.hidden_size = config.hidden_size
        self.intermediate_size = intermediate_size
        self.gate_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
        self.up_proj = nn.Linear(self.hidden_size, self.intermediate_size, bias=False)
        self.down_proj = nn.Linear(self.intermediate_size, self.hidden_size, bias=False)
        self.act_fn = ACT2FN[config.hidden_act]

    def forward(self, x):
        down_proj = self.down_proj(self.act_fn(self.gate_proj(x)) * self.up_proj(x))
        return down_proj


class Qwen3_5RMSNorm(nn.Module):
    def __init__(self, dim: int, eps: float = 1e-6):
        super().__init__()
        self.eps = eps
        self.weight = nn.Parameter(torch.zeros(dim))

    def _norm(self, x):
        return x * torch.rsqrt(x.pow(2).mean(-1, keepdim=True) + self.eps)

    def forward(self, x):
        if IS_NPU_AVAILABLE:
            # NPU optimized: fused rms_norm with pre-added bias (1.0 + weight)
            return torch_npu.npu_rms_norm(x, 1.0 + self.weight, self.eps)[0]
        output = self._norm(x.float())
        # Llama does x.to(float16) * w whilst Qwen3_5 is (x * w).to(float16)
        output = output * (1.0 + self.weight.float())
        return output.type_as(x)

    def extra_repr(self):
        return f"{tuple(self.weight.shape)}, eps={self.eps}"


class Qwen3_5DecoderLayer(GradientCheckpointingLayer):
    def __init__(self, config: Qwen3_5TextConfig, layer_idx: int, is_mtp: bool = False):
        super().__init__()
        self.hidden_size = config.hidden_size
        self.layer_type = config.layer_types[layer_idx] if not is_mtp else "full_attention"
        if self.layer_type == "linear_attention":
            self.linear_attn = Qwen3_5GatedDeltaNet(config, layer_idx)
        elif self.layer_type == "full_attention":
            self.self_attn = Qwen3_5Attention(config, layer_idx)
        self.mlp = Qwen3_5MLP(config, config.intermediate_size)
        self.input_layernorm = Qwen3_5RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.post_attention_layernorm = Qwen3_5RMSNorm(config.hidden_size, eps=config.rms_norm_eps)

    def forward(
        self,
        hidden_states: torch.Tensor,
        position_embeddings: tuple[torch.Tensor, torch.Tensor],
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        cache_position: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> torch.FloatTensor:
        residual = hidden_states

        hidden_states = self.input_layernorm(hidden_states)

        # Token Mixer
        if self.layer_type == "linear_attention":
            hidden_states = self.linear_attn(
                hidden_states=hidden_states,
                cache_params=past_key_values,
                cache_position=cache_position,
                attention_mask=attention_mask,
                **kwargs,
            )
        elif self.layer_type == "full_attention":
            # Self Attention
            hidden_states, _ = self.self_attn(
                hidden_states=hidden_states,
                attention_mask=attention_mask,
                position_ids=position_ids,
                past_key_values=past_key_values,
                cache_position=cache_position,
                position_embeddings=position_embeddings,
                **kwargs,
            )

        hidden_states = residual + hidden_states

        # Fully Connected
        residual = hidden_states
        hidden_states = self.post_attention_layernorm(hidden_states)
        hidden_states = self.mlp(hidden_states)
        hidden_states = residual + hidden_states

        return hidden_states


class Qwen3_5PreTrainedModel(PreTrainedModel):
    config: Qwen3_5Config
    base_model_prefix = "model"
    supports_gradient_checkpointing = True
    _no_split_modules = ["Qwen3_5DecoderLayer", "Qwen3_5VisionBlock"]
    _skip_keys_device_placement = "past_key_values"
    _supports_flash_attn = True
    _supports_sdpa = True
    _keys_to_ignore_on_load_unexpected = [r"^mtp.*"]
    _can_record_outputs = {
        "hidden_states": Qwen3_5DecoderLayer,
        "attentions": Qwen3_5Attention,
    }
    _is_stateful = True

    @torch.no_grad()
    def _init_weights(self, module):
        super()._init_weights(module)
        if isinstance(module, Qwen3_5GatedDeltaNet):
            init.ones_(module.dt_bias)
            init.copy_(module.A_log, torch.empty_like(module.A_log).uniform_(0, 16).log_())
        # We initialize with 0s to be 1 centered as the RMSNorm here does (1 + weight)
        elif isinstance(module, Qwen3_5RMSNorm):
            init.zeros_(module.weight)
        elif isinstance(module, Qwen3_5VisionRotaryEmbedding):
            inv_freq = 1.0 / (module.theta ** (torch.arange(0, module.dim, 2, dtype=torch.float) / module.dim))
            init.copy_(module.inv_freq, inv_freq)


class Qwen3_5VisionMLP(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.hidden_size = config.hidden_size
        self.intermediate_size = config.intermediate_size
        self.linear_fc1 = nn.Linear(self.hidden_size, self.intermediate_size, bias=True)
        self.linear_fc2 = nn.Linear(self.intermediate_size, self.hidden_size, bias=True)
        self.act_fn = ACT2FN[config.hidden_act]

    def forward(self, hidden_state):
        return self.linear_fc2(self.act_fn(self.linear_fc1(hidden_state)))


class Qwen3_5VisionPatchEmbed(nn.Module):
    def __init__(self, config) -> None:
        super().__init__()
        self.patch_size = config.patch_size
        self.temporal_patch_size = config.temporal_patch_size
        self.in_channels = config.in_channels
        self.embed_dim = config.hidden_size

        kernel_size = [self.temporal_patch_size, self.patch_size, self.patch_size]
        self.proj = nn.Conv3d(self.in_channels, self.embed_dim, kernel_size=kernel_size, stride=kernel_size, bias=True)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        target_dtype = self.proj.weight.dtype
        hidden_states = hidden_states.view(
            -1, self.in_channels, self.temporal_patch_size, self.patch_size, self.patch_size
        )
        hidden_states = self.proj(hidden_states.to(dtype=target_dtype)).view(-1, self.embed_dim)
        return hidden_states


class Qwen3_5VisionPatchMerger(nn.Module):
    def __init__(self, config: Qwen3_5VisionConfig, use_postshuffle_norm=False) -> None:
        super().__init__()
        self.hidden_size = config.hidden_size * (config.spatial_merge_size**2)
        self.use_postshuffle_norm = use_postshuffle_norm
        self.norm = nn.LayerNorm(self.hidden_size if use_postshuffle_norm else config.hidden_size, eps=1e-6)
        self.linear_fc1 = nn.Linear(self.hidden_size, self.hidden_size)
        self.act_fn = nn.GELU()
        self.linear_fc2 = nn.Linear(self.hidden_size, config.out_hidden_size)

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        ps = get_parallel_state()
        if ps.is_cp_enable():
            if self.use_postshuffle_norm:
                x = packed_data_gather_forward_split_backward_with_cp(x, dim=0, seq_lens=get_seq_len("per_visual"))
                x = x.view(-1, self.hidden_size)
                # after down_sample hidden_state, should split it again
                split_sizes = cal_split_sizes(x.shape[0], ps.get_ulysses_group_size())
                # Split the merged tensor back for distributed processing
                # Since no attention computation follows, we can use simple splitting
                x = split_forward_gather_backward(x, ps.get_ulysses_group(), dim=0, grad_scale="down", split_sizes=split_sizes)
                x = self.norm(x)
            else:
                x = self.norm(x)
                x = packed_data_gather_forward_split_backward_with_cp(x, dim=0, seq_lens=get_seq_len("per_visual"))
                x = x.view(-1, self.hidden_size)
                # after down_sample hidden_state, should split it again
                split_sizes = cal_split_sizes(x.shape[0], ps.get_ulysses_group_size())
                # Split the merged tensor back for distributed processing
                # Since no attention computation follows, we can use simple splitting
                x = split_forward_gather_backward(x, ps.get_ulysses_group(), dim=0, grad_scale="down", split_sizes=split_sizes)
            x = self.linear_fc2(self.act_fn(self.linear_fc1(x)))
        else:
            x = self.norm(x.view(-1, self.hidden_size) if self.use_postshuffle_norm else x).view(-1, self.hidden_size)
            x = self.linear_fc2(self.act_fn(self.linear_fc1(x)))
        return x


def apply_rotary_pos_emb_vision(
    q: torch.Tensor, k: torch.Tensor, cos: torch.Tensor, sin: torch.Tensor
) -> tuple[torch.Tensor, torch.Tensor]:
    orig_q_dtype = q.dtype
    orig_k_dtype = k.dtype
    q, k = q.float(), k.float()
    cos, sin = cos.unsqueeze(-2).float(), sin.unsqueeze(-2).float()
    if IS_NPU_AVAILABLE:
        # NPU optimized: fused rotary mul instead of separate rotate_half + multiply
        q_embed = torch_npu.npu_rotary_mul(q, cos, sin)
        k_embed = torch_npu.npu_rotary_mul(k, cos, sin)
    else:
        q_embed = (q * cos) + (rotate_half(q) * sin)
        k_embed = (k * cos) + (rotate_half(k) * sin)
    q_embed = q_embed.to(orig_q_dtype)
    k_embed = k_embed.to(orig_k_dtype)
    return q_embed, k_embed


class Qwen3_5VisionAttention(nn.Module):
    def __init__(self, config: Qwen3_5VisionConfig) -> None:
        super().__init__()
        self.dim = config.hidden_size
        self.num_heads = config.num_heads
        self.head_dim = self.dim // self.num_heads
        self.num_key_value_groups = 1  # needed for eager attention
        self.qkv = nn.Linear(self.dim, self.dim * 3, bias=True)
        self.proj = nn.Linear(self.dim, self.dim)
        self.scaling = self.head_dim**-0.5
        self.config = config
        self.attention_dropout = 0.0
        self.is_causal = False

    def forward(
        self,
        hidden_states: torch.Tensor,
        cu_seqlens: torch.Tensor,
        rotary_pos_emb: torch.Tensor | None = None,
        position_embeddings: tuple[torch.Tensor, torch.Tensor] | None = None,
        **kwargs,
    ) -> torch.Tensor:
        seq_length = hidden_states.shape[0]
        query_states, key_states, value_states = (
            self.qkv(hidden_states).reshape(seq_length, 3, self.num_heads, -1).permute(1, 0, 2, 3).unbind(0)
        )
        cos, sin = position_embeddings
        query_states, key_states = apply_rotary_pos_emb_vision(query_states, key_states, cos, sin)

        attention_interface: Callable = ALL_ATTENTION_FUNCTIONS.get_interface(
            self.config._attn_implementation, eager_attention_forward
        )

        # Modification: pass total_visual_seqlen
        if self.config._attn_implementation == "flash_attention_2":
            query_states = query_states.unsqueeze(0)
            key_states = key_states.unsqueeze(0)
            value_states = value_states.unsqueeze(0)

            # Flash Attention 2: Use cu_seqlens for variable length attention
            max_seqlen = (cu_seqlens[1:] - cu_seqlens[:-1]).max()
            attn_output, _ = attention_interface(
                self,
                query_states,
                key_states,
                value_states,
                attention_mask=None,
                scaling=self.scaling,
                dropout=0.0 if not self.training else self.attention_dropout,
                cu_seq_lens_q=cu_seqlens,
                cu_seq_lens_k=cu_seqlens,
                max_length_q=max_seqlen,
                max_length_k=max_seqlen,
                is_causal=False,
                total_seq_len=get_seq_len("visual"),
                input_layout="1TND",
                **kwargs,
            )
        else:
            query_states = query_states.transpose(0, 1).unsqueeze(0)
            key_states = key_states.transpose(0, 1).unsqueeze(0)
            value_states = value_states.transpose(0, 1).unsqueeze(0)

            # Other implementations: Process each chunk separately
            lengths = cu_seqlens[1:] - cu_seqlens[:-1]
            splits = [
                torch.split(tensor, lengths.tolist(), dim=2) for tensor in (query_states, key_states, value_states)
            ]

            attn_outputs = [
                attention_interface(
                    self,
                    q,
                    k,
                    v,
                    attention_mask=None,
                    scaling=self.scaling,
                    dropout=0.0 if not self.training else self.attention_dropout,
                    is_causal=False,
                    **kwargs,
                )[0]
                for q, k, v in zip(*splits)
            ]
            attn_output = torch.cat(attn_outputs, dim=1)

        attn_output = attn_output.reshape(seq_length, -1).contiguous()
        attn_output = self.proj(attn_output)
        return attn_output


class Qwen3_5VisionBlock(GradientCheckpointingLayer):
    def __init__(self, config, attn_implementation: str = "sdpa") -> None:
        super().__init__()
        self.norm1 = nn.LayerNorm(config.hidden_size, eps=1e-6)
        self.norm2 = nn.LayerNorm(config.hidden_size, eps=1e-6)
        self.attn = Qwen3_5VisionAttention(config=config)
        self.mlp = Qwen3_5VisionMLP(config=config)

    def forward(
        self,
        hidden_states: torch.Tensor,
        cu_seqlens: torch.Tensor,
        rotary_pos_emb: torch.Tensor | None = None,
        position_embeddings: tuple[torch.Tensor, torch.Tensor] | None = None,
        **kwargs,
    ) -> torch.Tensor:
        hidden_states = hidden_states + self.attn(
            self.norm1(hidden_states),
            cu_seqlens=cu_seqlens,
            rotary_pos_emb=rotary_pos_emb,
            position_embeddings=position_embeddings,
            **kwargs,
        )
        hidden_states = hidden_states + self.mlp(self.norm2(hidden_states))
        return hidden_states


class Qwen3_5VisionModel(Qwen3_5PreTrainedModel):
    config: Qwen3_5VisionConfig
    _no_split_modules = ["Qwen3_5VisionBlock"]
    _can_record_outputs = {
        "hidden_states": Qwen3_5VisionBlock,
        "attentions": Qwen3_5VisionAttention,
    }

    def __init__(self, config, *inputs, **kwargs) -> None:
        super().__init__(config, *inputs, **kwargs)
        self.spatial_merge_size = config.spatial_merge_size
        self.patch_size = config.patch_size
        self.spatial_merge_unit = self.spatial_merge_size * self.spatial_merge_size

        self.patch_embed = Qwen3_5VisionPatchEmbed(
            config=config,
        )

        self.pos_embed = nn.Embedding(config.num_position_embeddings, config.hidden_size)
        self.num_grid_per_side = int(config.num_position_embeddings**0.5)

        head_dim = config.hidden_size // config.num_heads
        self.rotary_pos_emb = Qwen3_5VisionRotaryEmbedding(head_dim // 2)

        self.blocks = nn.ModuleList([Qwen3_5VisionBlock(config) for _ in range(config.depth)])
        self.merger = Qwen3_5VisionPatchMerger(
            config=config,
            use_postshuffle_norm=False,
        )

        self.gradient_checkpointing = False

        self.post_init()

    def rot_pos_emb(self, grid_thw: torch.Tensor) -> torch.Tensor:
        merge_size = self.spatial_merge_size
        grid_thw_list = grid_thw.tolist()

        max_hw = max(max(h, w) for _, h, w in grid_thw_list)
        freq_table = self.rotary_pos_emb(max_hw)  # (max_hw, dim // 2)
        device = freq_table.device

        total_tokens = sum(t * h * w for t, h, w in grid_thw_list)
        pos_ids = torch.empty((total_tokens, 2), dtype=torch.long, device=device)

        offset = 0
        for num_frames, height, width in grid_thw_list:
            merged_h, merged_w = height // merge_size, width // merge_size

            block_rows = torch.arange(merged_h, device=device)  # block row indices
            block_cols = torch.arange(merged_w, device=device)  # block col indices
            intra_row = torch.arange(merge_size, device=device)  # intra-block row offsets
            intra_col = torch.arange(merge_size, device=device)  # intra-block col offsets

            # Compute full-resolution positions
            row_idx = block_rows[:, None, None, None] * merge_size + intra_row[None, None, :, None]
            col_idx = block_cols[None, :, None, None] * merge_size + intra_col[None, None, None, :]

            row_idx = row_idx.expand(merged_h, merged_w, merge_size, merge_size).reshape(-1)
            col_idx = col_idx.expand(merged_h, merged_w, merge_size, merge_size).reshape(-1)

            coords = torch.stack((row_idx, col_idx), dim=-1)

            if num_frames > 1:
                coords = coords.repeat(num_frames, 1)

            num_tokens = coords.shape[0]
            pos_ids[offset : offset + num_tokens] = coords
            offset += num_tokens

        embeddings = freq_table[pos_ids]  # lookup rotary embeddings
        embeddings = embeddings.flatten(1)
        return embeddings

    def fast_pos_embed_interpolate(self, grid_thw):
        grid_thw_list = grid_thw.tolist()
        grid_ts = [row[0] for row in grid_thw_list]
        grid_hs = [row[1] for row in grid_thw_list]
        grid_ws = [row[2] for row in grid_thw_list]
        device = self.pos_embed.weight.device

        idx_list = [[] for _ in range(4)]
        weight_list = [[] for _ in range(4)]

        for t, h, w in grid_thw_list:
            h_idxs = torch.linspace(0, self.num_grid_per_side - 1, h)
            w_idxs = torch.linspace(0, self.num_grid_per_side - 1, w)

            h_idxs_floor = h_idxs.int()
            w_idxs_floor = w_idxs.int()
            h_idxs_ceil = (h_idxs.int() + 1).clip(max=self.num_grid_per_side - 1)
            w_idxs_ceil = (w_idxs.int() + 1).clip(max=self.num_grid_per_side - 1)

            dh = h_idxs - h_idxs_floor
            dw = w_idxs - w_idxs_floor

            base_h = h_idxs_floor * self.num_grid_per_side
            base_h_ceil = h_idxs_ceil * self.num_grid_per_side

            indices = [
                (base_h[None].T + w_idxs_floor[None]).flatten(),
                (base_h[None].T + w_idxs_ceil[None]).flatten(),
                (base_h_ceil[None].T + w_idxs_floor[None]).flatten(),
                (base_h_ceil[None].T + w_idxs_ceil[None]).flatten(),
            ]

            weights = [
                ((1 - dh)[None].T * (1 - dw)[None]).flatten(),
                ((1 - dh)[None].T * dw[None]).flatten(),
                (dh[None].T * (1 - dw)[None]).flatten(),
                (dh[None].T * dw[None]).flatten(),
            ]

            for i in range(4):
                idx_list[i].extend(indices[i].tolist())
                weight_list[i].extend(weights[i].tolist())

        idx_tensor = torch.tensor(idx_list, dtype=torch.long, device=device)
        weight_tensor = torch.tensor(weight_list, dtype=self.pos_embed.weight.dtype, device=device)
        pos_embeds = self.pos_embed(idx_tensor).to(device) * weight_tensor[:, :, None]
        patch_pos_embeds = pos_embeds[0] + pos_embeds[1] + pos_embeds[2] + pos_embeds[3]

        patch_pos_embeds = patch_pos_embeds.split([h * w for h, w in zip(grid_hs, grid_ws)])

        patch_pos_embeds_permute = []
        merge_size = self.config.spatial_merge_size
        for pos_embed, t, h, w in zip(patch_pos_embeds, grid_ts, grid_hs, grid_ws):
            pos_embed = pos_embed.repeat(t, 1)
            pos_embed = (
                pos_embed.view(t, h // merge_size, merge_size, w // merge_size, merge_size, -1)
                .permute(0, 1, 3, 2, 4, 5)
                .flatten(0, 4)
            )
            patch_pos_embeds_permute.append(pos_embed)
        patch_pos_embeds = torch.cat(patch_pos_embeds_permute)
        return patch_pos_embeds

    @merge_with_config_defaults
    @capture_outputs
    def forward(self, hidden_states: torch.Tensor, grid_thw: torch.Tensor, **kwargs) -> torch.Tensor:
        """
        Args:
            hidden_states (`torch.Tensor` of shape `(seq_len, hidden_size)`):
                The final hidden states of the model.
            grid_thw (`torch.Tensor` of shape `(num_images_or_videos, 3)`):
                The temporal, height and width of feature shape of each image in LLM.

        Returns:
            `torch.Tensor`: hidden_states.
        """
        hidden_states = self.patch_embed(hidden_states)

        pos_embeds = self.fast_pos_embed_interpolate(grid_thw)
        hidden_states = hidden_states + pos_embeds

        rotary_pos_emb = self.rot_pos_emb(grid_thw)

        seq_len, _ = hidden_states.size()
        hidden_states = hidden_states.reshape(seq_len, -1)
        rotary_pos_emb = rotary_pos_emb.reshape(seq_len, -1)

        cu_seqlens = torch.repeat_interleave(grid_thw[:, 1] * grid_thw[:, 2], grid_thw[:, 0]).cumsum(
            dim=0,
            # Select dtype based on the following factors:
            #  - FA2 requires that cu_seqlens_q must have dtype int32
            #  - torch.onnx.export requires that cu_seqlens_q must have same dtype as grid_thw
            dtype=grid_thw.dtype if torch.jit.is_tracing() else torch.int32,
        )
        # Modification: cu_seqlens move to cpu, in case of cpu-gpu synchronizing on NPU
        cu_seqlens = F.pad(cu_seqlens, (1, 0), value=0)
        if IS_NPU_AVAILABLE:
            cu_seqlens = cu_seqlens.cpu()

        # Modification: slice rotary_pos_emb and hidden_states if using cp
        # Set global sequence length variables for cp
        sequence_lengths = torch.repeat_interleave(grid_thw[:, 1] * grid_thw[:, 2], grid_thw[:, 0]).cpu()
        set_seq_len("visual", seq_len) # s
        set_seq_len("per_visual", sequence_lengths) # s
        ps = get_parallel_state()
        # Split sequences across context parallel groups for distributed processing
        if ps.is_cp_enable():
            rotary_pos_emb = packed_data_split_forward_gather_backward_with_cp(rotary_pos_emb, dim=0, seq_lens=sequence_lengths)
            hidden_states = packed_data_split_forward_gather_backward_with_cp(hidden_states, dim=0, seq_lens=sequence_lengths)
        emb = torch.cat((rotary_pos_emb, rotary_pos_emb), dim=-1)
        position_embeddings = (emb.cos(), emb.sin())
        for blk in self.blocks:
            hidden_states = blk(
                hidden_states,
                cu_seqlens=cu_seqlens,
                position_embeddings=position_embeddings,
                **kwargs,
            )

        merged_hidden_states = self.merger(hidden_states)

        # Modification: Gather outputs from all context parallel ranks for the final result
        set_seq_len("visual", seq_len // self.spatial_merge_size ** 2)
        if ps.is_cp_enable():
            gather_sizes = cal_split_sizes(get_seq_len("visual"), ps.get_ulysses_group_size())
            merged_hidden_states = gather_forward_split_backward(
                merged_hidden_states,
                ps.get_ulysses_group(),
                dim=0,
                grad_scale="up",
                gather_sizes=gather_sizes,
            )
        set_seq_len("visual", seq_len) # for recompute
        return BaseModelOutputWithPooling(
            last_hidden_state=hidden_states,
            pooler_output=merged_hidden_states,
        )


@dataclass
@auto_docstring(
    custom_intro="""
    Base class for Llava outputs, with hidden states and attentions.
    """
)
class Qwen3_5ModelOutputWithPast(ModelOutput):
    r"""
    past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
        It is a [`~cache_utils.Cache`] instance.

        Contains pre-computed hidden-states (key and values in the self-attention blocks) that can be used (see
        `past_key_values` input) to speed up sequential decoding.
    rope_deltas (`torch.LongTensor` of shape `(batch_size, )`, *optional*):
        The rope index difference between sequence length and multimodal rope.
    """

    last_hidden_state: torch.FloatTensor | None = None
    past_key_values: Cache | None = None
    hidden_states: tuple[torch.FloatTensor] | None = None
    attentions: tuple[torch.FloatTensor] | None = None
    rope_deltas: torch.LongTensor | None = None
    position_ids: torch.LongTensor | None = None


class Qwen3_5TextModel(Qwen3_5PreTrainedModel):
    def __init__(self, config: Qwen3_5TextConfig):
        super().__init__(config)
        self.embed_tokens = nn.Embedding(config.vocab_size, config.hidden_size, config.pad_token_id)
        self.layers = nn.ModuleList(
            [Qwen3_5DecoderLayer(config, layer_idx) for layer_idx in range(config.num_hidden_layers)]
        )
        self.norm = Qwen3_5RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
        self.rotary_emb = Qwen3_5TextRotaryEmbedding(config=config)
        self.gradient_checkpointing = False
        # Initialize weights and apply final processing
        self.post_init()

    @merge_with_config_defaults
    @capture_outputs
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        use_cache: bool | None = None,
        cache_position: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> BaseModelOutputWithPast:
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if inputs_embeds is None:
            inputs_embeds = self.embed_tokens(input_ids)

        if use_cache and past_key_values is None:
            past_key_values = Qwen3_5DynamicCache(config=self.config)

        if cache_position is None:
            past_seen_tokens = past_key_values.get_seq_length() if past_key_values is not None else 0
            cache_position = torch.arange(
                past_seen_tokens, past_seen_tokens + inputs_embeds.shape[1], device=inputs_embeds.device
            )

        # mrope: the hard coded `3` is for temporal, height and width.
        if position_ids is None:
            position_ids = cache_position.view(1, 1, -1).expand(3, inputs_embeds.shape[0], -1)
        elif position_ids.ndim == 2:
            position_ids = position_ids[None, ...].expand(3, position_ids.shape[0], -1)

        if position_ids.ndim == 3 and position_ids.shape[0] == 4:
            text_position_ids = position_ids[0]
            position_ids = position_ids[1:]
        else:
            text_position_ids = position_ids[0]

        use_packing = "cu_seqlens" in kwargs and kwargs["cu_seqlens"] is not None
        if use_packing:
            causal_mask = None
            kwargs.update(generate_ulysses_cu_seqlen_params(text_position_ids, need_cpu_tensor=False))
        else:
            causal_mask = create_causal_mask(
                config=self.config,
                inputs_embeds=inputs_embeds,
                attention_mask=attention_mask,
                cache_position=cache_position,
                past_key_values=past_key_values,
                position_ids=text_position_ids,
            )
        linear_attn_mask = self._update_linear_attn_mask(attention_mask, cache_position)
        # Modification: For Ulysses, cu_seq_len needs to be calculated before position_ids split
        kwargs_fa = kwargs
        ps = get_parallel_state()
        if ps.is_ulysses_enable():
            if not use_packing:
                kwargs.update(generate_ulysses_cu_seqlen_params(text_position_ids))
            else:
                kwargs_fa = kwargs.copy()
                kwargs_fa["cu_seq_lens_q"] = kwargs_fa["cu_seq_lens_q"].cpu()
                kwargs_fa["cu_seq_lens_k"] = kwargs_fa["cu_seq_lens_k"].cpu()

        # Modification: sequence parallel patch
        total_seq_len = inputs_embeds.shape[1]
        set_seq_len("total", total_seq_len)
        if ps.is_ulysses_enable():
            position_ids = split_forward_gather_backward_with_cp(position_ids, dim=2)
            text_position_ids = split_forward_gather_backward_with_cp(text_position_ids, dim=1)
            inputs_embeds = split_forward_gather_backward_with_cp(inputs_embeds, dim=1)

        hidden_states = inputs_embeds
        position_embeddings = self.rotary_emb(hidden_states, position_ids)

        for layer_idx, decoder_layer in enumerate(self.layers[: self.config.num_hidden_layers]):
            layer_mask = linear_attn_mask if decoder_layer.layer_type == "linear_attention" else causal_mask
            new_kwargs = kwargs if decoder_layer.layer_type == "linear_attention" else kwargs_fa

            hidden_states = decoder_layer(
                hidden_states,
                position_embeddings=position_embeddings,
                attention_mask=layer_mask,
                position_ids=text_position_ids,
                past_key_values=past_key_values,
                use_cache=use_cache,
                cache_position=cache_position,
                **new_kwargs,
            )

        hidden_states = self.norm(hidden_states)

        return Qwen3_5ModelOutputWithPast(
            last_hidden_state=hidden_states,
            past_key_values=past_key_values,
        )

    def _update_linear_attn_mask(self, attention_mask, cache_position):
        """
        NOTE: Left-padding is used for linear attention mask.
        No need for zeroing states when
            1. Cached forward
            2. Attending to all inputs
        """
        linear_attn_mask = attention_mask
        if cache_position[0] > 0 or (attention_mask is not None and torch.all(attention_mask == 1)):
            linear_attn_mask = None
        return linear_attn_mask


@auto_docstring
class Qwen3_5Model(Qwen3_5PreTrainedModel):
    base_model_prefix = "model"
    _checkpoint_conversion_mapping = {}
    # Reference: fix gemma3 grad acc #37208
    accepts_loss_kwargs = False
    config: Qwen3_5Config
    _no_split_modules = ["Qwen3_5TextDecoderLayer", "Qwen3_5VisionBlock"]

    def __init__(self, config):
        super().__init__(config)
        self.visual = Qwen3_5VisionModel._from_config(config.vision_config)
        self.language_model = Qwen3_5TextModel._from_config(config.text_config)
        self.rope_deltas = None  # cache rope_deltas here

        # Initialize weights and apply final processing
        self.post_init()

    def get_input_embeddings(self):
        return self.language_model.get_input_embeddings()

    def set_input_embeddings(self, value):
        self.language_model.set_input_embeddings(value)

    def get_rope_index(
        self,
        input_ids: torch.LongTensor | None = None,
        image_grid_thw: torch.LongTensor | None = None,
        video_grid_thw: torch.LongTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        **kwargs,
    ) -> tuple[torch.Tensor, torch.Tensor]:
        """Different from the original implementation, Qwen3_5 use timestamps rather than absolute time position ids."""

        # Since we use timestamps to separate videos, like <t1> <vision_start> <frame1> <vision_end> <t2> <vision_start> <frame2> <vision_end>, the video_grid_thw should also be split
        if video_grid_thw is not None:
            video_grid_thw = torch.repeat_interleave(video_grid_thw, video_grid_thw[:, 0], dim=0)
            video_grid_thw[:, 0] = 1

        image_grid_thw_list = image_grid_thw.tolist() if image_grid_thw is not None else None
        video_grid_thw_list = video_grid_thw.tolist() if video_grid_thw is not None else None

        spatial_merge_size = self.config.vision_config.spatial_merge_size
        image_token_id = self.config.image_token_id
        video_token_id = self.config.video_token_id
        vision_start_token_id = self.config.vision_start_token_id
        mrope_position_deltas = []
        total_input_ids = input_ids
        if attention_mask is None:
            attention_mask = torch.ones_like(total_input_ids)
        position_ids = torch.zeros(
            3,
            input_ids.shape[0],
            input_ids.shape[1],
            dtype=input_ids.dtype,
            device=input_ids.device,
        )
        image_index, video_index = 0, 0
        attention_mask = attention_mask.to(total_input_ids.device)
        for i, input_ids in enumerate(total_input_ids):
            input_ids = input_ids[attention_mask[i] == 1]
            image_nums, video_nums = 0, 0
            vision_start_indices = torch.argwhere(input_ids == vision_start_token_id).squeeze(1)
            vision_tokens = input_ids[vision_start_indices + 1]
            image_nums = (vision_tokens == image_token_id).sum()
            video_nums = (vision_tokens == video_token_id).sum()
            input_tokens = input_ids.tolist()
            llm_pos_ids_list: list = []
            st = 0
            remain_images, remain_videos = image_nums, video_nums
            for _ in range(image_nums + video_nums):
                if image_token_id in input_tokens and remain_images > 0:
                    ed_image = input_tokens.index(image_token_id, st)
                else:
                    ed_image = len(input_tokens) + 1
                if video_token_id in input_tokens and remain_videos > 0:
                    ed_video = input_tokens.index(video_token_id, st)
                else:
                    ed_video = len(input_tokens) + 1
                if ed_image < ed_video:
                    t, h, w = image_grid_thw_list[image_index]
                    image_index += 1
                    remain_images -= 1
                    ed = ed_image
                else:
                    t, h, w = video_grid_thw_list[video_index]
                    video_index += 1
                    remain_videos -= 1
                    ed = ed_video
                llm_grid_t, llm_grid_h, llm_grid_w = (
                    t,
                    h // spatial_merge_size,
                    w // spatial_merge_size,
                )
                text_len = ed - st
                st_idx = llm_pos_ids_list[-1].max() + 1 if len(llm_pos_ids_list) > 0 else 0
                llm_pos_ids_list.append(torch.arange(text_len).view(1, -1).expand(3, -1) + st_idx)
                # t_index is always 0 because llm_grid_t is always 1 (we use timestamps to encode the temporal information for videos)
                t_index = torch.arange(llm_grid_t).view(-1, 1).expand(-1, llm_grid_h * llm_grid_w).flatten()
                h_index = torch.arange(llm_grid_h).view(1, -1, 1).expand(llm_grid_t, -1, llm_grid_w).flatten()
                w_index = torch.arange(llm_grid_w).view(1, 1, -1).expand(llm_grid_t, llm_grid_h, -1).flatten()
                llm_pos_ids_list.append(torch.stack([t_index, h_index, w_index]) + text_len + st_idx)
                st = ed + llm_grid_t * llm_grid_h * llm_grid_w
            if st < len(input_tokens):
                st_idx = llm_pos_ids_list[-1].max() + 1 if len(llm_pos_ids_list) > 0 else 0
                text_len = len(input_tokens) - st
                llm_pos_ids_list.append(torch.arange(text_len).view(1, -1).expand(3, -1) + st_idx)
            llm_positions = torch.cat(llm_pos_ids_list, dim=1).reshape(3, -1)
            position_ids[..., i, attention_mask[i] == 1] = llm_positions.to(position_ids.device)
            mrope_position_deltas.append(llm_positions.max() + 1 - len(total_input_ids[i]))
        mrope_position_deltas = torch.tensor(mrope_position_deltas, device=input_ids.device).unsqueeze(1)
        return position_ids, mrope_position_deltas

    @can_return_tuple
    @auto_docstring
    def get_video_features(
        self,
        pixel_values_videos: torch.FloatTensor,
        video_grid_thw: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        r"""
        pixel_values_videos (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
            The tensors corresponding to the input videos.
        video_grid_thw (`torch.LongTensor` of shape `(num_videos, 3)`, *optional*):
            The temporal, height and width of feature shape of each video in LLM.
        """
        # Same implementation as for images
        return self.get_image_features(pixel_values_videos, video_grid_thw, **kwargs)

    @can_return_tuple
    @auto_docstring
    def get_image_features(
        self,
        pixel_values: torch.FloatTensor,
        image_grid_thw: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        r"""
        pixel_values (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
            The tensors corresponding to the input images.
        image_grid_thw (`torch.LongTensor` of shape `(num_images, 3)`, *optional*):
            The temporal, height and width of feature shape of each image in LLM.
        """
        pixel_values = pixel_values.type(self.visual.dtype)
        vision_output: BaseModelOutputWithPooling = self.visual(
            pixel_values, grid_thw=image_grid_thw, return_dict=True, **kwargs
        )
        image_embeds = vision_output.pooler_output
        split_sizes = (image_grid_thw.prod(-1) // self.visual.spatial_merge_size**2).tolist()
        image_embeds = torch.split(image_embeds, split_sizes)
        vision_output.pooler_output = image_embeds

        return vision_output

    def get_placeholder_mask(
        self,
        input_ids: torch.LongTensor,
        inputs_embeds: torch.FloatTensor,
        image_features: torch.FloatTensor | None = None,
        video_features: torch.FloatTensor | None = None,
    ):
        """
        Obtains multimodal placeholder mask from `input_ids` or `inputs_embeds`, and checks that the placeholder token count is
        equal to the length of multimodal features. If the lengths are different, an error is raised.
        """
        if input_ids is None:
            special_image_mask = inputs_embeds == self.get_input_embeddings()(
                torch.tensor(self.config.image_token_id, dtype=torch.long, device=inputs_embeds.device)
            )
            special_image_mask = special_image_mask.all(-1)
            special_video_mask = inputs_embeds == self.get_input_embeddings()(
                torch.tensor(self.config.video_token_id, dtype=torch.long, device=inputs_embeds.device)
            )
            special_video_mask = special_video_mask.all(-1)
        else:
            special_image_mask = input_ids == self.config.image_token_id
            special_video_mask = input_ids == self.config.video_token_id

        # Keep mask at compact shape (batch, seq_len) instead of expanding to (batch, seq_len, hidden_dim).
        # The compact mask avoids allocating a huge boolean tensor and enables efficient nonzero + direct indexing
        # in forward(), replacing the expensive masked_scatter which scans the full (batch, seq_len, hidden_dim) space.
        if image_features is not None:
            n_image_tokens = special_image_mask.sum()
            if n_image_tokens != image_features.shape[0]:
                raise ValueError(
                    f"Image features and image tokens do not match, tokens: {n_image_tokens}, features: {image_features.shape[0]}"
                )
        else:
            special_image_mask = None

        if video_features is not None:
            n_video_tokens = special_video_mask.sum()
            if n_video_tokens != video_features.shape[0]:
                raise ValueError(
                    f"Video features and video tokens do not match, tokens: {n_video_tokens}, features: {video_features.shape[0]}"
                )
        else:
            special_video_mask = None

        return special_image_mask, special_video_mask

    def compute_3d_position_ids(
        self,
        input_ids: torch.Tensor | None,
        inputs_embeds: torch.Tensor | None,
        image_grid_thw: torch.Tensor | None = None,
        video_grid_thw: torch.Tensor | None = None,
        attention_mask: torch.Tensor | None = None,
        past_key_values: torch.Tensor | None = None,
    ) -> torch.Tensor | None:
        past_key_values_length = 0 if past_key_values is None else past_key_values.get_seq_length()
        can_compute_mrope = input_ids is not None and (image_grid_thw is not None or video_grid_thw is not None)

        if can_compute_mrope and (self.rope_deltas is None or past_key_values_length == 0):
            position_ids, rope_deltas = self.get_rope_index(
                input_ids,
                image_grid_thw=image_grid_thw,
                video_grid_thw=video_grid_thw,
                attention_mask=attention_mask,
            )
            self.rope_deltas = rope_deltas
        # Use pre-calculated rope-deltas to infer correct 3D position ids
        elif self.rope_deltas is not None:
            batch_size, seq_length, _ = inputs_embeds.shape
            if attention_mask is not None:
                position_ids = attention_mask.long().cumsum(-1) - 1
                position_ids = position_ids.masked_fill(attention_mask == 0, 0)
                position_ids = position_ids.view(1, batch_size, -1).repeat(3, 1, 1).to(inputs_embeds.device)
            else:
                position_ids = torch.arange(past_key_values_length, past_key_values_length + seq_length)
                position_ids = position_ids.view(1, 1, -1).expand(3, batch_size, -1).to(inputs_embeds.device)
            delta = self.rope_deltas.repeat_interleave(batch_size // self.rope_deltas.shape[0], dim=0)
            position_ids = position_ids + delta.to(device=position_ids.device)
        else:
            # Can't build correct 3D positions. Let the model infer it from `cache_position`
            position_ids = None
        return position_ids

    @auto_docstring
    @can_return_tuple
    def forward(
        self,
        input_ids: torch.LongTensor = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        pixel_values: torch.Tensor | None = None,
        pixel_values_videos: torch.FloatTensor | None = None,
        image_grid_thw: torch.LongTensor | None = None,
        video_grid_thw: torch.LongTensor | None = None,
        cache_position: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | Qwen3_5ModelOutputWithPast:
        r"""
        image_grid_thw (`torch.LongTensor` of shape `(num_images, 3)`, *optional*):
            The temporal, height and width of feature shape of each image in LLM.
        video_grid_thw (`torch.LongTensor` of shape `(num_videos, 3)`, *optional*):
            The temporal, height and width of feature shape of each video in LLM.
        """
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if inputs_embeds is None:
            inputs_embeds = self.get_input_embeddings()(input_ids)

        if pixel_values is not None:
            image_outputs: BaseModelOutputWithPooling = self.get_image_features(
                pixel_values, image_grid_thw, return_dict=True
            )
            image_embeds = image_outputs.pooler_output
            image_embeds = torch.cat(image_embeds, dim=0).to(inputs_embeds.device, inputs_embeds.dtype)
            image_mask, _ = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, image_features=image_embeds
            )
            # Use nonzero + direct indexing instead of masked_scatter to avoid scanning the full
            # (batch, seq_len, hidden_dim) tensor. nonzero finds target positions on the compact (batch, seq_len)
            # mask in O(batch * seq_len), then direct indexing writes only to those positions.
            image_indices_tuple = torch.nonzero(image_mask, as_tuple=True)
            inputs_embeds[image_indices_tuple] = image_embeds

        if pixel_values_videos is not None:
            video_outputs: BaseModelOutputWithPooling = self.get_video_features(
                pixel_values_videos, video_grid_thw, return_dict=True
            )
            video_embeds = video_outputs.pooler_output
            video_embeds = torch.cat(video_embeds, dim=0).to(inputs_embeds.device, inputs_embeds.dtype)
            _, video_mask = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, video_features=video_embeds
            )
            # Same optimization as image: nonzero + direct indexing replaces masked_scatter.
            video_indices_tuple = torch.nonzero(video_mask, as_tuple=True)
            inputs_embeds[video_indices_tuple] = video_embeds

        if position_ids is None:
            position_ids = self.compute_3d_position_ids(
                input_ids=input_ids,
                image_grid_thw=image_grid_thw,
                video_grid_thw=video_grid_thw,
                inputs_embeds=inputs_embeds,
                attention_mask=attention_mask,
                past_key_values=past_key_values,
            )

        outputs = self.language_model(
            input_ids=None,
            position_ids=position_ids,
            attention_mask=attention_mask,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            cache_position=cache_position,
            **kwargs,
        )

        return Qwen3_5ModelOutputWithPast(
            **outputs,
            rope_deltas=self.rope_deltas,
            position_ids=position_ids,
        )


@auto_docstring
class Qwen3_5ForCausalLM(Qwen3_5PreTrainedModel, GenerationMixin):
    _tied_weights_keys = {"lm_head.weight": "model.embed_tokens.weight"}
    _tp_plan = {"lm_head": "colwise_gather_output"}
    _pp_plan = {"lm_head": (["hidden_states"], ["logits"])}
    config: Qwen3_5TextConfig
    _keys_to_ignore_on_load_unexpected = [r"^mtp.*", r"^model.visual.*"]

    def __init__(self, config):
        super().__init__(config)
        self.model = Qwen3_5TextModel(config)
        self.vocab_size = config.vocab_size
        self.lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

        # Initialize weights and apply final processing
        self.post_init()

    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        use_cache: bool | None = None,
        cache_position: torch.LongTensor | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        **kwargs: Unpack[TransformersKwargs],
    ) -> CausalLMOutputWithPast:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
            config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
            (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.

        Example:

        ```python
        >>> from transformers import AutoTokenizer, Qwen3_5ForCausalLM

        >>> model = Qwen3_5ForCausalLM.from_pretrained("Qwen/Qwen3_5-8B")
        >>> tokenizer = AutoTokenizer.from_pretrained("Qwen/Qwen3_5-8B")

        >>> prompt = "Hey, are you conscious? Can you talk to me?"
        >>> inputs = tokenizer(prompt, return_tensors="pt")

        >>> # Generate
        >>> generate_ids = model.generate(inputs.input_ids, max_length=30)
        >>> tokenizer.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        "Hey, are you conscious? Can you talk to me?\nI'm not conscious, but I can talk to you."
        ```"""
        outputs: BaseModelOutputWithPast = self.model(
            input_ids=input_ids,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            cache_position=cache_position,
            **kwargs,
        )

        hidden_states = outputs.last_hidden_state
        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
        logits = self.lm_head(hidden_states[:, slice_indices, :])

        loss = None
        if labels is not None:
            loss = self.loss_function(logits=logits, labels=labels, vocab_size=self.config.vocab_size, **kwargs)

        return CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
        )


@dataclass
@auto_docstring(
    custom_intro="""
    Base class for Qwen3_5 causal language model (or autoregressive) outputs.
    """
)
class Qwen3_5CausalLMOutputWithPast(ModelOutput):
    r"""
    loss (`torch.FloatTensor` of shape `(1,)`, *optional*, returned when `labels` is provided):
        Language modeling loss (for next-token prediction).
    logits (`torch.FloatTensor` of shape `(batch_size, sequence_length, config.vocab_size)`):
        Prediction scores of the language modeling head (scores for each vocabulary token before SoftMax).
    past_key_values (`Cache`, *optional*, returned when `use_cache=True` is passed or when `config.use_cache=True`):
        It is a [`~cache_utils.Cache`] instance.

        Contains pre-computed hidden-states (key and values in the self-attention blocks) that can be used (see
        `past_key_values` input) to speed up sequential decoding.
    rope_deltas (`torch.LongTensor` of shape `(batch_size, )`, *optional*):
        The rope index difference between sequence length and multimodal rope.
    """

    loss: torch.FloatTensor | None = None
    logits: torch.FloatTensor | None = None
    past_key_values: Cache | None = None
    hidden_states: tuple[torch.FloatTensor] | None = None
    attentions: tuple[torch.FloatTensor] | None = None
    rope_deltas: torch.LongTensor | None = None
    mtp_loss: torch.FloatTensor | list[torch.FloatTensor] | None = None


@model_register.register("qwen3_5")
class Qwen3_5ForConditionalGeneration(Qwen3_5PreTrainedModel, GenerationMixin):
    _checkpoint_conversion_mapping = {}
    _tied_weights_keys = {"lm_head.weight": "model.language_model.embed_tokens.weight"}
    # Reference: fix gemma3 grad acc #37208
    accepts_loss_kwargs = False
    config: Qwen3_5Config

    def __init__(self, config):
        super().__init__(config)
        self.model = Qwen3_5Model(config)
        self.lm_head = nn.Linear(config.text_config.hidden_size, config.text_config.vocab_size, bias=False)
        self.enable_mtp = bool(config.text_config.mtp_num_layers)
        self.mtp = MultiTokenPredictionBlock(
            config.text_config, Qwen3_5DecoderLayer, Qwen3_5RMSNorm
        ) if self.enable_mtp else None

        self.post_init()

    @staticmethod
    def overwrite_transformer_config(transformer_config, model_args, feature_args):
        gdn_implementation = getattr(model_args, "gdn_implementation", "eager")
        if gdn_implementation not in ("eager", "triton", "AscendC"):
            raise ValueError(f"Invalid gdn_implementation='{gdn_implementation}'. Must be one of: 'eager', 'triton', 'AscendC'.")
        transformer_config.text_config.gdn_implementation= gdn_implementation
        causal_conv1d_implementation = getattr(model_args, "causal_conv1d_implementation", "eager")
        if causal_conv1d_implementation not in ("eager", "triton"):
            raise ValueError(f"Invalid causal_conv1d='{causal_conv1d_implementation}'. Must be one of: 'eager', 'triton'.")
        transformer_config.text_config.causal_conv1d_implementation = causal_conv1d_implementation
        # mtp
        mtp_num_layers = getattr(model_args, "mtp_num_layers", 0)
        if mtp_num_layers not in (0, 1):
            raise ValueError(f"Invalid mtp_num_layers='{mtp_num_layers}'. Must be one of: 0, 1.")
        transformer_config.text_config.mtp_num_layers = mtp_num_layers
        transformer_config.text_config.enable_chunk_loss = getattr(feature_args, "enable_chunk_loss", False)
        transformer_config.text_config.enable_dynamic_chunk_loss = getattr(feature_args, "enable_dynamic_chunk_loss", False)
        return transformer_config

    def get_input_embeddings(self):
        return self.model.get_input_embeddings()

    def set_input_embeddings(self, value):
        self.model.set_input_embeddings(value)

    @auto_docstring
    def get_video_features(
        self,
        pixel_values_videos: torch.FloatTensor,
        video_grid_thw: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        r"""
        pixel_values_videos (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
            The tensors corresponding to the input videos.
        video_grid_thw (`torch.LongTensor` of shape `(num_videos, 3)`, *optional*):
            The temporal, height and width of feature shape of each video in LLM.
        """
        return self.model.get_video_features(
            pixel_values_videos=pixel_values_videos, video_grid_thw=video_grid_thw, **kwargs
        )

    @auto_docstring
    def get_image_features(
        self,
        pixel_values: torch.FloatTensor,
        image_grid_thw: torch.LongTensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        r"""
        pixel_values (`torch.FloatTensor` of shape `(batch_size, num_channels, image_size, image_size)`):
            The tensors corresponding to the input images.
        image_grid_thw (`torch.LongTensor` of shape `(num_images, 3)`, *optional*):
            The temporal, height and width of feature shape of each image in LLM.
        """
        return self.model.get_image_features(pixel_values=pixel_values, image_grid_thw=image_grid_thw, **kwargs)

    def _compute_mtp_loss(self, hidden_states: torch.Tensor, **kwargs):
        if not self.enable_mtp:
            return None

        mtp_loss = self.mtp(
            hidden_states,
            embed_tokens=self.model.language_model.embed_tokens,
            rotary_emb=self.model.language_model.rotary_emb,
            output_layer=self.lm_head,
            loss_function=self.loss_function,
            seq_len=get_seq_len("total"),
            **kwargs,
        )
        return mtp_loss

    @can_return_tuple
    def forward(
        self,
        input_ids: torch.LongTensor = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        pixel_values: torch.Tensor | None = None,
        pixel_values_videos: torch.FloatTensor | None = None,
        image_grid_thw: torch.LongTensor | None = None,
        video_grid_thw: torch.LongTensor | None = None,
        cache_position: torch.LongTensor | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | Qwen3_5CausalLMOutputWithPast:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
            config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
            (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.
        image_grid_thw (`torch.LongTensor` of shape `(num_images, 3)`, *optional*):
            The temporal, height and width of feature shape of each image in LLM.
        video_grid_thw (`torch.LongTensor` of shape `(num_videos, 3)`, *optional*):
            The temporal, height and width of feature shape of each video in LLM.

        Example:

        ```python
        >>> from transformers import AutoProcessor, Qwen3_5ForConditionalGeneration

        >>> model = Qwen3_5ForConditionalGeneration.from_pretrained("Qwen/Qwen3-VL-8B-Instruct")
        >>> processor = AutoProcessor.from_pretrained("Qwen/Qwen3-VL-8B-Instruct")

        >>> messages = [
            {
                "role": "user",
                "content": [
                    {
                        "type": "image",
                        "image": "./pipeline-cat-chonk.jpeg",
                    },
                    {"type": "text", "text": "Describe the image."},
                ],
            }
        ]

        >>> inputs = processor.apply_chat_template(
            messages,
            tokenize=True,
            add_generation_prompt=True,
            return_dict=True,
            return_tensors="pt"
        )

        >>> # Generate
        >>> generated_ids = model.generate(**inputs, max_new_tokens=1024)
        >>> generated_ids_trimmed = [out_ids[len(in_ids) :] for in_ids, out_ids in zip(inputs.input_ids, generated_ids)]
        >>> output_text = processor.batch_decode(generated_ids_trimmed, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        >>> print(output_text)
        ```
        """

        outputs = self.model(
            input_ids=input_ids,
            pixel_values=pixel_values,
            pixel_values_videos=pixel_values_videos,
            image_grid_thw=image_grid_thw,
            video_grid_thw=video_grid_thw,
            position_ids=position_ids,
            attention_mask=attention_mask,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            cache_position=cache_position,
            **kwargs,
        )

        hidden_states = outputs[0]

        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
        if getattr(self, "enable_chunk_loss", False) or getattr(self, "enable_dynamic_chunk_loss", False):
            logits = None
            loss = self.lm_head(hidden_states[:, slice_indices, :], self.loss_function)
        else:
            logits = self.lm_head(hidden_states[:, slice_indices, :])

            loss = None
            if labels is not None:
                loss = self.loss_function(logits=logits, labels=labels, vocab_size=self.config.text_config.vocab_size)

        # Modification: all gather loss in all cp ranks for scaling up the grad.
        ps = get_parallel_state()
        if loss is not None and ps.is_cp_enable():
            loss = gather_forward_split_backward(loss.unsqueeze(0), ps.get_cp_group(), dim=0)
            loss = loss.sum()

        final_mtp_loss = self._compute_mtp_loss(
            hidden_states,
            input_ids=input_ids,
            labels=labels,
            attention_mask=attention_mask,
            position_ids=outputs.position_ids,
            past_key_values=outputs.past_key_values,
            cache_position=cache_position,
            logits_to_keep=logits_to_keep,
            **kwargs,
        )

        return Qwen3_5CausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            mtp_loss=final_mtp_loss,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            rope_deltas=outputs.rope_deltas,
        )

    def prepare_inputs_for_generation(
        self,
        input_ids,
        past_key_values=None,
        attention_mask=None,
        inputs_embeds=None,
        cache_position=None,
        position_ids=None,
        use_cache=True,
        pixel_values=None,
        pixel_values_videos=None,
        image_grid_thw=None,
        video_grid_thw=None,
        is_first_iteration=False,
        **kwargs,
    ):
        # Overwritten -- in specific circumstances we don't want to forward image inputs to the model

        model_inputs = super().prepare_inputs_for_generation(
            input_ids,
            past_key_values=past_key_values,
            attention_mask=attention_mask,
            inputs_embeds=inputs_embeds,
            cache_position=cache_position,
            position_ids=position_ids,
            pixel_values=pixel_values,
            pixel_values_videos=pixel_values_videos,
            image_grid_thw=image_grid_thw,
            video_grid_thw=video_grid_thw,
            use_cache=use_cache,
            is_first_iteration=is_first_iteration,
            **kwargs,
        )

        if not is_first_iteration and use_cache:
            model_inputs["pixel_values"] = None
            model_inputs["pixel_values_videos"] = None

        return model_inputs

    def _prepare_position_ids_for_generation(self, inputs_tensor, model_kwargs):
        # Overwritten -- requires 3D position ids

        text_positions = super()._prepare_position_ids_for_generation(inputs_tensor, model_kwargs)

        # Early exit in case we are continuing generation from past kv
        past_length = 0
        if (cache := model_kwargs.get("past_key_values")) is not None:
            past_length = cache.get_seq_length()
        if past_length != 0 and self.model.rope_deltas is not None:
            text_positions += self.model.rope_deltas
            return text_positions

        # Otherwise compute 3d position ids for vision tokens and concat with text position ids
        if "input_ids" in model_kwargs and model_kwargs["input_ids"].shape[1] > 0:
            inputs_tensor = model_kwargs["input_ids"]

        is_input_ids = len(inputs_tensor.shape) == 2 and inputs_tensor.dtype in [torch.int, torch.long]
        if is_input_ids and (
            model_kwargs.get("image_grid_thw") is not None or model_kwargs.get("video_grid_thw") is not None
        ):
            model_kwargs = {k: v for k, v in model_kwargs.items() if k != "input_ids"}
            vision_positions, rope_deltas = self.model.get_rope_index(inputs_tensor, **model_kwargs)
            self.model.rope_deltas = rope_deltas
        else:
            vision_positions = text_positions.unsqueeze(0).expand(3, -1, -1)
            self.model.rope_deltas = torch.zeros(
                inputs_tensor.shape[0], 1, dtype=torch.long, device=inputs_tensor.device
            )

        # Concatenate "text + vision" positions into [4, bs, seq-len]
        text_positions = text_positions[None, ...]
        position_ids = torch.cat([text_positions, vision_positions], dim=0)

        return position_ids

    def _get_image_nums_and_video_nums(
        self,
        input_ids: torch.LongTensor | None,
        inputs_embeds: torch.Tensor | None = None,
    ) -> tuple[torch.Tensor, torch.Tensor]:
        """
        Get the number of images and videos for each sample to calculate the separation length of the sample tensor.
        These parameters are not passed through the processor to avoid unpredictable impacts from interface modifications.

        Args:
            input_ids (`torch.LongTensor` of shape `(batch_size, sequence_length)`):
                Indices of input sequence tokens in the vocabulary.

        Returns:
            image_nums (`torch.LongTensor` of shape `(batch_size, num_images_sample)`)
            video_nums (`torch.LongTensor` of shape `(batch_size, num_videos_sample)`)
        """
        image_token_id = self.config.image_token_id
        video_token_id = self.config.video_token_id
        vision_start_token_id = self.config.vision_start_token_id

        if inputs_embeds is not None:
            vision_start_mask = (
                inputs_embeds
                == self.get_input_embeddings()(
                    torch.tensor(vision_start_token_id, dtype=torch.long, device=inputs_embeds.device)
                )
            )[..., 0]
            image_mask = (
                inputs_embeds
                == self.get_input_embeddings()(
                    torch.tensor(image_token_id, dtype=torch.long, device=inputs_embeds.device)
                )
            )[..., 0]
            video_mask = (
                inputs_embeds
                == self.get_input_embeddings()(
                    torch.tensor(video_token_id, dtype=torch.long, device=inputs_embeds.device)
                )
            )[..., 0]
        else:
            vision_start_mask = input_ids == vision_start_token_id
            image_mask = input_ids == image_token_id
            video_mask = input_ids == video_token_id

        vision_first_mask = torch.roll(vision_start_mask, shifts=1, dims=1)
        image_nums = torch.sum(vision_first_mask & image_mask, dim=1)
        video_nums = torch.sum(vision_first_mask & video_mask, dim=1)

        return image_nums, video_nums

    def _expand_inputs_for_generation(
        self,
        expand_size: int = 1,
        is_encoder_decoder: bool = False,
        input_ids: torch.LongTensor | None = None,
        **model_kwargs,
    ) -> tuple[torch.LongTensor, dict[str, Any]]:
        # Overwritten -- Qwen3_5 use timestamps and remove second_per_grid_ts
        # Support for expanding tensors without a batch size dimension
        # e.g., pixel_values, image_grid_thw, pixel_values_videos, video_grid_thw
        # pixel_values.shape[0] is sum(seqlen_images for samples)
        # image_grid_thw.shape[0] is sum(num_images for samples)

        if expand_size == 1:
            return input_ids, model_kwargs

        visual_keys = ["pixel_values", "image_grid_thw", "pixel_values_videos", "video_grid_thw"]

        def _expand_dict_for_generation_visual(dict_to_expand):
            image_grid_thw = model_kwargs.get("image_grid_thw", None)
            video_grid_thw = model_kwargs.get("video_grid_thw", None)
            image_nums, video_nums = self._get_image_nums_and_video_nums(
                input_ids, inputs_embeds=model_kwargs.get("inputs_embeds", None)
            )

            # video_nums: (batch_size,)
            # since video_nums is the number of videos in the input dependent on the input_ids(vision_start),
            # but Qwen3_5 append vision_start to each frame of each video, so we need to recover the real video_nums according to video_grid_thw
            if video_grid_thw is not None:
                cumulative_frame_counts = torch.cumsum(video_grid_thw[:, 0], dim=0)
                cumulative_token_video_counts = torch.cumsum(video_nums, dim=0)
                # Find video boundaries in cumulative_frame_counts
                video_boundary_indices = torch.searchsorted(cumulative_frame_counts, cumulative_token_video_counts)
                # example: video_boundary_indices = [3, 5] means video_nums = [4, 2]
                video_nums = torch.diff(torch.cat([-video_boundary_indices.new_ones(1), video_boundary_indices]))

            def _repeat_interleave_samples(x, lengths, repeat_times):
                samples = torch.split(x, lengths)
                repeat_args = [repeat_times] + [1] * (x.dim() - 1)
                result = torch.cat([sample.repeat(*repeat_args) for sample in samples], dim=0)
                return result

            for key in dict_to_expand:
                if key == "pixel_values":
                    # split images into samples
                    samples = torch.split(image_grid_thw, list(image_nums))
                    # compute the sequence length of images for each sample
                    lengths = [torch.prod(sample, dim=1).sum() for sample in samples]
                    dict_to_expand[key] = _repeat_interleave_samples(
                        dict_to_expand[key], lengths=lengths, repeat_times=expand_size
                    )
                elif key == "image_grid_thw":
                    # get the num of images for each sample
                    lengths = list(image_nums)
                    dict_to_expand[key] = _repeat_interleave_samples(
                        dict_to_expand[key], lengths=lengths, repeat_times=expand_size
                    )
                elif key == "pixel_values_videos":
                    samples = torch.split(video_grid_thw, list(video_nums))
                    lengths = [torch.prod(sample, dim=1).sum() for sample in samples]
                    dict_to_expand[key] = _repeat_interleave_samples(
                        dict_to_expand[key], lengths=lengths, repeat_times=expand_size
                    )
                elif key == "video_grid_thw":
                    lengths = list(video_nums)
                    dict_to_expand[key] = _repeat_interleave_samples(
                        dict_to_expand[key], lengths=lengths, repeat_times=expand_size
                    )
            return dict_to_expand

        def _expand_dict_for_generation(dict_to_expand):
            for key in dict_to_expand:
                if key == "position_ids" and dict_to_expand[key].ndim == 3:
                    dict_to_expand[key] = dict_to_expand[key].repeat_interleave(expand_size, dim=1)
                elif (
                    key != "cache_position"
                    and dict_to_expand[key] is not None
                    and isinstance(dict_to_expand[key], torch.Tensor)
                    and key not in visual_keys
                ):
                    dict_to_expand[key] = dict_to_expand[key].repeat_interleave(expand_size, dim=0)
            return dict_to_expand

        model_kwargs = _expand_dict_for_generation_visual(model_kwargs)

        if input_ids is not None:
            input_ids = input_ids.repeat_interleave(expand_size, dim=0)

        model_kwargs = _expand_dict_for_generation(model_kwargs)

        if is_encoder_decoder:
            if model_kwargs.get("encoder_outputs") is None:
                raise ValueError("If `is_encoder_decoder` is True, make sure that `encoder_outputs` is defined.")
            model_kwargs["encoder_outputs"] = _expand_dict_for_generation(model_kwargs["encoder_outputs"])

        return input_ids, model_kwargs


__all__ = [
    "Qwen3_5VisionModel",
    "Qwen3_5TextModel",
    "Qwen3_5Model",
    "Qwen3_5ForCausalLM",
    "Qwen3_5ForConditionalGeneration",
    "Qwen3_5PreTrainedModel",
]