# Copyright 2025 Google Inc. HuggingFace Inc. team. All rights reserved.
#
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#     http://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
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import math
from collections.abc import Callable, Sequence
from dataclasses import dataclass
from typing import Any

import torch
import torch.nn as nn
import torch.nn.functional as F
from huggingface_hub.dataclasses import strict

from ... import initialization as init
from ...activations import ACT2FN
from ...cache_utils import Cache, DynamicCache
from ...configuration_utils import PreTrainedConfig
from ...masking_utils import create_causal_mask, create_sliding_window_causal_mask
from ...modeling_outputs import BaseModelOutputWithPast, BaseModelOutputWithPooling
from ...modeling_rope_utils import ROPE_INIT_FUNCTIONS
from ...modeling_utils import ALL_ATTENTION_FUNCTIONS, PreTrainedModel
from ...processing_utils import Unpack
from ...utils import TransformersKwargs, auto_docstring, can_return_tuple, logging, torch_compilable_check
from ...utils.generic import merge_with_config_defaults
from ...utils.output_capturing import capture_outputs
from ..auto import AutoModel
from ..gemma2.modeling_gemma2 import (
    Gemma2MLP,
    Gemma2PreTrainedModel,
    eager_attention_forward,
    rotate_half,
)
from ..gemma3.configuration_gemma3 import Gemma3TextConfig
from ..gemma3.modeling_gemma3 import (
    Gemma3Attention,
    Gemma3DecoderLayer,
    Gemma3ForCausalLM,
    Gemma3RMSNorm,
    Gemma3RotaryEmbedding,
    Gemma3TextModel,
    Gemma3TextScaledWordEmbedding,
)
from ..paligemma.modeling_paligemma import (
    PaliGemmaCausalLMOutputWithPast,
    PaliGemmaForConditionalGeneration,
    PaliGemmaModel,
    PaligemmaModelOutputWithPast,
)
from ..timm_wrapper.configuration_timm_wrapper import TimmWrapperConfig


logger = logging.get_logger(__name__)


@auto_docstring(checkpoint="google/gemma-3n-E4B")
@strict
class Gemma3nTextConfig(Gemma3TextConfig):
    r"""
    vocab_size_per_layer_input (`int`, *optional*, defaults to 262144):
        Vocabulary size of the per-layer text embeddings that augment the standard embeddings.
    hidden_size_per_layer_input (`int`, *optional*, defaults to 256):
        Dimension of the hidden representations for per-layer emebeddings.
    altup_active_idx (`int`, *optional*, defaults to 0):
        The index of the prediction from which AltUp will compute additional predictions or correct
    altup_coef_clip (`float`, *optional*, defaults to 120.0):
        The maximum amplitude of an AltUp prediction or correction coefficient weight.
    altup_correct_scale (`bool`, *optional*, defaults to `True`):
        If True, apply the `AltUp.correct_output_scale` to the corrected prediction at `altup_active_idx`.
    altup_num_inputs (`int`, *optional*, defaults to 4):
        The number of predictions that AltUp should be make given the input sequence.
    num_kv_shared_layers (`int`, *optional*, defaults to 15):
        The number of layer that share KV cache values. During the forward pass, the last `num_kv_shared_layers`
        layers in the model "share" the KV values in that each local and global layer in this range uses the KV
        cache values computed for the last local or global layer, respectively, before entering this range. The
        value should be a multiple of the attention pattern size (see `layer_types` parameter).
    laurel_rank (int, *optional*, defaults to 64):
        The intermediate size for the linear projections in the Learned Augmented Residual Layer.
    activation_sparsity_pattern (Sequence[float], *optional*):
        The sparsity factor used to extract the top-k activations for a given layer. The provided Sequence must
        explicitly provide a sparsity value for each layer in the model. By default, the first 10 layers are
        sparse with a sparsity factor of 0.95 and the rest are dense.

    ```python
    >>> from transformers import Gemma3nTextModel, Gemma3nTextConfig

    >>> # Initializing a Gemma3nText gemma3n_text-E4B style configuration
    >>> configuration = Gemma3nTextConfig()

    >>> # Initializing a model from the gemma3n_text-E4B style configuration
    >>> model = Gemma3nTextModel(configuration)

    >>> # Accessing the model configuration
    >>> configuration = model.config
    ```
    """

    model_type = "gemma3n_text"
    base_model_tp_plan = {
        "layers.*.self_attn.q_proj": "colwise",
        "layers.*.self_attn.k_proj": "colwise",
        "layers.*.self_attn.v_proj": "colwise",
        "layers.*.self_attn.q_norm": "replicated_with_grad_allreduce",
        "layers.*.self_attn.k_norm": "replicated_with_grad_allreduce",
        "layers.*.self_attn.v_norm": "replicated_with_grad_allreduce",
        "layers.*.self_attn.o_proj": "rowwise",
        "layers.*.mlp.gate_proj": "colwise",
        "layers.*.mlp.up_proj": "colwise",
        "layers.*.mlp.down_proj": "rowwise",
    }
    default_theta = {"global": 1_000_000.0, "local": 10_000.0}

    vocab_size: int = 262_400
    vocab_size_per_layer_input: int = 262_144
    hidden_size: int = 2048
    hidden_size_per_layer_input: int = 256
    intermediate_size: int | list[int] = 16_384
    num_hidden_layers: int = 35
    num_key_value_heads: int = 2
    max_position_embeddings: int = 32_768
    sliding_window: int = 512
    layer_types: list[str] | None = None
    final_logit_softcapping: float = 30.0
    altup_active_idx: int = 0
    altup_coef_clip: float = 120.0
    altup_correct_scale: bool = True
    altup_num_inputs: int = 4
    num_kv_shared_layers: int = 15
    laurel_rank: int = 64
    activation_sparsity_pattern: float | list[float] | None = None
    attn_logit_softcapping = AttributeError()
    use_bidirectional_attention = AttributeError()
    query_pre_attn_scalar = AttributeError()

    def __post_init__(self, **kwargs):
        if (
            isinstance(self.intermediate_size, Sequence)
            and (intsize_len := len(self.intermediate_size)) != self.num_hidden_layers
        ):
            raise ValueError(
                "intermediate_size must have an explicit intermediate size for every layer or one for all layers. "
                f"Expected {self.num_hidden_layers} values but got {intsize_len}."
            )
        elif not isinstance(self.intermediate_size, Sequence):
            self.intermediate_size = [self.intermediate_size] * self.num_hidden_layers

        if self.layer_types is None:
            self.layer_types = [
                "full_attention" if (i + 1) % 5 == 0 else "sliding_attention" for i in range(self.num_hidden_layers)
            ]

        if self.activation_sparsity_pattern is None:
            num_sparse_layers = 10 if self.num_hidden_layers > 10 else 0
            self.activation_sparsity_pattern = [0.95] * num_sparse_layers + [0.0] * (
                self.num_hidden_layers - num_sparse_layers
            )

        if (len_asp := len(self.activation_sparsity_pattern)) != self.num_hidden_layers:
            raise ValueError(
                "activation_sparsity_pattern must have an explicit activation sparsity value for every layer."
                f"Expected {self.num_hidden_layers} values but got {len_asp}."
            )

        PreTrainedConfig.__post_init__(**kwargs)

    def convert_rope_params_to_dict(self, **kwargs):
        rope_scaling = kwargs.pop("rope_scaling", None)

        # Try to set `rope_scaling` if available, otherwise use `rope_parameters`. If we find `rope_parameters`
        # as arg in the inputs, we can safely assume that it is in the new format. New naming used -> new format
        default_rope_params = {
            "sliding_attention": {"rope_type": "default"},
            "full_attention": {"rope_type": "default"},
        }
        self.rope_parameters = self.rope_parameters if self.rope_parameters is not None else default_rope_params
        if rope_scaling is not None:
            self.rope_parameters["full_attention"].update(rope_scaling)

        # Set default values if not present
        if self.rope_parameters.get("full_attention") is None:
            self.rope_parameters["full_attention"] = {"rope_type": "default"}
        self.rope_parameters["full_attention"].setdefault(
            "rope_theta", kwargs.pop("rope_theta", self.default_theta["global"])
        )
        if self.rope_parameters.get("sliding_attention") is None:
            self.rope_parameters["sliding_attention"] = {"rope_type": "default"}
        self.rope_parameters["sliding_attention"].setdefault(
            "rope_theta", kwargs.pop("rope_local_base_freq", self.default_theta["local"])
        )

        # Standardize and validate the correctness of rotary position embeddings parameters
        self.standardize_rope_params()
        return kwargs


@auto_docstring(checkpoint="google/gemma-3n-E4B")
@strict
class Gemma3nAudioConfig(PreTrainedConfig):
    r"""
    vocab_offset (`int`, *optional*, defaults to 262272):
        Offset between the tokenizer vocab index for the token ids embedded by `Gemma3nMultimodalEmbedder` and the
        0-indexed `Gemma3nMultimodalEmbedder.embedding` table.
    input_feat_size (`int`, *optional*, defaults to 128):
        The number of channels in each mel-spectrogram frame.
    gradient_clipping (`float`, *optional*, defaults to 10000000000.0):
        Clipping value used to stabilize extremely large gradient values.
    conf_attention_chunk_size (`int`, *optional*, defaults to 12):
        The sub-sequence size for local attention processing inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_attention_context_left (`int`, *optional*, defaults to 13):
        The left context size of the local attention inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_attention_context_right (`int`, *optional*, defaults to 0):
        The right context size of the local attention inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_attention_logit_cap (`float`, *optional*, defaults to 50.0):
        Logit cap applied during local attention inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_num_attention_heads (`int`, *optional*, defaults to 8):
        The number of attention heads in local attention inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_num_hidden_layers (`int`, *optional*, defaults to 12):
        The number of layers that use local attention inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_conv_kernel_size (`int`, *optional*, defaults to 5):
        Convolution kernel size for the conformer block inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_reduction_factor (`int`, *optional*, defaults to 4):
        Reduction factor used in the conformer block inside the Conformer ("conf") section of the
        Universal Speech Model.
    conf_residual_weight (`float`, *optional*, defaults to 0.5):
        Residual connection weight inside the Conformer ("conf") section of the
        Universal Speech Model.
    sscp_conv_channel_size (`tuple(int, int)`, *optional*, defaults to `(128, 32)`):
        The channel sizes for the first and second convolutional layers in the Sub-sample Convolution Projection
        ("sscp") section of the Universal Speech Model.
    sscp_conv_group_norm_eps (`float`, *optional*, defaults to 0.001):
        Epsilon used in group normalization in the subsample convolution projection in the Sub-sample Convolution
        Projection ("sscp") section of the Universal Speech Model.
    sscp_conv_kernel_size (`tuple(tuple(int, int), tuple(int, int))`, *optional*, defaults to `((3, 3), (3, 3))`):
        Kernel sizes of the two convolutional layers in the subsample convolution projection  in the Sub-sample
        Convolution Projection ("sscp") section of the Universal Speech Model. The kernel sizes are specified as a
        tuple of height and width for each layer, where the height corresponds to the time dimension and the width
        corresponds to the frequency dimension.
    sscp_conv_stride_size (`tuple(tuple(int, int), tuple(int, int))`, *optional*, defaults to `((2, 2), (2, 2))`):
        Stride sizes of the two convolutional layers in the subsample convolution projection in the Sub-sample
        Convolution Projection ("sscp") section of the Universal Speech Model. The stride sizes are specified as a
        tuple of height and width for each layer, where the height corresponds to the time dimension and the width
        corresponds to the frequency dimension.

    Example:

    ```python
    >>> from transformers import Gemma3nAudioConfig, Gemma3nAudioEncoder

    >>> # Initializing a Gemma3nAudioEncoder gemma3n_audio-E4B-style configuration
    >>> configuration = Gemma3nAudioConfig()

    >>> # Initializing a model from the gemma3n_audio-E4B style configuration
    >>> model = Gemma3nAudioEncoder(configuration)

    >>> # Accessing the model configuration
    >>> configuration = model.config
    ```
    """

    model_type = "gemma3n_audio"

    vocab_size: int = 128
    vocab_offset: int = 262_144 + 128  # text vocab size + vision vocab size
    input_feat_size: int = 128
    hidden_size: int = 1536
    rms_norm_eps: float = 1e-6
    gradient_clipping: float = 10_000_000_000.0
    conf_attention_chunk_size: int = 12
    conf_attention_context_left: int = 13
    conf_attention_context_right: int = 0
    conf_attention_logit_cap: float = 50.0
    conf_num_attention_heads: int = 8
    conf_num_hidden_layers: int = 12
    conf_conv_kernel_size: int = 5
    conf_reduction_factor: int = 4
    conf_residual_weight: float = 0.5
    sscp_conv_channel_size: list[int] | tuple[int, int] = (128, 32)
    sscp_conv_group_norm_eps: float = 1e-3
    sscp_conv_kernel_size: list | tuple[tuple[int, int], tuple[int, int]] = (
        (3, 3),
        (3, 3),
    )
    sscp_conv_stride_size: list | tuple[tuple[int, int], tuple[int, int]] = (
        (2, 2),
        (2, 2),
    )


@auto_docstring(checkpoint="google/gemma-3n-E4B")
@strict
class Gemma3nVisionConfig(TimmWrapperConfig):
    r"""
    architecture (`str`, *optional*, defaults to `"resnet50"`):
        The timm architecture to load.
    do_pooling (`bool`, *optional*, defaults to `True`):
        Whether to do pooling for the last_hidden_state in `TimmWrapperModel` or not.
    model_args (`dict[str, Any]`, *optional*):
        Additional keyword arguments to pass to the `timm.create_model` function. e.g. `model_args={"depth": 3}`
        for `timm/vit_base_patch32_clip_448.laion2b_ft_in12k_in1k` to create a model with 3 blocks. Defaults to `None`.
    vocab_offset (`int`, *optional*, defaults to 262144):
        Offset between the tokenizer vocab index for the token ids embedded by `Gemma3nMultimodalEmbedder` and the
        0-indexed `Gemma3nMultimodalEmbedder.embedding` table.

    Example:
    ```python
    >>> from transformers import Gemma3nVisionConfig, TimmWrapper

    >>> # Initializing a TimmWrapper gemma3n_vision-E4B-style configuration
    >>> configuration = Gemma3nVisionConfig()

    >>> # Initializing a gemma3n_vision-E4B-style TimmWrapper from the configuration
    >>> model = TimmWrapper(configuration)

    >>> # Accessing the model configuration
    >>> configuration = model.config
    ```
    """

    model_type = "gemma3n_vision"

    initializer_range: float = 0.02
    do_pooling: bool = False
    architecture: str = "mobilenetv5_300m_enc"
    hidden_size: int = 2048
    vocab_size: int = 128
    vocab_offset: int = 262_144
    rms_norm_eps: float = 1e-06
    model_args: dict | None = None


@auto_docstring(checkpoint="google/gemma-3n-E4B")
@strict
class Gemma3nConfig(PreTrainedConfig):
    r"""
    audio_soft_tokens_per_image (`int`, *optional*, defaults to 188):
        The number of soft tokens per audio clip.
    vision_soft_tokens_per_image (`int`, *optional*, defaults to 256):
        The number of soft tokens per image.
    boi_token_id (`int`, *optional*, defaults to 255999):
        The begin-of-image token index to wrap the image prompt.
    eoi_token_id (`int`, *optional*, defaults to 262144):
        The end-of-image token index to wrap the image prompt.
    boa_token_id (`int`, *optional*, defaults to 256000):
        The begin-of-audio token index to wrap the audio prompt.
    eoa_token_id (`int`, *optional*, defaults to 262272):
        The end-of-audio token index to wrap the audio prompt.

    Example:

    ```python
    >>> from transformers import Gemma3nForConditionalGeneration, Gemma3nConfig, Gemma3nTextConfig

    >>> # Initializing a MobileNet vision config, which is loaded from TIMM
    >>> vision_config = Gemma3nVisionConfig()

    >>> # Initializing a Gemma3n Audio config
    >>> audio_config = Gemma3nAudioConfig()

    >>> # Initializing a Gemma3n Text config
    >>> text_config = Gemma3nTextConfig()

    >>> # Initializing a Gemma3n gemma-3-4b style configuration
    >>> configuration = Gemma3nConfig(text_config, vision_config, audio_config)

    >>> # Initializing a model from the gemma-3-4b style configuration
    >>> model = Gemma3nTextConfig(configuration)

    >>> # Accessing the model configuration
    >>> configuration = model.config
    ```"""

    model_type = "gemma3n"
    sub_configs = {
        "text_config": Gemma3nTextConfig,
        "vision_config": Gemma3nVisionConfig,
        "audio_config": Gemma3nAudioConfig,
    }

    text_config: Gemma3nTextConfig | dict[str, Any] | None = None
    vision_config: Gemma3nVisionConfig | dict[str, Any] | None = None
    audio_config: Gemma3nAudioConfig | dict[str, Any] | None = None
    audio_soft_tokens_per_image: int | None = 188
    vision_soft_tokens_per_image: int | None = 256
    boi_token_id: int | None = 255_999
    eoi_token_id: int | None = 262_144
    image_token_id: int | None = 262_145
    boa_token_id: int | None = 256_000
    eoa_token_id: int | None = 262_272
    audio_token_id: int | None = 262_273
    initializer_range: float | None = 0.02
    tie_word_embeddings: bool | None = True

    def __post_init__(self, **kwargs):
        if self.text_config is None:
            self.text_config = Gemma3nTextConfig()
            logger.info("text_config is None, using default Gemma3nTextConfig text config.")
        elif isinstance(self.text_config, dict):
            self.text_config = Gemma3nTextConfig(**self.text_config)

        if isinstance(self.vision_config, dict):
            self.vision_config = Gemma3nVisionConfig(**self.vision_config)
        elif self.vision_config is None:
            self.vision_config = Gemma3nVisionConfig()
            logger.info("vision_config is None, using default Gemma3nVisionConfig vision config.")

        if isinstance(self.audio_config, dict):
            self.audio_config = Gemma3nAudioConfig(**self.audio_config)
        elif self.audio_config is None:
            self.audio_config = Gemma3nAudioConfig()
            logger.info("audio_config is None. Using default Gemma3nAudioConfig.")

        super().__post_init__(**kwargs)


@dataclass
@auto_docstring
class Gemma3nAudioEncoderModelOutput(BaseModelOutputWithPooling):
    r"""
    audio_mel_mask (`torch.BoolTensor`, *optional*):
        A torch.BoolTensor of shape `(batch_size, num_frames)`
    """

    audio_mel_mask: torch.BoolTensor | None = None


class Gemma3nModelOutputWithPast(PaligemmaModelOutputWithPast):
    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. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).

        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.
    image_hidden_states (`torch.FloatTensor`, *optional*):
        A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
        image_hidden_states of the model produced by the vision encoder and after projecting the last hidden state.
    audio_hidden_states (`torch.FloatTensor`, *optional*):
        A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
        audio_hidden_states of the model produced by the audio encoder and after projecting the last hidden state.
    """

    audio_hidden_states: torch.FloatTensor | None = None


class Gemma3nCausalLMOutputWithPast(PaliGemmaCausalLMOutputWithPast):
    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.text_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. For more details, see our [kv cache guide](https://huggingface.co/docs/transformers/en/kv_cache).

        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.
    image_hidden_states (`torch.FloatTensor`, *optional*):
        A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
        image_hidden_states of the model produced by the vision encoder after projecting last hidden state.
    audio_hidden_states (`torch.FloatTensor`, *optional*):
        A `torch.FloatTensor` of size `(batch_size, num_images, sequence_length, hidden_size)`.
        audio_hidden_states of the model produced by the audio encoder and after projecting the last hidden state.
    """

    audio_hidden_states: torch.FloatTensor | None = None


class Gemma3nRMSNorm(Gemma3RMSNorm):
    def __init__(self, dim: int, eps: float = 1e-6, with_scale: bool = True):
        super().__init__(dim, eps=eps)
        del self.weight
        self.with_scale = with_scale

        if self.with_scale:
            self.weight = nn.Parameter(torch.ones(dim))
        else:
            self.register_buffer("weight", torch.tensor(1.0), persistent=False)

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

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        # Llama does x.to(float16) * w whilst Gemma2 is (x * w).to(float16)
        # See https://github.com/huggingface/transformers/pull/29402
        output = self._norm(x.float()) * self.weight.float()
        return output.type_as(x)


# ==== Audio Encoder ====


class Gemma3nAudioRelativePositionEmbedding(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        self.num_heads = self.config.conf_num_attention_heads
        self.channels = self.config.hidden_size
        self.head_dim = self.channels // self.num_heads
        self.max_backward = max(0, self.config.conf_attention_context_left - 1)
        self.max_forward = self.config.conf_attention_context_right

        self.pos_proj = nn.Linear(self.channels, self.num_heads * self.head_dim, bias=False)

        min_timescale = 1.0
        max_timescale = 1.0e4
        num_timescales = self.channels // 2
        log_timescale_increment = math.log(float(max_timescale) / float(min_timescale)) / max(num_timescales - 1, 1)
        inv_timescales = min_timescale * torch.exp(torch.arange(num_timescales) * -log_timescale_increment)
        self.register_buffer(
            "inv_timescales",
            inv_timescales.float().unsqueeze(0).unsqueeze(0),
            persistent=False,
        )

    def _get_timing_signal_1d_pos(self, position: torch.Tensor, dtype: torch.dtype) -> torch.Tensor:
        position = position.float().unsqueeze(-1)
        scaled_time = position * self.inv_timescales.to(device=position.device, dtype=torch.float32)
        timing_signal = torch.cat([torch.sin(scaled_time), torch.cos(scaled_time)], dim=-1)
        return timing_signal.type(dtype)

    def _relative_shift(
        self,
        term_bd_before_shift: torch.Tensor,
        batch_size: int,
        num_heads: int,
        num_query_blocks: int,
        query_block_size: int,
        key_context_size: int,
        max_span_plus_1: int,
    ) -> torch.Tensor:
        """Performs the relative shift.

        Args:
          term_bd_before_shift: Tensor of shape [B, N, U, W, F_span]. batch_size
            (B), num_heads (N), num_query_blocks (U), query_block_size (W),
            key_context_size (C = W+L+R), max_span_plus_1 (F_span = L+R+1).

        Returns:
          Tensor of shape [B, N, U, W, C].
        """
        # term_bd_before_shift shape: [B, N, U, W, F_span]
        # Target shape after shift:  [B, N, U, W, C]

        # Padding amount for the last dimension (F_span) to become (C + 1)
        # C = key_context_size
        # F_span = max_span_plus_1
        pad_amount_last_dim = (key_context_size + 1) - max_span_plus_1

        # PyTorch F.pad expects (pad_left, pad_right, pad_top, pad_bottom ...)
        # We only pad the last dimension on the right.
        padding_tuple = (0, pad_amount_last_dim)

        term_bd_padded = nn.functional.pad(term_bd_before_shift, padding_tuple)
        # Shape after pad: [B, N, U, W, C+1]

        # Reshape for slicing (emulating JAX's behavior)
        # [B, N, U, W * (C+1)]
        term_bd_reshaped = term_bd_padded.reshape(
            (
                batch_size,
                num_heads,
                num_query_blocks,
                query_block_size * (key_context_size + 1),
            )
        )

        # Slice to effective [B, N, U, W * C]
        term_bd_sliced = term_bd_reshaped[:, :, :, : query_block_size * key_context_size]

        # Reshape back to [B, N, U, W, C]
        term_bd_shifted = term_bd_sliced.reshape(
            (
                batch_size,
                num_heads,
                num_query_blocks,
                query_block_size,
                key_context_size,
            )
        )
        return term_bd_shifted

    def forward(self, queries: torch.Tensor, keys: torch.Tensor) -> torch.Tensor:
        # queries: [B, U, W, N, H] (batch, num_query_blocks, query_block_size, num_heads, head_dim)
        # keys:    [B, U, C, N, H] (batch, num_query_blocks, key_context_size, num_heads, head_dim)
        # C = W + L + R (key_context_size)
        # F_span = L + R + 1 (max_span + 1)

        batch_size, num_query_blocks, query_block_size, num_heads, head_dim = queries.shape
        _, _, key_context_size, _, _ = keys.shape

        # Relative positions for sinusoidal embeddings: [L, L-1, ..., -R]
        # Length is L+R+1 = self.max_span + 1
        pos_indices = torch.arange(self.max_backward, -self.max_forward - 1, -1, device=queries.device).unsqueeze(
            0
        )  # Shape [1, F_span]

        max_span_plus_1 = pos_indices.shape[1]  # F_span

        sin_emb_timing_signal = self._get_timing_signal_1d_pos(
            pos_indices, dtype=queries.dtype
        )  # Shape [1, F_span, self.channels]

        # Project sinusoidal embeddings: [1, F_span, self.channels] -> [1, F_span, N*H]
        projected_sin_emb = self.pos_proj(sin_emb_timing_signal)
        # Reshape to [1, F_span, N, H] then squeeze to [F_span, N, H]
        sin_emb = projected_sin_emb.reshape(1, max_span_plus_1, self.num_heads, self.head_dim).squeeze(
            0
        )  # Shape [F, N, H]

        # term_ac: Query-Key content interaction
        # queries: [B, U, W, N, H] -> permute to [B, N, U, W, H] for matmul
        # keys:    [B, U, C, N, H] -> permute to [B, N, U, H, C] for matmul
        queries_p = queries.permute(0, 3, 1, 2, 4)  # [B, N, U, W, H]
        keys_p_t = keys.permute(0, 3, 1, 4, 2)  # [B, N, U, H, C]
        term_ac = torch.matmul(queries_p, keys_p_t)  # [B, N, U, W, C]

        # term_bd: Query-Position interaction
        # Original einsum: term_bd_unshifed = torch.einsum('buwnh,fnh->bnuwf', queries, sin_emb)
        # queries shape: [B, U, W, N, H]
        # sin_emb shape: [F, N, H]
        # Target output shape: [B, N, U, W, F]

        # Permute queries to [B, N, U, W, H] for easier broadcasting with sin_emb
        q_permuted = queries.permute(0, 3, 1, 2, 4)

        # Permute sin_emb to [N, H, F] to prepare for matmul
        # sin_emb original is [F, N, H]
        s_permuted = sin_emb.permute(1, 2, 0)  # Shape: [N, H, F]

        # Reshape queries for matmul: [B, N, U*W, H]
        q_reshaped = q_permuted.reshape(batch_size, num_heads, num_query_blocks * query_block_size, head_dim)

        # Perform matmul: [B, N, U*W, H] @ [N, H, F]
        # s_permuted ([N, H, F]) will be broadcast to [B, N, H, F]
        # Result: [B, N, U*W, F]
        term_bd_unshifed_matmul = torch.matmul(q_reshaped, s_permuted)

        # Reshape to target [B, N, U, W, F]
        term_bd_unshifed = term_bd_unshifed_matmul.reshape(
            batch_size,
            num_heads,
            num_query_blocks,
            query_block_size,
            max_span_plus_1,
        )

        # Apply relative shift to term_bd_unshifed
        term_bd_shifted = self._relative_shift(
            term_bd_unshifed,
            batch_size,
            num_heads,
            num_query_blocks,
            query_block_size,
            key_context_size,
            max_span_plus_1,
        )  # Shape [B, N, U, W, C]

        return term_ac + term_bd_shifted


class Gemma3nAudioAttention(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        self.num_heads = self.config.conf_num_attention_heads
        self.hidden_size = self.config.hidden_size
        self.head_dim = self.hidden_size // self.num_heads

        self.chunk_size = self.config.conf_attention_chunk_size
        self.max_future_horizon = self.config.conf_attention_context_right
        self.max_past_horizon = max(0, self.config.conf_attention_context_left - 1)
        self.attention_logits_soft_cap = self.config.conf_attention_logit_cap
        self.context_size = self.chunk_size + self.max_past_horizon + self.max_future_horizon

        self.relative_position_embedding = Gemma3nAudioRelativePositionEmbedding(config)
        self.per_dim_scale = nn.Parameter(torch.zeros((self.head_dim,)))

        self.q_proj = nn.Linear(self.hidden_size, self.num_heads * self.head_dim, bias=False)
        self.k_proj = nn.Linear(self.hidden_size, self.num_heads * self.head_dim, bias=False)
        self.v_proj = nn.Linear(self.hidden_size, self.num_heads * self.head_dim, bias=False)

        q_scale = self.head_dim**-0.5
        r_softplus_0 = 1.0 / torch.nn.functional.softplus(torch.tensor(0.0))
        self.register_buffer("q_scale", (q_scale * r_softplus_0).clone().detach(), persistent=False)

        local_causal_valid_mask = self.create_local_causal_valid_mask()
        self.register_buffer("local_causal_valid_mask", local_causal_valid_mask, persistent=False)

        self.register_buffer(
            "softcap",
            torch.tensor(self.attention_logits_soft_cap).float(),
            persistent=False,
        )

    def create_local_causal_valid_mask(self):
        lower_causal_mask = torch.tril(
            torch.ones((self.context_size, self.chunk_size), dtype=torch.bool),
            diagonal=0,
        ).T
        upper_causal_mask = torch.tril(
            torch.ones((self.chunk_size, self.context_size), dtype=torch.bool),
            diagonal=self.max_past_horizon + self.max_future_horizon,
        )
        local_causal_valid_mask = torch.ones((self.chunk_size, self.context_size), dtype=torch.bool)
        local_causal_valid_mask = local_causal_valid_mask * lower_causal_mask * upper_causal_mask
        return local_causal_valid_mask

    def _pad_dim1(self, x: torch.Tensor, pad_left: int, pad_right: int) -> torch.Tensor:
        batch, _, *tail_shape = x.shape
        left = x.new_zeros((batch, pad_left, *tail_shape))
        right = x.new_zeros((batch, pad_right, *tail_shape))
        x = torch.cat([left, x, right], dim=1)
        return x

    def _convert_to_block(self, hidden_states: torch.Tensor) -> torch.Tensor:
        """Turns a sequence to non overlapping blocks.

        Args:
            hidden_states: a tensor of [batch, time, ...].

        Returns:
            A tensor of [batch, num_blocks, block_size, ...], with necessary
            paddings,
            where output[:, i, ...] are x[:, i*block_size:(i+1)*block_size, ...].
        """
        shape = hidden_states.shape
        b, t = shape[:2]
        num_blocks = (t + self.chunk_size - 1) // self.chunk_size

        if (padding_len := num_blocks * self.chunk_size - t) > 0:
            hidden_states = self._pad_dim1(hidden_states, 0, padding_len)

        permute_dims = (b, num_blocks, self.chunk_size) + shape[2:]
        hidden_states = hidden_states.reshape(permute_dims).contiguous()
        return hidden_states

    def _extract_block_context(self, hidden_states: torch.Tensor) -> torch.Tensor:
        """Extracts temporal context for every block.

        Args:
            hidden_states: a tensor of [batch, time, ...].

        Returns:
            A tensor of [batch, num_blocks, context_size, ...], with necessary
            paddings,
            where context_size = block_size + left_context + right_context,
            and output[:, i, ...] are x[:, start-left_context:end+right_context,
            ...],
            start = i * block_size, end = (i + 1) * block_size.
        """
        pad_left = self.max_past_horizon
        # The JAX equivalent padding for signal.frame with pad_mode='valid' is
        # (left_context, right_context + block_size - 1) on the time dimension.
        # PyTorch's _pad_dim1 applies padding symmetrically if only one value is given,
        # or (pad_dim_start, pad_dim_end) if two are given.
        # Our _pad_dim1(x, pad_left, pad_right) pads dim -2 (time for [B,T,N,H])
        # or dim 1 (time for [B,T]).
        # The current pad_right calculation matches the JAX effective padding.
        pad_right = self.max_future_horizon + self.chunk_size - 1
        hidden_states = self._pad_dim1(hidden_states, pad_left, pad_right)

        frame_len = self.context_size
        frame_step = self.chunk_size

        # Directly use unfold without the subframe_factor logic
        # x.unfold(dimension, size, step)
        # dimension=1 (time dimension, assuming x is [B, T_padded, ...])
        # size=frame_len (context_size)
        # step=frame_step (chunk_size)
        x_unfolded = hidden_states.unfold(dimension=1, size=frame_len, step=frame_step)

        # If x was [B, T_padded], x_unfolded is [B, num_blocks, frame_len]
        # If x was [B, T_padded, N, H], x_unfolded is [B, num_blocks, N, H, frame_len]
        # We want to match JAX's typical output for such operations which might be
        # [B, num_blocks, frame_len, N, H] if N, H are present.
        # The relative_position_embedding expects keys as [B, U, C, N, H].
        # If x_unfolded is [B, U, N, H, C(frame_len)], we need to move C.
        if hidden_states.ndim > 2 and x_unfolded.ndim > 3:  # Check if inner dimensions (like N, H) exist
            # Current shape after unfold for [B, T_pad, N, H] is [B, U, N, H, C]
            # Target shape for keys in RPE: [B, U, C, N, H]
            x_unfolded = torch.movedim(x_unfolded, source=-1, destination=2)

        return x_unfolded.contiguous()

    def forward(self, hidden_states: torch.Tensor, mask: torch.BoolTensor) -> torch.Tensor:
        # sl.Dense uses jax.numpy.einsum("...a,abcd->...bcd") and jax.numpy.select()
        qkv_shape = (*hidden_states.shape[:-1], self.num_heads, self.head_dim)
        query_states = self.q_proj(hidden_states).reshape(qkv_shape).contiguous()
        key_states = self.k_proj(hidden_states).reshape(qkv_shape).contiguous()
        value_states = self.v_proj(hidden_states).reshape(qkv_shape).contiguous()

        per_dim_scale_sp = torch.nn.functional.softplus(self.per_dim_scale)

        broadcast_shape = (1, 1, 1, self.head_dim)
        per_dim_scale_sp_broadcast = per_dim_scale_sp.view(broadcast_shape)
        query_states = query_states * self.q_scale * per_dim_scale_sp_broadcast

        batch_size, q_time = query_states.shape[:2]

        query_blocks = self._convert_to_block(query_states)
        key_blocks = self._extract_block_context(key_states)
        value_blocks = self._extract_block_context(value_states)
        num_query_blocks = query_blocks.shape[1]

        # 1. Create a mask indicating originally valid positions.
        original_valid_mask = ~mask  # True for valid, False for padded

        # 2. Extract blocks from this validity mask.
        extracted_valid_mask_blocks = self._extract_block_context(original_valid_mask)

        # If subframe_factor was used in _extract_block_context for a [B, T] input mask,
        # the shape might be [B, U, C/SF, SF]. Reshape to [B, U, C].
        # batch_size and num_query_blocks are known from query_blocks.
        # self.context_size is C.
        if (
            extracted_valid_mask_blocks.ndim == 4
            and extracted_valid_mask_blocks.shape[2] * extracted_valid_mask_blocks.shape[3] == self.context_size
        ):
            extracted_valid_mask_blocks = extracted_valid_mask_blocks.reshape(
                batch_size, num_query_blocks, self.context_size
            )
        # After potential reshape, ensure it's [B, U, C] if it was from a [B,T] mask.
        # This assertion might be too strict if _extract_block_context handles higher-rank inputs differently,
        # but for the mask case, this should hold.
        if extracted_valid_mask_blocks.shape != (
            batch_size,
            num_query_blocks,
            self.context_size,
        ):
            raise ValueError(
                "Shape of extracted_valid_mask_blocks"
                f" {extracted_valid_mask_blocks.shape} is not ({batch_size},"
                f" {num_query_blocks}, {self.context_size}) after potential reshape."
            )

        # 3. Expand dimensions for broadcasting with logits and causal mask.
        # Target shape for broadcasting with logits [B,N,U,W,C]
        # extracted_valid_mask_blocks to [B, 1, U, 1, C]
        condition_from_input_validity = extracted_valid_mask_blocks.unsqueeze(1).unsqueeze(-2)

        # self.local_causal_valid_mask is [W, C], True where allowed by local window.
        # Expand to [1, 1, 1, W, C]
        condition_from_causality = self.local_causal_valid_mask.unsqueeze(0).unsqueeze(0).unsqueeze(0)

        # 4. Combine the two conditions.
        # final_condition will be True where a key is *both* originally valid *and* causally accessible.
        # Broadcasts to [B, 1, U, W, C]
        final_condition_for_where = torch.logical_and(
            condition_from_input_validity,
            condition_from_causality.to(condition_from_input_validity.device),  # Ensure same device
        )

        # Embed queries and keys
        logits = self.relative_position_embedding(query_blocks, key_blocks)

        # Apply attention logit softcap
        # Ensure softcap is on the same device as logits
        softcap_val = self.softcap.to(logits.device)
        logits = logits / softcap_val
        logits = torch.tanh(logits)
        logits = logits * softcap_val

        # Apply the combined mask.
        # final_condition_for_where will broadcast with logits [B,N,U,W,C]
        logits = torch.where(final_condition_for_where, logits, torch.finfo(logits.dtype).min)
        probabilities = torch.nn.functional.softmax(logits, dim=-1, dtype=torch.float32).to(dtype=value_blocks.dtype)

        # context_vectors is adapted from jax.numpy.einsum("BNuwc,BucNH->BuwNH", ...)
        b_dim, n_dim, u_dim, w_dim, c_dim = probabilities.shape
        h_dim = value_blocks.shape[-1]
        prob_bun = probabilities.permute(0, 2, 1, 3, 4).reshape(-1, w_dim, c_dim)
        v_bun = value_blocks.permute(0, 1, 3, 2, 4).reshape(-1, c_dim, h_dim)
        result_bmm = torch.bmm(prob_bun, v_bun)
        context_vectors = result_bmm.reshape(b_dim, u_dim, n_dim, w_dim, h_dim).permute(0, 1, 3, 2, 4)
        context_vectors = context_vectors.reshape(
            (
                batch_size,
                num_query_blocks * self.chunk_size,
                self.num_heads,
                self.head_dim,
            )
        )
        context_vectors = context_vectors[:, :q_time]

        return context_vectors


class Gemma3nAudioCumulativeGroupNorm(nn.Module):
    """Applies Group Normalization cumulatively over the time dimension.

    This layer normalizes the input by calculating the mean and variance
    cumulatively over the time dimension (dim 1). The statistics are computed
    over all feature dimensions (specified by `feature_dims` and `num_channels`)
    for elements marked as valid by the optional `mask`.

    If a `mask` is provided (True for valid, False for invalid/padded),
    invalid time steps do not contribute to the statistics calculation, and
    their corresponding output values are zeroed out.

    Scale and bias, if enabled, are applied per-channel (last dimension).
    This behavior is similar to JAX's `GroupNormalization` with `num_groups=1`
    and `cumulative=True`.
    """

    def __init__(
        self,
        num_channels: int,  # Number of channels (size of the last dimension)
        feature_dims: Sequence[int],  # Sizes of non-channel feature dimensions, e.g., (H, W) for input [B,T,H,W,C]
        eps: float = 1e-3,
    ):
        super().__init__()
        self.num_channels = num_channels
        self.feature_dims = tuple(feature_dims)
        self.eps = eps

        # Scale parameter depends only on the channel dimension
        self.weight = nn.Parameter(torch.ones(num_channels))

        # Axes for normalization: all dimensions except Batch (0) and Time (1).
        # For input [B, T, *feature_dims, C], these are dims from 2 onwards.
        self.reduction_axes = tuple(range(2, 2 + len(self.feature_dims) + 1))

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        """Applies cumulative group norm, optionally using a mask.

        Args:
          hidden_states: Input tensor, shape [B, T, *feature_dims, C].

        Returns:
          Normalized tensor with the same shape as x.
        """
        expected_input_suffix = self.feature_dims + (self.num_channels,)
        if hidden_states.shape[2:] != expected_input_suffix:
            raise ValueError(
                f"Input tensor shape suffix {hidden_states.shape[2:]} does not match expected"
                f" suffix (feature_dims + num_channels) {expected_input_suffix}"
            )

        input_dtype = hidden_states.dtype
        # Calculations are performed in float32 for numerical stability.
        calc_dtype = torch.float32
        x_calc = hidden_states.to(calc_dtype)

        # Prepare a broadcastable mask (`mask_calc`).
        # If no mask is provided, treat all elements as valid
        # (mask_calc is all ones).
        # Otherwise, expand the [B, T] mask to [B, T, 1, ..., 1] for broadcasting.
        mask_calc = torch.ones_like(x_calc, dtype=calc_dtype)

        # Cumulative Statistics Calculation
        # 1. Sum of values over reduction axes at each time step.
        sum_values_at_t = torch.sum(x_calc, dim=self.reduction_axes, keepdim=True)
        # 2. Cumulative sum of values over time.
        cum_sum_values = torch.cumsum(sum_values_at_t, dim=1)

        # 3. Count of valid elements in the normalization group at each time step.
        #    (A "group" here consists of all features at a given Batch, Time).
        elements_in_group_at_t = torch.sum(mask_calc, dim=self.reduction_axes, keepdim=True)
        # 4. Cumulative count of valid elements over time.
        cum_count_elements = torch.cumsum(elements_in_group_at_t, dim=1)
        # Avoid division by zero if all preceding elements were masked.
        safe_cum_count_elements = torch.clamp(cum_count_elements, min=1.0)

        # 5. Cumulative mean.
        cum_mean = cum_sum_values / safe_cum_count_elements

        # 6. Sum of squared differences from the cumulative mean.
        #    Only sum for valid elements: (x_calc - cum_mean)^2 * mask_calc.
        #    Using x_calc here for the difference, as cum_mean already accounts for masking.
        squared_diff_from_mean = (x_calc - cum_mean).pow(2)
        sum_sq_diff_at_t = torch.sum(squared_diff_from_mean, dim=self.reduction_axes, keepdim=True)

        # 7. Cumulative sum of squared differences over time.
        cum_sum_sq_diff = torch.cumsum(sum_sq_diff_at_t, dim=1)

        # 8. Cumulative variance.
        cum_variance = cum_sum_sq_diff / safe_cum_count_elements

        # Normalize the input using the calculated cumulative statistics:
        # (x - E[x]) / sqrt(Var[x] + eps)
        normalized_x = (x_calc - cum_mean) * torch.rsqrt(cum_variance + self.eps)

        # Apply affine transformation (scale and bias) if enabled.
        # Scale and bias are applied per-channel (last dimension).
        scale = self.weight.to(calc_dtype)
        # Reshape for broadcasting: [C] -> [1, ..., 1, C]
        scale_view_shape = [1] * (hidden_states.dim() - 1) + [self.num_channels]
        normalized_x = normalized_x * scale.view(scale_view_shape)

        # Zero out outputs for time steps that were originally masked (where mask_calc is 0).
        # This ensures padded/invalid positions in the input result in zero output.
        final_output = normalized_x * mask_calc

        return final_output.to(input_dtype)


class Gemma3nAudioSSCPConvBlock(nn.Module):
    """A single convolution block for the SubSampleConvProjection.

    This block consists of a 2D convolution, followed by CumulativeGroupNorm,
    and a ReLU activation. It handles manual padding for the convolution.
    """

    def __init__(
        self,
        config: Gemma3nAudioConfig,
        idx: int,
        input_freq_dim: int,  # Changed from input_spatial_dim
        manual_padding: tuple[int, int, int, int] = (0, 0, 0, 0),
    ):
        super().__init__()
        self.config = config
        self.manual_padding = manual_padding

        # in_channels is 1 for the first block, or C_out from previous block's conv
        in_channels = 1 if idx == 0 else self.config.sscp_conv_channel_size[idx - 1]
        out_channels = self.config.sscp_conv_channel_size[idx]
        kernel_h, kernel_w = self.config.sscp_conv_kernel_size[idx]
        stride_h, stride_w = self.config.sscp_conv_stride_size[idx]

        self.conv = nn.Conv2d(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=(
                kernel_h,
                kernel_w,
            ),  # Kernel (kH, kW) operates on (Time, Freq_dim)
            stride=(stride_h, stride_w),
            padding=(0, 0),  # Manual padding is used
            bias=False,
        )

        # Calculate output frequency dimension (f_out_conv) after this convolution.
        # input_freq_dim is the unpadded width (feature dimension).
        # self.manual_padding is (pad_F_left, pad_F_right, pad_T_top, pad_T_bottom)
        f_in_padded = input_freq_dim + self.manual_padding[0] + self.manual_padding[1]
        f_out_conv = (f_in_padded - kernel_w) // stride_w + 1

        self.norm = Gemma3nAudioCumulativeGroupNorm(
            num_channels=out_channels,  # Channels of the conv output
            feature_dims=(f_out_conv,),  # The frequency dimension size after conv
            eps=self.config.sscp_conv_group_norm_eps,
        )

        self.activation = nn.ReLU()

    def forward(self, audio_encodings: torch.Tensor) -> torch.Tensor:
        # Input audio_encodings is [B, C_in, T_in, F_in] (e.g., C_in=1)
        # manual_padding is (pad_F_left, pad_F_right, pad_T_top, pad_T_bottom)
        # F.pad applies to last two dims: F_in then T_in
        audio_encodings_padded = F.pad(audio_encodings, self.manual_padding, mode="constant", value=0.0).to(
            self.conv.weight.dtype
        )
        # Expected padded shape for F_in, k_w=3, pad_F=(1,1) -> F_padded = F_in+2
        # Expected padded shape for T_in, k_h=3, pad_T=(0,2) -> T_padded = T_in+2
        audio_encodings_conv = self.conv(audio_encodings_padded)
        # Expected conv output shape: [B, C_out, T_out, F_out]
        # Input to norm is [B, T_out, F_out, C_out]
        x_for_norm = audio_encodings_conv.permute(0, 2, 3, 1).contiguous()
        x_normed = self.norm(x_for_norm)
        # Output of norm is [B, T_out, F_out, C_out], permute back to [B, C_out, T_out, F_out]
        audio_encodings_normed = x_normed.permute(0, 3, 1, 2).contiguous()
        return self.activation(audio_encodings_normed)


class Gemma3nAudioSubSampleConvProjection(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        current_f_for_block_input = config.input_feat_size  # Start with original feature dim
        calculated_block_padding = []
        calculated_f_out_dims = []  # Tracking frequency dimension output sizes

        for i in range(2):  # Assuming 2 conv layers as per sscp_conv_... arrays
            kernel_h, kernel_w = config.sscp_conv_kernel_size[i]
            stride_h, stride_w = config.sscp_conv_stride_size[i]

            # Padding for Time (Height for Conv2d) - REVERSE_CAUSAL like
            # JAX 'reverse_causal' padding is (0, kernel_size - 1)
            pad_t_top = 0
            pad_t_bottom = kernel_h - 1

            # Frequency Padding (Width for Conv2d)
            # Based on JAX effective padding (1,1) for F_in=10, K_w=3, S_w=2
            # and the successful test configuration.
            # If kernel/stride/input_freq for frequency changes, this might need re-evaluation
            # to match generic JAX 'SAME' behavior if it differs.
            pad_f_left = 1
            pad_f_right = 1

            manual_padding_tuple = (
                pad_f_left,
                pad_f_right,
                pad_t_top,
                pad_t_bottom,
            )
            calculated_block_padding.append(manual_padding_tuple)

            # Calculate output frequency dimension after this convolution
            # This uses the actual padding applied and kernel/stride.
            f_in_padded = current_f_for_block_input + pad_f_left + pad_f_right
            f_out_after_conv = (f_in_padded - kernel_w) // stride_w + 1  # Assuming dilation_w = 1
            calculated_f_out_dims.append(f_out_after_conv)
            current_f_for_block_input = f_out_after_conv

        self.conv_0 = Gemma3nAudioSSCPConvBlock(
            idx=0,
            input_freq_dim=config.input_feat_size,  # Pass original feature dim
            config=config,
            manual_padding=calculated_block_padding[0],
        )
        self.conv_1 = Gemma3nAudioSSCPConvBlock(
            idx=1,
            input_freq_dim=calculated_f_out_dims[0],  # Output freq dim from conv_0
            config=config,
            manual_padding=calculated_block_padding[1],
        )
        final_c_out = config.sscp_conv_channel_size[-1]
        final_f_out = calculated_f_out_dims[-1]  # Final frequency dimension
        self.input_proj_in_features = final_c_out * final_f_out
        self.input_proj_linear = nn.Linear(self.input_proj_in_features, self.config.hidden_size, bias=False)

    def forward(self, audio_encodings: torch.Tensor) -> torch.Tensor:
        # audio_encodings is [B, T, F_in]
        # Reshape to [B, 1, T, F_in] (Batch, Channels=1, Height=Time, Width=F_in)
        audio_encodings_reshaped = audio_encodings.unsqueeze(1)
        x = self.conv_0(audio_encodings_reshaped)
        x = self.conv_1(x)
        # x from conv_1 is [B, C_out_1, T_out_1, F_out_1]
        b, c_out, t_out, f_out = x.shape
        # Permute to [B, T_out_1, F_out_1, C_out_1] then flatten F_out_1 and C_out_1
        x_permuted = x.permute(0, 2, 3, 1).contiguous()
        output_flattened = x_permuted.view(b, t_out, f_out * c_out)
        output = self.input_proj_linear(output_flattened)
        return output


class Gemma3nAudioConformerAttention(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config
        self.post_in_features = self.config.hidden_size
        self.register_buffer("gradient_clipping", torch.tensor(self.config.gradient_clipping), persistent=False)
        self.pre_attn_norm = Gemma3nRMSNorm(self.config.hidden_size)
        self.attn = Gemma3nAudioAttention(config)
        self.post = nn.Linear(self.post_in_features, self.config.hidden_size, bias=False)
        self.post_norm = Gemma3nRMSNorm(self.config.hidden_size)

    def forward(self, audio_encodings: torch.Tensor, audio_mel_mask: torch.BoolTensor) -> torch.Tensor:
        audio_encodings_input_to_attn = audio_encodings
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        audio_encodings_norm = self.pre_attn_norm(audio_encodings)
        # Output of self.attn is [B, T, NumHeads, HeadDim]
        audio_encodings_attn_out = self.attn(audio_encodings_norm, audio_mel_mask)

        # Reshape from [B, T, NumHeads, HeadDim] to [B, T, NumHeads * HeadDim]
        # NumHeads * HeadDim = hidden_size
        b, t, num_heads, head_dim = audio_encodings_attn_out.shape
        audio_encodings_reshaped = audio_encodings_attn_out.reshape(b, t, num_heads * head_dim)

        audio_encodings = self.post(audio_encodings_reshaped)
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        return audio_encodings_input_to_attn + self.post_norm(audio_encodings)


class Gemma3nAudioConformerFeedForward(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        self.register_buffer("gradient_clipping", torch.tensor(self.config.gradient_clipping), persistent=False)

        self.pre_layer_norm = Gemma3nRMSNorm(self.config.hidden_size)
        self.ffw_layer_1 = nn.Linear(self.config.hidden_size, self.config.hidden_size * 4, bias=False)
        self.ffw_layer_2 = nn.Linear(self.config.hidden_size * 4, self.config.hidden_size, bias=False)
        self.post_layer_norm = Gemma3nRMSNorm(self.config.hidden_size)
        self.post_layer_scale = self.config.conf_residual_weight

    def forward(self, audio_encodings: torch.Tensor) -> torch.Tensor:
        residual = audio_encodings
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        audio_encodings = self.pre_layer_norm(audio_encodings)
        audio_encodings: torch.Tensor = self.ffw_layer_1(audio_encodings)
        audio_encodings = nn.functional.silu(audio_encodings)
        audio_encodings: torch.Tensor = self.ffw_layer_2(audio_encodings)
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        audio_encodings = self.post_layer_norm(audio_encodings)
        return residual + (audio_encodings * self.post_layer_scale)


class Gemma3nAudioConformerLightConv1d(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        self.pre_layer_norm = Gemma3nRMSNorm(self.config.hidden_size, eps=self.config.rms_norm_eps)
        self.linear_start = nn.Linear(self.config.hidden_size, self.config.hidden_size * 2, bias=False)
        self.depthwise_conv1d = nn.Conv1d(
            in_channels=self.config.hidden_size,
            out_channels=self.config.hidden_size,
            kernel_size=self.config.conf_conv_kernel_size,
            stride=1,
            padding=0,  # Manual causal padding
            groups=self.config.hidden_size,  # Depthwise
            bias=False,
        )
        self.register_buffer("gradient_clipping", torch.tensor(self.config.gradient_clipping), persistent=False)
        self.conv_norm = Gemma3nRMSNorm(self.config.hidden_size, eps=self.config.rms_norm_eps)
        self.linear_end = nn.Linear(self.config.hidden_size, self.config.hidden_size, bias=False)

        self.causal_padding = self.config.conf_conv_kernel_size - 1

    def forward(self, audio_encodings: torch.Tensor) -> torch.Tensor:
        audio_encodings_residual = audio_encodings  # Save for residual connection

        audio_encodings = self.pre_layer_norm(audio_encodings)
        audio_encodings = self.linear_start(audio_encodings)
        audio_encodings = torch.nn.functional.glu(audio_encodings, dim=-1)
        # Permute for Conv1d: [B, T, D] -> [B, D, T]
        audio_encodings_permuted = audio_encodings.permute(0, 2, 1)
        # Apply manual causal padding
        audio_encodings_permuted_padded = F.pad(audio_encodings_permuted, (self.causal_padding, 0))
        audio_encodings = self.depthwise_conv1d(audio_encodings_permuted_padded)
        # Permute back: [B, D, T_out] -> [B, T_out, D]
        audio_encodings = audio_encodings.permute(0, 2, 1)
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        audio_encodings = self.conv_norm(audio_encodings)
        audio_encodings = nn.functional.silu(audio_encodings)
        audio_encodings = self.linear_end(audio_encodings)
        output = audio_encodings + audio_encodings_residual
        return output


class Gemma3nAudioConformerBlock(nn.Module):
    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__()
        self.config = config

        self.ffw_layer_start = Gemma3nAudioConformerFeedForward(self.config)
        self.attention = Gemma3nAudioConformerAttention(self.config)
        self.lconv1d = Gemma3nAudioConformerLightConv1d(self.config)
        self.ffw_layer_end = Gemma3nAudioConformerFeedForward(self.config)
        self.register_buffer("gradient_clipping", torch.tensor(self.config.gradient_clipping), persistent=False)
        self.norm = Gemma3nRMSNorm(self.config.hidden_size)

    def forward(self, audio_encodings: torch.Tensor, audio_mel_mask: torch.BoolTensor) -> torch.Tensor:
        audio_encodings = self.ffw_layer_start(audio_encodings)
        audio_encodings = self.attention(audio_encodings, audio_mel_mask)
        validity_mask_for_lconv = ~audio_mel_mask  # True for valid
        audio_encodings_for_lconv_input = audio_encodings * validity_mask_for_lconv.unsqueeze(-1).to(
            audio_encodings.dtype
        )
        audio_encodings = self.lconv1d(audio_encodings_for_lconv_input)

        audio_encodings = self.ffw_layer_end(audio_encodings)
        audio_encodings = torch.clamp(audio_encodings, -self.gradient_clipping, self.gradient_clipping)
        output = self.norm(audio_encodings)
        return output


# ==== Language Model ====


class Gemma3nTextScaledWordEmbedding(Gemma3TextScaledWordEmbedding):
    pass


class Gemma3nTextLaurelBlock(nn.Module):
    """Learned Augmented Residual Layer"""

    def __init__(self, config: Gemma3nTextConfig):
        super().__init__()
        self.config = config

        self.linear_left = nn.Linear(self.config.hidden_size, self.config.laurel_rank, bias=False)
        self.linear_right = nn.Linear(self.config.laurel_rank, self.config.hidden_size, bias=False)
        self.post_laurel_norm = Gemma3nRMSNorm(self.config.hidden_size, eps=self.config.rms_norm_eps)

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        laurel_hidden_states: torch.Tensor = self.linear_left(hidden_states)
        laurel_hidden_states: torch.Tensor = self.linear_right(laurel_hidden_states)
        normed_laurel_hidden_states = self.post_laurel_norm(laurel_hidden_states)
        return hidden_states + normed_laurel_hidden_states


class Gemma3nTextMLP(Gemma2MLP):
    def __init__(self, config: Gemma3nTextConfig, layer_idx: int = 0):
        super().__init__(config)
        self.intermediate_size = config.intermediate_size[layer_idx]
        self.activation_sparsity = config.activation_sparsity_pattern[layer_idx]

    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
        gate_proj = self.gate_proj(hidden_states)
        if self.activation_sparsity > 0.0:
            gate_proj = self._gaussian_topk(gate_proj)
        activations = self.act_fn(gate_proj)
        up_proj = self.up_proj(hidden_states)
        down_proj = self.down_proj(activations * up_proj)
        return down_proj

    def _gaussian_topk(self, inputs: torch.Tensor) -> torch.Tensor:
        target_sparsity_tensor = torch.tensor(self.activation_sparsity, dtype=torch.float32, device=inputs.device)
        # normal_dist and std_multiplier are adapted from jax.scipy.stats.norm.ppf().
        #
        # References:
        #   *   https://docs.jax.dev/en/latest/_autosummary/jax.scipy.stats.norm.ppf.html
        #   *   https://pytorch.org/docs/stable/distributions.html#torch.distributions.normal.Normal
        #   *   https://pytorch.org/docs/stable/distributions.html#torch.distributions.transformed_distribution.TransformedDistribution.icdf
        normal_dist = torch.distributions.normal.Normal(0, 1)
        std_multiplier: torch.Tensor = normal_dist.icdf(target_sparsity_tensor)
        std_multiplier = std_multiplier.type(inputs.dtype)
        inputs_mean = torch.mean(inputs, dim=-1, keepdim=True)
        inputs_std = torch.std(inputs, dim=-1, keepdim=True, unbiased=False)
        cutoff_x = inputs_mean + inputs_std * std_multiplier
        return nn.functional.relu(inputs - cutoff_x)


class Gemma3nTextAltUp(nn.Module):
    """Alternating Updates (AltUp)

    The AltUp module wraps transformer layers. The `predict` step modifies the
    input to the transformer layer, and the `correct` step propagates the output
    of the transformer layer to the sparsely updated dimensions.

    See more in the research paper:

    https://proceedings.neurips.cc/paper_files/paper/2023/file/f2059277ac6ce66e7e5543001afa8bb5-Paper-Conference.pdf
    """

    def __init__(self, config: Gemma3nTextConfig):
        super().__init__()
        self.config = config
        self.correct_output_scale = nn.Parameter(torch.zeros(self.config.hidden_size))
        self.correction_coefs = nn.Linear(self.config.altup_num_inputs, self.config.altup_num_inputs, bias=False)
        self.prediction_coefs = nn.Linear(self.config.altup_num_inputs, self.config.altup_num_inputs**2, bias=False)
        self.modality_router = nn.Linear(self.config.hidden_size, self.config.altup_num_inputs, bias=False)
        self.router_norm = Gemma3nRMSNorm(self.config.hidden_size, eps=self.config.rms_norm_eps)
        self.register_buffer("router_input_scale", torch.tensor(self.config.hidden_size**-1.0), persistent=False)

    def compute_router_modalities(self, x: torch.Tensor) -> torch.Tensor:
        router_inputs = self.router_norm(x) * self.router_input_scale
        routed = self.modality_router(router_inputs)
        return torch.tanh(routed.float()).type_as(x)

    def predict(self, hidden_states: torch.Tensor) -> torch.Tensor:
        """Predicts the output of a layer using a trainable map.

        Args:
            hidden_states: A 4D tensor of shape `[num_altup_inputs, batch_size, num_tokens, hidden_size]` derived by
                stacking the input embeddings and preprocessing the last `num_altup_inputs - 1` matrices.

        Returns:
            A 4D tensor of shape `[num_altup_inputs, batch_size, num_tokens, hidden_size]` containing the predictions.
        """
        modalities = self.compute_router_modalities(hidden_states[self.config.altup_active_idx])

        if self.training and self.config.altup_coef_clip is not None:
            self.prediction_coefs.weight.data.clamp_(-self.config.altup_coef_clip, self.config.altup_coef_clip)

        # Project and then transpose all 2D matrices contained so that mulmat gives the correct result
        all_coefs: torch.Tensor = (
            self.prediction_coefs(modalities)
            .reshape(*modalities.shape[:-1], self.config.altup_num_inputs, self.config.altup_num_inputs)
            .permute(0, 1, 3, 2)
        )

        # permute hidden_states to [batch_size, num_tokens, hidden_size, altup_num_inputs]
        predictions = torch.matmul(hidden_states.permute(1, 2, 3, 0), all_coefs)
        predictions = predictions.permute(3, 0, 1, 2)  # undo the permute
        predictions += hidden_states  # add the original input
        return predictions.contiguous().type_as(hidden_states)

    def correct(self, predictions: torch.Tensor, activated: torch.Tensor) -> torch.Tensor:
        """Corrects the predictions relative to the

        Args:
            predictions: A 4D tensor of shape `[num_altup_inputs, batch_size, num_tokens, hidden_size]` derived by
                stacking the input embeddings and preprocessing the last `num_altup_inputs - 1` matrices.
            activated: A 3D tensor of shape `[batch_size, num_tokens, hidden_size]` containing the activated inputs.

        Returns:
            A 4D tensor of shape `[num_altup_inputs, batch_size, num_tokens, hidden_size]` correcting the original
                predictions relative to the activated input embeddings.
        """
        modalities = self.compute_router_modalities(activated)
        innovation = activated - predictions[self.config.altup_active_idx]  # (batch, num_tokens, hidden_size)
        innovation = innovation.repeat(self.config.altup_num_inputs, 1, 1, 1)  # Repeat on dim0 to match predictions

        if self.training and self.config.altup_coef_clip is not None:
            weight = self.correction_coefs.weight.clamp(-self.config.altup_coef_clip, self.config.altup_coef_clip)
            all_coefs = torch.nn.functional.linear(modalities, weight, bias=None) + 1.0
        else:
            all_coefs = self.correction_coefs(modalities) + 1.0

        # all_coefs adapted from jax.numpy.einsum("...p,pi->...i", ...)
        # Permute to (altup_num_inputs, batch_size, num_tokens) as the last dim is a scalar applied to each altup input
        # and expand on dim1 for broadcastability
        all_coefs = all_coefs.permute(2, 0, 1).unsqueeze(-1)

        corrected = torch.mul(innovation, all_coefs)
        corrected += predictions  # add the original input
        return corrected.contiguous().type_as(activated)

    def forward(self, corrected: torch.Tensor) -> torch.Tensor:
        """
        This is only defined as the `forward` so that accelerate hooks can move correctly `correct_output_scale`
        (which is a nn.Parameter, not a Module) between devices when offloading. It is otherwise only used in
        `scale_corrected_output`
        """
        return (corrected.type_as(self.correct_output_scale) * self.correct_output_scale).type_as(corrected)

    def scale_corrected_output(self, corrected: torch.Tensor) -> torch.Tensor:
        """Scales the provided 3D tensor of shape [batch_size, num_tokens, hidden_size]."""
        return self.forward(corrected)


def apply_rotary_pos_emb(x: torch.Tensor, cos: torch.Tensor, sin: torch.Tensor, unsqueeze_dim: int = 1):
    """Applies Rotary Position Embedding to the query and key tensors.

    Args:
        x (`torch.Tensor`): The tensor to embed.
        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)
    return (x * cos) + (rotate_half(x) * sin)


class Gemma3nTextAttention(Gemma3Attention):
    def __init__(self, config: Gemma3nTextConfig, layer_idx: int):
        super().__init__(config, layer_idx)
        self.is_causal = True
        del self.attn_logit_softcapping
        self.scaling = 1.0
        self.v_norm = Gemma3nRMSNorm(dim=config.head_dim, eps=config.rms_norm_eps, with_scale=False)

        first_kv_shared_layer_idx = self.config.num_hidden_layers - self.config.num_kv_shared_layers
        self.is_kv_shared_layer = layer_idx >= first_kv_shared_layer_idx > 0
        prev_layers = config.layer_types[:first_kv_shared_layer_idx]
        if self.is_kv_shared_layer:
            # For shared layers, find the last non-shared layer of the same type before sharing starts
            self.kv_shared_layer_index = len(prev_layers) - 1 - prev_layers[::-1].index(config.layer_types[layer_idx])
            self.store_full_length_kv = False
        else:
            self.kv_shared_layer_index = None
            # For non-shared layers, store full-length kv if this is the last non-shared layer of its type
            self.store_full_length_kv = layer_idx == len(prev_layers) - 1 - prev_layers[::-1].index(
                config.layer_types[layer_idx]
            )

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

        cos, sin = position_embeddings
        query_states = self.q_proj(hidden_states).view(hidden_shape)
        query_states = self.q_norm(query_states)
        query_states = apply_rotary_pos_emb(query_states, cos, sin, unsqueeze_dim=2)
        query_states = query_states.transpose(1, 2)

        # For layers with shared KV (from kv sharing point onwards), we reuse the same keys/values states as the last non-sharing layer
        if self.is_kv_shared_layer and past_key_values is not None:
            key_states, value_states = past_key_values.shared_layers[self.kv_shared_layer_index]
            # Device of past layer may be different from current one
            key_states = key_states.to(query_states.device)
            value_states = value_states.to(query_states.device)
        else:
            key_states = self.k_proj(hidden_states).view(hidden_shape)
            key_states = self.k_norm(key_states)
            key_states = apply_rotary_pos_emb(key_states, cos, sin, unsqueeze_dim=2)
            key_states = key_states.transpose(1, 2)

            value_states = self.v_proj(hidden_states).view(hidden_shape)
            value_states = self.v_norm(value_states)
            value_states = value_states.transpose(1, 2)

        if past_key_values is not None:
            if not self.is_kv_shared_layer:
                key_states, value_states = past_key_values.update(key_states, value_states, self.layer_idx)
            if self.store_full_length_kv:
                if not hasattr(past_key_values, "shared_layers"):
                    past_key_values.shared_layers = {}
                past_key_values.shared_layers[self.layer_idx] = key_states, value_states

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

        attn_output, attn_weights = attention_interface(
            self,
            query_states,
            key_states,
            value_states,
            attention_mask,
            dropout=self.attention_dropout if self.training else 0.0,
            scaling=self.scaling,
            sliding_window=self.sliding_window,
            **kwargs,
        )

        attn_output = attn_output.reshape(*input_shape, -1).contiguous()
        attn_output = self.o_proj(attn_output)
        return attn_output, attn_weights


class Gemma3nTextDecoderLayer(Gemma3DecoderLayer):
    def __init__(self, config: Gemma3nTextConfig, layer_idx: int):
        super().__init__(config, layer_idx)
        self.mlp = Gemma3nTextMLP(config, layer_idx=layer_idx)

        self.hidden_size_per_layer_input = config.hidden_size_per_layer_input
        self.act_fn = ACT2FN[config.hidden_activation]

        self.altup = Gemma3nTextAltUp(config)
        self.laurel = Gemma3nTextLaurelBlock(config)
        self.self_attn = Gemma3nTextAttention(config, layer_idx)
        self.per_layer_input_gate = nn.Linear(self.hidden_size, self.hidden_size_per_layer_input, bias=False)
        self.per_layer_projection = nn.Linear(self.hidden_size_per_layer_input, self.hidden_size, bias=False)
        self.post_per_layer_input_norm = Gemma3nRMSNorm(self.hidden_size, eps=config.rms_norm_eps)

    def forward(
        self,
        hidden_states: torch.Tensor,
        position_embeddings: torch.Tensor = None,
        per_layer_input: torch.Tensor = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple[torch.Tensor, tuple[torch.FloatTensor, torch.FloatTensor] | None]:
        predictions = self.altup.predict(hidden_states)
        active_prediction = predictions[self.config.altup_active_idx]

        active_prediction_normed = self.input_layernorm(active_prediction)
        laurel_output = self.laurel(active_prediction_normed)

        attn, _ = self.self_attn(
            hidden_states=active_prediction_normed,
            attention_mask=attention_mask,
            position_ids=position_ids,
            position_embeddings=position_embeddings,
            past_key_values=past_key_values,
            **kwargs,
        )
        attn = self.post_attention_layernorm(attn)

        attn_gated = active_prediction + attn
        attn_laurel = (attn_gated + laurel_output) / math.sqrt(2)

        attn_norm = self.pre_feedforward_layernorm(attn_laurel)
        attn_ffw = self.mlp(attn_norm)
        attn_ffw_norm = self.post_feedforward_layernorm(attn_ffw)
        attn_ffw_laurel_gated = attn_laurel + attn_ffw_norm
        corrected_predictions = self.altup.correct(predictions, attn_ffw_laurel_gated)

        first_prediction = corrected_predictions[self.config.altup_active_idx].clone()
        if self.config.altup_correct_scale:
            first_prediction = self.altup.scale_corrected_output(first_prediction)

        # per_layer_input_gate adapted from jax.numpy.einsum("btd,dp->btp", ...)
        first_prediction = self.per_layer_input_gate(first_prediction)
        first_prediction = self.act_fn(first_prediction)
        first_prediction = torch.multiply(first_prediction, per_layer_input)

        # per_layer_projection adapted from jax.numpy.einsum("btp,pd->btd", ...)
        first_prediction = self.per_layer_projection(first_prediction)
        first_prediction = self.post_per_layer_input_norm(first_prediction)
        corrected_predictions[1:] += first_prediction

        return corrected_predictions


class Gemma3nPreTrainedModel(Gemma2PreTrainedModel):
    config: Gemma3nConfig
    input_modalities = ("image", "text", "audio")
    _no_split_modules = ["Gemma3nTextDecoderLayer"]
    _can_record_outputs = {
        "hidden_states": Gemma3nTextDecoderLayer,
        "attentions": Gemma3nTextAttention,
    }

    @torch.no_grad()
    def _init_weights(self, module):
        PreTrainedModel._init_weights(self, module)
        if isinstance(module, Gemma3nAudioCumulativeGroupNorm):
            init.ones_(module.weight)
        elif isinstance(module, Gemma3nAudioAttention):
            init.zeros_(module.per_dim_scale)
            q_scale = module.head_dim**-0.5
            r_softplus_0 = 1.0 / torch.nn.functional.softplus(torch.tensor(0.0))
            init.copy_(module.q_scale, q_scale * r_softplus_0)
            init.constant_(module.softcap, module.attention_logits_soft_cap)
            init.copy_(module.local_causal_valid_mask, module.create_local_causal_valid_mask())
        elif isinstance(module, Gemma3nTextScaledWordEmbedding):
            init.constant_(module.embed_scale, module.scalar_embed_scale)
        elif isinstance(module, Gemma3nTextAltUp):
            init.zeros_(module.correct_output_scale)
            init.constant_(module.router_input_scale, self.config.hidden_size**-1.0)
        elif isinstance(module, Gemma3nAudioRelativePositionEmbedding):
            min_timescale, max_timescale = 1.0, 1.0e4
            num_timescales = module.channels // 2
            log_timescale_increment = math.log(float(max_timescale) / float(min_timescale)) / max(
                num_timescales - 1, 1
            )
            inv_timescales = min_timescale * torch.exp(torch.arange(num_timescales) * -log_timescale_increment)
            init.copy_(module.inv_timescales, inv_timescales.float().unsqueeze(0).unsqueeze(0))
        elif isinstance(module, Gemma3nTextModel):
            init.constant_(module.per_layer_projection_scale, self.hidden_size**-0.5)
            init.constant_(module.per_layer_input_scale, 1 / math.sqrt(2.0))
        elif isinstance(module, Gemma3nRotaryEmbedding):
            for layer_type in module.layer_types:
                rope_init_fn = module.compute_default_rope_parameters
                if module.rope_type[layer_type] != "default":
                    rope_init_fn = ROPE_INIT_FUNCTIONS[module.rope_type[layer_type]]
                curr_inv_freq, _ = rope_init_fn(module.config, layer_type=layer_type)
                init.copy_(getattr(module, f"{layer_type}_inv_freq"), curr_inv_freq)
                init.copy_(getattr(module, f"{layer_type}_original_inv_freq"), curr_inv_freq)

        if hasattr(module, "gradient_clipping"):
            init.constant_(module.gradient_clipping, self.config.gradient_clipping)


class Gemma3nAudioEncoder(Gemma3nPreTrainedModel):
    """
    An audio encoder based on the [Universal Speech Model](https://huggingface.co/papers/2303.01037) architecture.
    """

    config: Gemma3nAudioConfig

    main_input_name = "audio_mel"
    input_modalities = "audio"

    def __init__(self, config: Gemma3nAudioConfig):
        super().__init__(config)
        self.config = config

        self.subsample_conv_projection = Gemma3nAudioSubSampleConvProjection(config)
        self.conformer = nn.ModuleList(
            [Gemma3nAudioConformerBlock(config) for _ in range(config.conf_num_hidden_layers)]
        )
        self.post_init()

    @merge_with_config_defaults
    @capture_outputs
    def forward(
        self, audio_mel: torch.Tensor, audio_mel_mask: torch.BoolTensor, **kwargs: Unpack[TransformersKwargs]
    ) -> tuple | Gemma3nAudioEncoderModelOutput:
        """Encodes a batch of MELs.

        Args:
            audio_mel: a torch.Tensor of shape [batch, num_frames, num_channels,
              mel_bins].

        Returns:
            audio_encodings: a torch.Tensor of shape
                `[batch_size, self.config.audio_soft_tokens_per_image,
                self.config.audio_config.hidden_size]`
            audio_mel_mask: a torch.BoolTensor of shape [batch, num_frames].
        """
        audio_encodings = self.subsample_conv_projection(audio_mel)  # audio_encodings: [B, T_sub, D]

        # Subsample the input audio_mel_mask to match the time dimension of audio_encodings (T_sub)
        t_sub = audio_encodings.shape[1]

        time_stride_product = 1
        for stride_pair_idx in range(len(self.config.sscp_conv_stride_size)):
            time_stride_product *= self.config.sscp_conv_stride_size[stride_pair_idx][0]

        # Create indices for gathering from the original mask.
        # These indices map to original time steps corresponding to the start of each
        # receptive field in the subsampled output.
        indices = torch.arange(t_sub, device=audio_mel_mask.device) * time_stride_product
        indices = torch.clamp(indices, max=audio_mel_mask.shape[1] - 1)  # Ensure indices are valid

        # Expand indices for batch compatibility if B > 1 and indices is 1D.
        if audio_mel_mask.ndim > 1 and indices.ndim == 1:
            indices = indices.unsqueeze(0).expand(audio_mel_mask.shape[0], -1)  # [B, T_sub]
        elif (
            audio_mel_mask.ndim == indices.ndim
            and audio_mel_mask.shape[0] == 1
            and indices.shape[0] != 1
            and t_sub == indices.shape[0]
        ):
            # Handle case where B=1 but indices became [T_sub] instead of [1, T_sub]
            indices = indices.unsqueeze(0)

        current_mask = torch.gather(audio_mel_mask, 1, indices)  # [B, T_sub]

        for block in self.conformer:
            audio_encodings = block(audio_encodings, current_mask)  # Pass the processed mask

        if self.config.conf_reduction_factor > 1:
            audio_encodings = audio_encodings[:, :: self.config.conf_reduction_factor]
            # Reduce the mask as well
            current_mask = current_mask[:, :: self.config.conf_reduction_factor]

        audio_encodings = audio_encodings.masked_fill(current_mask.unsqueeze(-1), 0.0)
        return Gemma3nAudioEncoderModelOutput(
            last_hidden_state=audio_encodings,
            audio_mel_mask=current_mask,
        )


class Gemma3nRotaryEmbedding(Gemma3RotaryEmbedding):
    pass


@auto_docstring(custom_intro="The base Gemma 3n language model without a language modeling head.")
class Gemma3nTextModel(Gemma3TextModel):
    config: Gemma3nTextConfig

    def __init__(self, config: Gemma3nTextConfig):
        super().__init__(config)

        self.hidden_size = config.hidden_size
        self.hidden_size_per_layer_input = config.hidden_size_per_layer_input

        self.embed_tokens_per_layer = Gemma3nTextScaledWordEmbedding(
            config.vocab_size_per_layer_input,
            config.num_hidden_layers * config.hidden_size_per_layer_input,
            self.padding_idx,
            embed_scale=config.hidden_size_per_layer_input**0.5,
        )

        self.per_layer_model_projection = nn.Linear(
            self.hidden_size,
            config.num_hidden_layers * config.hidden_size_per_layer_input,
            bias=False,
        )

        self.per_layer_projection_norm = Gemma3nRMSNorm(config.hidden_size_per_layer_input, eps=config.rms_norm_eps)
        self.layers = nn.ModuleList(
            [Gemma3nTextDecoderLayer(config, layer_idx) for layer_idx in range(config.num_hidden_layers)]
        )

        self.norm = Gemma3nRMSNorm(config.hidden_size, eps=config.rms_norm_eps)

        self.altup_projections = nn.ModuleList(
            [nn.Linear(self.hidden_size, self.hidden_size, bias=False) for _ in range(1, self.config.altup_num_inputs)]
        )

        self.altup_unembed_projections = nn.ModuleList(
            [nn.Linear(self.hidden_size, self.hidden_size, bias=False) for _ in range(1, self.config.altup_num_inputs)]
        )

        self.register_buffer("per_layer_projection_scale", torch.tensor(self.hidden_size**-0.5), persistent=False)
        self.register_buffer("per_layer_input_scale", torch.rsqrt(torch.tensor(2.0)), persistent=False)

    def get_per_layer_inputs(self, input_ids: torch.LongTensor) -> torch.Tensor:
        return self.embed_tokens_per_layer(input_ids).reshape(
            *input_ids.shape,
            self.config.num_hidden_layers,
            self.hidden_size_per_layer_input,
        )

    def project_per_layer_inputs(
        self,
        inputs_embeds: torch.Tensor,
        per_layer_inputs: torch.Tensor | None = None,
    ) -> torch.Tensor:
        per_layer_projection: torch.Tensor = self.per_layer_model_projection(inputs_embeds)
        per_layer_projection *= self.per_layer_projection_scale.to(
            dtype=inputs_embeds.dtype, device=per_layer_projection.device
        )
        per_layer_projection = per_layer_projection.reshape(
            *inputs_embeds.shape[:-1],
            self.config.num_hidden_layers,
            self.hidden_size_per_layer_input,
        )
        per_layer_projection = self.per_layer_projection_norm(per_layer_projection)

        if per_layer_inputs is None:
            return per_layer_projection

        if per_layer_projection.shape != per_layer_inputs.shape:
            # per-layer inputs are sometimes padded with zeros, slice the relevant embeddings.
            per_layer_inputs = per_layer_inputs[..., : self.config.num_hidden_layers, :]

        return (per_layer_projection + per_layer_inputs) * self.per_layer_input_scale.to(
            dtype=inputs_embeds.dtype, device=per_layer_projection.device
        )

    # Last hidden states should be before reprojecting, to stay consistent with the other layer outputs
    @merge_with_config_defaults
    @capture_outputs(tie_last_hidden_states=False)
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        per_layer_inputs: torch.Tensor | 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,
        **kwargs: Unpack[TransformersKwargs],
    ) -> BaseModelOutputWithPast:
        r"""
        per_layer_inputs (torch.Tensor, *optional*, defaults to None):
            Pre-computed per-layer embeddings. If None, they are derived from input_ids if provided.
        """
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if input_ids is not None:
            inputs_embeds = self.embed_tokens(input_ids)
            per_layer_inputs = self.get_per_layer_inputs(input_ids)

        per_layer_inputs = self.project_per_layer_inputs(inputs_embeds, per_layer_inputs)

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

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

        # It may already have been prepared by e.g. `generate`
        if not isinstance(causal_mask_mapping := attention_mask, dict):
            # Prepare mask arguments
            mask_kwargs = {
                "config": self.config,
                "inputs_embeds": inputs_embeds,
                "attention_mask": attention_mask,
                "past_key_values": past_key_values,
                "position_ids": position_ids,
            }
            # Create the masks
            causal_mask_mapping = {
                "full_attention": create_causal_mask(**mask_kwargs),
                "sliding_attention": create_sliding_window_causal_mask(**mask_kwargs),
            }

        # embed positions
        hidden_states_0 = inputs_embeds

        # Expand hidden_states to support per-layer inputs
        target_magnitude = torch.mean(hidden_states_0**2, dim=-1, keepdim=True) ** 0.5
        epsilon_tensor = torch.tensor(1e-5)

        temp_hidden_states = [hidden_states_0]
        for i in range(1, self.config.altup_num_inputs):
            # altup_proj adapted from jax.numpy.einsum("btp,pd->btd", ...)
            altup_proj = self.altup_projections[i - 1](hidden_states_0)
            current_hidden_state = altup_proj.to(dtype=hidden_states_0.dtype, device=target_magnitude.device)
            new_magnitude = torch.mean(current_hidden_state**2, dim=-1, keepdim=True)
            new_magnitude = torch.sqrt(torch.maximum(new_magnitude, epsilon_tensor.to(target_magnitude.device)))
            current_hidden_state = current_hidden_state * target_magnitude / new_magnitude
            temp_hidden_states.append(current_hidden_state)

        hidden_states = torch.stack(temp_hidden_states, dim=0)  # [num_altup_inputs, batch, seq_len, hidden_size]
        position_embeddings = {}
        for layer_type in self.config.layer_types:
            position_embeddings[layer_type] = self.rotary_emb(hidden_states, position_ids, layer_type)

        for i, decoder_layer in enumerate(self.layers[: self.config.num_hidden_layers]):
            causal_mask = causal_mask_mapping[self.config.layer_types[i]]
            per_layer_input = per_layer_inputs[:, :, i, :]

            hidden_states = decoder_layer(
                hidden_states,
                position_embeddings[self.config.layer_types[i]],
                per_layer_input,
                attention_mask=causal_mask,
                position_ids=position_ids,
                past_key_values=past_key_values,
                **kwargs,
            )

        # Per-layer inputs to single output
        target_magnitude = torch.mean(hidden_states[0] ** 2, dim=-1, keepdim=True) ** 0.5
        temp_hidden_states = [hidden_states[0]]
        for i in range(1, self.config.altup_num_inputs):
            # altup_unembed_projections adapted from jax.numpy.einsum("btp,pd->btd", ...)
            altup_unemb_proj: torch.Tensor = self.altup_unembed_projections[i - 1](hidden_states[i])
            current_hidden_state = altup_unemb_proj.to(dtype=hidden_states_0.dtype, device=target_magnitude.device)
            new_magnitude = torch.mean(current_hidden_state**2, dim=-1, keepdim=True)
            new_magnitude = torch.sqrt(torch.maximum(new_magnitude, epsilon_tensor.to(target_magnitude.device)))
            current_hidden_state = current_hidden_state * target_magnitude / new_magnitude
            temp_hidden_states.append(current_hidden_state)

        hidden_states = torch.stack(temp_hidden_states)
        hidden_states = torch.mean(hidden_states, dim=0)
        hidden_states = self.norm(hidden_states)

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


@auto_docstring(custom_intro="The base Gemma 3n language model with a language modeling head.")
class Gemma3nForCausalLM(Gemma3ForCausalLM):
    pass


class Gemma3nMultimodalEmbedder(nn.Module):
    """Embeds token ids or soft tokens for multimodal content into language model space."""

    def __init__(
        self,
        multimodal_config: Gemma3nAudioConfig | Gemma3nVisionConfig,
        text_config: Gemma3nTextConfig,
    ):
        super().__init__()

        self.multimodal_hidden_size = multimodal_config.hidden_size
        self.eps = multimodal_config.rms_norm_eps
        self.vocab_offset = multimodal_config.vocab_offset
        self.vocab_size = multimodal_config.vocab_size
        self.text_hidden_size = text_config.hidden_size

        self.embedding = nn.Embedding(self.vocab_size, self.multimodal_hidden_size)
        self.hard_embedding_norm = Gemma3nRMSNorm(self.multimodal_hidden_size, eps=self.eps)
        self.soft_embedding_norm = Gemma3nRMSNorm(self.multimodal_hidden_size, eps=self.eps)
        self.embedding_projection = nn.Linear(self.multimodal_hidden_size, self.text_hidden_size, bias=False)
        self.embedding_post_projection_norm = Gemma3nRMSNorm(self.text_hidden_size, eps=self.eps, with_scale=False)

    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        inputs_embeds: torch.Tensor | None = None,
    ) -> torch.Tensor:
        """Embeds token ids or soft tokens for multimodal content into language model space.

        Args:
            input_ids: A torch.LongTensor containing the token ids to embed. Values should be in the range
                `[vocab_offset, vocab_offset + vocab_size)`.
            inputs_embeds: A torch.Tensor containing the soft tokens to embed.

        Returns:
            A torch.Tensor of embeddings with  shape `[batch_size, seq_len, self.config.text_config.hidden_size]`.
        """
        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 not None:
            emb_norm = self.soft_embedding_norm(inputs_embeds)
        else:
            hard_emb = self.embedding(input_ids - self.vocab_offset)
            emb_norm = self.hard_embedding_norm(hard_emb)

        emb_norm_proj = self.embedding_projection(emb_norm)
        return self.embedding_post_projection_norm(emb_norm_proj)


@auto_docstring(
    custom_intro="""
    The base Gemma 3n model comprising a vision backbone, an audio backbone, and a language model without a
    language modeling head.
    """
)
class Gemma3nModel(PaliGemmaModel):
    def __init__(self, config: Gemma3nConfig):
        super().__init__(config)
        del self.multi_modal_projector  # Replaced by Gemma3nVisionEmbedder
        del self.text_config_dtype
        self.vocab_size_per_layer_input = config.text_config.vocab_size_per_layer_input
        self.audio_tower = AutoModel.from_config(config.audio_config)
        self.embed_vision = Gemma3nMultimodalEmbedder(config.vision_config, config.text_config)
        self.embed_audio = Gemma3nMultimodalEmbedder(config.audio_config, config.text_config)

    @can_return_tuple
    @auto_docstring(custom_intro="Projects the last hidden state from the vision model into language model space.")
    def get_image_features(
        self,
        pixel_values: torch.FloatTensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | BaseModelOutputWithPooling:
        vision_outputs = self.vision_tower(pixel_values=pixel_values, do_pooling=False, return_dict=True, **kwargs)
        last_hidden_state = vision_outputs.last_hidden_state
        # Convert from (batch, channels, height, width) to (batch, height * width, channels) where:
        # height == width and height * width == Gemma3nConfig.vision_soft_tokens_per_image.
        last_hidden_state = last_hidden_state.reshape(
            last_hidden_state.shape[0],
            self.config.vision_config.hidden_size,
            self.config.vision_soft_tokens_per_image,
        ).permute(0, 2, 1)
        # Normalize and embed the soft tokens into language model space.
        last_hidden_state *= self.config.vision_config.hidden_size**0.5
        vision_outputs.pooler_output = self.embed_vision(inputs_embeds=last_hidden_state)

        return vision_outputs

    def get_placeholder_mask(
        self,
        input_ids: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        image_features: torch.FloatTensor | None = None,
        audio_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_audio_mask = (
                inputs_embeds
                == self.get_input_embeddings()(
                    torch.tensor(self.config.audio_token_id, dtype=torch.long, device=inputs_embeds.device)
                )
            ).all(-1)
        else:
            special_image_mask = input_ids == self.config.image_token_id
            special_audio_mask = input_ids == self.config.audio_token_id

        n_image_tokens = special_image_mask.sum()
        special_image_mask = special_image_mask.unsqueeze(-1).expand_as(inputs_embeds).to(inputs_embeds.device)
        if image_features is not None:
            torch_compilable_check(
                inputs_embeds[special_image_mask].numel() == image_features.numel(),
                f"Image features and image tokens do not match, tokens: {n_image_tokens}, features: {image_features.shape[0] * image_features.shape[1]}",
            )

        n_audio_tokens = special_audio_mask.sum()
        special_audio_mask = special_audio_mask.unsqueeze(-1).expand_as(inputs_embeds).to(inputs_embeds.device)
        if audio_features is not None:
            torch_compilable_check(
                inputs_embeds[special_audio_mask].numel() == audio_features.numel(),
                f"Audio features and audio tokens do not match, tokens: {n_audio_tokens}, features: {audio_features.shape[0] * audio_features.shape[1]}",
            )

        return special_image_mask, special_audio_mask

    @can_return_tuple
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,  # text inputs
        pixel_values: torch.FloatTensor | None = None,  # vision inputs
        input_features: torch.FloatTensor | None = None,  # audio inputs
        attention_mask: torch.Tensor | None = None,
        input_features_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        token_type_ids: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        use_cache: bool | None = None,
        **lm_kwargs: Unpack[TransformersKwargs],
    ) -> Gemma3nModelOutputWithPast:
        r"""
        input_features_mask (`torch.Tensor` of shape `(batch_size, sequence_length)`, *optional*):
            Attention mask for `input_features` where non-zero values mark valid audio frames.
        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.text_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.text_config.vocab_size]`.

        Example:

        ```python
        >>> from PIL import Image
        >>> import httpx
        >>> from io import BytesIO
        >>> from transformers import AutoProcessor, Gemma3nForConditionalGeneration

        >>> model = Gemma3nForConditionalGeneration.from_pretrained("google/gemma3n2-3b-mix-224")
        >>> processor = AutoProcessor.from_pretrained("google/gemma3n2-3b-mix-224")

        >>> prompt = "Where is the cat standing?"
        >>> url = "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"
        >>> with httpx.stream("GET", url) as response:
        ...     image = Image.open(BytesIO(response.read()))

        >>> inputs = processor(images=image, text=prompt,  return_tensors="pt")

        >>> # Generate
        >>> generate_ids = model.generate(**inputs,)
        >>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        "Where is the cat standing?\nsnow"
        ```
        """
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if input_ids is not None:
            inputs_embeds = self.get_input_embeddings()(input_ids)

            # Prepare per-layer inputs from inputs_ids
            per_layer_inputs_mask = torch.logical_and(input_ids >= 0, input_ids < self.vocab_size_per_layer_input)
            per_layer_inputs_tokens = torch.where(per_layer_inputs_mask, input_ids, torch.zeros_like(input_ids))
            per_layer_inputs = self.language_model.get_per_layer_inputs(per_layer_inputs_tokens)

            # Handle vision tokens (>= embed_vision.vocab_offset and < embed_audio.vocab_offset)
            vision_mask = torch.logical_and(
                input_ids >= self.embed_vision.vocab_offset, input_ids < self.embed_audio.vocab_offset
            )
            dummy_vision_token_id = self.embed_vision.vocab_offset + self.embed_vision.vocab_size - 1
            vision_input_ids = torch.where(vision_mask, input_ids, dummy_vision_token_id).to(inputs_embeds.device)
            vision_embeds = self.embed_vision(input_ids=vision_input_ids)
            vision_embeds = vision_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            expanded_vision_mask = vision_mask.unsqueeze(-1).expand_as(inputs_embeds)
            inputs_embeds = torch.where(expanded_vision_mask, vision_embeds, inputs_embeds)

            # Handle audio tokens (>= embed_audio.vocab_offset)
            audio_mask = input_ids >= self.embed_audio.vocab_offset
            dummy_audio_token_id = self.embed_audio.vocab_offset + self.embed_audio.vocab_size - 1
            audio_input_ids = torch.where(audio_mask, input_ids, dummy_audio_token_id).to(inputs_embeds.device)
            audio_embeds = self.embed_audio(input_ids=audio_input_ids)
            audio_embeds = audio_embeds.to(inputs_embeds.device, inputs_embeds.dtype)
            expanded_audio_mask = audio_mask.unsqueeze(-1).expand_as(inputs_embeds)
            inputs_embeds = torch.where(expanded_audio_mask, audio_embeds, inputs_embeds)
        else:
            per_layer_inputs = None

        # Merge text and images
        if pixel_values is not None:
            image_features = self.get_image_features(pixel_values, return_dict=True).pooler_output
            image_features = image_features.to(inputs_embeds.device, inputs_embeds.dtype)
            special_image_mask, _ = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, image_features=image_features
            )
            inputs_embeds = inputs_embeds.masked_scatter(special_image_mask, image_features)

        # Merge text and audio
        if input_features is not None and input_features_mask is not None:
            audio_outputs = self.get_audio_features(input_features, ~input_features_mask, return_dict=True)
            audio_features = audio_outputs.pooler_output
            audio_mask = audio_outputs.audio_mel_mask

            # The Gemma3nProcessor expects all audio will be 30s in length and inserts 188 audio soft tokens into the
            # text to account for this. However, the audio preprocessing and encoder do not gurarantee they will
            # produce 188 soft tokens; they will produce at most that many tokens, but they may produce fewer tokens
            # depending on the length of the longest audio input in the batch. When we encounter this situation, we pad
            # the audio feature out to 188 soft tokens with the emebedding of the last token in the embed_audio vocab.
            audio_padding_toks = torch.tensor([[self.vocab_size - 1]], dtype=torch.long, device=audio_features.device)
            audio_padding_embs = self.embed_audio(input_ids=audio_padding_toks)
            audio_features = torch.where(audio_mask.unsqueeze(-1), audio_padding_embs, audio_features)

            audio_batch_size, audio_seq_len, audio_embed_dim = audio_features.shape
            extra_padding_tokens = self.config.audio_soft_tokens_per_image - audio_seq_len
            extra_padding_features = audio_padding_embs.expand(audio_batch_size, extra_padding_tokens, audio_embed_dim)

            audio_features = torch.cat((audio_features, extra_padding_features), dim=1)
            audio_features = audio_features.to(inputs_embeds.device, inputs_embeds.dtype)
            _, special_audio_mask = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, audio_features=audio_features
            )
            inputs_embeds = inputs_embeds.masked_scatter(special_audio_mask, audio_features)

        outputs = self.language_model(
            input_ids=None,
            per_layer_inputs=per_layer_inputs,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            return_dict=True,
            **lm_kwargs,
        )

        return Gemma3nModelOutputWithPast(
            last_hidden_state=outputs.last_hidden_state,
            past_key_values=outputs.past_key_values if use_cache else None,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            image_hidden_states=image_features if pixel_values is not None else None,
            audio_hidden_states=audio_features if input_features is not None else None,
        )

    @can_return_tuple
    @auto_docstring(custom_intro="Projects the last hidden state from the audio encoder into language model space.")
    def get_audio_features(
        self,
        input_features: torch.Tensor,
        input_features_mask: torch.Tensor,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | Gemma3nAudioEncoderModelOutput:
        r"""
        input_features (`torch.FloatTensor]` of shape `(num_images, seq_length, num_features)`):
            The tensors corresponding to the input audio.
        input_features_mask (`torch.FloatTensor]` of shape `(num_images, seq_length)`):
            The attention mask for the input audio.
        """
        audio_outputs: Gemma3nAudioEncoderModelOutput = self.audio_tower(
            input_features, input_features_mask, return_dict=True, **kwargs
        )
        audio_embeds = self.embed_audio(inputs_embeds=audio_outputs.last_hidden_state)
        audio_outputs.pooler_output = audio_embeds

        return audio_outputs


@auto_docstring(
    custom_intro="""
    The base Gemma 3n model comprising a vision backbone, an audio backbone, a language model, and a language modeling
    head.
    """
)
class Gemma3nForConditionalGeneration(PaliGemmaForConditionalGeneration):
    @can_return_tuple
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,  # text inputs
        pixel_values: torch.FloatTensor | None = None,  # vision inputs
        input_features: torch.FloatTensor | None = None,  # audio inputs
        attention_mask: torch.Tensor | None = None,
        input_features_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        token_type_ids: torch.LongTensor | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        use_cache: bool | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        **lm_kwargs: Unpack[TransformersKwargs],
    ) -> Gemma3nCausalLMOutputWithPast:
        r"""
        input_features_mask (torch.Tensor, *optional*, defaults to None):
            The attention mask for the input audio.
        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.text_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.text_config.vocab_size]`.

        Example:

        ```python
        >>> from PIL import Image
        >>> import httpx
        >>> from io import BytesIO
        >>> from transformers import AutoProcessor, Gemma3ForConditionalGeneration

        >>> model = Gemma3ForConditionalGeneration.from_pretrained("google/gemma-3-4b-it")
        >>> processor = AutoProcessor.from_pretrained("google/gemma-3-4b-it")

        >>> messages = [
        ...     {
        ...         "role": "system",
        ...         "content": [
        ...             {"type": "text", "text": "You are a helpful assistant."}
        ...         ]
        ...     },
        ...     {
        ...         "role": "user", "content": [
        ...             {"type": "image", "url": "https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/pipeline-cat-chonk.jpeg"},
        ...             {"type": "text", "text": "Where is the cat standing?"},
        ...         ]
        ...     },
        ... ]

        >>> inputs = processor.apply_chat_template(
        ...     messages,
        ...     tokenizer=True,
        ...     return_dict=True,
        ...     return_tensors="pt",
        ...     add_generation_prompt=True
        ... )
        >>> # Generate
        >>> generate_ids = model.generate(**inputs)
        >>> processor.batch_decode(generate_ids, skip_special_tokens=True, clean_up_tokenization_spaces=False)[0]
        "user\nYou are a helpful assistant.\n\n\n\n\n\nWhere is the cat standing?\nmodel\nBased on the image, the cat is standing in a snowy area, likely outdoors. It appears to"
        ```
        """
        outputs = self.model(
            input_ids=input_ids,
            pixel_values=pixel_values,
            input_features=input_features,
            attention_mask=attention_mask,
            input_features_mask=input_features_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            token_type_ids=token_type_ids,
            inputs_embeds=inputs_embeds,
            labels=labels,
            use_cache=use_cache,
            return_dict=True,
            **lm_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, :])
        if (final_logit_softcapping := self.config.get_text_config().final_logit_softcapping) is not None:
            logits = logits / final_logit_softcapping
            logits = torch.tanh(logits)
            logits = logits * final_logit_softcapping

        loss = None
        if labels is not None:
            # Upcast to float if we need to compute the loss to avoid potential precision issues
            logits = logits.float()
            shift_logits = logits[..., :-1, :]
            shift_labels = labels[..., 1:]
            if attention_mask is not None:
                # we use the input attention mask to shift the logits and labels, because it is 2D.
                # we also crop attn mask in case it is longer, which happens in PrefixTuning with peft
                shift_attention_mask = attention_mask[:, -shift_logits.shape[1] :].to(logits.device)
                shift_logits = shift_logits[shift_attention_mask.to(logits.device) != 0].contiguous()
                shift_labels = shift_labels[shift_attention_mask.to(shift_labels.device) != 0].contiguous()
            else:
                shift_logits = shift_logits.contiguous()
                shift_labels = shift_labels.contiguous()
            # Flatten the tokens
            loss_fct = nn.CrossEntropyLoss()

            flat_logits = shift_logits.view(-1, self.config.text_config.vocab_size)
            flat_labels = shift_labels.view(-1).to(shift_logits.device)
            loss = loss_fct(flat_logits, flat_labels)

        return Gemma3nCausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            image_hidden_states=outputs.image_hidden_states,
            audio_hidden_states=outputs.audio_hidden_states,
        )

    def prepare_inputs_for_generation(
        self,
        input_ids,
        past_key_values=None,
        inputs_embeds=None,
        position_ids=None,
        pixel_values=None,
        input_features=None,
        attention_mask=None,
        input_features_mask=None,
        token_type_ids=None,
        use_cache=True,
        logits_to_keep=None,
        labels=None,
        is_first_iteration=False,
        **kwargs,
    ):
        # Overwritten -- custom `position_ids` and `pixel_values` handling
        model_inputs = super().prepare_inputs_for_generation(
            input_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            attention_mask=attention_mask,
            position_ids=position_ids,
            use_cache=use_cache,
            logits_to_keep=logits_to_keep,
            token_type_ids=token_type_ids,
            is_first_iteration=is_first_iteration,
            **kwargs,
        )

        # If we're in cached decoding stage, multimodal inputs should be None because input ids do not contain special
        # tokens anymore. Otherwise multimodal inputs should be passed to model.
        # NOTE: use_cache=False always needs pixel_values, input_features, and input_features_mask
        if is_first_iteration or not use_cache:
            model_inputs["pixel_values"] = pixel_values
            model_inputs["input_features"] = input_features
            model_inputs["input_features_mask"] = input_features_mask

        return model_inputs

    def create_masks_for_generate(self, **super_kwargs):
        raise AttributeError("Do not inherit create_masks_for_generate from PaliGemma")


__all__ = [
    "Gemma3nAudioConfig",
    "Gemma3nAudioEncoder",
    "Gemma3nConfig",
    "Gemma3nForCausalLM",
    "Gemma3nForConditionalGeneration",
    "Gemma3nModel",
    "Gemma3nPreTrainedModel",
    "Gemma3nTextConfig",
    "Gemma3nTextModel",
    "Gemma3nVisionConfig",
]