Upload modeling_esm_plusplus.py with huggingface_hub

modeling_esm_plusplus.py

@@ -1,1159 +1,1197 @@
-"""
-ESM++ model implementation.
-
-ESM++ is a faithful implementation of ESMC that allows for batching and standard Huggingface compatibility
-The ESM Python package is not required
-
-Modified from https://github.com/evolutionaryscale/esm
-License: https://www.evolutionaryscale.ai/policies/cambrian-non-commercial-license-agreement
-"""
-
-import entrypoint_setup
-import math
-import os
-import warnings
-import torch
-import torch.nn as nn
-import torch.nn.functional as F
-from dataclasses import dataclass
-from functools import cache, partial
-from pathlib import Path
-from typing import Optional, Tuple, Union, List
-from einops import rearrange, repeat
-from huggingface_hub import snapshot_download
-from tokenizers import Tokenizer
-from tokenizers.models import BPE
-from tokenizers.processors import TemplateProcessing
-from torch.nn.attention.flex_attention import create_block_mask
-from torch.nn.attention.flex_attention import flex_attention
-from transformers import PreTrainedModel, PreTrainedTokenizerFast, PretrainedConfig
-from transformers.modeling_outputs import ModelOutput
-
-try:
-    # when used from AutoModel, these are in the same directory
-    from .embedding_mixin import EmbeddingMixin, Pooler
-except:
-    # when running from our repo, these are in the base directory
-    from embedding_mixin import EmbeddingMixin, Pooler
-
-
-def _create_pad_block_mask(attention_mask_2d: torch.Tensor):
-    token_valid = attention_mask_2d.bool()
-    batch_size, seq_len = token_valid.shape
-
-    def mask_mod(batch_idx, head_idx, q_idx, kv_idx):
-        return token_valid[batch_idx, q_idx] & token_valid[batch_idx, kv_idx]
-
-    return create_block_mask(
-        mask_mod,
-        batch_size,
-        1,
-        seq_len,
-        seq_len,
-        device=attention_mask_2d.device,
-    )
-
-
-class ESMplusplusConfig(PretrainedConfig):
-    """Configuration class for ESM++ model.
-    
-    Args:
-        vocab_size: Size of the vocabulary
-        hidden_size: Dimension of hidden layers
-        num_attention_heads: Number of attention heads
-        num_hidden_layers: Number of transformer layers
-        num_labels: Number of output labels for classification
-        problem_type: Type of problem - regression, single/multi label classification
-    """
-    model_type = "ESMplusplus"
-    def __init__(
-        self,
-        vocab_size: int = 64,
-        hidden_size: int = 960,
-        num_attention_heads: int = 15,
-        num_hidden_layers: int = 30,
-        num_labels: int = 2,
-        problem_type: str | None = None,
-        dropout: float = 0.0,
-        initializer_range: float = 0.02,
-        attn_backend: str = "sdpa",
-        **kwargs,
-    ):
-        super().__init__(**kwargs)
-        self.vocab_size = vocab_size
-        self.hidden_size = hidden_size
-        self.num_attention_heads = num_attention_heads
-        self.num_hidden_layers = num_hidden_layers
-        self.num_labels = num_labels
-        self.problem_type = problem_type
-        self.dropout = dropout
-        self.initializer_range = initializer_range
-        self.tie_word_embeddings = False
-        self.attn_backend = attn_backend
-
-
-### Rotary Embeddings
-def rotate_half(x: torch.Tensor, interleaved: bool = False) -> torch.Tensor:
-    """Rotates half the hidden dims of the input."""
-    if not interleaved:
-        x1, x2 = x.chunk(2, dim=-1)
-        return torch.cat((-x2, x1), dim=-1)
-    else:
-        x1, x2 = x[..., ::2], x[..., 1::2]
-        return rearrange(
-            torch.stack((-x2, x1), dim=-1), "... d two -> ... (d two)", two=2
-        )
-
-
-def apply_rotary_emb_torch(
-    x: torch.Tensor,
-    cos: torch.Tensor,
-    sin: torch.Tensor,
-    interleaved: bool = False,
-    _inplace: bool = False,
-) -> torch.Tensor:
-    """Apply rotary embeddings to input based on cos and sin."""
-    ro_dim = cos.shape[-1] * 2
-    assert ro_dim <= x.shape[-1]
-    seqlen = x.size(1)
-    cos = cos[:seqlen]
-    sin = sin[:seqlen]
-    cos = repeat(cos, "s d -> s 1 (2 d)")
-    sin = repeat(sin, "s d -> s 1 (2 d)")
-    return torch.cat(
-        [
-            x[..., :ro_dim] * cos + rotate_half(x[..., :ro_dim], interleaved) * sin,
-            x[..., ro_dim:],
-        ],
-        dim=-1,
-    )
-
-
-class RotaryEmbedding(torch.nn.Module):
-    """Rotary position embeddings.
-    
-    Based on the paper "RoFormer: Enhanced Transformer with Rotary Position Embedding"
-    
-    Args:
-        dim: Dimension of the embedding
-        base: Base for computing angular frequencies
-        interleaved: Whether to use interleaved rotations
-        scale_base: Base for scaling
-        scaling_factor: Factor for scaling positions
-        pos_idx_in_fp32: Whether to compute position indices in fp32
-        device: Computation device
-    """
-    def __init__(
-        self,
-        dim: int,
-        base: float = 10000.0,
-        interleaved: bool = False,
-        scale_base: Optional[float] = None,
-        scaling_factor: float = 1.0,
-        pos_idx_in_fp32: bool = True,
-        device: Optional[torch.device] = None,
-    ):
-        super().__init__()
-        self.dim = dim
-        self.base = float(base)
-        self.pos_idx_in_fp32 = pos_idx_in_fp32
-        self.interleaved = interleaved
-        self.scale_base = scale_base
-        self.scaling_factor = scaling_factor
-        self.device = device
-
-        self._seq_len_cached = 0
-        self._cos_cached = None
-        self._sin_cached = None
-        self._cos_k_cached = None
-        self._sin_k_cached = None
-        self.reset_parameters()
-
-    def reset_parameters(self):
-        """Reset the parameters of the embedding."""
-        inv_freq = self._compute_inv_freq(self.device)
-        self.register_buffer("inv_freq", inv_freq, persistent=False)
-        arange = torch.arange(0, self.dim, 2, device=self.device, dtype=torch.float32)
-        scale = (
-            (arange + 0.4 * self.dim) / (1.4 * self.dim)
-            if self.scale_base is not None
-            else None
-        )
-        self.register_buffer("scale", scale)
-
-    def _compute_inv_freq(self, device: Optional[torch.device] = None) -> torch.Tensor:
-        """Compute inverse frequency bands."""
-        return 1 / (
-            self.base
-            ** (
-                torch.arange(0, self.dim, 2, device=device, dtype=torch.float32)
-                / self.dim
-            )
-        )
-
-    def _update_cos_sin_cache(self, seqlen: int, device: Optional[torch.device] = None, dtype: Optional[torch.dtype] = None):
-        """Update the cached cosine and sine values."""
-        if (
-            seqlen > self._seq_len_cached
-            or self._cos_cached is None
-            or self._cos_cached.device != device
-            or self._cos_cached.dtype != dtype
-            or (self.training and self._cos_cached.is_inference())
-        ):
-            self._seq_len_cached = seqlen
-            if self.pos_idx_in_fp32:
-                t = torch.arange(seqlen, device=device, dtype=torch.float32)
-                t /= self.scaling_factor
-                if self.inv_freq.dtype != torch.float32:
-                    inv_freq = self.inv_freq.to(torch.float32)
-                else:
-                    inv_freq = self.inv_freq
-            else:
-                t = torch.arange(seqlen, device=device, dtype=self.inv_freq.dtype)
-                t /= self.scaling_factor
-                inv_freq = self.inv_freq
-            freqs = torch.outer(t, inv_freq)
-
-            if self.scale is None:
-                self._cos_cached = torch.cos(freqs).to(dtype)
-                self._sin_cached = torch.sin(freqs).to(dtype)
-            else:
-                power = (
-                    torch.arange(
-                        seqlen, dtype=self.scale.dtype, device=self.scale.device
-                    )
-                    - seqlen // 2
-                ) / self.scale_base
-                scale = self.scale.to(device=power.device) ** power.unsqueeze(-1)
-                self._cos_cached = (torch.cos(freqs) * scale).to(dtype)
-                self._sin_cached = (torch.sin(freqs) * scale).to(dtype)
-                self._cos_k_cached = (torch.cos(freqs) / scale).to(dtype)
-                self._sin_k_cached = (torch.sin(freqs) / scale).to(dtype)
-
-    def forward(self, q: torch.Tensor, k: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
-        """Apply rotary embeddings to queries and keys.
-        
-        Args:
-            q: Query tensor of shape (batch, seqlen, nheads, headdim)
-            k: Key tensor of shape (batch, seqlen, nheads, headdim)
-            
-        Returns:
-            Tuple of rotated query and key tensors
-        """
-        self._update_cos_sin_cache(q.shape[1], device=q.device, dtype=q.dtype)
-        assert self._cos_cached is not None
-        assert self._sin_cached is not None
-        if self.scale is None:
-            return (
-                apply_rotary_emb_torch(
-                    q,
-                    self._cos_cached,
-                    self._sin_cached,
-                    self.interleaved,
-                    True,  # inplace=True
-                ),
-                apply_rotary_emb_torch(
-                    k,
-                    self._cos_cached,
-                    self._sin_cached,
-                    self.interleaved,
-                    True,  # inplace=True
-                ),
-            )  # type: ignore
-        else:
-            assert False
-
-
-### Feedforward Network Components
-def swiglu_correction_fn(expansion_ratio: float, d_model: int) -> int:
-    """Compute corrected dimension for SwiGLU."""
-    return int(((expansion_ratio * d_model) + 255) // 256 * 256)
-
-
-class SwiGLU(nn.Module):
-    """SwiGLU activation function."""
-    def __init__(self):
-        super(SwiGLU, self).__init__()
-
-    def forward(self, x: torch.Tensor) -> torch.Tensor:
-        x1, x2 = x.chunk(2, dim=-1)
-        return F.silu(x1) * x2
-
-
-def swiglu_ln_ffn(d_model: int, expansion_ratio: float) -> nn.Sequential:
-    """Create SwiGLU feedforward network with layer normalization."""
-    return nn.Sequential(
-        nn.LayerNorm(d_model),
-        nn.Linear(
-            d_model, swiglu_correction_fn(expansion_ratio, d_model) * 2, bias=False
-        ),
-        SwiGLU(),
-        nn.Linear(swiglu_correction_fn(expansion_ratio, d_model), d_model, bias=False),
-    )
-
-
-### Attention
-class MultiHeadAttention(nn.Module):
-    """Multi-head attention with rotary embeddings.
-    
-    Args:
-        d_model: Model dimension
-        n_heads: Number of attention heads
-    """
-    def __init__(
-        self,
-        d_model: int,
-        n_heads: int,
-        attn_backend: str = "sdpa",
-    ):
-        super().__init__()
-        self.d_model = d_model
-        self.n_heads = n_heads
-        self.d_head = self.d_model // self.n_heads
-        self.attn_backend = attn_backend
-        self._warned_flex_fallback = False
-        self.layernorm_qkv = nn.Sequential(
-            nn.LayerNorm(d_model), nn.Linear(d_model, d_model * 3, bias=False)
-        )
-        self.out_proj = nn.Linear(d_model, d_model, bias=False)
-        self.q_ln = nn.LayerNorm(d_model, bias=False)
-        self.k_ln = nn.LayerNorm(d_model, bias=False)
-        self.reshaper = partial(rearrange, pattern="b s (h d) -> b h s d", h=n_heads)
-        self.rotary = RotaryEmbedding(d_model // n_heads)
-
-    def _apply_rotary(self, q: torch.Tensor, k: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
-        """Apply rotary embeddings to query and key."""
-        q = q.unflatten(-1, (self.n_heads, self.d_head))
-        k = k.unflatten(-1, (self.n_heads, self.d_head))
-        q, k = self.rotary(q, k)
-        q = q.flatten(-2, -1)
-        k = k.flatten(-2, -1)
-        return q, k
-
-    def forward(
-        self,
-        x: torch.Tensor,
-        attention_mask: Optional[torch.Tensor] = None,
-        flex_block_mask: Optional[object] = None,
-        output_attentions: bool = False,
-    ) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
-        """
-        Args:
-            x: Input tensor
-            attention_mask: Optional attention mask
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            Output tensor after self attention, and optionally attention weights
-        """
-        attn_weights = None
-        qkv_BLD3 = self.layernorm_qkv(x)
-        query_BLD, key_BLD, value_BLD = torch.chunk(qkv_BLD3, 3, dim=-1)
-        query_BLD, key_BLD = (
-            self.q_ln(query_BLD).to(query_BLD.dtype),
-            self.k_ln(key_BLD).to(query_BLD.dtype),
-        )
-        query_BLD, key_BLD = self._apply_rotary(query_BLD, key_BLD)
-        query_BHLD, key_BHLD, value_BHLD = map(self.reshaper, (query_BLD, key_BLD, value_BLD))
-        scale = 1 / math.sqrt(self.d_head)
-
-        if output_attentions: # Manual attention computation
-            b, h, l, _ = query_BHLD.shape
-            attn_bias = torch.zeros(b, h, l, l, dtype=query_BLD.dtype, device=query_BLD.device)
-            if attention_mask is not None:
-                attn_bias.masked_fill_(attention_mask.logical_not(), float('-inf'))
-            attn_weights = torch.matmul(query_BHLD, key_BHLD.transpose(-2, -1)) * scale
-            attn_weights += attn_bias
-            attn_weights = F.softmax(attn_weights, dim=-1)
-            context_BHLD = torch.matmul(attn_weights, value_BHLD)
-        else:
-            sdpa_mask = None
-            if attention_mask is not None:
-                sdpa_mask = torch.zeros_like(attention_mask, dtype=query_BHLD.dtype)
-                sdpa_mask.masked_fill_(attention_mask.logical_not(), float("-inf"))
-            use_flex = (
-                self.attn_backend == "flex"
-                and (attention_mask is None or flex_block_mask is not None)
-            )
-            if use_flex:
-                try:
-                    context_BHLD = flex_attention(
-                        query_BHLD,
-                        key_BHLD,
-                        value_BHLD,
-                        block_mask=flex_block_mask,
-                        scale=scale,
-                    )
-                except Exception as exc:
-                    if not self._warned_flex_fallback:
-                        warnings.warn(
-                            f"Flex attention failed in ESM++ attention; falling back to SDPA. Error: {exc}",
-                            RuntimeWarning,
-                        )
-                        self._warned_flex_fallback = True
-                    context_BHLD = F.scaled_dot_product_attention(
-                        query_BHLD,
-                        key_BHLD,
-                        value_BHLD,
-                        attn_mask=sdpa_mask,
-                        scale=scale,
-                    )
-            else:
-                context_BHLD = F.scaled_dot_product_attention(
-                    query_BHLD,
-                    key_BHLD,
-                    value_BHLD,
-                    attn_mask=sdpa_mask,
-                    scale=scale,
-                )
-            
-        context_BLD = rearrange(context_BHLD, "b h s d -> b s (h d)")
-        output = self.out_proj(context_BLD)
-        return output, attn_weights
-
-
-### Regression Head
-def RegressionHead(d_model: int, output_dim: int, hidden_dim: Optional[int] = None) -> nn.Module:
-    """Create a regression head with optional hidden dimension.
-    
-    Args:
-        d_model: Input dimension
-        output_dim: Output dimension
-        hidden_dim: Optional hidden dimension (defaults to d_model)
-    """
-    hidden_dim = hidden_dim if hidden_dim is not None else d_model
-    return nn.Sequential(
-        nn.Linear(d_model, hidden_dim),
-        nn.GELU(),
-        nn.LayerNorm(hidden_dim),
-        nn.Linear(hidden_dim, output_dim),
-    )
-
-
-### Transformer Block
-class UnifiedTransformerBlock(nn.Module):
-    """Transformer block with attention and feedforward layers.
-    
-    Args:
-        d_model: Model dimension
-        n_heads: Number of attention heads
-        residue_scaling_factor: Factor for scaling residual connections
-        expansion_ratio: Expansion ratio for feedforward network
-    """
-    def __init__(
-        self,
-        d_model: int,
-        n_heads: int,
-        residue_scaling_factor: float = 1,
-        expansion_ratio: float = 8 / 3,
-        dropout: float = 0.0,
-        attn_backend: str = "sdpa",
-    ):
-        super().__init__()
-        self.attn = MultiHeadAttention(
-            d_model=d_model,
-            n_heads=n_heads,
-            attn_backend=attn_backend,
-        )
-        self.ffn = swiglu_ln_ffn(d_model, expansion_ratio)
-        self.scaling_factor = residue_scaling_factor
-        self.dropout = nn.Dropout(dropout)
-
-    def forward(
-        self,
-        x: torch.Tensor,
-        attention_mask: Optional[torch.Tensor] = None,
-        flex_block_mask: Optional[object] = None,
-        output_attentions: bool = False,
-    ) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
-        """
-        Args:
-            x: Input tensor
-            attention_mask: Optional attention mask
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            Output tensor after transformer block, and optionally attention weights
-        """
-        attn_output, attn_weights = self.attn(
-            x,
-            attention_mask,
-            flex_block_mask,
-            output_attentions,
-        )
-        x = x + self.dropout(attn_output) / self.scaling_factor
-        x = x + self.dropout(self.ffn(x)) / self.scaling_factor
-        return x, attn_weights
-
-
-### Model Outputs
-@dataclass
-class TransformerOutput(ModelOutput):
-    """Output type for transformer encoder."""
-    last_hidden_state: Optional[torch.Tensor] = None
-    hidden_states: Optional[Tuple[torch.Tensor]] = None
-    attentions: Optional[Tuple[torch.Tensor]] = None
-
-
-@dataclass
-class ESMplusplusOutput(ModelOutput):
-    """Output type for ESM++ models."""
-    loss: Optional[torch.Tensor] = None
-    logits: Optional[torch.Tensor] = None
-    last_hidden_state: Optional[torch.Tensor] = None
-    hidden_states: Optional[Tuple[torch.Tensor]] = None
-    attentions: Optional[Tuple[torch.Tensor]] = None
-
-
-### Transformer Stack
-class TransformerStack(nn.Module):
-    """Stack of transformer blocks.
-    
-    Args:
-        d_model: Model dimension
-        n_heads: Number of attention heads
-        n_layers: Number of transformer layers
-        dropout: Dropout rate
-    """
-    def __init__(
-        self,
-        d_model: int,
-        n_heads: int,
-        n_layers: int,
-        dropout: float = 0.0,
-        attn_backend: str = "sdpa",
-    ):
-        super().__init__()
-        self.attn_backend = attn_backend
-        self.blocks = nn.ModuleList(
-            [
-                UnifiedTransformerBlock(
-                    d_model,
-                    n_heads,
-                    residue_scaling_factor=math.sqrt(n_layers / 36),
-                    dropout=dropout,
-                    attn_backend=attn_backend,
-                )
-                for i in range(n_layers)
-            ]
-        )
-        self.norm = nn.LayerNorm(d_model, bias=False)
-        self.gradient_checkpointing = False
-
-    def forward(
-        self,
-        x: torch.Tensor,
-        attention_mask: Optional[torch.Tensor] = None,
-        output_hidden_states: bool = False,
-        output_attentions: bool = False,
-    ) -> TransformerOutput:
-        """
-        Args:
-            x: Input tensor
-            attention_mask: Optional attention mask
-            output_hidden_states: Whether to return all hidden states
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            TransformerOutput containing last hidden state and optionally all hidden states and attention weights
-        """
-        batch_size, seq_len, _ = x.shape
-        hidden_states = () if output_hidden_states else None
-        attentions = () if output_attentions else None
-        
-        if attention_mask is not None:
-            attention_mask = attention_mask[:, None, None, :].expand(batch_size, 1, seq_len, seq_len).bool()
-            if self.attn_backend == "flex" and not output_attentions:
-                token_attention_mask = attention_mask[:, 0, 0, :]
-                flex_block_mask = _create_pad_block_mask(token_attention_mask)
-            else:
-                flex_block_mask = None
-        else:
-            flex_block_mask = None
-            
-        for block in self.blocks:
-            if self.gradient_checkpointing and self.training:
-                x, attn_weights = self._gradient_checkpointing_func(
-                    block.__call__,
-                    x,
-                    attention_mask,
-                    flex_block_mask,
-                    output_attentions,
-                )
-            else:
-                x, attn_weights = block(x, attention_mask, flex_block_mask, output_attentions)
-
-            if attentions is not None:
-                attentions += (attn_weights,)
-                
-            if output_hidden_states:
-                assert hidden_states is not None
-                hidden_states += (x,)
-                
-        return TransformerOutput(
-            last_hidden_state=self.norm(x), 
-            hidden_states=hidden_states,
-            attentions=attentions
-        )
-
-
-class PreTrainedESMplusplusModel(PreTrainedModel):
-    """
-    init weights for ESM++ models
-    """
-    config_class = ESMplusplusConfig
-    base_model_prefix = "esm++"
-    supports_gradient_checkpointing = True
-    all_tied_weights_keys = {}
-
-    def _init_weights(self, module):
-        """Initialize the weights"""
-        if isinstance(module, nn.Linear):
-            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
-            if module.bias is not None:
-                module.bias.data.zero_()
-        elif isinstance(module, nn.Embedding):
-            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
-            if module.padding_idx is not None:
-                module.weight.data[module.padding_idx].zero_()
-        elif isinstance(module, nn.LayerNorm):
-            if module.bias is not None:
-                module.bias.data.zero_()
-            module.weight.data.fill_(1.0)
-
-    @classmethod
-    def from_pretrained_esm(cls, model_name: str):
-        """Load a pretrained ESM++ model."""
-        if '300' in model_name:
-            return ESMplusplus_300M()
-        elif '600' in model_name:
-            return ESMplusplus_600M()
-        else:
-            raise ValueError(f"Invalid model name: {model_name}")
-
-
-### ESM++ Models
-class ESMplusplusModel(PreTrainedESMplusplusModel, EmbeddingMixin):
-    """
-    ESM++ model. transformer model with no heads
-    """
-    config_class = ESMplusplusConfig
-    def __init__(self, config: ESMplusplusConfig, **kwargs):
-        PreTrainedESMplusplusModel.__init__(self, config, **kwargs)
-        self.config = config
-        self.vocab_size = config.vocab_size
-        self.embed = nn.Embedding(self.vocab_size, config.hidden_size)
-        self.transformer = TransformerStack(
-            d_model=config.hidden_size,
-            n_heads=config.num_attention_heads,
-            n_layers=config.num_hidden_layers,
-            dropout=config.dropout,
-            attn_backend=config.attn_backend,
-        )
-        self.tokenizer = EsmSequenceTokenizer()
-        self.init_weights()
-
-    def get_input_embeddings(self):
-        return self.embed
-
-    def set_input_embeddings(self, value):
-        self.embed = value
-
-    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
-        x = self.embed(input_ids)
-        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
-
-    def forward(
-        self,
-        input_ids: Optional[torch.Tensor] = None,
-        attention_mask: Optional[torch.Tensor] = None,
-        inputs_embeds: Optional[torch.Tensor] = None,
-        output_attentions: Optional[bool] = None,
-        output_hidden_states: Optional[bool] = None,
-        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
-        **kwargs,
-    ) -> TransformerOutput:
-        """Forward pass for masked language modeling.
-        
-        Args:
-            input_ids: Input token IDs
-            attention_mask: Attention mask
-            inputs_embeds: Optional precomputed embeddings
-            output_hidden_states: Whether to return all hidden states
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            TransformerOutput containing last hidden state and optionally all hidden states and attention weights
-        """
-        if inputs_embeds is None:
-            x = self.embed(input_ids)
-        else:
-            x = inputs_embeds
-        return self.transformer(x, attention_mask, output_hidden_states, output_attentions)
-        
-
-class ESMplusplusForMaskedLM(PreTrainedESMplusplusModel, EmbeddingMixin):
-    """
-    ESM++ model for masked language modeling.
-    Implements the base ESM++ architecture with a masked language modeling head.
-    """
-    config_class = ESMplusplusConfig
-    def __init__(self, config: ESMplusplusConfig, **kwargs):
-        PreTrainedESMplusplusModel.__init__(self, config, **kwargs)
-        self.config = config
-        self.vocab_size = config.vocab_size
-        self.embed = nn.Embedding(self.vocab_size, config.hidden_size)
-        self.transformer = TransformerStack(
-            d_model=config.hidden_size,
-            n_heads=config.num_attention_heads,
-            n_layers=config.num_hidden_layers,
-            dropout=config.dropout,
-            attn_backend=config.attn_backend,
-        )
-        self.sequence_head = RegressionHead(config.hidden_size, self.vocab_size)
-        self.ce_loss = nn.CrossEntropyLoss()
-        self.tokenizer = EsmSequenceTokenizer()
-        self.init_weights()
-
-    def get_input_embeddings(self):
-        return self.embed
-
-    def set_input_embeddings(self, value):
-        self.embed = value
-
-    def get_output_embeddings(self):
-        return self.sequence_head[-1]
-
-    def set_output_embeddings(self, new_embeddings):
-        self.sequence_head[-1] = new_embeddings
-
-    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
-        x = self.embed(input_ids)
-        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
-
-    def forward(
-        self,
-        input_ids: Optional[torch.Tensor] = None,
-        attention_mask: Optional[torch.Tensor] = None,
-        inputs_embeds: Optional[torch.Tensor] = None,
-        labels: Optional[torch.Tensor] = None,
-        output_attentions: Optional[bool] = None,
-        output_hidden_states: Optional[bool] = None,
-        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
-        **kwargs,
-    ) -> ESMplusplusOutput:
-        """Forward pass for masked language modeling.
-        
-        Args:
-            input_ids: Input token IDs
-            attention_mask: Attention mask
-            inputs_embeds: Optional precomputed embeddings
-            labels: Optional labels for masked tokens
-            output_hidden_states: Whether to return all hidden states
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            ESMplusplusOutput containing loss, logits, hidden states and attention weights
-        """
-        if inputs_embeds is None:
-            x = self.embed(input_ids)
-        else:
-            x = inputs_embeds
-        output = self.transformer(x, attention_mask, output_hidden_states, output_attentions)
-        x = output.last_hidden_state
-        logits = self.sequence_head(x)
-        loss = None
-        if labels is not None:
-            loss = self.ce_loss(logits.view(-1, self.vocab_size), labels.view(-1))
-        return ESMplusplusOutput(
-            loss=loss,
-            logits=logits,
-            last_hidden_state=x,
-            hidden_states=output.hidden_states,
-            attentions=output.attentions,
-        )
-
-
-class ESMplusplusForSequenceClassification(ESMplusplusForMaskedLM, EmbeddingMixin):
-    """
-    ESM++ model for sequence classification.
-    Extends the base ESM++ model with a classification head.
-    """
-    def __init__(self, config: ESMplusplusConfig, **kwargs):
-        ESMplusplusForMaskedLM.__init__(self, config, **kwargs)
-        self.config = config
-        self.num_labels = config.num_labels
-        self.classifier = RegressionHead(config.hidden_size * 2, config.num_labels, config.hidden_size * 4)
-        # Large intermediate projections help with sequence classification tasks (*4)
-        self.mse = nn.MSELoss()
-        self.ce = nn.CrossEntropyLoss()
-        self.bce = nn.BCEWithLogitsLoss()
-        # if kwargs has pooling_types, use them, otherwise use ['cls', 'mean']
-        if 'pooling_types' in kwargs and isinstance(kwargs['pooling_types'], List[str]) and len(kwargs['pooling_types']) > 0:
-            pooling_types = kwargs['pooling_types']
-        else:
-            pooling_types = ['cls', 'mean']
-        self.pooler = Pooler(pooling_types)
-        self.init_weights()
-
-    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
-        x = self.embed(input_ids)
-        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
-
-    def forward(
-        self,
-        input_ids: Optional[torch.Tensor] = None,
-        attention_mask: Optional[torch.Tensor] = None,
-        inputs_embeds: Optional[torch.Tensor] = None,
-        labels: Optional[torch.Tensor] = None,
-        output_attentions: Optional[bool] = None,
-        output_hidden_states: Optional[bool] = None,
-        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
-        **kwargs,
-    ) -> ESMplusplusOutput:
-        """Forward pass for sequence classification.
-        
-        Args:
-            input_ids: Input token IDs
-            attention_mask: Attention mask
-            inputs_embeds: Optional precomputed embeddings
-            labels: Optional labels for classification
-            output_hidden_states: Whether to return all hidden states
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            ESMplusplusOutput containing loss, logits, and hidden states
-        """
-        output = super().forward(
-            input_ids=input_ids,
-            attention_mask=attention_mask,
-            inputs_embeds=inputs_embeds,
-            labels=None,
-            output_attentions=output_attentions,
-            output_hidden_states=output_hidden_states
-        )
-        x = output.last_hidden_state
-        features = self.pooler(x, attention_mask)
-        logits = self.classifier(features)
-        loss = None
-        if labels is not None:
-            labels = labels.to(logits.device)
-            if self.config.problem_type is None:
-                if self.num_labels == 1:
-                    self.config.problem_type = "regression"
-                elif self.num_labels > 1 and (labels.dtype == torch.long or labels.dtype == torch.int):
-                    self.config.problem_type = "single_label_classification"
-                else:
-                    self.config.problem_type = "multi_label_classification"
-
-            if self.config.problem_type == "regression":
-                if self.num_labels == 1:
-                    loss = self.mse(logits.flatten(), labels.flatten())
-                else:
-                    loss = self.mse(logits, labels)
-            elif self.config.problem_type == "single_label_classification":
-                loss = self.ce(logits.view(-1, self.num_labels), labels.view(-1))
-            elif self.config.problem_type == "multi_label_classification":
-                loss = self.bce(logits, labels)
-
-        return ESMplusplusOutput(
-            loss=loss,
-            logits=logits,
-            last_hidden_state=x,
-            hidden_states=output.hidden_states,
-            attentions=output.attentions,
-        )
-
-
-class ESMplusplusForTokenClassification(ESMplusplusForMaskedLM, EmbeddingMixin):
-    """
-    ESM++ model for token classification.
-    Extends the base ESM++ model with a token classification head.
-    """
-    def __init__(self, config: ESMplusplusConfig, **kwargs):
-        ESMplusplusForMaskedLM.__init__(self, config, **kwargs)
-        self.config = config
-        self.num_labels = config.num_labels
-        self.classifier = RegressionHead(config.hidden_size, config.num_labels, config.hidden_size * 4)
-        # Large intermediate projections help with sequence classification tasks (*4)
-        self.loss_fct = nn.CrossEntropyLoss()
-        self.init_weights()
-
-    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
-        x = self.embed(input_ids)
-        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
-
-    def forward(
-        self,
-        input_ids: Optional[torch.Tensor] = None,
-        attention_mask: Optional[torch.Tensor] = None,
-        inputs_embeds: Optional[torch.Tensor] = None,
-        labels: Optional[torch.Tensor] = None,
-        output_attentions: Optional[bool] = None,
-        output_hidden_states: Optional[bool] = None,
-        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
-        **kwargs,
-    ) -> ESMplusplusOutput:
-        """Forward pass for token classification.
-        
-        Args:
-            input_ids: Input token IDs
-            attention_mask: Attention mask
-            inputs_embeds: Optional precomputed embeddings
-            labels: Optional labels for token classification
-            output_hidden_states: Whether to return all hidden states
-            output_attentions: Whether to return attention weights
-            
-        Returns:
-            ESMplusplusOutput containing loss, logits, and hidden states
-        """
-        output = super().forward(
-            input_ids=input_ids,
-            attention_mask=attention_mask,
-            inputs_embeds=inputs_embeds,
-            labels=None,
-            output_attentions=output_attentions,
-            output_hidden_states=output_hidden_states
-        )
-        x = output.last_hidden_state
-        logits = self.classifier(x)
-        loss = None
-        if labels is not None:
-            loss = self.loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
-        return ESMplusplusOutput(
-            loss=loss,
-            logits=logits,
-            last_hidden_state=x,
-            hidden_states=output.hidden_states,
-            attentions=output.attentions,
-        )
-
-
-### Loading from EvolutionaryScale
-@staticmethod
-@cache
-def data_root(model: str):
-    if "INFRA_PROVIDER" in os.environ:
-        return Path("")
-    # Try to download from hugginface if it doesn't exist
-    if model.startswith("esmc-300"):
-        path = Path(snapshot_download(repo_id="EvolutionaryScale/esmc-300m-2024-12"))
-    elif model.startswith("esmc-600"):
-        path = Path(snapshot_download(repo_id="EvolutionaryScale/esmc-600m-2024-12"))
-    else:
-        raise ValueError(f"{model=} is an invalid model name.")
-    return path
-
-
-def ESMplusplus_300M(device: torch.device | str = "cpu"):
-    with torch.device(device):
-        config = ESMplusplusConfig(
-            hidden_size=960,
-            num_attention_heads=15,
-            num_hidden_layers=30,
-        )
-        model = ESMplusplusForMaskedLM(config)
-    state_dict = torch.load(
-        data_root("esmc-300") / "data/weights/esmc_300m_2024_12_v0.pth",
-        map_location=device,
-    )
-    model.load_state_dict(state_dict)
-    return model
-
-
-def ESMplusplus_600M(device: torch.device | str = "cpu"):
-    with torch.device(device):
-        config = ESMplusplusConfig(
-            hidden_size=1152,
-            num_attention_heads=18,
-            num_hidden_layers=36,
-        )
-        model = ESMplusplusForMaskedLM(config)
-    state_dict = torch.load(
-        data_root("esmc-600") / "data/weights/esmc_600m_2024_12_v0.pth",
-        map_location=device,
-    )
-    model.load_state_dict(state_dict)
-    return model
-
-
-### Tokenization
-SEQUENCE_VOCAB = [
-    "<cls>", "<pad>", "<eos>", "<unk>",
-    "L", "A", "G", "V", "S", "E", "R", "T", "I", "D", "P", "K",
-    "Q", "N", "F", "Y", "M", "H", "W", "C", "X", "B", "U", "Z",
-    "O", ".", "-", "|",
-    "<mask>",
-]
-
-class EsmSequenceTokenizer(PreTrainedTokenizerFast):
-    model_input_names = ["input_ids", "attention_mask"]
-
-    def __init__(
-        self,
-        unk_token="<unk>",
-        cls_token="<cls>",
-        pad_token="<pad>",
-        mask_token="<mask>",
-        eos_token="<eos>",
-        chain_break_token="|",
-        **kwargs,
-    ):
-        all_tokens = SEQUENCE_VOCAB
-        token_to_id = {tok: ind for ind, tok in enumerate(all_tokens)}
-
-        # a character-level tokenizer is the same as BPE with no token merges
-        bpe = BPE(token_to_id, merges=[], unk_token=unk_token)
-        tokenizer = Tokenizer(bpe)
-        special_tokens = [
-            cls_token,
-            pad_token,
-            mask_token,
-            eos_token,
-            chain_break_token,
-        ]
-        self.cb_token = chain_break_token
-        additional_special_tokens = [chain_break_token]
-
-        tokenizer.add_special_tokens(special_tokens)
-
-        # This is where we configure the automatic addition of special tokens when we call
-        # tokenizer(text, add_special_tokens=True). Note that you can also configure how two
-        # sequences are merged if you want.
-        tokenizer.post_processor = TemplateProcessing(  # type: ignore
-            single="<cls> $A <eos>",
-            pair="<cls>:0 $A:0 <eos>:0 $B:1 <eos>:1",
-            special_tokens=[
-                ("<cls>", tokenizer.token_to_id("<cls>")),
-                ("<eos>", tokenizer.token_to_id("<eos>")),
-            ],
-        )
-        super().__init__(
-            tokenizer_object=tokenizer,
-            unk_token=unk_token,
-            cls_token=cls_token,
-            pad_token=pad_token,
-            mask_token=mask_token,
-            eos_token=eos_token,
-            additional_special_tokens=additional_special_tokens,
-            **kwargs,
-        )
-
-    # These are a footgun, we never use the `bos` token anywhere so we're just overriding it here.
-    @property
-    def bos_token(self):
-        return self.cls_token
-
-    @property
-    def bos_token_id(self):
-        return self.cls_token_id
-
-    @property
-    def chain_break_token(self):
-        return self.cb_token
-
-    @property
-    def chain_break_token_id(self):
-        return self.convert_tokens_to_ids(self.chain_break_token)
-
-    @property
-    def all_token_ids(self):
-        return list(range(self.vocab_size))
-
-    @property
-    def special_token_ids(self):
-        return self.all_special_ids
-
-
-if __name__ == "__main__":    
-    # Set device to CPU for testing
-    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
-    print(f"Using device: {device}")
-    
-    # Test tokenizer
-    tokenizer = EsmSequenceTokenizer()
-    sample_sequence = "MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYNIQKESTLHLVLRLRGG"
-    encoding = tokenizer(sample_sequence, return_tensors="pt")
-    print(f"Input sequence length: {len(sample_sequence)}")
-    print(f"Tokenized sequence: {encoding['input_ids'].shape}")
-    
-    # Prepare inputs
-    input_ids = encoding['input_ids'].to(device)
-    attention_mask = encoding['attention_mask'].to(device)
-    
-    # Test base model with smaller config for quick testing
-    print("\n=== Testing ESMplusplus Base Model ===")
-    base_config = ESMplusplusConfig(
-        hidden_size=384,
-        num_attention_heads=6,
-        num_hidden_layers=4
-    )
-    base_model = ESMplusplusModel(base_config).to(device)
-    
-    with torch.no_grad():
-        outputs = base_model(input_ids=input_ids, attention_mask=attention_mask)
-    
-    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
-    
-    # Test embedding functionality
-    print("\nTesting embedding functionality:")
-    with torch.no_grad():
-        embeddings = base_model._embed(input_ids, attention_mask)
-    print(f"Embedding shape: {embeddings.shape}")
-    
-    # Test masked language modeling
-    print("\n=== Testing ESMplusplus For Masked LM ===")
-    mlm_model = ESMplusplusForMaskedLM(base_config).to(device)
-    
-    with torch.no_grad():
-        outputs = mlm_model(input_ids=input_ids, attention_mask=attention_mask)
-    
-    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
-    print(f"Logits shape: {outputs.logits.shape}")
-    
-    # Test sequence classification model
-    print("\n=== Testing Sequence Classification Model ===")
-    classification_model = ESMplusplusForSequenceClassification(base_config).to(device)
-    
-    with torch.no_grad():
-        outputs = classification_model(input_ids=input_ids, attention_mask=attention_mask)
-    
-    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
-    print(f"Logits shape: {outputs.logits.shape}")
-    
-    # Test token classification model
-    print("\n=== Testing Token Classification Model ===")
-    token_model = ESMplusplusForTokenClassification(base_config).to(device)
-    
-    with torch.no_grad():
-        outputs = token_model(input_ids=input_ids, attention_mask=attention_mask)
-    
-    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
-    print(f"Logits shape: {outputs.logits.shape}")
-    
-    # Test embedding dataset functionality with a mini dataset
-    print("\n=== Testing Embed Dataset Functionality ===")
-    mini_dataset = [sample_sequence, sample_sequence[:50], sample_sequence[:30]]
-    print(f"Creating embeddings for {len(mini_dataset)} sequences")
-    
-    # Only run this if save path doesn't exist to avoid overwriting
-    if not os.path.exists("test_embeddings.pth"):
-        embeddings = mlm_model.embed_dataset(
-            sequences=mini_dataset,
-            tokenizer=tokenizer,
-            batch_size=2,
-            max_len=100,
-            full_embeddings=False,
-            pooling_types=['mean'],
-            save_path="test_embeddings.pth"
-        )
-        if embeddings:
-            print(f"Embedding dictionary size: {len(embeddings)}")
-            for seq, emb in embeddings.items():
-                print(f"Sequence length: {len(seq)}, Embedding shape: {emb.shape}")
-                break
-    else:
-        print("Skipping embedding test as test_embeddings.pth already exists")
-    
-    print("\nAll tests completed successfully!")
-    
+"""
+ESM++ model implementation.
+
+ESM++ is a faithful implementation of ESMC that allows for batching and standard Huggingface compatibility
+The ESM Python package is not required
+
+Modified from https://github.com/evolutionaryscale/esm
+License: https://www.evolutionaryscale.ai/policies/cambrian-non-commercial-license-agreement
+"""
+
+import entrypoint_setup
+import math
+import os
+import warnings
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from dataclasses import dataclass
+from functools import cache, partial
+from pathlib import Path
+from typing import Optional, Tuple, Union, List
+from einops import rearrange, repeat
+from huggingface_hub import snapshot_download
+from tokenizers import Tokenizer
+from tokenizers.models import BPE
+from tokenizers.processors import TemplateProcessing
+from torch.nn.attention.flex_attention import create_block_mask
+from torch.nn.attention.flex_attention import flex_attention
+from transformers import PreTrainedModel, PreTrainedTokenizerFast, PretrainedConfig
+from transformers.modeling_outputs import ModelOutput
+
+try:
+    # when used from AutoModel, these are in the same directory
+    from .embedding_mixin import EmbeddingMixin, Pooler
+except:
+    # when running from our repo, these are in the base directory
+    from embedding_mixin import EmbeddingMixin, Pooler
+
+
+def _create_pad_block_mask(attention_mask_2d: torch.Tensor):
+    token_valid = attention_mask_2d.bool()
+    batch_size, seq_len = token_valid.shape
+
+    def mask_mod(batch_idx, head_idx, q_idx, kv_idx):
+        return token_valid[batch_idx, q_idx] & token_valid[batch_idx, kv_idx]
+
+    return create_block_mask(
+        mask_mod,
+        batch_size,
+        1,
+        seq_len,
+        seq_len,
+        device=attention_mask_2d.device,
+    )
+
+
+class ESMplusplusConfig(PretrainedConfig):
+    """Configuration class for ESM++ model.
+    
+    Args:
+        vocab_size: Size of the vocabulary
+        hidden_size: Dimension of hidden layers
+        num_attention_heads: Number of attention heads
+        num_hidden_layers: Number of transformer layers
+        num_labels: Number of output labels for classification
+        problem_type: Type of problem - regression, single/multi label classification
+    """
+    model_type = "ESMplusplus"
+    def __init__(
+        self,
+        vocab_size: int = 64,
+        hidden_size: int = 960,
+        num_attention_heads: int = 15,
+        num_hidden_layers: int = 30,
+        num_labels: int = 2,
+        problem_type: str | None = None,
+        dropout: float = 0.0,
+        initializer_range: float = 0.02,
+        attn_backend: str = "sdpa",
+        **kwargs,
+    ):
+        super().__init__(**kwargs)
+        self.vocab_size = vocab_size
+        self.hidden_size = hidden_size
+        self.num_attention_heads = num_attention_heads
+        self.num_hidden_layers = num_hidden_layers
+        self.num_labels = num_labels
+        self.problem_type = problem_type
+        self.dropout = dropout
+        self.initializer_range = initializer_range
+        self.tie_word_embeddings = False
+        self.attn_backend = attn_backend
+
+
+### Rotary Embeddings
+def rotate_half(x: torch.Tensor, interleaved: bool = False) -> torch.Tensor:
+    """Rotates half the hidden dims of the input."""
+    if not interleaved:
+        x1, x2 = x.chunk(2, dim=-1)
+        return torch.cat((-x2, x1), dim=-1)
+    else:
+        x1, x2 = x[..., ::2], x[..., 1::2]
+        return rearrange(
+            torch.stack((-x2, x1), dim=-1), "... d two -> ... (d two)", two=2
+        )
+
+
+def apply_rotary_emb_torch(
+    x: torch.Tensor,
+    cos: torch.Tensor,
+    sin: torch.Tensor,
+    interleaved: bool = False,
+    _inplace: bool = False,
+) -> torch.Tensor:
+    """Apply rotary embeddings to input based on cos and sin."""
+    ro_dim = cos.shape[-1] * 2
+    assert ro_dim <= x.shape[-1]
+    seqlen = x.size(1)
+    cos = cos[:seqlen]
+    sin = sin[:seqlen]
+    cos = repeat(cos, "s d -> s 1 (2 d)")
+    sin = repeat(sin, "s d -> s 1 (2 d)")
+    return torch.cat(
+        [
+            x[..., :ro_dim] * cos + rotate_half(x[..., :ro_dim], interleaved) * sin,
+            x[..., ro_dim:],
+        ],
+        dim=-1,
+    )
+
+
+class RotaryEmbedding(torch.nn.Module):
+    """Rotary position embeddings.
+    
+    Based on the paper "RoFormer: Enhanced Transformer with Rotary Position Embedding"
+    
+    Args:
+        dim: Dimension of the embedding
+        base: Base for computing angular frequencies
+        interleaved: Whether to use interleaved rotations
+        scale_base: Base for scaling
+        scaling_factor: Factor for scaling positions
+        pos_idx_in_fp32: Whether to compute position indices in fp32
+        device: Computation device
+    """
+    def __init__(
+        self,
+        dim: int,
+        base: float = 10000.0,
+        interleaved: bool = False,
+        scale_base: Optional[float] = None,
+        scaling_factor: float = 1.0,
+        pos_idx_in_fp32: bool = True,
+        device: Optional[torch.device] = None,
+    ):
+        super().__init__()
+        self.dim = dim
+        self.base = float(base)
+        self.pos_idx_in_fp32 = pos_idx_in_fp32
+        self.interleaved = interleaved
+        self.scale_base = scale_base
+        self.scaling_factor = scaling_factor
+        self.device = device
+
+        self._seq_len_cached = 0
+        self._cos_cached = None
+        self._sin_cached = None
+        self._cos_k_cached = None
+        self._sin_k_cached = None
+        self.reset_parameters()
+
+    def reset_parameters(self):
+        """Reset the parameters of the embedding."""
+        inv_freq = self._compute_inv_freq(self.device)
+        self.register_buffer("inv_freq", inv_freq, persistent=False)
+        arange = torch.arange(0, self.dim, 2, device=self.device, dtype=torch.float32)
+        scale = (
+            (arange + 0.4 * self.dim) / (1.4 * self.dim)
+            if self.scale_base is not None
+            else None
+        )
+        self.register_buffer("scale", scale)
+
+    def _compute_inv_freq(self, device: Optional[torch.device] = None) -> torch.Tensor:
+        """Compute inverse frequency bands."""
+        return 1 / (
+            self.base
+            ** (
+                torch.arange(0, self.dim, 2, device=device, dtype=torch.float32)
+                / self.dim
+            )
+        )
+
+    def _update_cos_sin_cache(self, seqlen: int, device: Optional[torch.device] = None, dtype: Optional[torch.dtype] = None):
+        """Update the cached cosine and sine values."""
+        if (
+            seqlen > self._seq_len_cached
+            or self._cos_cached is None
+            or self._cos_cached.device != device
+            or self._cos_cached.dtype != dtype
+            or (self.training and self._cos_cached.is_inference())
+        ):
+            self._seq_len_cached = seqlen
+            if self.pos_idx_in_fp32:
+                t = torch.arange(seqlen, device=device, dtype=torch.float32)
+                t /= self.scaling_factor
+                if self.inv_freq.dtype != torch.float32:
+                    inv_freq = self.inv_freq.to(torch.float32)
+                else:
+                    inv_freq = self.inv_freq
+            else:
+                t = torch.arange(seqlen, device=device, dtype=self.inv_freq.dtype)
+                t /= self.scaling_factor
+                inv_freq = self.inv_freq
+            freqs = torch.outer(t, inv_freq)
+
+            if self.scale is None:
+                self._cos_cached = torch.cos(freqs).to(dtype)
+                self._sin_cached = torch.sin(freqs).to(dtype)
+            else:
+                power = (
+                    torch.arange(
+                        seqlen, dtype=self.scale.dtype, device=self.scale.device
+                    )
+                    - seqlen // 2
+                ) / self.scale_base
+                scale = self.scale.to(device=power.device) ** power.unsqueeze(-1)
+                self._cos_cached = (torch.cos(freqs) * scale).to(dtype)
+                self._sin_cached = (torch.sin(freqs) * scale).to(dtype)
+                self._cos_k_cached = (torch.cos(freqs) / scale).to(dtype)
+                self._sin_k_cached = (torch.sin(freqs) / scale).to(dtype)
+
+    def forward(self, q: torch.Tensor, k: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
+        """Apply rotary embeddings to queries and keys.
+        
+        Args:
+            q: Query tensor of shape (batch, seqlen, nheads, headdim)
+            k: Key tensor of shape (batch, seqlen, nheads, headdim)
+            
+        Returns:
+            Tuple of rotated query and key tensors
+        """
+        self._update_cos_sin_cache(q.shape[1], device=q.device, dtype=q.dtype)
+        assert self._cos_cached is not None
+        assert self._sin_cached is not None
+        if self.scale is None:
+            return (
+                apply_rotary_emb_torch(
+                    q,
+                    self._cos_cached,
+                    self._sin_cached,
+                    self.interleaved,
+                    True,  # inplace=True
+                ),
+                apply_rotary_emb_torch(
+                    k,
+                    self._cos_cached,
+                    self._sin_cached,
+                    self.interleaved,
+                    True,  # inplace=True
+                ),
+            )  # type: ignore
+        else:
+            assert False
+
+
+### Feedforward Network Components
+def swiglu_correction_fn(expansion_ratio: float, d_model: int) -> int:
+    """Compute corrected dimension for SwiGLU."""
+    return int(((expansion_ratio * d_model) + 255) // 256 * 256)
+
+
+class SwiGLU(nn.Module):
+    """SwiGLU activation function."""
+    def __init__(self):
+        super(SwiGLU, self).__init__()
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        x1, x2 = x.chunk(2, dim=-1)
+        return F.silu(x1) * x2
+
+
+def swiglu_ln_ffn(d_model: int, expansion_ratio: float) -> nn.Sequential:
+    """Create SwiGLU feedforward network with layer normalization."""
+    return nn.Sequential(
+        nn.LayerNorm(d_model),
+        nn.Linear(
+            d_model, swiglu_correction_fn(expansion_ratio, d_model) * 2, bias=False
+        ),
+        SwiGLU(),
+        nn.Linear(swiglu_correction_fn(expansion_ratio, d_model), d_model, bias=False),
+    )
+
+
+### Attention
+class MultiHeadAttention(nn.Module):
+    """Multi-head attention with rotary embeddings.
+    
+    Args:
+        d_model: Model dimension
+        n_heads: Number of attention heads
+    """
+    def __init__(
+        self,
+        d_model: int,
+        n_heads: int,
+        attn_backend: str = "sdpa",
+    ):
+        super().__init__()
+        self.d_model = d_model
+        self.n_heads = n_heads
+        self.d_head = self.d_model // self.n_heads
+        self.attn_backend = attn_backend
+        self._warned_flex_fallback = False
+        self.layernorm_qkv = nn.Sequential(
+            nn.LayerNorm(d_model), nn.Linear(d_model, d_model * 3, bias=False)
+        )
+        self.out_proj = nn.Linear(d_model, d_model, bias=False)
+        self.q_ln = nn.LayerNorm(d_model, bias=False)
+        self.k_ln = nn.LayerNorm(d_model, bias=False)
+        self.reshaper = partial(rearrange, pattern="b s (h d) -> b h s d", h=n_heads)
+        self.rotary = RotaryEmbedding(d_model // n_heads)
+
+    def _apply_rotary(self, q: torch.Tensor, k: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]:
+        """Apply rotary embeddings to query and key."""
+        q = q.unflatten(-1, (self.n_heads, self.d_head))
+        k = k.unflatten(-1, (self.n_heads, self.d_head))
+        q, k = self.rotary(q, k)
+        q = q.flatten(-2, -1)
+        k = k.flatten(-2, -1)
+        return q, k
+
+    def forward(
+        self,
+        x: torch.Tensor,
+        attention_mask: Optional[torch.Tensor] = None,
+        flex_block_mask: Optional[object] = None,
+        output_attentions: bool = False,
+    ) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
+        """
+        Args:
+            x: Input tensor
+            attention_mask: Optional attention mask
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            Output tensor after self attention, and optionally attention weights
+        """
+        attn_weights = None
+        qkv_BLD3 = self.layernorm_qkv(x)
+        query_BLD, key_BLD, value_BLD = torch.chunk(qkv_BLD3, 3, dim=-1)
+        query_BLD, key_BLD = (
+            self.q_ln(query_BLD).to(query_BLD.dtype),
+            self.k_ln(key_BLD).to(query_BLD.dtype),
+        )
+        query_BLD, key_BLD = self._apply_rotary(query_BLD, key_BLD)
+        query_BHLD, key_BHLD, value_BHLD = map(self.reshaper, (query_BLD, key_BLD, value_BLD))
+        scale = 1 / math.sqrt(self.d_head)
+
+        if output_attentions: # Manual attention computation
+            b, h, l, _ = query_BHLD.shape
+            attn_bias = torch.zeros(b, h, l, l, dtype=query_BLD.dtype, device=query_BLD.device)
+            if attention_mask is not None:
+                attn_bias.masked_fill_(attention_mask.logical_not(), float('-inf'))
+            attn_weights = torch.matmul(query_BHLD, key_BHLD.transpose(-2, -1)) * scale
+            attn_weights += attn_bias
+            attn_weights = F.softmax(attn_weights, dim=-1)
+            context_BHLD = torch.matmul(attn_weights, value_BHLD)
+        else:
+            sdpa_mask = None
+            if attention_mask is not None:
+                sdpa_mask = torch.zeros_like(attention_mask, dtype=query_BHLD.dtype)
+                sdpa_mask.masked_fill_(attention_mask.logical_not(), float("-inf"))
+            use_flex = (
+                self.attn_backend == "flex"
+                and (attention_mask is None or flex_block_mask is not None)
+            )
+            if use_flex:
+                try:
+                    context_BHLD = flex_attention(
+                        query_BHLD,
+                        key_BHLD,
+                        value_BHLD,
+                        block_mask=flex_block_mask,
+                        scale=scale,
+                    )
+                except Exception as exc:
+                    if not self._warned_flex_fallback:
+                        warnings.warn(
+                            f"Flex attention failed in ESM++ attention; falling back to SDPA. Error: {exc}",
+                            RuntimeWarning,
+                        )
+                        self._warned_flex_fallback = True
+                    context_BHLD = F.scaled_dot_product_attention(
+                        query_BHLD,
+                        key_BHLD,
+                        value_BHLD,
+                        attn_mask=sdpa_mask,
+                        scale=scale,
+                    )
+            else:
+                context_BHLD = F.scaled_dot_product_attention(
+                    query_BHLD,
+                    key_BHLD,
+                    value_BHLD,
+                    attn_mask=sdpa_mask,
+                    scale=scale,
+                )
+            
+        context_BLD = rearrange(context_BHLD, "b h s d -> b s (h d)")
+        output = self.out_proj(context_BLD)
+        return output, attn_weights
+
+
+### Regression Head
+def RegressionHead(d_model: int, output_dim: int, hidden_dim: Optional[int] = None) -> nn.Module:
+    """Create a regression head with optional hidden dimension.
+    
+    Args:
+        d_model: Input dimension
+        output_dim: Output dimension
+        hidden_dim: Optional hidden dimension (defaults to d_model)
+    """
+    hidden_dim = hidden_dim if hidden_dim is not None else d_model
+    return nn.Sequential(
+        nn.Linear(d_model, hidden_dim),
+        nn.GELU(),
+        nn.LayerNorm(hidden_dim),
+        nn.Linear(hidden_dim, output_dim),
+    )
+
+
+### Transformer Block
+class UnifiedTransformerBlock(nn.Module):
+    """Transformer block with attention and feedforward layers.
+    
+    Args:
+        d_model: Model dimension
+        n_heads: Number of attention heads
+        residue_scaling_factor: Factor for scaling residual connections
+        expansion_ratio: Expansion ratio for feedforward network
+    """
+    def __init__(
+        self,
+        d_model: int,
+        n_heads: int,
+        residue_scaling_factor: float = 1,
+        expansion_ratio: float = 8 / 3,
+        dropout: float = 0.0,
+        attn_backend: str = "sdpa",
+    ):
+        super().__init__()
+        self.attn = MultiHeadAttention(
+            d_model=d_model,
+            n_heads=n_heads,
+            attn_backend=attn_backend,
+        )
+        self.ffn = swiglu_ln_ffn(d_model, expansion_ratio)
+        self.scaling_factor = residue_scaling_factor
+        self.dropout = nn.Dropout(dropout)
+
+    def forward(
+        self,
+        x: torch.Tensor,
+        attention_mask: Optional[torch.Tensor] = None,
+        flex_block_mask: Optional[object] = None,
+        output_attentions: bool = False,
+    ) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
+        """
+        Args:
+            x: Input tensor
+            attention_mask: Optional attention mask
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            Output tensor after transformer block, and optionally attention weights
+        """
+        attn_output, attn_weights = self.attn(
+            x,
+            attention_mask,
+            flex_block_mask,
+            output_attentions,
+        )
+        x = x + self.dropout(attn_output) / self.scaling_factor
+        x = x + self.dropout(self.ffn(x)) / self.scaling_factor
+        return x, attn_weights
+
+
+### Model Outputs
+@dataclass
+class TransformerOutput(ModelOutput):
+    """Output type for transformer encoder."""
+    last_hidden_state: Optional[torch.Tensor] = None
+    hidden_states: Optional[Tuple[torch.Tensor]] = None
+    attentions: Optional[Tuple[torch.Tensor]] = None
+
+
+@dataclass
+class ESMplusplusOutput(ModelOutput):
+    """Output type for ESM++ models."""
+    loss: Optional[torch.Tensor] = None
+    logits: Optional[torch.Tensor] = None
+    last_hidden_state: Optional[torch.Tensor] = None
+    hidden_states: Optional[Tuple[torch.Tensor]] = None
+    attentions: Optional[Tuple[torch.Tensor]] = None
+
+
+### Transformer Stack
+class TransformerStack(nn.Module):
+    """Stack of transformer blocks.
+    
+    Args:
+        d_model: Model dimension
+        n_heads: Number of attention heads
+        n_layers: Number of transformer layers
+        dropout: Dropout rate
+    """
+    def __init__(
+        self,
+        d_model: int,
+        n_heads: int,
+        n_layers: int,
+        dropout: float = 0.0,
+        attn_backend: str = "sdpa",
+    ):
+        super().__init__()
+        self.attn_backend = attn_backend
+        self.blocks = nn.ModuleList(
+            [
+                UnifiedTransformerBlock(
+                    d_model,
+                    n_heads,
+                    residue_scaling_factor=math.sqrt(n_layers / 36),
+                    dropout=dropout,
+                    attn_backend=attn_backend,
+                )
+                for i in range(n_layers)
+            ]
+        )
+        self.norm = nn.LayerNorm(d_model, bias=False)
+        self.gradient_checkpointing = False
+
+    def forward(
+        self,
+        x: torch.Tensor,
+        attention_mask: Optional[torch.Tensor] = None,
+        output_hidden_states: bool = False,
+        output_attentions: bool = False,
+    ) -> TransformerOutput:
+        """
+        Args:
+            x: Input tensor
+            attention_mask: Optional attention mask
+            output_hidden_states: Whether to return all hidden states
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            TransformerOutput containing last hidden state and optionally all hidden states and attention weights
+        """
+        hidden_states = () if output_hidden_states else None
+        attentions = () if output_attentions else None
+        
+        if attention_mask is not None:
+            assert attention_mask.ndim == 2, f"Expected 2D token attention mask, got shape {attention_mask.shape}."
+            token_attention_mask = attention_mask.bool()
+            pairwise_attention_mask = token_attention_mask.unsqueeze(-1) & token_attention_mask.unsqueeze(-2)
+            attention_mask = pairwise_attention_mask.unsqueeze(1)
+            if self.attn_backend == "flex" and not output_attentions:
+                flex_block_mask = _create_pad_block_mask(token_attention_mask)
+            else:
+                flex_block_mask = None
+        else:
+            flex_block_mask = None
+            
+        for block in self.blocks:
+            if self.gradient_checkpointing and self.training:
+                x, attn_weights = self._gradient_checkpointing_func(
+                    block.__call__,
+                    x,
+                    attention_mask,
+                    flex_block_mask,
+                    output_attentions,
+                )
+            else:
+                x, attn_weights = block(x, attention_mask, flex_block_mask, output_attentions)
+
+            if attentions is not None:
+                attentions += (attn_weights,)
+                
+            if output_hidden_states:
+                assert hidden_states is not None
+                hidden_states += (x,)
+                
+        return TransformerOutput(
+            last_hidden_state=self.norm(x), 
+            hidden_states=hidden_states,
+            attentions=attentions
+        )
+
+
+class PreTrainedESMplusplusModel(PreTrainedModel):
+    """
+    init weights for ESM++ models
+    """
+    config_class = ESMplusplusConfig
+    base_model_prefix = "esm++"
+    supports_gradient_checkpointing = True
+    all_tied_weights_keys = {}
+
+    def _init_weights(self, module):
+        """Initialize the weights"""
+        if isinstance(module, nn.Linear):
+            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
+            if module.bias is not None:
+                module.bias.data.zero_()
+        elif isinstance(module, nn.Embedding):
+            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
+            if module.padding_idx is not None:
+                module.weight.data[module.padding_idx].zero_()
+        elif isinstance(module, nn.LayerNorm):
+            if module.bias is not None:
+                module.bias.data.zero_()
+            module.weight.data.fill_(1.0)
+
+    @classmethod
+    def from_pretrained_esm(cls, model_name: str):
+        """Load a pretrained ESM++ model."""
+        if '300' in model_name:
+            return ESMplusplus_300M()
+        elif '600' in model_name:
+            return ESMplusplus_600M()
+        else:
+            raise ValueError(f"Invalid model name: {model_name}")
+
+
+### ESM++ Models
+class ESMplusplusModel(PreTrainedESMplusplusModel, EmbeddingMixin):
+    """
+    ESM++ model. transformer model with no heads
+    """
+    config_class = ESMplusplusConfig
+    def __init__(self, config: ESMplusplusConfig, **kwargs):
+        PreTrainedESMplusplusModel.__init__(self, config, **kwargs)
+        self.config = config
+        self.vocab_size = config.vocab_size
+        self.embed = nn.Embedding(self.vocab_size, config.hidden_size)
+        self.transformer = TransformerStack(
+            d_model=config.hidden_size,
+            n_heads=config.num_attention_heads,
+            n_layers=config.num_hidden_layers,
+            dropout=config.dropout,
+            attn_backend=config.attn_backend,
+        )
+        self.tokenizer = EsmSequenceTokenizer()
+        self.init_weights()
+
+    def get_input_embeddings(self):
+        return self.embed
+
+    def set_input_embeddings(self, value):
+        self.embed = value
+
+    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
+        x = self.embed(input_ids)
+        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
+
+    def forward(
+        self,
+        input_ids: Optional[torch.Tensor] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        inputs_embeds: Optional[torch.Tensor] = None,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
+        **kwargs,
+    ) -> TransformerOutput:
+        """Forward pass for masked language modeling.
+        
+        Args:
+            input_ids: Input token IDs
+            attention_mask: Attention mask
+            inputs_embeds: Optional precomputed embeddings
+            output_hidden_states: Whether to return all hidden states
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            TransformerOutput containing last hidden state and optionally all hidden states and attention weights
+        """
+        if inputs_embeds is None:
+            x = self.embed(input_ids)
+        else:
+            x = inputs_embeds
+        return self.transformer(x, attention_mask, output_hidden_states, output_attentions)
+        
+
+class ESMplusplusForMaskedLM(PreTrainedESMplusplusModel, EmbeddingMixin):
+    """
+    ESM++ model for masked language modeling.
+    Implements the base ESM++ architecture with a masked language modeling head.
+    """
+    config_class = ESMplusplusConfig
+    def __init__(self, config: ESMplusplusConfig, **kwargs):
+        PreTrainedESMplusplusModel.__init__(self, config, **kwargs)
+        self.config = config
+        self.vocab_size = config.vocab_size
+        self.embed = nn.Embedding(self.vocab_size, config.hidden_size)
+        self.transformer = TransformerStack(
+            d_model=config.hidden_size,
+            n_heads=config.num_attention_heads,
+            n_layers=config.num_hidden_layers,
+            dropout=config.dropout,
+            attn_backend=config.attn_backend,
+        )
+        self.sequence_head = RegressionHead(config.hidden_size, self.vocab_size)
+        self.ce_loss = nn.CrossEntropyLoss()
+        self.tokenizer = EsmSequenceTokenizer()
+        self.init_weights()
+
+    def get_input_embeddings(self):
+        return self.embed
+
+    def set_input_embeddings(self, value):
+        self.embed = value
+
+    def get_output_embeddings(self):
+        return self.sequence_head[-1]
+
+    def set_output_embeddings(self, new_embeddings):
+        self.sequence_head[-1] = new_embeddings
+
+    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
+        x = self.embed(input_ids)
+        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
+
+    def forward(
+        self,
+        input_ids: Optional[torch.Tensor] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        inputs_embeds: Optional[torch.Tensor] = None,
+        labels: Optional[torch.Tensor] = None,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
+        **kwargs,
+    ) -> ESMplusplusOutput:
+        """Forward pass for masked language modeling.
+        
+        Args:
+            input_ids: Input token IDs
+            attention_mask: Attention mask
+            inputs_embeds: Optional precomputed embeddings
+            labels: Optional labels for masked tokens
+            output_hidden_states: Whether to return all hidden states
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            ESMplusplusOutput containing loss, logits, hidden states and attention weights
+        """
+        if inputs_embeds is None:
+            x = self.embed(input_ids)
+        else:
+            x = inputs_embeds
+        output = self.transformer(x, attention_mask, output_hidden_states, output_attentions)
+        x = output.last_hidden_state
+        logits = self.sequence_head(x)
+        loss = None
+        if labels is not None:
+            loss = self.ce_loss(logits.view(-1, self.vocab_size), labels.view(-1))
+        return ESMplusplusOutput(
+            loss=loss,
+            logits=logits,
+            last_hidden_state=x,
+            hidden_states=output.hidden_states,
+            attentions=output.attentions,
+        )
+
+
+class ESMplusplusForSequenceClassification(ESMplusplusForMaskedLM, EmbeddingMixin):
+    """
+    ESM++ model for sequence classification.
+    Extends the base ESM++ model with a classification head.
+    """
+    def __init__(self, config: ESMplusplusConfig, **kwargs):
+        ESMplusplusForMaskedLM.__init__(self, config, **kwargs)
+        self.config = config
+        self.num_labels = config.num_labels
+        self.classifier = RegressionHead(config.hidden_size * 2, config.num_labels, config.hidden_size * 4)
+        # Large intermediate projections help with sequence classification tasks (*4)
+        self.mse = nn.MSELoss()
+        self.ce = nn.CrossEntropyLoss()
+        self.bce = nn.BCEWithLogitsLoss()
+        # if kwargs has pooling_types, use them, otherwise use ['cls', 'mean']
+        if 'pooling_types' in kwargs and isinstance(kwargs['pooling_types'], List[str]) and len(kwargs['pooling_types']) > 0:
+            pooling_types = kwargs['pooling_types']
+        else:
+            pooling_types = ['cls', 'mean']
+        self.pooler = Pooler(pooling_types)
+        self.init_weights()
+
+    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
+        x = self.embed(input_ids)
+        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
+
+    def forward(
+        self,
+        input_ids: Optional[torch.Tensor] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        inputs_embeds: Optional[torch.Tensor] = None,
+        labels: Optional[torch.Tensor] = None,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
+        **kwargs,
+    ) -> ESMplusplusOutput:
+        """Forward pass for sequence classification.
+        
+        Args:
+            input_ids: Input token IDs
+            attention_mask: Attention mask
+            inputs_embeds: Optional precomputed embeddings
+            labels: Optional labels for classification
+            output_hidden_states: Whether to return all hidden states
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            ESMplusplusOutput containing loss, logits, and hidden states
+        """
+        output = super().forward(
+            input_ids=input_ids,
+            attention_mask=attention_mask,
+            inputs_embeds=inputs_embeds,
+            labels=None,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states
+        )
+        x = output.last_hidden_state
+        features = self.pooler(x, attention_mask)
+        logits = self.classifier(features)
+        loss = None
+        if labels is not None:
+            labels = labels.to(logits.device)
+            if self.config.problem_type is None:
+                if self.num_labels == 1:
+                    self.config.problem_type = "regression"
+                elif self.num_labels > 1 and (labels.dtype == torch.long or labels.dtype == torch.int):
+                    self.config.problem_type = "single_label_classification"
+                else:
+                    self.config.problem_type = "multi_label_classification"
+
+            if self.config.problem_type == "regression":
+                if self.num_labels == 1:
+                    loss = self.mse(logits.flatten(), labels.flatten())
+                else:
+                    loss = self.mse(logits, labels)
+            elif self.config.problem_type == "single_label_classification":
+                loss = self.ce(logits.view(-1, self.num_labels), labels.view(-1))
+            elif self.config.problem_type == "multi_label_classification":
+                loss = self.bce(logits, labels)
+
+        return ESMplusplusOutput(
+            loss=loss,
+            logits=logits,
+            last_hidden_state=x,
+            hidden_states=output.hidden_states,
+            attentions=output.attentions,
+        )
+
+
+class ESMplusplusForTokenClassification(ESMplusplusForMaskedLM, EmbeddingMixin):
+    """
+    ESM++ model for token classification.
+    Extends the base ESM++ model with a token classification head.
+    """
+    def __init__(self, config: ESMplusplusConfig, **kwargs):
+        ESMplusplusForMaskedLM.__init__(self, config, **kwargs)
+        self.config = config
+        self.num_labels = config.num_labels
+        self.classifier = RegressionHead(config.hidden_size, config.num_labels, config.hidden_size * 4)
+        # Large intermediate projections help with sequence classification tasks (*4)
+        self.loss_fct = nn.CrossEntropyLoss()
+        self.init_weights()
+
+    def _embed(self, input_ids: torch.Tensor, attention_mask: Optional[torch.Tensor] = None) -> torch.Tensor:
+        x = self.embed(input_ids)
+        return self.transformer(x, attention_mask, output_hidden_states=False, output_attentions=False).last_hidden_state
+
+    def forward(
+        self,
+        input_ids: Optional[torch.Tensor] = None,
+        attention_mask: Optional[torch.Tensor] = None,
+        inputs_embeds: Optional[torch.Tensor] = None,
+        labels: Optional[torch.Tensor] = None,
+        output_attentions: Optional[bool] = None,
+        output_hidden_states: Optional[bool] = None,
+        return_dict: Optional[bool] = None, # to play nice with HF adjacent packages
+        **kwargs,
+    ) -> ESMplusplusOutput:
+        """Forward pass for token classification.
+        
+        Args:
+            input_ids: Input token IDs
+            attention_mask: Attention mask
+            inputs_embeds: Optional precomputed embeddings
+            labels: Optional labels for token classification
+            output_hidden_states: Whether to return all hidden states
+            output_attentions: Whether to return attention weights
+            
+        Returns:
+            ESMplusplusOutput containing loss, logits, and hidden states
+        """
+        output = super().forward(
+            input_ids=input_ids,
+            attention_mask=attention_mask,
+            inputs_embeds=inputs_embeds,
+            labels=None,
+            output_attentions=output_attentions,
+            output_hidden_states=output_hidden_states
+        )
+        x = output.last_hidden_state
+        logits = self.classifier(x)
+        loss = None
+        if labels is not None:
+            loss = self.loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
+        return ESMplusplusOutput(
+            loss=loss,
+            logits=logits,
+            last_hidden_state=x,
+            hidden_states=output.hidden_states,
+            attentions=output.attentions,
+        )
+
+
+### Loading from EvolutionaryScale
+_ESMC_CHECKPOINT_SPECS = {
+    "esmc-300": {
+        "repo_id": "EvolutionaryScale/esmc-300m-2024-12",
+        "weights_relpath": "data/weights/esmc_300m_2024_12_v0.pth",
+        "hidden_size": 960,
+        "num_attention_heads": 15,
+        "num_hidden_layers": 30,
+    },
+    "esmc-600": {
+        "repo_id": "EvolutionaryScale/esmc-600m-2024-12",
+        "weights_relpath": "data/weights/esmc_600m_2024_12_v0.pth",
+        "hidden_size": 1152,
+        "num_attention_heads": 18,
+        "num_hidden_layers": 36,
+    },
+}
+
+
+def _resolve_esmc_checkpoint_key(model: str) -> str:
+    if "esmc-300" in model:
+        return "esmc-300"
+    if "esmc-600" in model:
+        return "esmc-600"
+    raise ValueError(f"{model=} is an invalid ESMC model name.")
+
+
+@staticmethod
+@cache
+def data_root(model: str):
+    if "INFRA_PROVIDER" in os.environ:
+        return Path("")
+    key = _resolve_esmc_checkpoint_key(model)
+    return Path(snapshot_download(repo_id=_ESMC_CHECKPOINT_SPECS[key]["repo_id"]))
+
+
+def get_esmc_checkpoint_path(model: str) -> Path:
+    key = _resolve_esmc_checkpoint_key(model)
+    return data_root(key) / _ESMC_CHECKPOINT_SPECS[key]["weights_relpath"]
+
+
+def _load_esmc_checkpoint_model(
+    config: ESMplusplusConfig,
+    model: str,
+    device: torch.device | str = "cpu",
+) -> ESMplusplusForMaskedLM:
+    key = _resolve_esmc_checkpoint_key(model)
+    spec = _ESMC_CHECKPOINT_SPECS[key]
+    assert config.hidden_size == spec["hidden_size"], (
+        f"ESMC loader expected hidden_size={spec['hidden_size']} for {key}, "
+        f"but got {config.hidden_size}."
+    )
+    assert config.num_attention_heads == spec["num_attention_heads"], (
+        f"ESMC loader expected num_attention_heads={spec['num_attention_heads']} for {key}, "
+        f"but got {config.num_attention_heads}."
+    )
+    assert config.num_hidden_layers == spec["num_hidden_layers"], (
+        f"ESMC loader expected num_hidden_layers={spec['num_hidden_layers']} for {key}, "
+        f"but got {config.num_hidden_layers}."
+    )
+    with torch.device(device):
+        model_obj = ESMplusplusForMaskedLM(config)
+    state_dict = torch.load(get_esmc_checkpoint_path(key), map_location=device)
+    model_obj.load_state_dict(state_dict)
+    return model_obj
+
+
+def ESMplusplus_300M(device: torch.device | str = "cpu"):
+    config = ESMplusplusConfig(
+        hidden_size=960,
+        num_attention_heads=15,
+        num_hidden_layers=30,
+    )
+    return _load_esmc_checkpoint_model(config=config, model="esmc-300", device=device)
+
+
+def ESMplusplus_600M(device: torch.device | str = "cpu"):
+    config = ESMplusplusConfig(
+        hidden_size=1152,
+        num_attention_heads=18,
+        num_hidden_layers=36,
+    )
+    return _load_esmc_checkpoint_model(config=config, model="esmc-600", device=device)
+
+
+### Tokenization
+SEQUENCE_VOCAB = [
+    "<cls>", "<pad>", "<eos>", "<unk>",
+    "L", "A", "G", "V", "S", "E", "R", "T", "I", "D", "P", "K",
+    "Q", "N", "F", "Y", "M", "H", "W", "C", "X", "B", "U", "Z",
+    "O", ".", "-", "|",
+    "<mask>",
+]
+
+class EsmSequenceTokenizer(PreTrainedTokenizerFast):
+    model_input_names = ["input_ids", "attention_mask"]
+
+    def __init__(
+        self,
+        unk_token="<unk>",
+        cls_token="<cls>",
+        pad_token="<pad>",
+        mask_token="<mask>",
+        eos_token="<eos>",
+        chain_break_token="|",
+        **kwargs,
+    ):
+        all_tokens = SEQUENCE_VOCAB
+        token_to_id = {tok: ind for ind, tok in enumerate(all_tokens)}
+
+        # a character-level tokenizer is the same as BPE with no token merges
+        bpe = BPE(token_to_id, merges=[], unk_token=unk_token)
+        tokenizer = Tokenizer(bpe)
+        special_tokens = [
+            cls_token,
+            pad_token,
+            mask_token,
+            eos_token,
+            chain_break_token,
+        ]
+        self.cb_token = chain_break_token
+        additional_special_tokens = [chain_break_token]
+
+        tokenizer.add_special_tokens(special_tokens)
+
+        # This is where we configure the automatic addition of special tokens when we call
+        # tokenizer(text, add_special_tokens=True). Note that you can also configure how two
+        # sequences are merged if you want.
+        tokenizer.post_processor = TemplateProcessing(  # type: ignore
+            single="<cls> $A <eos>",
+            pair="<cls>:0 $A:0 <eos>:0 $B:1 <eos>:1",
+            special_tokens=[
+                ("<cls>", tokenizer.token_to_id("<cls>")),
+                ("<eos>", tokenizer.token_to_id("<eos>")),
+            ],
+        )
+        super().__init__(
+            tokenizer_object=tokenizer,
+            unk_token=unk_token,
+            cls_token=cls_token,
+            pad_token=pad_token,
+            mask_token=mask_token,
+            eos_token=eos_token,
+            additional_special_tokens=additional_special_tokens,
+            **kwargs,
+        )
+
+    # These are a footgun, we never use the `bos` token anywhere so we're just overriding it here.
+    @property
+    def bos_token(self):
+        return self.cls_token
+
+    @property
+    def bos_token_id(self):
+        return self.cls_token_id
+
+    @property
+    def chain_break_token(self):
+        return self.cb_token
+
+    @property
+    def chain_break_token_id(self):
+        return self.convert_tokens_to_ids(self.chain_break_token)
+
+    @property
+    def all_token_ids(self):
+        return list(range(self.vocab_size))
+
+    @property
+    def special_token_ids(self):
+        return self.all_special_ids
+
+
+if __name__ == "__main__":    
+    # Set device to CPU for testing
+    device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
+    print(f"Using device: {device}")
+    
+    # Test tokenizer
+    tokenizer = EsmSequenceTokenizer()
+    sample_sequence = "MQIFVKTLTGKTITLEVEPSDTIENVKAKIQDKEGIPPDQQRLIFAGKQLEDGRTLSDYNIQKESTLHLVLRLRGG"
+    encoding = tokenizer(sample_sequence, return_tensors="pt")
+    print(f"Input sequence length: {len(sample_sequence)}")
+    print(f"Tokenized sequence: {encoding['input_ids'].shape}")
+    
+    # Prepare inputs
+    input_ids = encoding['input_ids'].to(device)
+    attention_mask = encoding['attention_mask'].to(device)
+    
+    # Test base model with smaller config for quick testing
+    print("\n=== Testing ESMplusplus Base Model ===")
+    base_config = ESMplusplusConfig(
+        hidden_size=384,
+        num_attention_heads=6,
+        num_hidden_layers=4
+    )
+    base_model = ESMplusplusModel(base_config).to(device)
+    
+    with torch.no_grad():
+        outputs = base_model(input_ids=input_ids, attention_mask=attention_mask)
+    
+    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
+    
+    # Test embedding functionality
+    print("\nTesting embedding functionality:")
+    with torch.no_grad():
+        embeddings = base_model._embed(input_ids, attention_mask)
+    print(f"Embedding shape: {embeddings.shape}")
+    
+    # Test masked language modeling
+    print("\n=== Testing ESMplusplus For Masked LM ===")
+    mlm_model = ESMplusplusForMaskedLM(base_config).to(device)
+    
+    with torch.no_grad():
+        outputs = mlm_model(input_ids=input_ids, attention_mask=attention_mask)
+    
+    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
+    print(f"Logits shape: {outputs.logits.shape}")
+    
+    # Test sequence classification model
+    print("\n=== Testing Sequence Classification Model ===")
+    classification_model = ESMplusplusForSequenceClassification(base_config).to(device)
+    
+    with torch.no_grad():
+        outputs = classification_model(input_ids=input_ids, attention_mask=attention_mask)
+    
+    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
+    print(f"Logits shape: {outputs.logits.shape}")
+    
+    # Test token classification model
+    print("\n=== Testing Token Classification Model ===")
+    token_model = ESMplusplusForTokenClassification(base_config).to(device)
+    
+    with torch.no_grad():
+        outputs = token_model(input_ids=input_ids, attention_mask=attention_mask)
+    
+    print(f"Last hidden state shape: {outputs.last_hidden_state.shape}")
+    print(f"Logits shape: {outputs.logits.shape}")
+    
+    # Test embedding dataset functionality with a mini dataset
+    print("\n=== Testing Embed Dataset Functionality ===")
+    mini_dataset = [sample_sequence, sample_sequence[:50], sample_sequence[:30]]
+    print(f"Creating embeddings for {len(mini_dataset)} sequences")
+    
+    # Only run this if save path doesn't exist to avoid overwriting
+    if not os.path.exists("test_embeddings.pth"):
+        embeddings = mlm_model.embed_dataset(
+            sequences=mini_dataset,
+            tokenizer=tokenizer,
+            batch_size=2,
+            max_len=100,
+            full_embeddings=False,
+            pooling_types=['mean'],
+            save_path="test_embeddings.pth"
+        )
+        if embeddings:
+            print(f"Embedding dictionary size: {len(embeddings)}")
+            for seq, emb in embeddings.items():
+                print(f"Sequence length: {len(seq)}, Embedding shape: {emb.shape}")
+                break
+    else:
+        print("Skipping embedding test as test_embeddings.pth already exists")
+    
+    print("\nAll tests completed successfully!")
+