model: implement bert in ollama engine (#9080)

* fix truncate

* s/SentencePieceModel/SentencePiece/

* bert

* wordpiece

* refactor pooling

* more tokenizers

* normalize embeddings

convert/convert_bert.go

@@ -28,6 +28,7 @@ type bertModel struct {
 	LayerNormEPS          float32 `json:"layer_norm_eps"`
 	LayerNormEpsilon      float32 `json:"layer_norm_epsilon"`
 	NormEpsilon           float32 `json:"norm_epsilon"`
+	normalizeEmbeddings   bool
 
 	PoolingType uint32
 }
@@ -54,9 +55,11 @@ func (p *bertModel) parseMore(fsys fs.FS) error {
 
 	var pooling string
 	for _, m := range modules {
-		if m.Type == "sentence_transformers.models.Pooling" {
+		switch m.Type {
+		case "sentence_transformers.models.Pooling":
 			pooling = m.Path
-			break
+		case "sentence_transformers.models.Normalize":
+			p.normalizeEmbeddings = true
 		}
 	}
 
@@ -90,6 +93,7 @@ func (p *bertModel) KV(t *Tokenizer) ggml.KV {
 	kv["general.architecture"] = "bert"
 	kv["bert.attention.causal"] = false
 	kv["bert.pooling_type"] = p.PoolingType
+	kv["bert.normalize_embeddings"] = p.normalizeEmbeddings
 
 	kv["bert.block_count"] = cmp.Or(p.NLayers, p.NumHiddenLayers, p.NLayer)
 

ml/backend.go

@@ -416,6 +416,7 @@ type Tensor interface {
 	AddID(ctx Context, t2, ids Tensor) Tensor
 
 	Softmax(ctx Context) Tensor
+	L2Norm(ctx Context, eps float32) Tensor
 	LayerNorm(ctx Context, weight, bias Tensor, eps float32) Tensor
 	RMSNorm(ctx Context, weight Tensor, eps float32) Tensor
 	Scale(ctx Context, s float64) Tensor

ml/backend/ggml/ggml.go

@@ -1205,6 +1205,13 @@ func (t *Tensor) AddID(ctx ml.Context, t2, ids ml.Tensor) ml.Tensor {
 	}
 }
 
+func (t *Tensor) L2Norm(ctx ml.Context, eps float32) ml.Tensor {
+	return &Tensor{
+		b: t.b,
+		t: C.ggml_l2_norm(ctx.(*Context).ctx, t.t, C.float(eps)),
+	}
+}
+
 func (t *Tensor) LayerNorm(ctx ml.Context, w, b ml.Tensor, eps float32) ml.Tensor {
 	tt := C.ggml_norm(ctx.(*Context).ctx, t.t, C.float(eps))
 	if w != nil {

ml/nn/pooling/pooling.go

@@ -0,0 +1,36 @@
+package pooling
+
+import (
+	"github.com/ollama/ollama/ml"
+)
+
+type Type uint32
+
+const (
+	TypeNone Type = iota
+	TypeMean
+	TypeCLS
+	TypeLast
+	TypeRank
+
+	TypeUnknown     = 0xFFFFFFFE
+	TypeUnspecified = 0xFFFFFFFF
+)
+
+func Pooling(ctx ml.Context, hiddenStates ml.Tensor, poolingType Type) ml.Tensor {
+	switch poolingType {
+	case TypeNone:
+		return hiddenStates
+	case TypeMean:
+		hiddenStates = hiddenStates.Permute(ctx, 1, 0, 2, 3).Contiguous(ctx).Mean(ctx)
+		return hiddenStates.Permute(ctx, 1, 0, 2, 3).Contiguous(ctx)
+	case TypeCLS:
+		return hiddenStates.View(ctx, 0, hiddenStates.Dim(0))
+	case TypeLast:
+		panic("not implemented")
+	case TypeRank:
+		panic("not implemented")
+	default:
+		panic("not implemented")
+	}
+}

model/model.go

@@ -24,7 +24,11 @@ import (
 	"github.com/ollama/ollama/model/input"
 )
 
-var ErrNoVisionModel = errors.New("this model is missing data required for image input")
+var (
+	ErrNoVisionModel        = errors.New("this model is missing data required for image input")
+	ErrUnsupportedModel     = errors.New("model not supported")
+	ErrUnsupportedTokenizer = errors.New("tokenizer not supported")
+)
 
 // Model implements a specific model architecture, defining the forward pass and any model-specific configuration
 type Model interface {
@@ -242,7 +246,7 @@ func setPointer(base Base, v reflect.Value, tags []Tag) {
 		vv = vv.Elem()
 	}
 
-	vv = vv.Elem()
+	vv = reflect.Indirect(vv)
 	if v.IsNil() {
 		vv = reflect.New(v.Type().Elem()).Elem()
 	}

model/models/bert/model.go

@@ -0,0 +1,181 @@
+package bert
+
+import (
+	"cmp"
+	"math"
+
+	"github.com/ollama/ollama/fs"
+	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/ml/nn"
+	"github.com/ollama/ollama/ml/nn/pooling"
+	"github.com/ollama/ollama/model"
+	"github.com/ollama/ollama/model/input"
+)
+
+type Model struct {
+	model.Base
+	model.TextProcessor
+
+	TokenEmbedding     *nn.Embedding `gguf:"token_embd"`
+	TypeEmbedding      *nn.Embedding `gguf:"token_types"`
+	PositionEmbedding  *nn.Embedding `gguf:"position_embd"`
+	TokenEmbeddingNorm *nn.LayerNorm `gguf:"token_embd_norm"`
+
+	Layers []EncoderLayer `gguf:"blk"`
+
+	Options
+}
+
+// Forward implements model.Model.
+func (m *Model) Forward(ctx ml.Context, batch input.Batch) (ml.Tensor, error) {
+	hiddenStates := m.TokenEmbedding.Forward(ctx, batch.Inputs)
+	hiddenStates = hiddenStates.Add(ctx, m.TypeEmbedding.Weight.View(ctx, 0, m.hiddenSize))
+	hiddenStates = hiddenStates.Add(ctx, m.PositionEmbedding.Forward(ctx, ctx.Input().FromIntSlice(batch.Positions, len(batch.Positions))))
+	hiddenStates = m.TokenEmbeddingNorm.Forward(ctx, hiddenStates, m.eps)
+
+	for _, layer := range m.Layers {
+		hiddenStates = layer.Forward(ctx, hiddenStates, &m.Options)
+	}
+
+	hiddenStates = pooling.Pooling(ctx, hiddenStates, m.poolingType)
+	if m.normalize {
+		hiddenStates = hiddenStates.L2Norm(ctx, 1e-12)
+	}
+
+	return hiddenStates, nil
+}
+
+type EncoderLayer struct {
+	*Attention
+	AttentionNorm *nn.LayerNorm `gguf:"attn_output_norm"`
+
+	*MLP
+	MLPNorm *nn.LayerNorm `gguf:"layer_output_norm"`
+}
+
+func (e *EncoderLayer) Forward(ctx ml.Context, hiddenStates ml.Tensor, opts *Options) ml.Tensor {
+	// Attention
+	residual := hiddenStates
+	hiddenStates = e.Attention.Forward(ctx, hiddenStates, opts)
+	hiddenStates = hiddenStates.Add(ctx, residual)
+	hiddenStates = e.AttentionNorm.Forward(ctx, hiddenStates, opts.eps)
+
+	// MLP
+	residual = hiddenStates
+	hiddenStates = e.MLP.Forward(ctx, hiddenStates, opts)
+	hiddenStates = hiddenStates.Add(ctx, residual)
+	hiddenStates = e.MLPNorm.Forward(ctx, hiddenStates, opts.eps)
+
+	return hiddenStates
+}
+
+type Attention struct {
+	Query     *nn.Linear    `gguf:"attn_q"`
+	QueryNorm *nn.LayerNorm `gguf:"attn_q_norm"`
+
+	Key     *nn.Linear    `gguf:"attn_k"`
+	KeyNorm *nn.LayerNorm `gguf:"attn_k_norm"`
+
+	Value *nn.Linear `gguf:"attn_v"`
+
+	Output *nn.Linear `gguf:"attn_output"`
+}
+
+func (a *Attention) Forward(ctx ml.Context, hiddenStates ml.Tensor, opts *Options) ml.Tensor {
+	batchSize := hiddenStates.Dim(1)
+
+	query := a.Query.Forward(ctx, hiddenStates)
+	if a.QueryNorm != nil {
+		query = a.QueryNorm.Forward(ctx, query, opts.eps)
+	}
+	query = query.Reshape(ctx, opts.headDim(), opts.numHeads, batchSize)
+
+	key := a.Key.Forward(ctx, hiddenStates)
+	if a.KeyNorm != nil {
+		key = a.KeyNorm.Forward(ctx, key, opts.eps)
+	}
+	key = key.Reshape(ctx, opts.headDim(), cmp.Or(opts.numKVHeads, opts.numHeads), batchSize)
+
+	value := a.Value.Forward(ctx, hiddenStates)
+	value = value.Reshape(ctx, opts.headDim(), cmp.Or(opts.numKVHeads, opts.numHeads), batchSize)
+
+	attention := nn.Attention(ctx, query, key, value, 1/math.Sqrt(float64(opts.headDim())), nil)
+	attention = attention.Reshape(ctx, opts.hiddenSize, batchSize)
+	return a.Output.Forward(ctx, attention)
+}
+
+type MLP struct {
+	Up   *nn.Linear `gguf:"ffn_up"`
+	Down *nn.Linear `gguf:"ffn_down"`
+}
+
+func (m *MLP) Forward(ctx ml.Context, hiddenStates ml.Tensor, opts *Options) ml.Tensor {
+	return m.Down.Forward(ctx, m.Up.Forward(ctx, hiddenStates).GELU(ctx))
+}
+
+type Options struct {
+	hiddenSize,
+	numHeads,
+	numKVHeads,
+	keyLength,
+	valueLength int
+	poolingType pooling.Type
+	eps         float32
+	normalize   bool
+}
+
+func (o Options) headDim() int {
+	return cmp.Or(o.keyLength, o.valueLength, o.hiddenSize/o.numHeads)
+}
+
+func New(c fs.Config) (model.Model, error) {
+	var processor model.TextProcessor
+	switch c.String("tokenizer.ggml.model", "bert") {
+	case "bert":
+		processor = model.NewWordPiece(
+			&model.Vocabulary{
+				Values: c.Strings("tokenizer.ggml.tokens"),
+				Scores: c.Floats("tokenizer.ggml.scores"),
+				Types:  c.Ints("tokenizer.ggml.token_type"),
+				AddBOS: c.Bool("tokenizer.ggml.add_bos_token", true),
+				BOS: []int32{
+					int32(cmp.Or(
+						c.Uint("tokenizer.ggml.cls_token_id"),
+						c.Uint("tokenizer.ggml.bos_token_id"),
+					)),
+				},
+				AddEOS: c.Bool("tokenizer.ggml.add_eos_token", true),
+				EOS: []int32{
+					int32(cmp.Or(
+						c.Uint("tokenizer.ggml.separator_token_id"),
+						//nolint:misspell
+						// NOTE: "seperator_token_id" is a typo in model metadata but we need to
+						// support it for compatibility.
+						c.Uint("tokenizer.ggml.seperator_token_id"),
+						c.Uint("tokenizer.ggml.eos_token_id"),
+					)),
+				},
+			},
+		)
+	default:
+		return nil, model.ErrUnsupportedTokenizer
+	}
+
+	return &Model{
+		TextProcessor: processor,
+		Layers:        make([]EncoderLayer, c.Uint("block_count")),
+		Options: Options{
+			hiddenSize:  int(c.Uint("embedding_length")),
+			numHeads:    int(c.Uint("attention.head_count")),
+			numKVHeads:  int(c.Uint("attention.head_count_kv")),
+			eps:         c.Float("attention.layer_norm_epsilon"),
+			poolingType: pooling.Type(c.Uint("pooling_type")),
+			normalize:   c.Bool("normalize_embeddings", true),
+		},
+	}, nil
+}
+
+func init() {
+	model.Register("bert", New)
+	model.Register("bert_embed", New)
+}

model/models/gemma2/model.go

@@ -24,7 +24,7 @@ type Options struct {
 
 type Model struct {
 	model.Base
-	model.SentencePieceModel
+	model.SentencePiece
 
 	TokenEmbedding *nn.Embedding `gguf:"token_embd"`
 	Layers         []Layer       `gguf:"blk"`
@@ -40,7 +40,7 @@ const (
 
 func New(c fs.Config) (model.Model, error) {
 	m := Model{
-		SentencePieceModel: model.NewSentencePieceModel(
+		SentencePiece: model.NewSentencePiece(
 			&model.Vocabulary{
 				Values: c.Strings("tokenizer.ggml.tokens"),
 				Scores: c.Floats("tokenizer.ggml.scores"),

model/models/gemma3/embed.go

@@ -1,48 +1,38 @@
 package gemma3
 
 import (
-	"errors"
-
 	"github.com/ollama/ollama/fs"
 	"github.com/ollama/ollama/kvcache"
 	"github.com/ollama/ollama/ml"
 	"github.com/ollama/ollama/ml/nn"
+	"github.com/ollama/ollama/ml/nn/pooling"
 	"github.com/ollama/ollama/model"
 	"github.com/ollama/ollama/model/input"
 )
 
 type embedModel struct {
 	model.Base
-	model.SentencePieceModel
+	model.SentencePiece
 
 	*TextModel
-	PoolingType uint32
+	poolingType pooling.Type
 
 	Dense [2]*nn.Linear `gguf:"dense"`
 }
 
 func (m *embedModel) Forward(ctx ml.Context, batch input.Batch) (ml.Tensor, error) {
 	hiddenStates := m.TextModel.Forward(ctx, batch, m.Cache)
-
+	hiddenStates = pooling.Pooling(ctx, hiddenStates, m.poolingType)
-	switch m.PoolingType {
-	case 0: // None
-	case 1: // Mean
-		hiddenStates = hiddenStates.Permute(ctx, 1, 0, 2, 3).Contiguous(ctx).Mean(ctx)
-		hiddenStates = hiddenStates.Permute(ctx, 1, 0, 2, 3).Contiguous(ctx)
-	default:
-		return nil, errors.New("unsupported pooling type")
-	}
-
 	for _, dense := range m.Dense {
 		hiddenStates = dense.Forward(ctx, hiddenStates)
 	}
-
+	hiddenStates = hiddenStates.L2Norm(ctx, 1e-12)
 	return hiddenStates, nil
 }
 
 func newEmbedModel(c fs.Config) (model.Model, error) {
 	m := &embedModel{
-		SentencePieceModel: model.NewSentencePieceModel(
+		SentencePiece: model.NewSentencePiece(
 			&model.Vocabulary{
 				Values: c.Strings("tokenizer.ggml.tokens"),
 				Scores: c.Floats("tokenizer.ggml.scores"),
@@ -60,7 +50,7 @@ func newEmbedModel(c fs.Config) (model.Model, error) {
 			},
 		),
 		TextModel:   newTextModel(c),
-		PoolingType: c.Uint("pooling_type", 0),
+		poolingType: pooling.Type(c.Uint("pooling_type", 0)),
 	}
 
 	m.Cache = kvcache.NewWrapperCache(

model/models/gemma3/model.go

@@ -16,7 +16,7 @@ import (
 
 type Model struct {
 	model.Base
-	model.SentencePieceModel
+	model.SentencePiece
 
 	*VisionModel `gguf:"v"`
 	*TextModel
@@ -55,7 +55,7 @@ func (p *MultiModalProjector) Forward(ctx ml.Context, visionOutputs ml.Tensor, i
 
 func New(c fs.Config) (model.Model, error) {
 	m := Model{
-		SentencePieceModel: model.NewSentencePieceModel(
+		SentencePiece: model.NewSentencePiece(
 			&model.Vocabulary{
 				Values: c.Strings("tokenizer.ggml.tokens"),
 				Scores: c.Floats("tokenizer.ggml.scores"),

model/models/gemma3n/model.go

@@ -10,7 +10,7 @@ import (
 
 type Model struct {
 	model.Base
-	model.SentencePieceModel
+	model.SentencePiece
 
 	*TextModel
 }
@@ -23,7 +23,7 @@ func (m *Model) Forward(ctx ml.Context, batch input.Batch) (ml.Tensor, error) {
 func New(c fs.Config) (model.Model, error) {
 	m := Model{
 		TextModel: newTextModel(c),
-		SentencePieceModel: model.NewSentencePieceModel(
+		SentencePiece: model.NewSentencePiece(
 			&model.Vocabulary{
 				Values: c.Strings("tokenizer.ggml.tokens"),
 				Scores: c.Floats("tokenizer.ggml.scores"),

model/models/models.go

@@ -1,6 +1,7 @@
 package models
 
 import (
+	_ "github.com/ollama/ollama/model/models/bert"
 	_ "github.com/ollama/ollama/model/models/gemma2"
 	_ "github.com/ollama/ollama/model/models/gemma3"
 	_ "github.com/ollama/ollama/model/models/gemma3n"

model/sentencepiece.go

@@ -12,18 +12,18 @@ import (
 
 const spmWhitespaceSep = "▁"
 
-type SentencePieceModel struct {
+type SentencePiece struct {
 	maxTokenLen int
 	vocab       *Vocabulary
 }
 
-var _ TextProcessor = (*SentencePieceModel)(nil)
+var _ TextProcessor = (*SentencePiece)(nil)
 
-func (spm SentencePieceModel) Vocabulary() *Vocabulary {
+func (spm SentencePiece) Vocabulary() *Vocabulary {
 	return spm.vocab
 }
 
-func NewSentencePieceModel(vocab *Vocabulary) SentencePieceModel {
+func NewSentencePiece(vocab *Vocabulary) SentencePiece {
 	logutil.Trace("Tokens", "num tokens", len(vocab.Values), "vals", vocab.Values[:5], "scores", vocab.Scores[:5], "types", vocab.Types[:5])
 
 	counter := map[int]int{}
@@ -42,17 +42,17 @@ func NewSentencePieceModel(vocab *Vocabulary) SentencePieceModel {
 		"user defined", counter[TOKEN_TYPE_USER_DEFINED], "unused", counter[TOKEN_TYPE_UNUSED], "byte", counter[TOKEN_TYPE_BYTE],
 		"max token len", maxTokenLen)
 
-	return SentencePieceModel{
+	return SentencePiece{
 		maxTokenLen: maxTokenLen,
 		vocab:       vocab,
 	}
 }
 
-func (spm SentencePieceModel) Is(id int32, special Special) bool {
+func (spm SentencePiece) Is(id int32, special Special) bool {
 	return spm.vocab.Is(id, special)
 }
 
-func (spm SentencePieceModel) Encode(s string, addSpecial bool) ([]int32, error) {
+func (spm SentencePiece) Encode(s string, addSpecial bool) ([]int32, error) {
 	fragments := []fragment{{value: s}}
 	for _, special := range spm.vocab.SpecialVocabulary() {
 		id := spm.vocab.Encode(special)
@@ -218,7 +218,7 @@ func (q *queue) Pop() interface{} {
 	return item
 }
 
-func (spm SentencePieceModel) Decode(ids []int32) (string, error) {
+func (spm SentencePiece) Decode(ids []int32) (string, error) {
 	var sb strings.Builder
 	for _, id := range ids {
 		data := spm.vocab.Decode(id)

model/sentencepiece_test.go

@@ -12,7 +12,7 @@ import (
 	"github.com/ollama/ollama/convert/sentencepiece"
 )
 
-func loadSentencePieceVocab(t *testing.T) SentencePieceModel {
+func loadSentencePieceVocab(t *testing.T) SentencePiece {
 	t.Helper()
 
 	bts, err := os.ReadFile(filepath.Join("testdata", "gemma2", "tokenizer.model"))
@@ -45,7 +45,7 @@ func loadSentencePieceVocab(t *testing.T) SentencePieceModel {
 		}
 	}
 
-	return NewSentencePieceModel(&v)
+	return NewSentencePiece(&v)
 }
 
 func TestSentencePieceEncode(t *testing.T) {
@@ -115,7 +115,7 @@ func TestSentencePieceEncode(t *testing.T) {
 	})
 }
 
-func TestSentencePieceModelDecodeByteTokens(t *testing.T) {
+func TestSentencePieceDecodeByteTokens(t *testing.T) {
 	vocab := &Vocabulary{
 		Values: []string{
 			"normal",
@@ -134,7 +134,7 @@ func TestSentencePieceModelDecodeByteTokens(t *testing.T) {
 		Scores: []float32{0, 0, 0, 0, 0},
 	}
 
-	spm := NewSentencePieceModel(vocab)
+	spm := NewSentencePiece(vocab)
 
 	tests := []struct {
 		name     string

model/wordpiece.go

@@ -0,0 +1,167 @@
+package model
+
+import (
+	"fmt"
+	"iter"
+	"strings"
+	"unicode"
+
+	"github.com/ollama/ollama/logutil"
+)
+
+type WordPiece struct {
+	vocab *Vocabulary
+}
+
+// ggmlPrefix is the prefix used by GGML vocabularies to indicate word boundaries.
+// this differs from original word piece which uses "##" to indicate subwords.
+const ggmlPrefix = "▁"
+
+var wordPieceReplacer = strings.NewReplacer(
+	" .", ".",
+	" ?", "?",
+	" !", "!",
+	" ,", ",",
+	" ' ", "'",
+	" n't", "n't",
+	" 'm", "'m",
+	" do not", " don't",
+	" 's", "'s",
+	" 've", "'ve",
+	" 're", "'re",
+)
+
+// Decode implements TextProcessor.
+func (wpm WordPiece) Decode(ids []int32) (string, error) {
+	var sb strings.Builder
+	for i, id := range ids {
+		if id < 0 || int(id) >= len(wpm.vocab.Values) {
+			return "", fmt.Errorf("invalid token id: %d", id)
+		}
+
+		var separator string
+		piece := wpm.vocab.Values[id]
+		if i > 0 &&
+			(strings.HasPrefix(piece, ggmlPrefix) ||
+				(strings.HasPrefix(piece, "[") && strings.HasSuffix(piece, "]"))) {
+			separator = " "
+		}
+
+		sb.WriteString(wordPieceReplacer.Replace(separator + strings.TrimPrefix(piece, ggmlPrefix)))
+	}
+
+	return sb.String(), nil
+}
+
+// words splits a string into words, treating CJK characters as separate words.
+// TODO: this is specifically for BERT and may need to be adjusted or refactored for other models.
+func (wpm WordPiece) words(s string) iter.Seq[string] {
+	return func(yield func(string) bool) {
+		runes := make([]rune, 0, len(s)*3)
+		for _, r := range s {
+			switch {
+			case r >= 0x4E00 && r <= 0x9FFF,
+				r >= 0x3400 && r <= 0x4DBF,
+				r >= 0x20000 && r <= 0x2A6DF,
+				r >= 0x2A700 && r <= 0x2B73F,
+				r >= 0x2B740 && r <= 0x2B81F,
+				r >= 0x2B820 && r <= 0x2CEAF,
+				r >= 0xF900 && r <= 0xFAFF,
+				r >= 0x2F800 && r <= 0x2FA1F:
+				runes = append(runes, ' ', r, ' ')
+			default:
+				runes = append(runes, r)
+			}
+		}
+
+		for w := range strings.FieldsFuncSeq(string(runes), unicode.IsSpace) {
+			// split on but keep punctuation
+			var start int
+			for start < len(w) {
+				end := strings.IndexFunc(w[start:], unicode.IsPunct)
+				if end < 0 {
+					end = len(w) - start
+				} else if end == 0 {
+					end = 1
+				}
+
+				if !yield(w[start : start+end]) {
+					return
+				}
+
+				start += end
+			}
+		}
+	}
+}
+
+// Encode implements TextProcessor.
+func (wpm WordPiece) Encode(s string, addSpecial bool) ([]int32, error) {
+	var ids []int32
+
+	// TODO: use [UNK] from config
+	unk := wpm.vocab.Encode("[UNK]")
+	for word := range wpm.words(s) {
+		var start int
+		var pieces []int32
+		for start < len(word) {
+			end := len(word)
+
+			var piece int32
+			for start < end {
+				subword := word[start:end]
+				if start == 0 {
+					subword = ggmlPrefix + subword
+				}
+
+				// TODO: some models might not want [ToLower]
+				piece = wpm.vocab.Encode(strings.ToLower(subword))
+				if piece >= 0 {
+					break
+				}
+
+				end--
+			}
+
+			if piece < 0 {
+				// Unknown token
+				pieces = pieces[:0]
+				break
+			}
+
+			pieces = append(pieces, piece)
+			start = end
+		}
+
+		if len(pieces) > 0 {
+			ids = append(ids, pieces...)
+		} else {
+			ids = append(ids, unk)
+		}
+	}
+
+	if addSpecial && len(ids) > 0 {
+		ids = wpm.vocab.addSpecials(ids)
+	}
+
+	logutil.Trace("encoded", "string", s, "ids", ids)
+	return ids, nil
+}
+
+// Is implements TextProcessor.
+func (wpm WordPiece) Is(id int32, special Special) bool {
+	return wpm.vocab.Is(id, special)
+}
+
+// Vocabulary implements TextProcessor.
+func (wpm WordPiece) Vocabulary() *Vocabulary {
+	return wpm.vocab
+}
+
+var _ TextProcessor = (*WordPiece)(nil)
+
+func NewWordPiece(vocab *Vocabulary) WordPiece {
+	return WordPiece{
+		vocab: vocab,
+	}
+}

model/wordpiece_test.go

@@ -0,0 +1,51 @@
+package model
+
+import (
+	"slices"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+func TestWordPiece(t *testing.T) {
+	wpm := NewWordPiece(
+		&Vocabulary{
+			Values: []string{"[UNK]", "[CLS]", "[SEP]", "▁hello", "▁world", "s", "▁!", "▁@", "▁#"},
+			AddBOS: true,
+			AddEOS: true,
+			BOS:    []int32{1},
+			EOS:    []int32{2},
+		})
+
+	ids, err := wpm.Encode("Hello world!", true)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if diff := cmp.Diff([]int32{1, 3, 4, 6, 2}, ids); diff != "" {
+		t.Errorf("unexpected ids (-want +got):\n%s", diff)
+	}
+
+	words, err := wpm.Decode(ids)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if diff := cmp.Diff("[CLS] hello world! [SEP]", words); diff != "" {
+		t.Errorf("unexpected words (-want +got):\n%s", diff)
+	}
+}
+
+func TestWordPieceWords(t *testing.T) {
+	var wpm WordPiece
+
+	basic := slices.Collect(wpm.words("Hey friend!     How are you?!?"))
+	if diff := cmp.Diff([]string{"Hey", "friend", "!", "How", "are", "you", "?", "!", "?"}, basic); diff != "" {
+		t.Errorf("unexpected words (-want +got):\n%s", diff)
+	}
+
+	chinese := slices.Collect(wpm.words("野口里佳 Noguchi Rika"))
+	if diff := cmp.Diff([]string{"野", "口", "里", "佳", "Noguchi", "Rika"}, chinese); diff != "" {
+		t.Errorf("unexpected words (-want +got):\n%s", diff)
+	}
+}

server/routes.go

@@ -488,7 +488,6 @@ func (s *Server) EmbedHandler(c *gin.Context) {
 	}
 
 	truncate := true
-
 	if req.Truncate != nil && !*req.Truncate {
 		truncate = false
 	}
@@ -555,7 +554,16 @@ func (s *Server) EmbedHandler(c *gin.Context) {
 				return
 			}
 
+			if bos := kvData.Uint("tokenizer.ggml.bos_token_id"); tokens[0] != int(bos) && kvData.Bool("add_bos_token", true) {
+				ctxLen--
+			}
+
+			if eos := kvData.Uint("tokenizer.ggml.eos_token_id"); tokens[len(tokens)-1] != int(eos) && kvData.Bool("add_eos_token", true) {
+				ctxLen--
+			}
+
 			tokens = tokens[:ctxLen]
+
 			s, err = r.Detokenize(c.Request.Context(), tokens)
 			if err != nil {
 				c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})