sample: use json unmarshal for sampling params

This change allows the gemma3 template to be autodetected during `ollama
create`.

convert/convert.go

@@ -201,7 +201,7 @@ func ConvertModel(fsys fs.FS, ws io.WriteSeeker) error {
 	case "CohereForCausalLM":
 		conv = &commandrModel{}
 	default:
-		return errors.New("unsupported architecture")
+		return fmt.Errorf("unsupported architecture %q", p.Architectures[0])
 	}
 
 	if err := json.Unmarshal(bts, conv); err != nil {

ml/backend/ggml/ggml.go

@@ -330,7 +330,7 @@ func New(r *os.File, params ml.BackendParams) (ml.Backend, error) {
 		}
 	}
 
-	if g.Wait() != nil {
+	if err := g.Wait(); err != nil {
 		return nil, err
 	}
 

model/models/gemma2/model.go

@@ -179,7 +179,7 @@ func (m *Model) Forward(ctx ml.Context, opts input.Options) (ml.Tensor, error) {
 		return nil, err
 	}
 
-	outputs, err := ctx.Output().FromIntSlice(opts.Outputs, len(opts.Outputs))
+	outputs, err := ctx.Input().FromIntSlice(opts.Outputs, len(opts.Outputs))
 	if err != nil {
 		return nil, err
 	}
@@ -211,8 +211,7 @@ func (m *Model) Forward(ctx ml.Context, opts input.Options) (ml.Tensor, error) {
 	// final logit softcap
 	hiddenState = hiddenState.Scale(ctx, 1.0/float64(m.Options.finalLogitSoftcap))
 	hiddenState = hiddenState.Tanh(ctx)
-	hiddenState = hiddenState.Scale(ctx, float64(m.Options.finalLogitSoftcap))
+	return hiddenState.Scale(ctx, float64(m.Options.finalLogitSoftcap)), nil
-	return hiddenState.Rows(ctx, outputs), nil
 }
 
 func init() {

model/models/gemma3/model.go

@@ -150,7 +150,7 @@ func (m *Model) Forward(ctx ml.Context, opts input.Options) (ml.Tensor, error) {
 		return nil, err
 	}
 
-	outputs, err := ctx.Output().FromIntSlice(opts.Outputs, len(opts.Outputs))
+	outputs, err := ctx.Input().FromIntSlice(opts.Outputs, len(opts.Outputs))
 	if err != nil {
 		return nil, err
 	}

model/models/llama/model.go

@@ -150,7 +150,7 @@ func (m *Model) Forward(ctx ml.Context, opts input.Options) (ml.Tensor, error) {
 		return nil, err
 	}
 
-	outputs, err := ctx.Output().FromIntSlice(opts.Outputs, len(opts.Outputs))
+	outputs, err := ctx.Input().FromIntSlice(opts.Outputs, len(opts.Outputs))
 	if err != nil {
 		return nil, err
 	}

model/models/mllama/model.go

@@ -154,7 +154,7 @@ func (m *Model) Forward(ctx ml.Context, opts input.Options) (ml.Tensor, error) {
 		return nil, err
 	}
 
-	outputs, err := ctx.Output().FromIntSlice(opts.Outputs, len(opts.Outputs))
+	outputs, err := ctx.Input().FromIntSlice(opts.Outputs, len(opts.Outputs))
 	if err != nil {
 		return nil, err
 	}

runner/ollamarunner/runner.go

@@ -561,14 +561,7 @@ func (s *Server) completion(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	sampler := sample.NewSampler(
+	sampler := sample.NewSampler(req.Options, grammar)
-		req.Options.Temperature,
-		req.Options.TopK,
-		req.Options.TopP,
-		req.Options.MinP,
-		req.Options.Seed,
-		grammar,
-	)
 
 	seq, err := s.NewSequence(req.Prompt, req.Images, NewSequenceParams{
 		numPredict: req.Options.NumPredict,

sample/samplers.go

@@ -1,12 +1,14 @@
 package sample
 
 import (
+	"encoding/json"
 	"errors"
 	"math"
 	"math/rand/v2"
 	"slices"
 	"sync"
 
+	"github.com/ollama/ollama/api"
 	"github.com/ollama/ollama/llama"
 )
 
@@ -26,6 +28,10 @@ type Sampler struct {
 }
 
 func (s *Sampler) Sample(logits []float32) (int32, error) {
+	if len(logits) == 0 {
+		return -1, errors.New("sample: no logits provided to sample")
+	}
+
 	tokens := make([]token, len(logits))
 	for i := range logits {
 		tokens[i].id = int32(i)
@@ -94,13 +100,6 @@ func (s *Sampler) sample(tokens []token) (token, error) {
 	tokens = topP(tokens, s.topP)
 	tokens = minP(tokens, s.minP)
 
-	// TODO: this should fall back to greedy sampling
-	// or topP, topK values etc should be such that
-	// there are always tokens to sample from
-	if len(tokens) == 0 {
-		return token{}, errors.New("no tokens to sample from")
-	}
-
 	var r float32
 	if s.rng != nil {
 		r = s.rng.Float32()
@@ -123,43 +122,71 @@ func (s *Sampler) sample(tokens []token) (token, error) {
 		return 1
 	})
 
+	if math.IsNaN(float64(sum)) {
+		return token{}, errors.New("sample: logits sum to NaN, check model output")
+	}
 	return tokens[idx], nil
 }
 
-// TODO(parthsareen): update sampler interface to use json unmarshal https://github.com/ollama/ollama/issues/9278
+// SamplerParams contains the validated and normalized parameters for a sampler
-func NewSampler(temperature float32, topK int, topP float32, minP float32, seed int, grammar *Grammar) Sampler {
+type SamplerParams struct {
+	Temperature float32 `json:"temperature"`
+	TopK        int     `json:"top_k"`
+	TopP        float32 `json:"top_p"`
+	MinP        float32 `json:"min_p"`
+	Seed        int     `json:"seed"`
+}
+
+// UnmarshalJSON implements json.Unmarshaler to handle validation during JSON unmarshaling
+func (p *SamplerParams) UnmarshalJSON(data []byte) error {
+	type rawParams SamplerParams
+	if err := json.Unmarshal(data, (*rawParams)(p)); err != nil {
+		return err
+	}
+
+	// Validate and normalize after unmarshaling
+	if p.Temperature < 0.0 {
+		p.Temperature = 0.0
+	}
+
+	if p.TopP < 0.0 {
+		p.TopP = 0.0
+	}
+	if p.TopP >= 1.0 {
+		p.TopP = 1.0
+	}
+
+	if p.MinP < 0.0 {
+		p.MinP = 0.0
+	}
+	if p.MinP >= 1.0 {
+		p.MinP = 1.0
+	}
+
+	return nil
+}
+
+// NewSampler creates a new sampler with the given options
+func NewSampler(opts *api.Options, grammar *Grammar) Sampler {
+	var params SamplerParams
+	data, _ := json.Marshal(opts)
+	_ = json.Unmarshal(data, &params)
+
 	var rng *rand.Rand
-	if seed != -1 {
+	if params.Seed != -1 {
 		// PCG requires two parameters: sequence and stream
 		// Use original seed for sequence
-		sequence := uint64(seed)
+		sequence := uint64(params.Seed)
 		// Use golden ratio hash to generate statistically independent seeds
 		rng = rand.New(rand.NewPCG(sequence, sequence^0x9E3779B9))
 	}
-	if temperature < 0.0 {
-		temperature = 0.0
-	}
-
-	if topP < 0.0 {
-		topP = 0.0
-	}
-	if topP >= 1.0 {
-		topP = 1.0
-	}
-
-	if minP < 0.0 {
-		minP = 0.0
-	}
-	if minP >= 1.0 {
-		minP = 1.0
-	}
 
 	return Sampler{
 		rng:         rng,
-		topK:        topK,
+		topK:        params.TopK,
-		topP:        topP,
+		topP:        params.TopP,
-		minP:        minP,
+		minP:        params.MinP,
-		temperature: temperature,
+		temperature: params.Temperature,
 		grammar:     grammar,
 	}
 }

sample/samplers_benchmark_test.go

@@ -16,7 +16,7 @@ func BenchmarkWeightedSampler(b *testing.B) {
 				logits[i] = float32(rand.Float64()*10 - 5)
 			}
 
-			sampler := NewSampler(0.8, 0, 0, 0, 42, nil)
+			sampler := NewSampler(createSamplerOptions(0.8, 0, 0, 0, 42), nil)
 			b.ResetTimer()
 			for b.Loop() {
 				sampler.Sample(logits)
@@ -49,7 +49,7 @@ func BenchmarkWeightedSampler(b *testing.B) {
 
 	for _, tc := range configs {
 		b.Run("Config"+tc.name, func(b *testing.B) {
-			sampler := NewSampler(tc.temperature, tc.topK, tc.topP, tc.minP, tc.seed, nil)
+			sampler := NewSampler(createSamplerOptions(tc.temperature, tc.topK, tc.topP, tc.minP, tc.seed), nil)
 			sampler.Sample(logits)
 
 			b.ResetTimer()
@@ -62,7 +62,7 @@ func BenchmarkWeightedSampler(b *testing.B) {
 
 	// Test with combined transforms separately - topK influences performance greatly
 	b.Run("TransformCombined", func(b *testing.B) {
-		sampler := NewSampler(0.8, 50, 0.9, 0.05, 42, nil)
+		sampler := NewSampler(createSamplerOptions(0.8, 50, 0.9, 0.05, 42), nil)
 		b.ResetTimer()
 
 		for b.Loop() {
@@ -81,7 +81,7 @@ func BenchmarkGreedySampler(b *testing.B) {
 				logits[i] = float32(rand.Float64()*10 - 5)
 			}
 
-			sampler := NewSampler(0, -1, 0, 0, -1, nil)
+			sampler := NewSampler(createSamplerOptions(0, -1, 0, 0, -1), nil)
 			b.ResetTimer()
 
 			for b.Loop() {

sample/samplers_test.go

@@ -1,13 +1,26 @@
 package sample
 
 import (
+	"math"
 	"math/rand/v2"
 	"testing"
+
+	"github.com/ollama/ollama/api"
 )
 
+func createSamplerOptions(temperature float32, topK int, topP float32, minP float32, seed int) *api.Options {
+	return &api.Options{
+		Temperature: temperature,
+		TopK:        topK,
+		TopP:        topP,
+		MinP:        minP,
+		Seed:        seed,
+	}
+}
+
 func TestWeighted(t *testing.T) {
 	logits := []float32{-10, 3, -10, -10}
-	sampler := NewSampler(0, 0, 0, 0, 0, nil)
+	sampler := NewSampler(createSamplerOptions(0, 0, 0, 0, 0), nil)
 	got, err := sampler.Sample(logits)
 	if err != nil {
 		t.Error(err)
@@ -19,7 +32,7 @@ func TestWeighted(t *testing.T) {
 	}
 
 	logits = []float32{-100, -10, 0, 10}
-	sampler = NewSampler(0, 0, 0, 0, 0, nil)
+	sampler = NewSampler(createSamplerOptions(0, 0, 0, 0, 0), nil)
 	got, err = sampler.Sample(logits)
 	if err != nil {
 		t.Error(err)
@@ -29,12 +42,35 @@ func TestWeighted(t *testing.T) {
 	if want != got {
 		t.Errorf("index mismatch: want %d, got %d", want, got)
 	}
+
+	// Test very high p
+	logits = []float32{1.0, 0.9999999999999999, 0.5, 0.1}
+	// Use extremely small topP to filter out all tokens
+	sampler = NewSampler(createSamplerOptions(1.0, 0, 1e-10, 0, 0), nil)
+	got, err = sampler.Sample(logits)
+	if err != nil {
+		t.Error(err)
+		return
+	}
+	// Should get the token with the highest logit
+	want = int32(0)
+	if want != got {
+		t.Errorf("index mismatch: want %d, got %d", want, got)
+	}
+
+	logits = []float32{float32(math.NaN()), float32(math.NaN()), float32(math.NaN())}
+	sampler = NewSampler(createSamplerOptions(1, 0, 0.95, 0.05, 0), nil)
+	got, err = sampler.Sample(logits)
+	if err == nil {
+		t.Errorf("expected error, got %d", got)
+		return
+	}
 }
 
 func BenchmarkSample(b *testing.B) {
 	samplers := map[string]Sampler{
-		"Greedy":   NewSampler(0, 0, 0, 0, 0, nil), // Use NewSampler with temp=0 for greedy
+		"Greedy":   NewSampler(createSamplerOptions(0, 0, 0, 0, 0), nil), // Use NewSampler with temp=0 for greedy
-		"Weighted": NewSampler(0.5, 10, 0.9, 0.2, -1, nil),
+		"Weighted": NewSampler(createSamplerOptions(0.5, 10, 0.9, 0.2, -1), nil),
 	}
 
 	// Generate random logits for benchmarking

sample/transforms_test.go

@@ -168,27 +168,53 @@ func TestTopP(t *testing.T) {
 	softmax(tokens)
 	tokens = topK(tokens, 20)
 
-	// Then apply topP
+	// Test with very high p value
-	tokens = topP(tokens, 0.95)
+	got := topP(tokens, 1.0)
 
-	// Should keep tokens until cumsum > 0.95
+	// Should keep all tokens since p is 1
-	if len(tokens) > 3 {
+	if len(got) != len(input) {
+		t.Errorf("topP(1.0): should keep all tokens, got %d, want %d", len(got), len(input))
+	}
+
+	// Test with normal p value
+	got = topP(tokens, 0.95)
+
+	if len(got) > 3 {
 		t.Errorf("topP(0.95): kept too many tokens: got %d", len(tokens))
-		t.Logf("got: %v", tokens)
+		t.Logf("got: %v", got)
 	}
 
 	// Test edge case - ensure at least one token remains
-	input = []float32{-1e6, -1e6, -1e6} // One dominant token
+	input = []float32{-1e6, -1e6, -1e7}
 	tokens = toTokens(input)
+	tokens = topK(tokens, 20)
 	softmax(tokens)
-	tokens = topP(tokens, 0.0) // Very small p
+	got = topP(tokens, 0.0)
-	if len(tokens) < 1 {
+	if len(got) < 1 {
 		t.Error("topP should keep at least one token")
 	}
+
+	// Test with zero p value
+	got = topP(tokens, 0.0)
+
+	// Should keep only the highest probability token
+	if len(got) != 1 {
+		t.Errorf("topP(0.0): should keep only one token, got %d", len(got))
+		t.Logf("got: %v", got)
+	}
+
+	tokens = toTokens(input)
+	tokens = topK(tokens, 20)
+	softmax(tokens)
+	got = topP(tokens, 1e-10)
+	if len(got) == 0 {
+		t.Errorf("topP(1e-10): should keep at least one token, got %d", len(got))
+		t.Logf("got: %v", got)
+	}
 }
 
 func TestMinP(t *testing.T) {
-	input := []float32{-3, -2, -1, 0, 1, 2, 4, 3}
+	input := []float32{-2, 0, -1, -3, 2, 1, 4, 3}
 	tokens := toTokens(input)
 
 	// First apply temperature and softmax
@@ -225,30 +251,48 @@ func TestMinP(t *testing.T) {
 		t.Logf("got: %v", tokens)
 	}
 
+	// Test with single token
+	tokens = toTokens(input[:1])
+	tokens = topK(tokens, 20)
+	softmax(tokens)
+	tokens = minP(tokens, 0.1)
+
+	// Should keep only the highest probability token
+	if len(tokens) != 1 {
+		t.Errorf("minP(0.1): should return single token, got %d", len(tokens))
+		t.Logf("got: %v", tokens)
+	}
+
 	input = []float32{1e-10, 1e-10, 1e-10}
 	tokens = toTokens(input)
 	softmax(tokens)
 	tokens = minP(tokens, 1.0)
 	if len(tokens) < 1 {
 		t.Error("minP should keep at least one token even with extreme probabilities")
-	}
+		got := minP(tokens, 1.0)
+
+		if len(got) != 1 {
+			t.Errorf("minP(1.0): should keep all tokens, got %d, want %d", len(got), len(tokens))
 		}
 
-func TestSortLogits(t *testing.T) {
+		// Test with normal p value
-	input := []float32{0.026986899, 0.043722924, 0.036774673, 0.27755088, 0.0046718004, 0.08582123, 0.20409796, 0.00412893, 0.15720603, 0.045046154, 0.0030491839, 0.01681367}
+		got = minP(tokens, 0.2)
-	tokens := toTokens(input)
 
-	tokens = topK(tokens, 20)
+		// Should keep tokens with prob >= 0.2 * max_prob
-
+		if len(got) > 3 {
-	for i := 1; i < len(tokens); i++ {
+			t.Errorf("minP(0.2): kept too many tokens: got %d", len(got))
-		if tokens[i].value > tokens[i-1].value {
+			t.Logf("got: %v", got)
-			t.Errorf("sortLogits: tokens not sorted in descending order at index %d: %f > %f",
-				i, tokens[i].value, tokens[i-1].value)
-		}
 		}
 
-	want := []float32{0.27755088, 0.20409796, 0.15720603, 0.08582123, 0.045046154, 0.043722924, 0.036774673, 0.026986899, 0.01681367, 0.0046718004, 0.00412893, 0.0030491839}
+		// Test with zero p value
-	compareLogits(t, "sortLogits", want, tokens)
+		got = minP(tokens, 0.0)
+
+		// Should keep only the highest probability token
+		if len(got) != len(tokens) {
+			t.Errorf("minP(0.0): should keep only one token, got %d", len(got))
+			t.Logf("got: %v", got)
+		}
+	}
 }
 
 func BenchmarkTransforms(b *testing.B) {

server/internal/client/ollama/registry.go

@@ -37,7 +37,6 @@ import (
 	"golang.org/x/sync/errgroup"
 
 	"github.com/ollama/ollama/server/internal/cache/blob"
-	"github.com/ollama/ollama/server/internal/internal/backoff"
 	"github.com/ollama/ollama/server/internal/internal/names"
 
 	_ "embed"
@@ -213,12 +212,6 @@ type Registry struct {
 	// request. If zero, [DefaultChunkingThreshold] is used.
 	ChunkingThreshold int64
 
-	// MaxChunkSize is the maximum size of a chunk to download. If zero,
-	// the default is [DefaultMaxChunkSize].
-	//
-	// It is only used when a layer is larger than [MaxChunkingThreshold].
-	MaxChunkSize int64
-
 	// Mask, if set, is the name used to convert non-fully qualified names
 	// to fully qualified names. If empty, [DefaultMask] is used.
 	Mask string
@@ -447,6 +440,11 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 	if err != nil {
 		return err
 	}
+
+	// TODO(bmizerany): decide if this should be considered valid. Maybe
+	// server-side we special case '{}' to have some special meaning? Maybe
+	// "archiving" a tag (which is how we reason about it in the registry
+	// already, just with a different twist).
 	if len(m.Layers) == 0 {
 		return fmt.Errorf("%w: no layers", ErrManifestInvalid)
 	}
@@ -456,11 +454,7 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 		return err
 	}
 
-	exists := func(l *Layer) bool {
+	// TODO(bmizerany): work to remove the need to do this
-		info, err := c.Get(l.Digest)
-		return err == nil && info.Size == l.Size
-	}
-
 	layers := m.Layers
 	if m.Config != nil && m.Config.Digest.IsValid() {
 		layers = append(layers, m.Config)
@@ -469,19 +463,16 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 	// Send initial layer trace events to allow clients to have an
 	// understanding of work to be done before work starts.
 	t := traceFromContext(ctx)
-	skip := make([]bool, len(layers))
+	for _, l := range layers {
-	for i, l := range layers {
 		t.update(l, 0, nil)
-		if exists(l) {
-			skip[i] = true
-			t.update(l, l.Size, ErrCached)
-		}
 	}
 
-	g, ctx := errgroup.WithContext(ctx)
+	var g errgroup.Group
 	g.SetLimit(r.maxStreams())
-	for i, l := range layers {
+	for _, l := range layers {
-		if skip[i] {
+		info, err := c.Get(l.Digest)
+		if err == nil && info.Size == l.Size {
+			t.update(l, l.Size, ErrCached)
 			continue
 		}
 
@@ -490,23 +481,26 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 			t.update(l, 0, err)
 			continue
 		}
+		// TODO(bmizerany): fix this unbounded use of defer
 		defer chunked.Close()
 
 		var progress atomic.Int64
 		for cs, err := range r.chunksums(ctx, name, l) {
 			if err != nil {
+				// Bad chunksums response, update tracing
+				// clients and then bail.
 				t.update(l, progress.Load(), err)
-				break
+				return err
 			}
 
 			g.Go(func() (err error) {
-				defer func() { t.update(l, progress.Load(), err) }()
+				defer func() {
-
-				for _, err := range backoff.Loop(ctx, 3*time.Second) {
 					if err != nil {
-						return err
+						err = fmt.Errorf("error downloading %s: %w", cs.Digest.Short(), err)
 					}
-					err := func() error {
+					t.update(l, progress.Load(), err)
+				}()
+
 				req, err := http.NewRequestWithContext(ctx, "GET", cs.URL, nil)
 				if err != nil {
 					return err
@@ -518,35 +512,19 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 				}
 				defer res.Body.Close()
 
-						// Count bytes towards
+				// Count bytes towards progress, as they
-						// progress, as they arrive, so
+				// arrive, so that our bytes piggyback other
-						// that our bytes piggyback
+				// chunk updates on completion.
-						// other chunk updates on
-						// completion.
 				//
-						// This tactic is enough to
+				// This tactic is enough to show "smooth"
-						// show "smooth" progress given
+				// progress given the current CLI client. In
-						// the current CLI client. In
+				// the near future, the server should report
-						// the near future, the server
+				// download rate since it knows better than a
-						// should report download rate
+				// client that is measuring rate based on
-						// since it knows better than
+				// wall-clock time-since-last-update.
-						// a client that is measuring
-						// rate based on wall-clock
-						// time-since-last-update.
 				body := &trackingReader{r: res.Body, n: &progress}
 
-						err = chunked.Put(cs.Chunk, cs.Digest, body)
+				return chunked.Put(cs.Chunk, cs.Digest, body)
-						if err != nil {
-							return err
-						}
-
-						return nil
-					}()
-					if !canRetry(err) {
-						return err
-					}
-				}
-				return nil
 			})
 		}
 	}
@@ -554,13 +532,10 @@ func (r *Registry) Pull(ctx context.Context, name string) error {
 		return err
 	}
 
-	// store the manifest blob
 	md := blob.DigestFromBytes(m.Data)
 	if err := blob.PutBytes(c, md, m.Data); err != nil {
 		return err
 	}
-
-	// commit the manifest with a link
 	return c.Link(m.Name, md)
 }
 
@@ -782,12 +757,15 @@ func (r *Registry) chunksums(ctx context.Context, name string, l *Layer) iter.Se
 		}
 		blobURL := res.Header.Get("Content-Location")
 
+		var size int64
 		s := bufio.NewScanner(res.Body)
 		s.Split(bufio.ScanWords)
 		for {
 			if !s.Scan() {
 				if s.Err() != nil {
 					yield(chunksum{}, s.Err())
+				} else if size != l.Size {
+					yield(chunksum{}, fmt.Errorf("size mismatch: layer size %d != sum of chunks %d", size, l.Size))
 				}
 				return
 			}
@@ -811,6 +789,12 @@ func (r *Registry) chunksums(ctx context.Context, name string, l *Layer) iter.Se
 				return
 			}
 
+			size += chunk.Size()
+			if size > l.Size {
+				yield(chunksum{}, fmt.Errorf("chunk size %d exceeds layer size %d", size, l.Size))
+				return
+			}
+
 			cs := chunksum{
 				URL:    blobURL,
 				Chunk:  chunk,

server/internal/client/ollama/registry_test.go

@@ -17,6 +17,7 @@ import (
 	"reflect"
 	"slices"
 	"strings"
+	"sync"
 	"testing"
 	"time"
 
@@ -70,7 +71,7 @@ func (rr recordRoundTripper) RoundTrip(req *http.Request) (*http.Response, error
 // communication is attempted.
 //
 // To simulate a network error, pass a handler that returns a 499 status code.
-func newClient(t *testing.T, h http.HandlerFunc) (*Registry, *blob.DiskCache) {
+func newClient(t *testing.T, upstreamRegistry http.HandlerFunc) (*Registry, *blob.DiskCache) {
 	t.Helper()
 
 	c, err := blob.Open(t.TempDir())
@@ -88,7 +89,7 @@ func newClient(t *testing.T, h http.HandlerFunc) (*Registry, *blob.DiskCache) {
 	r := &Registry{
 		Cache: c,
 		HTTPClient: &http.Client{
-			Transport: recordRoundTripper(h),
+			Transport: recordRoundTripper(upstreamRegistry),
 		},
 	}
 
@@ -767,3 +768,74 @@ func TestUnlink(t *testing.T) {
 		}
 	})
 }
+
+func TestPullChunksums(t *testing.T) {
+	check := testutil.Checker(t)
+
+	content := "hello"
+	var chunksums string
+	contentDigest := func() blob.Digest {
+		return blob.DigestFromBytes(content)
+	}
+	rc, c := newClient(t, func(w http.ResponseWriter, r *http.Request) {
+		switch {
+		case strings.Contains(r.URL.Path, "/manifests/latest"):
+			fmt.Fprintf(w, `{"layers":[{"digest":%q,"size":%d}]}`, contentDigest(), len(content))
+		case strings.HasSuffix(r.URL.Path, "/chunksums/"+contentDigest().String()):
+			loc := fmt.Sprintf("http://blob.store/v2/library/test/blobs/%s", contentDigest())
+			w.Header().Set("Content-Location", loc)
+			io.WriteString(w, chunksums)
+		case strings.Contains(r.URL.Path, "/blobs/"+contentDigest().String()):
+			http.ServeContent(w, r, contentDigest().String(), time.Time{}, strings.NewReader(content))
+		default:
+			t.Errorf("unexpected request: %v", r)
+			http.NotFound(w, r)
+		}
+	})
+
+	rc.MaxStreams = 1        // prevent concurrent chunk downloads
+	rc.ChunkingThreshold = 1 // for all blobs to be chunked
+
+	var mu sync.Mutex
+	var reads []int64
+	ctx := WithTrace(t.Context(), &Trace{
+		Update: func(l *Layer, n int64, err error) {
+			t.Logf("Update: %v %d %v", l, n, err)
+			mu.Lock()
+			reads = append(reads, n)
+			mu.Unlock()
+		},
+	})
+
+	chunksums = fmt.Sprintf("%s 0-2\n%s 3-4\n",
+		blob.DigestFromBytes("hel"),
+		blob.DigestFromBytes("lo"),
+	)
+	err := rc.Pull(ctx, "test")
+	check(err)
+	if !slices.Equal(reads, []int64{0, 3, 5}) {
+		t.Errorf("reads = %v; want %v", reads, []int64{0, 3, 5})
+	}
+
+	mw, err := rc.Resolve(t.Context(), "test")
+	check(err)
+	mg, err := rc.ResolveLocal("test")
+	check(err)
+	if !reflect.DeepEqual(mw, mg) {
+		t.Errorf("mw = %v; mg = %v", mw, mg)
+	}
+	for i := range mg.Layers {
+		_, err = c.Get(mg.Layers[i].Digest)
+		if err != nil {
+			t.Errorf("Get(%v): %v", mg.Layers[i].Digest, err)
+		}
+	}
+
+	// missing chunks
+	content = "llama"
+	chunksums = fmt.Sprintf("%s 0-1\n", blob.DigestFromBytes("ll"))
+	err = rc.Pull(ctx, "missingchunks")
+	if err == nil {
+		t.Error("expected error because of missing chunks")
+	}
+}

server/model.go

@@ -82,7 +82,7 @@ func detectChatTemplate(layers []*layerGGML) ([]*layerGGML, error) {
 	for _, layer := range layers {
 		if s := layer.GGML.KV().ChatTemplate(); s != "" {
 			if t, err := template.Named(s); err != nil {
-				slog.Debug("template detection", "error", err)
+				slog.Debug("template detection", "error", err, "template", s)
 			} else {
 				layer, err := NewLayer(t.Reader(), "application/vnd.ollama.image.template")
 				if err != nil {

template/gemma3-instruct.gotmpl

@@ -0,0 +1,13 @@
+{{- range $i, $_ := .Messages }}
+{{- $last := eq (len (slice $.Messages $i)) 1 }}
+{{- if eq .Role "user" }}<start_of_turn>user
+{{- if and (eq $i 1) $.System }}
+{{ $.System }}
+{{ end }}
+{{ .Content }}<end_of_turn>
+{{ else if eq .Role "assistant" }}<start_of_turn>model
+{{ .Content }}<end_of_turn>
+{{ end }}
+{{- if $last }}<start_of_turn>model
+{{ end }}
+{{- end }}

template/gemma3-instruct.json

@@ -0,0 +1,6 @@
+{
+  "stop": [
+    "<end_of_turn>"
+  ],
+  "temperature": 0.1
+}

template/index.json

@@ -87,6 +87,10 @@
     "template": "{{ bos_token }}{% if messages[0]['role'] == 'system' %}{{ raise_exception('System role not supported') }}{% endif %}{% for message in messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if (message['role'] == 'assistant') %}{% set role = 'model' %}{% else %}{% set role = message['role'] %}{% endif %}{{ '<start_of_turn>' + role + '\n' + message['content'] | trim + '<end_of_turn>\n' }}{% endfor %}{% if add_generation_prompt %}{{'<start_of_turn>model\n'}}{% endif %}",
     "name": "gemma-instruct"
   },
+  {
+    "template": "{{ bos_token }}\n{%- if messages[0]['role'] == 'system' -%}\n    {%- if messages[0]['content'] is string -%}\n        {%- set first_user_prefix = messages[0]['content'] + '\n\n' -%}\n    {%- else -%}\n        {%- set first_user_prefix = messages[0]['content'][0]['text'] + '\n\n' -%}\n    {%- endif -%}\n    {%- set loop_messages = messages[1:] -%}\n{%- else -%}\n    {%- set first_user_prefix = \"\" -%}\n    {%- set loop_messages = messages -%}\n{%- endif -%}\n{%- for message in loop_messages -%}\n    {%- if (message['role'] == 'user') != (loop.index0 % 2 == 0) -%}\n        {{ raise_exception(\"Conversation roles must alternate user/assistant/user/assistant/...\") }}\n    {%- endif -%}\n    {%- if (message['role'] == 'assistant') -%}\n        {%- set role = \"model\" -%}\n    {%- else -%}\n        {%- set role = message['role'] -%}\n    {%- endif -%}\n    {{ '<start_of_turn>' + role + '\n' + (first_user_prefix if loop.first else \"\") }}\n    {%- if message['content'] is string -%}\n        {{ message['content'] | trim }}\n    {%- elif message['content'] is iterable -%}\n        {%- for item in message['content'] -%}\n            {%- if item['type'] == 'image' -%}\n                {{ '<start_of_image>' }}\n            {%- elif item['type'] == 'text' -%}\n                {{ item['text'] | trim }}\n            {%- endif -%}\n        {%- endfor -%}\n    {%- else -%}\n        {{ raise_exception(\"Invalid content type\") }}\n    {%- endif -%}\n    {{ '<end_of_turn>\n' }}\n{%- endfor -%}\n{%- if add_generation_prompt -%}\n    {{'<start_of_turn>model\n'}}\n{%- endif -%}\n",
+    "name": "gemma3-instruct"
+  },
   {
     "template": "{% set loop_messages = messages %}{% for message in loop_messages %}{% set content = '<|start_header_id|>' + message['role'] + '<|end_header_id|>\n\n'+ message['content'] | trim + '<|eot_id|>' %}{% if loop.index0 == 0 %}{% set content = bos_token + content %}{% endif %}{{ content }}{% endfor %}{% if add_generation_prompt %}{{ '<|start_header_id|>assistant<|end_header_id|>\n\n' }}{% endif %}",
     "name": "llama3-instruct"

template/testdata/gemma3-instruct.gotmpl/system-user-assistant-user

@@ -0,0 +1,10 @@
+<start_of_turn>user
+You are a helpful assistant.
+
+Hello, how are you?<end_of_turn>
+<start_of_turn>model
+I'm doing great. How can I help you today?<end_of_turn>
+<start_of_turn>user
+I'd like to show off how chat templating works!<end_of_turn>
+<start_of_turn>model
+

template/testdata/gemma3-instruct.gotmpl/user

@@ -0,0 +1,4 @@
+<start_of_turn>user
+Hello, how are you?<end_of_turn>
+<start_of_turn>model
+

template/testdata/gemma3-instruct.gotmpl/user-assistant-user

@@ -0,0 +1,8 @@
+<start_of_turn>user
+Hello, how are you?<end_of_turn>
+<start_of_turn>model
+I'm doing great. How can I help you today?<end_of_turn>
+<start_of_turn>user
+I'd like to show off how chat templating works!<end_of_turn>
+<start_of_turn>model
+