diff --git a/runner/ollamarunner/runner_test.go b/runner/ollamarunner/runner_test.go
new file mode 100644
index 000000000..cc10933ad
--- /dev/null
+++ b/runner/ollamarunner/runner_test.go
@@ -0,0 +1,218 @@
+package ollamarunner
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/ollama/ollama/fs"
+	"github.com/ollama/ollama/ml"
+	"github.com/ollama/ollama/model"
+	"github.com/ollama/ollama/model/input"
+	"github.com/ollama/ollama/sample"
+	"golang.org/x/sync/semaphore"
+)
+
+// testBackend implements ml.Backend with minimal functionality required for tests.
+type testBackend struct{}
+
+func (b *testBackend) Config() fs.Config             { return testConfig{} }
+func (b *testBackend) Get(string) ml.Tensor          { return nil }
+func (b *testBackend) NewContext() ml.Context        { return &testContext{} }
+func (b *testBackend) NewContextSize(int) ml.Context { return &testContext{} }
+
+// testConfig is a stub implementation of fs.Config used by testBackend.
+type testConfig struct{}
+
+func (testConfig) Architecture() string                  { return "" }
+func (testConfig) String(string, ...string) string       { return "" }
+func (testConfig) Uint(string, ...uint32) uint32         { return 0 }
+func (testConfig) Float(string, ...float32) float32      { return 0 }
+func (testConfig) Bool(string, ...bool) bool             { return false }
+func (testConfig) Strings(string, ...[]string) []string  { return nil }
+func (testConfig) Ints(string, ...[]int32) []int32       { return nil }
+func (testConfig) Floats(string, ...[]float32) []float32 { return nil }
+
+type testContext struct{}
+
+func (c *testContext) Empty(dtype ml.DType, shape ...int) ml.Tensor {
+	sz := 1
+	for _, s := range shape {
+		sz *= s
+	}
+	return &testTensor{dtype: dtype, data: make([]float32, sz), shape: shape}
+}
+func (c *testContext) Zeros(dtype ml.DType, shape ...int) ml.Tensor { return c.Empty(dtype, shape...) }
+func (c *testContext) FromFloatSlice(s []float32, shape ...int) (ml.Tensor, error) {
+	t := c.Empty(ml.DTypeF32, shape...).(*testTensor)
+	copy(t.data, s)
+	return t, nil
+}
+func (c *testContext) FromIntSlice(s []int32, shape ...int) (ml.Tensor, error) {
+	f := make([]float32, len(s))
+	for i, v := range s {
+		f[i] = float32(v)
+	}
+	out, _ := c.FromFloatSlice(f, shape...)
+	out.(*testTensor).dtype = ml.DTypeI32
+	return out, nil
+}
+func (c *testContext) Arange(start, stop, step float32, dtype ml.DType) ml.Tensor {
+	return c.Empty(dtype, int((stop-start)/step))
+}
+func (c *testContext) Forward(...ml.Tensor) ml.Context { return c }
+func (c *testContext) Compute(...ml.Tensor)            {}
+func (c *testContext) Reserve() error                  { return nil }
+func (c *testContext) MaxGraphNodes() int              { return 0 }
+func (c *testContext) Close()                          {}
+func (c *testContext) Input() ml.Context               { return c }
+func (c *testContext) Layer(int) ml.Context            { return c }
+
+type testTensor struct {
+	ml.Tensor
+	dtype ml.DType
+	data  []float32
+	shape []int
+}
+
+func (t *testTensor) Dim(n int) int    { return t.shape[n] }
+func (t *testTensor) Stride(n int) int { return 0 }
+func (t *testTensor) Shape() []int     { return t.shape }
+func (t *testTensor) DType() ml.DType  { return t.dtype }
+func (t *testTensor) Bytes() []byte    { return nil }
+func (t *testTensor) Floats() []float32 {
+	out := make([]float32, len(t.data))
+	copy(out, t.data)
+	return out
+}
+func (t *testTensor) Neg(ctx ml.Context) ml.Tensor { return nil }
+func (t *testTensor) Add(ctx ml.Context, t2 ml.Tensor) ml.Tensor {
+	out, _ := ctx.(*testContext).FromFloatSlice(nil, len(t.data))
+	return out
+}
+func (t *testTensor) Mul(ctx ml.Context, t2 ml.Tensor) ml.Tensor            { return nil }
+func (t *testTensor) Mulmat(ctx ml.Context, t2 ml.Tensor) ml.Tensor         { return nil }
+func (t *testTensor) MulmatFullPrec(ctx ml.Context, t2 ml.Tensor) ml.Tensor { return nil }
+func (t *testTensor) MulmatID(ctx ml.Context, t2, ids ml.Tensor) ml.Tensor  { return nil }
+func (t *testTensor) Softmax(ctx ml.Context) ml.Tensor                      { return nil }
+func (t *testTensor) LayerNorm(ctx ml.Context, w, b ml.Tensor, e float32) ml.Tensor {
+	return nil
+}
+func (t *testTensor) View(ctx ml.Context, offset int, shape ...int) ml.Tensor {
+	return ctx.(*testContext).Empty(t.dtype, shape...)
+}
+func (t *testTensor) Copy(ctx ml.Context, dest ml.Tensor) ml.Tensor {
+	copy(dest.(*testTensor).data, t.data)
+	return nil
+}
+
+// fakeModel implements model.Model and model.TextProcessor.
+type fakeModel struct {
+	model.Base
+	decode  map[int32]string
+	logits  [][]float32
+	call    int
+	backend ml.Backend
+}
+
+func (f *fakeModel) Forward(ctx ml.Context, batch input.Batch) (ml.Tensor, error) {
+	idx := f.call
+	if idx >= len(f.logits) {
+		idx = len(f.logits) - 1
+	}
+	f.call++
+	return ctx.FromFloatSlice(f.logits[idx], len(f.logits[idx]))
+}
+
+func (f *fakeModel) Backend() ml.Backend {
+	if f.backend == nil {
+		f.backend = &testBackend{}
+	}
+	return f.backend
+}
+
+func (f *fakeModel) Encode(string, bool) ([]int32, error) { return nil, nil }
+func (f *fakeModel) Decode(ids []int32) (string, error) {
+	var s string
+	for _, id := range ids {
+		s += f.decode[id]
+	}
+	return s, nil
+}
+func (f *fakeModel) Is(id int32, sp model.Special) bool { return false }
+func (f *fakeModel) Vocabulary() *model.Vocabulary      { return &model.Vocabulary{} }
+
+var _ model.Model = (*fakeModel)(nil)
+var _ model.TextProcessor = (*fakeModel)(nil)
+
+func TestProcessBatchUnicode(t *testing.T) {
+	tests := []struct {
+		name   string
+		decode map[int32]string
+		logits [][]float32
+		want   string
+	}{
+		{
+			name:   "emoji",
+			decode: map[int32]string{0: "A", 1: "😀", 2: "👍", 3: "!"},
+			logits: [][]float32{{10, 0, 0, 0}, {0, 10, 0, 0}, {0, 0, 10, 0}, {0, 0, 0, 10}},
+			want:   "A😀👍!",
+		},
+		{
+			name:   "ascii",
+			decode: map[int32]string{0: "H", 1: "e", 2: "y"},
+			logits: [][]float32{{10, 0, 0}, {0, 10, 0}, {0, 0, 10}},
+			want:   "Hey",
+		},
+		{
+			name:   "multibyte",
+			decode: map[int32]string{0: "世", 1: "界", 2: "😊"},
+			logits: [][]float32{{10, 0, 0}, {0, 10, 0}, {0, 0, 10}},
+			want:   "世界😊",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			m := &fakeModel{decode: tt.decode, logits: tt.logits}
+
+			s := &Server{model: m, batchSize: 1, parallel: 1}
+			s.cache = &InputCache{enabled: true, slots: []InputCacheSlot{{Id: 0}}, numCtx: 10}
+			s.seqs = make([]*Sequence, 1)
+			s.seqsSem = semaphore.NewWeighted(1)
+			if err := s.seqsSem.Acquire(context.Background(), 1); err != nil {
+				t.Fatal(err)
+			}
+			s.cond = sync.NewCond(&s.mu)
+
+			seq := &Sequence{
+				inputs:     []input.Input{{Token: 0}},
+				cache:      &s.cache.slots[0],
+				responses:  make(chan string, 10),
+				quit:       make(chan bool, 1),
+				numPredict: len(tt.logits),
+				sampler:    sample.NewSampler(0, 0, 0, 0, 0, nil),
+				embedding:  make(chan []float32, 1),
+			}
+			s.seqs[0] = seq
+
+			for {
+				if err := s.processBatch(); err != nil {
+					t.Fatal(err)
+				}
+				if s.seqs[0] == nil {
+					break
+				}
+			}
+
+			var result string
+			for r := range seq.responses {
+				result += r
+			}
+
+			if result != tt.want {
+				t.Fatalf("got %q want %q", result, tt.want)
+			}
+		})
+	}
+}