feat: add support for multimodal projector in GGUF model building

pkg/distribution/huggingface/model.go

@@ -90,7 +90,9 @@ func BuildModel(ctx context.Context, client *Client, repo, revision, tag string,
 		_ = progress.WriteProgress(progressWriter, "Building model artifact...", 0, 0, 0, "", "pull")
 	}
 
-	model, err := buildModelFromFiles(result.LocalPaths, weightFiles, configFiles, tempDir, createdTime)
+	model, err := buildModelFromFiles(
+		result.LocalPaths, weightFiles, configFiles, mmprojFile, tempDir, createdTime,
+	)
 	if err != nil {
 		return nil, fmt.Errorf("build model: %w", err)
 	}
@@ -103,14 +105,20 @@ func BuildModel(ctx context.Context, client *Client, repo, revision, tag string,
 // which preserves directory structure and adds each file as an individual layer with
 // filepath annotations. For GGUF models, it uses the V0.1 packaging (FromPaths)
 // for backward compatibility.
-func buildModelFromFiles(localPaths map[string]string, weightFiles, configFiles []RepoFile, tempDir string, createdTime *time.Time) (types.ModelArtifact, error) {
+func buildModelFromFiles(
+	localPaths map[string]string,
+	weightFiles, configFiles []RepoFile,
+	mmprojFile *RepoFile,
+	tempDir string,
+	createdTime *time.Time,
+) (types.ModelArtifact, error) {
 	// Check if this is a safetensors model - use V0.2 packaging
 	if isSafetensorsModel(weightFiles) {
 		return buildSafetensorsModelV02(tempDir, createdTime)
 	}
 
 	// For GGUF models, use V0.1 packaging (backward compatible)
-	return buildGGUFModelV01(localPaths, weightFiles, configFiles, createdTime)
+	return buildGGUFModelV01(localPaths, weightFiles, configFiles, mmprojFile, createdTime)
 }
 
 // buildSafetensorsModelV02 builds a safetensors model using V0.2 layer-per-file packaging.
@@ -133,7 +141,12 @@ func buildSafetensorsModelV02(tempDir string, createdTime *time.Time) (types.Mod
 }
 
 // buildGGUFModelV01 builds a GGUF model using V0.1 packaging (backward compatible).
-func buildGGUFModelV01(localPaths map[string]string, weightFiles, configFiles []RepoFile, createdTime *time.Time) (types.ModelArtifact, error) {
+func buildGGUFModelV01(
+	localPaths map[string]string,
+	weightFiles, configFiles []RepoFile,
+	mmprojFile *RepoFile,
+	createdTime *time.Time,
+) (types.ModelArtifact, error) {
 	// Collect weight file paths (sorted for reproducibility)
 	var weightPaths []string
 	for _, f := range weightFiles {
@@ -157,7 +170,19 @@ func buildGGUFModelV01(localPaths map[string]string, weightFiles, configFiles []
 		return nil, fmt.Errorf("create builder: %w", err)
 	}
 
-	// Check for chat template and add it
+	// Add multimodal projector if present (F16 preferred, selected upstream).
+	if mmprojFile != nil {
+		localPath, ok := localPaths[mmprojFile.Path]
+		if !ok {
+			return nil, fmt.Errorf("missing local path for mmproj %s", mmprojFile.Path)
+		}
+		b, err = b.WithMultimodalProjector(localPath)
+		if err != nil {
+			return nil, fmt.Errorf("add mmproj: %w", err)
+		}
+	}
+
+	// Check for chat template and add it.
 	for _, f := range configFiles {
 		if isChatTemplate(f.Path) {
 			localPath := localPaths[f.Path]

pkg/distribution/huggingface/model_test.go

@@ -0,0 +1,83 @@
+package huggingface
+
+import (
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/docker/model-runner/pkg/distribution/types"
+)
+
+// TestBuildGGUFModelV01WithMMProj verifies that buildGGUFModelV01 includes
+// the multimodal projector as a MediaTypeMultimodalProjector layer when an
+// mmprojFile is provided.
+func TestBuildGGUFModelV01WithMMProj(t *testing.T) {
+	assetsDir := filepath.Join("..", "assets")
+	ggufPath := filepath.Join(assetsDir, "dummy.gguf")
+	mmprojPath := filepath.Join(assetsDir, "dummy.mmproj")
+
+	weightFiles := []RepoFile{
+		{Type: "file", Path: "dummy.gguf"},
+	}
+	mmprojFile := &RepoFile{Type: "file", Path: "mmproj-model-f16.gguf"}
+	localPaths := map[string]string{
+		"dummy.gguf":            ggufPath,
+		"mmproj-model-f16.gguf": mmprojPath,
+	}
+
+	artifact, err := buildGGUFModelV01(localPaths, weightFiles, nil, mmprojFile, nil)
+	if err != nil {
+		t.Fatalf("buildGGUFModelV01 failed: %v", err)
+	}
+
+	// Retrieve the manifest and look for the mmproj layer.
+	manifest, err := artifact.Manifest()
+	if err != nil {
+		t.Fatalf("get manifest: %v", err)
+	}
+
+	found := false
+	for _, layer := range manifest.Layers {
+		if layer.MediaType == types.MediaTypeMultimodalProjector {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Errorf("expected manifest to contain a %s layer, but none was found",
+			types.MediaTypeMultimodalProjector)
+	}
+}
+
+// TestBuildGGUFModelV01WithoutMMProj verifies that buildGGUFModelV01 succeeds
+// and produces no MediaTypeMultimodalProjector layer when no mmprojFile is
+// provided.
+func TestBuildGGUFModelV01WithoutMMProj(t *testing.T) {
+	assetsDir := filepath.Join("..", "assets")
+	ggufPath := filepath.Join(assetsDir, "dummy.gguf")
+
+	weightFiles := []RepoFile{
+		{Type: "file", Path: "dummy.gguf"},
+	}
+	localPaths := map[string]string{
+		"dummy.gguf": ggufPath,
+	}
+	createdTime := time.Now()
+
+	artifact, err := buildGGUFModelV01(localPaths, weightFiles, nil, nil, &createdTime)
+	if err != nil {
+		t.Fatalf("buildGGUFModelV01 failed: %v", err)
+	}
+
+	manifest, err := artifact.Manifest()
+	if err != nil {
+		t.Fatalf("get manifest: %v", err)
+	}
+
+	for _, layer := range manifest.Layers {
+		if layer.MediaType == types.MediaTypeMultimodalProjector {
+			t.Errorf("expected no %s layer, but one was found",
+				types.MediaTypeMultimodalProjector)
+		}
+	}
+}