fix: omit empty service source fields

cli/azd/pkg/project/project_test.go

@@ -1232,6 +1232,35 @@ func Test_Save(t *testing.T) {
 	assert.Equal(t, dir, prjConfig.Path)
 }
 
+func Test_Save_OmitsEmptyServiceSourceFields(t *testing.T) {
+	dir := t.TempDir()
+	filePath := filepath.Join(dir, "azure.yaml")
+
+	prjConfig := &ProjectConfig{
+		Name: "test-save",
+		Services: map[string]*ServiceConfig{
+			"foundry": {
+				Host: ServiceTargetKind("azure.ai.project"),
+				AdditionalProperties: map[string]any{
+					"endpoint": "https://account.services.ai.azure.com/api/projects/project",
+				},
+			},
+		},
+	}
+
+	err := Save(t.Context(), prjConfig, filePath)
+	require.NoError(t, err)
+
+	data, err := os.ReadFile(filePath)
+	require.NoError(t, err)
+
+	content := string(data)
+	assert.Contains(t, content, "host: azure.ai.project")
+	assert.Contains(t, content, "endpoint: https://account.services.ai.azure.com/api/projects/project")
+	assert.NotContains(t, content, "project: \"\"")
+	assert.NotContains(t, content, "language: \"\"")
+}
+
 func Test_Save_CustomSchemaVersion(t *testing.T) {
 	dir := t.TempDir()
 	filePath := filepath.Join(dir, "azure.yaml")

cli/azd/pkg/project/service_config.go

@@ -35,11 +35,11 @@ type ServiceConfig struct {
 	// The ARM api version to use for the service. If not specified, the latest version is used.
 	ApiVersion string `yaml:"apiVersion,omitempty"`
 	// The relative path to the project folder from the project root
-	RelativePath string `yaml:"project"`
+	RelativePath string `yaml:"project,omitempty"`
 	// The azure hosting model to use, ex) appservice, function, containerapp
 	Host ServiceTargetKind `yaml:"host"`
 	// The programming language of the project
-	Language ServiceLanguageKind `yaml:"language"`
+	Language ServiceLanguageKind `yaml:"language,omitempty"`
 	// The output path for build artifacts
 	OutputPath string `yaml:"dist,omitempty"`
 	// The source image to use for container based applications