Add enableLightningPreviewPref to login scratch --setting Options

command/login.go

@@ -99,6 +99,7 @@ const (
 	NetworksEnabled
 	EnableApexApprovalLockUnlock
 	PermsetsInFieldCreation
+	EnableLightningPreviewPref
 )
 
 var ScratchSettingIds = map[ScratchSetting][]string{
@@ -107,6 +108,7 @@ var ScratchSettingIds = map[ScratchSetting][]string{
 	NetworksEnabled:              {"networksEnabled"},
 	EnableApexApprovalLockUnlock: {"enableApexApprovalLockUnlock"},
 	PermsetsInFieldCreation:      {"permsetsInFieldCreation"},
+	EnableLightningPreviewPref:   {"enableLightningPreviewPref"},
 }
 
 type ScratchRelease enumflag.Flag
@@ -225,6 +227,7 @@ Available Settings (deployed after org creation):
   networksEnabled     - Enable Experience Cloud (Communities)
   enableApexApprovalLockUnlock - Allow Apex to lock/unlock approval processes
   permsetsInFieldCreation - Allow assigning permission sets during field creation
+  enableLightningPreviewPref - Enable Lightning Experience preview pref
 
 Available Releases:
   preview  - Create scratch org on the next (preview) release

command/login_test.go

@@ -338,13 +338,24 @@ func TestConvertSettingsToStrings_PermsetsInFieldCreation(t *testing.T) {
 	}
 }
 
+func TestConvertSettingsToStrings_EnableLightningPreviewPref(t *testing.T) {
+	result := convertSettingsToStrings([]ScratchSetting{EnableLightningPreviewPref})
+	if len(result) != 1 {
+		t.Errorf("Expected 1 setting, got %d", len(result))
+	}
+	if result[0] != "enableLightningPreviewPref" {
+		t.Errorf("Expected enableLightningPreviewPref, got %s", result[0])
+	}
+}
+
 func TestScratchSettingIds_AllSettingsDefined(t *testing.T) {
 	expectedSettings := map[string]bool{
 		"enableEnhancedNotes":          true,
 		"enableQuote":                  true,
 		"networksEnabled":              true,
 		"enableApexApprovalLockUnlock": true,
 		"permsetsInFieldCreation":      true,
+		"enableLightningPreviewPref":   true,
 	}
 
 	if len(ScratchSettingIds) != len(expectedSettings) {

docs/force_login_scratch.md

@@ -38,6 +38,7 @@ Available Settings (deployed after org creation):
   networksEnabled     - Enable Experience Cloud (Communities)
   enableApexApprovalLockUnlock - Allow Apex to lock/unlock approval processes
   permsetsInFieldCreation - Allow assigning permission sets during field creation
+  enableLightningPreviewPref - Enable Lightning Experience preview pref
 
 Available Releases:
   preview  - Create scratch org on the next (preview) release

lib/scratch.go

@@ -205,6 +205,7 @@ func buildSettingsMetadata(settings []string) ForceMetadataFiles {
 	// Create settings file for each requested setting
 	apexSettings := false
 	userManagementSettings := false
+	lightningExperienceSettings := false
 
 	for _, setting := range settings {
 		switch setting {
@@ -231,6 +232,8 @@ func buildSettingsMetadata(settings []string) ForceMetadataFiles {
 			apexSettings = true
 		case "permsetsInFieldCreation":
 			userManagementSettings = true
+		case "enableLightningPreviewPref":
+			lightningExperienceSettings = true
 		}
 	}
 
@@ -252,6 +255,15 @@ func buildSettingsMetadata(settings []string) ForceMetadataFiles {
 		files["unpackaged/settings/UserManagement.settings"] = userMgmtBuffer.Bytes()
 	}
 
+	if lightningExperienceSettings {
+		var lexBuffer bytes.Buffer
+		lexBuffer.WriteString(`<?xml version="1.0" encoding="UTF-8"?>
+<LightningExperienceSettings xmlns="http://soap.sforce.com/2006/04/metadata">
+    <enableLightningPreviewPref>true</enableLightningPreviewPref>
+</LightningExperienceSettings>`)
+		files["unpackaged/settings/LightningExperience.settings"] = lexBuffer.Bytes()
+	}
+
 	return files
 }
 

lib/scratch_test.go

@@ -49,6 +49,26 @@ func TestBuildSettingsMetadata_ExcludesUserManagementSettingsWhenUnused(t *testi
 	}
 }
 
+func TestBuildSettingsMetadata_AddsLightningExperienceSettings(t *testing.T) {
+	files := buildSettingsMetadata([]string{"enableLightningPreviewPref"})
+
+	content, ok := files["unpackaged/settings/LightningExperience.settings"]
+	if !ok {
+		t.Fatalf("LightningExperience.settings not generated")
+	}
+	if !strings.Contains(string(content), "<enableLightningPreviewPref>true</enableLightningPreviewPref>") {
+		t.Errorf("LightningExperience.settings missing enableLightningPreviewPref preference:\n%s", content)
+	}
+}
+
+func TestBuildSettingsMetadata_ExcludesLightningExperienceSettingsWhenUnused(t *testing.T) {
+	files := buildSettingsMetadata([]string{"enableEnhancedNotes"})
+
+	if _, ok := files["unpackaged/settings/LightningExperience.settings"]; ok {
+		t.Fatalf("LightningExperience.settings should not be generated when not requested")
+	}
+}
+
 func TestGetScratchOrg_returns_error_when_SignupUsername_is_nil(t *testing.T) {
 	f := &Force{}
 	f.Credentials = &ForceSession{}