feat: require explicit region for env creation and add region resolution tests

**Added:**

- Unit tests for ResolveRegion and ResolveRegionWithInventory to verify
  correct region selection and error handling in different scenarios -
  config_test.go

**Changed:**

- Region flag for env create now defaults to empty and is required, with
  improved help text describing all ways to set the region
- Logic for env creation updated to resolve region using config, environment
  variable, or flag, and to error clearly if no region is set
- Refactored environment scaffolding logic into a new scaffoldEnv function
  to improve readability and separation of concerns in env_cmd.go

Author: l50

cli/cmd/env_cmd.go

@@ -51,7 +51,7 @@ func init() {
 	envCmd.AddCommand(envCreateCmd)
 	envCmd.AddCommand(envListCmd)
 
-	envCreateCmd.Flags().String("region", "us-east-1", "AWS region for the environment")
+	envCreateCmd.Flags().String("region", "", "AWS region for the environment (required; or set via dreadgoad.yaml / DREADGOAD_REGION / --region)")
 	envCreateCmd.Flags().String("vpc-cidr", "", "VPC CIDR block (default: auto-assigned)")
 	envCreateCmd.Flags().String("reference", "staging", "Reference environment to copy infrastructure from")
 	envCreateCmd.Flags().Bool("variant", false, "Generate randomized variant config")
@@ -70,17 +70,26 @@ func runEnvCreate(cmd *cobra.Command, args []string) error {
 	}
 
 	region, _ := cmd.Flags().GetString("region")
+	if region == "" {
+		region, err = cfg.ResolveRegion()
+		if err != nil {
+			return fmt.Errorf("env create requires a region: pass --region, set 'region' in dreadgoad.yaml, or export DREADGOAD_REGION")
+		}
+	}
 	vpcCIDR, _ := cmd.Flags().GetString("vpc-cidr")
 	reference, _ := cmd.Flags().GetString("reference")
 	useVariant, _ := cmd.Flags().GetBool("variant")
 	force, _ := cmd.Flags().GetBool("force")
 
-	deployment := cfg.Infra.Deployment
-	infraBase := filepath.Join(cfg.ProjectRoot, "infra", deployment)
-
 	if vpcCIDR == "" {
 		vpcCIDR = cfg.VpcCIDR(envName)
 	}
+
+	return scaffoldEnv(cfg, envName, region, vpcCIDR, reference, useVariant, force)
+}
+
+func scaffoldEnv(cfg *config.Config, envName, region, vpcCIDR, reference string, useVariant, force bool) error {
+	infraBase := filepath.Join(cfg.ProjectRoot, "infra", cfg.Infra.Deployment)
 	envDir := filepath.Join(infraBase, envName)
 	regionDir := filepath.Join(envDir, region)
 

cli/internal/config/config_test.go

@@ -5,8 +5,90 @@ import (
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"github.com/dreadnode/dreadgoad/internal/inventory"
 )
 
+func TestResolveRegion(t *testing.T) {
+	t.Run("returns configured region", func(t *testing.T) {
+		c := &Config{Region: "eu-west-1"}
+		got, err := c.ResolveRegion()
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if got != "eu-west-1" {
+			t.Errorf("ResolveRegion() = %q, want %q", got, "eu-west-1")
+		}
+	})
+
+	t.Run("errors when region is empty", func(t *testing.T) {
+		c := &Config{Region: ""}
+		_, err := c.ResolveRegion()
+		if err == nil {
+			t.Fatal("expected error for empty region, got nil")
+		}
+		if !strings.Contains(err.Error(), "region") {
+			t.Errorf("error should mention region, got: %v", err)
+		}
+	})
+}
+
+func TestResolveRegionWithInventory(t *testing.T) {
+	t.Run("prefers inventory region", func(t *testing.T) {
+		c := &Config{Region: "us-west-1"}
+		inv := &inventory.Inventory{
+			Vars: map[string]string{"ansible_aws_ssm_region": "ap-southeast-1"},
+		}
+		got, err := c.ResolveRegionWithInventory(inv)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if got != "ap-southeast-1" {
+			t.Errorf("ResolveRegionWithInventory() = %q, want %q", got, "ap-southeast-1")
+		}
+	})
+
+	t.Run("falls back to config when inventory has no region", func(t *testing.T) {
+		c := &Config{Region: "us-east-2"}
+		inv := &inventory.Inventory{Vars: map[string]string{}}
+		got, err := c.ResolveRegionWithInventory(inv)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if got != "us-east-2" {
+			t.Errorf("ResolveRegionWithInventory() = %q, want %q", got, "us-east-2")
+		}
+	})
+
+	t.Run("falls back to config when inventory is nil", func(t *testing.T) {
+		c := &Config{Region: "eu-central-1"}
+		got, err := c.ResolveRegionWithInventory(nil)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if got != "eu-central-1" {
+			t.Errorf("ResolveRegionWithInventory() = %q, want %q", got, "eu-central-1")
+		}
+	})
+
+	t.Run("errors when both inventory and config have no region", func(t *testing.T) {
+		c := &Config{Region: ""}
+		inv := &inventory.Inventory{Vars: map[string]string{}}
+		_, err := c.ResolveRegionWithInventory(inv)
+		if err == nil {
+			t.Fatal("expected error when no region available, got nil")
+		}
+	})
+
+	t.Run("errors when nil inventory and config has no region", func(t *testing.T) {
+		c := &Config{Region: ""}
+		_, err := c.ResolveRegionWithInventory(nil)
+		if err == nil {
+			t.Fatal("expected error when no region available, got nil")
+		}
+	})
+}
+
 func TestConfigInventoryPath(t *testing.T) {
 	c := &Config{ProjectRoot: "/opt/goad", Env: "dev"}
 	got := c.InventoryPath()