feat: add automatic inventory bootstrapping from example template

cli/cmd/bootstrap_test.go

@@ -0,0 +1,64 @@
+package cmd
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestBootstrapInventory(t *testing.T) {
+	t.Run("copies example when inventory missing", func(t *testing.T) {
+		dir := t.TempDir()
+		invPath := filepath.Join(dir, "dev-inventory")
+		examplePath := invPath + ".example"
+
+		exampleContent := []byte("[all:vars]\nenv=dev\nregion=us-west-2\n")
+		if err := os.WriteFile(examplePath, exampleContent, 0o644); err != nil {
+			t.Fatalf("write example: %v", err)
+		}
+
+		if err := bootstrapInventory(invPath); err != nil {
+			t.Fatalf("bootstrapInventory() error: %v", err)
+		}
+
+		got, err := os.ReadFile(invPath)
+		if err != nil {
+			t.Fatalf("read bootstrapped inventory: %v", err)
+		}
+		if string(got) != string(exampleContent) {
+			t.Errorf("content mismatch:\ngot:  %q\nwant: %q", got, exampleContent)
+		}
+	})
+
+	t.Run("no-op when inventory exists", func(t *testing.T) {
+		dir := t.TempDir()
+		invPath := filepath.Join(dir, "dev-inventory")
+
+		existing := []byte("[all:vars]\nenv=dev\ninstance=i-abc123\n")
+		if err := os.WriteFile(invPath, existing, 0o644); err != nil {
+			t.Fatalf("write existing: %v", err)
+		}
+
+		if err := bootstrapInventory(invPath); err != nil {
+			t.Fatalf("bootstrapInventory() error: %v", err)
+		}
+
+		got, err := os.ReadFile(invPath)
+		if err != nil {
+			t.Fatalf("read inventory: %v", err)
+		}
+		if string(got) != string(existing) {
+			t.Errorf("existing inventory was overwritten")
+		}
+	})
+
+	t.Run("errors when neither file exists", func(t *testing.T) {
+		dir := t.TempDir()
+		invPath := filepath.Join(dir, "dev-inventory")
+
+		err := bootstrapInventory(invPath)
+		if err == nil {
+			t.Fatal("expected error when no inventory or example exists")
+		}
+	})
+}

cli/cmd/inventory.go

@@ -63,8 +63,8 @@ func runInventorySync(cmd *cobra.Command, args []string) error {
 	}
 	invPath := cfg.InventoryPath()
 
-	if _, err := os.Stat(invPath); os.IsNotExist(err) {
-		return fmt.Errorf("inventory file not found: %s", invPath)
+	if err := bootstrapInventory(invPath); err != nil {
+		return err
 	}
 
 	backup, _ := cmd.Flags().GetBool("backup")

cli/cmd/provision.go

@@ -145,11 +145,36 @@ func preflightChecks(ctx context.Context, cfg *config.Config) error {
 	return nil
 }
 
+// bootstrapInventory copies the example inventory file to the target path if
+// the target does not exist. This allows provision and inventory commands to
+// work on a fresh environment without a manual copy step.
+func bootstrapInventory(invPath string) error {
+	if _, err := os.Stat(invPath); err == nil {
+		return nil
+	}
+	examplePath := invPath + ".example"
+	if _, err := os.Stat(examplePath); err != nil {
+		return fmt.Errorf("inventory file not found: %s (no .example template either)", invPath)
+	}
+	data, err := os.ReadFile(examplePath)
+	if err != nil {
+		return fmt.Errorf("read example inventory: %w", err)
+	}
+	if err := os.WriteFile(invPath, data, 0o644); err != nil {
+		return fmt.Errorf("write inventory from example: %w", err)
+	}
+	slog.Info("bootstrapped inventory from example template", "path", invPath)
+	return nil
+}
+
 // ensureInventorySynced compares inventory instance IDs against live EC2
 // state and auto-syncs if they diverge. This prevents provisioning against
 // stale instance IDs after an infra destroy/apply cycle.
 func ensureInventorySynced(ctx context.Context, cfg *config.Config) error {
 	invPath := cfg.InventoryPath()
+	if err := bootstrapInventory(invPath); err != nil {
+		return err
+	}
 	parsed, err := inv.Parse(invPath)
 	if err != nil {
 		return fmt.Errorf("parse inventory: %w", err)