M4: CLI polish — version flag, mountpoint override, stable aliases

Add --version flag with build-time injection via ldflags. Add
--mountpoint/-m flag to mount for one-off mount point override. Change
init aliases from device path basename (sda1) to UUID prefix (b8b2f8e3)
for stability across boots. Add .gitignore. Update flake.nix with
version injection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,2 @@
+/arca
+result

cmd/init.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 
+
 	"git.wntrmute.dev/kyle/arca/internal/config"
 	"git.wntrmute.dev/kyle/arca/internal/udisks"
 	"github.com/godbus/dbus/v5"
@@ -62,7 +63,7 @@ func runInit(cmd *cobra.Command, args []string) error {
 			continue
 		}
 
-		alias := aliasFromPath(dev.DevicePath)
+		alias := aliasFromUUID(dev.UUID)
 		cfg.Devices[alias] = config.DeviceConfig{
 			UUID:    dev.UUID,
 			Methods: []string{"passphrase"},
@@ -101,8 +102,12 @@ func isRootBacking(path dbus.ObjectPath, rootDevices []dbus.ObjectPath) bool {
 	return false
 }
 
-func aliasFromPath(devPath string) string {
-	// "/dev/sda1" -> "sda1", "/dev/nvme0n1p2" -> "nvme0n1p2"
-	base := filepath.Base(devPath)
-	return strings.TrimPrefix(base, "dm-")
+func aliasFromUUID(uuid string) string {
+	// Use first 8 chars of UUID as a stable alias.
+	// "b8b2f8e3-4cde-4aca-a96e-df9274019f9f" -> "b8b2f8e3"
+	clean := strings.ReplaceAll(uuid, "-", "")
+	if len(clean) > 8 {
+		clean = clean[:8]
+	}
+	return clean
 }

cmd/mount.go

@@ -12,6 +12,8 @@ import (
 	"golang.org/x/term"
 )
 
+var mountpoint string
+
 var mountCmd = &cobra.Command{
 	Use:   "mount <device|alias>",
 	Short: "Unlock and mount a LUKS volume",
@@ -20,6 +22,7 @@ var mountCmd = &cobra.Command{
 }
 
 func init() {
+	mountCmd.Flags().StringVarP(&mountpoint, "mountpoint", "m", "", "mount point override (privileged path only)")
 	rootCmd.AddCommand(mountCmd)
 }
 
@@ -35,6 +38,12 @@ func runMount(cmd *cobra.Command, args []string) error {
 
 	devCfg := cfg.ResolveDevice(target)
 
+	// CLI flag overrides config mountpoint.
+	mp := devCfg.Mountpoint
+	if mountpoint != "" {
+		mp = mountpoint
+	}
+
 	dev, err := client.FindDevice(devCfg.UUID, target)
 	if err != nil {
 		return err
@@ -43,12 +52,12 @@ func runMount(cmd *cobra.Command, args []string) error {
 	// Check if already unlocked.
 	if cleartext, err := client.CleartextDevice(dev); err == nil {
 		// Already unlocked — check if mounted too.
-		if mp, mounted := client.IsMounted(cleartext); mounted {
-			fmt.Println(mp)
+		if existing, mounted := client.IsMounted(cleartext); mounted {
+			fmt.Println(existing)
 			return nil
 		}
 		// Unlocked but not mounted — just mount it.
-		return doMount(client, cleartext, devCfg)
+		return doMount(client, cleartext, mp)
 	}
 
 	// Need to unlock.
@@ -63,23 +72,35 @@ func runMount(cmd *cobra.Command, args []string) error {
 	}
 
 	if result.Privileged {
-		mountpoint, err := cryptsetup.Mount(result.Device.DevicePath, devCfg.Mountpoint)
+		mnt, err := cryptsetup.Mount(result.Device.DevicePath, mp)
 		if err != nil {
 			return fmt.Errorf("mounting: %w", err)
 		}
-		fmt.Println(mountpoint)
+		fmt.Println(mnt)
 		return nil
 	}
 
-	return doMount(client, result.Device, devCfg)
+	if mp != "" {
+		fmt.Fprintf(os.Stderr, "warning: --mountpoint is ignored for udisks2 mounts (passphrase/keyfile path)\n")
+	}
+	return doMount(client, result.Device, "")
 }
 
-func doMount(client *udisks.Client, cleartext *udisks.BlockDevice, devCfg config.ResolvedDevice) error {
-	mountpoint, err := client.Mount(cleartext)
+func doMount(client *udisks.Client, cleartext *udisks.BlockDevice, mp string) error {
+	if mp != "" {
+		// udisks2 doesn't support custom mount points; use privileged mount.
+		mnt, err := cryptsetup.Mount(cleartext.DevicePath, mp)
 		if err != nil {
 			return fmt.Errorf("mounting: %w", err)
 		}
-	fmt.Println(mountpoint)
+		fmt.Println(mnt)
+		return nil
+	}
+	mnt, err := client.Mount(cleartext)
+	if err != nil {
+		return fmt.Errorf("mounting: %w", err)
+	}
+	fmt.Println(mnt)
 	return nil
 }
 

cmd/root.go

@@ -12,6 +12,10 @@ var rootCmd = &cobra.Command{
 	Short: "Mount and unmount LUKS-encrypted volumes",
 }
 
+func SetVersion(v string) {
+	rootCmd.Version = v
+}
+
 func Execute() {
 	if err := rootCmd.Execute(); err != nil {
 		fmt.Fprintln(os.Stderr, err)

flake.nix

@@ -10,13 +10,17 @@
     let
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.${system};
+      version = "1.0.0";
     in
     {
       packages.${system}.default = pkgs.buildGoModule {
         pname = "arca";
-        version = "0.1.0";
+        inherit version;
         src = ./.;
         vendorHash = null;
+        ldflags = [
+          "-X main.version=${version}"
+        ];
       };
     };
 }

main.go

@@ -2,6 +2,9 @@ package main
 
 import "git.wntrmute.dev/kyle/arca/cmd"
 
+var version = "dev"
+
 func main() {
+	cmd.SetVersion(version)
 	cmd.Execute()
 }