feat(cli): wire arch-binary subcommand

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <[email protected]>

cmd/zeta-reconstruct/main.go

@@ -6,6 +6,7 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"strings"
 
 	"git.spectoria.dev/huntedbytheirs/zeta-reconstruct/internal/registry"
 
@@ -39,6 +40,29 @@ func main() {
 	os.Exit(run(os.Args[1:]))
 }
 
+// normalizeArgs reorders args into [flags and their values..., positionals...]
+// because stdlib flag.Parse stops at the first non-flag token, which would
+// misparse flags placed after the positional input.
+func normalizeArgs(args []string, valueFlags map[string]bool) []string {
+	var flags, positionals []string
+	for i := 0; i < len(args); i++ {
+		tok := args[i]
+		if !strings.HasPrefix(tok, "-") || tok == "-" {
+			positionals = append(positionals, tok)
+			continue
+		}
+		flags = append(flags, tok)
+		if !strings.Contains(tok, "=") {
+			name := tok
+			if valueFlags[name] && i+1 < len(args) {
+				i++
+				flags = append(flags, args[i])
+			}
+		}
+	}
+	return append(flags, positionals...)
+}
+
 func run(args []string) int {
 	if len(args) == 0 {
 		fmt.Fprintln(os.Stderr, "error: no command specified")
@@ -67,21 +91,25 @@ func run(args []string) int {
 	fs := flag.NewFlagSet(frontend.Name(), flag.ContinueOnError)
 	fs.SetOutput(os.Stderr)
 	opts := registry.Options{Output: "."}
+	valueFlags := make(map[string]bool)
 	switch frontend.Name() {
 	case "arch-binary":
 		opts.Repo = defaultRepo
 		fs.StringVar(&opts.Repo, "repo", opts.Repo, "repository base URL")
+		valueFlags["--repo"] = true
 	case "arch-src":
 		opts.Arch = "x86_64"
 		fs.StringVar(&opts.Arch, "arch", opts.Arch, "target architecture")
+		valueFlags["--arch"] = true
 	}
 	fs.StringVar(&opts.Output, "output", opts.Output, "output directory")
+	valueFlags["--output"] = true
 	fs.Usage = func() {
 		fmt.Fprintf(os.Stderr, "usage: zeta-reconstruct %s [flags] <input>\n", frontend.Name())
 		fmt.Fprintln(os.Stderr, "Run 'zeta-reconstruct --help' for usage.")
 	}
 
-	if err := fs.Parse(args[1:]); err != nil {
+	if err := fs.Parse(normalizeArgs(args[1:], valueFlags)); err != nil {
 		if err == flag.ErrHelp {
 			fs.Usage()
 			return 0
@@ -100,6 +128,11 @@ func run(args []string) int {
 		fs.Usage()
 		return 2
 	}
+	if frontend.Name() == "arch-binary" && !strings.HasSuffix(rest[0], ".pkg.tar.zst") {
+		fmt.Fprintln(os.Stderr, "error: arch-binary input must end with .pkg.tar.zst")
+		fs.Usage()
+		return 2
+	}
 
 	if err := frontend.Convert(rest[0], opts); err != nil {
 		fmt.Fprintf(os.Stderr, "error: %v\n", err)