Initialize narratio Go module and CLI scaffold

internal/app/commands.go

@@ -0,0 +1,56 @@
+package app
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"strings"
+)
+
+var supportedCommands = []string{"run", "plan", "status", "resume", "run-stage"}
+
+// Execute dispatches CLI commands and returns a process exit code.
+func Execute(args []string, stdout, stderr io.Writer) int {
+	if len(args) == 0 {
+		printUsage(stderr)
+		return 1
+	}
+
+	ctx := context.Background()
+	cmd := args[0]
+	cmdArgs := args[1:]
+
+	var err error
+	switch cmd {
+	case "run":
+		err = Run(ctx, cmdArgs, stdout)
+	case "plan":
+		err = Plan(ctx, cmdArgs, stdout)
+	case "status":
+		err = Status(ctx, cmdArgs, stdout)
+	case "resume":
+		err = Resume(ctx, cmdArgs, stdout)
+	case "run-stage":
+		err = RunStage(ctx, cmdArgs, stdout)
+	default:
+		fmt.Fprintf(stderr, "unknown command: %q\n\n", cmd)
+		printUsage(stderr)
+		return 1
+	}
+
+	if err != nil {
+		fmt.Fprintf(stderr, "%v\n", err)
+		return 1
+	}
+
+	return 0
+}
+
+func printUsage(w io.Writer) {
+	fmt.Fprintf(w, "Usage: narratio <%s>\n", strings.Join(supportedCommands, "|"))
+}
+
+func placeholder(out io.Writer, command string) error {
+	_, err := fmt.Fprintf(out, "narratio %s: not yet implemented\n", command)
+	return err
+}