fix: honor '-' as stdin sentinel for message-text argument

cmd/message.go

@@ -321,10 +321,11 @@ var messageReactRemoveCmd = &cobra.Command{
 }
 
 // resolveMessageText resolves a message body from, in order of precedence:
-// the --file flag ('-' means stdin), the positional text argument at textArg,
-// or piped stdin when neither is given. This lets callers avoid passing
-// formatted message bodies as shell arguments, where backticks, $, and quotes
-// would otherwise be interpreted by the shell and corrupt the message.
+// the --file flag ('-' means stdin), the positional text argument at textArg
+// ('-' also means stdin there), or piped stdin when neither is given. This
+// lets callers avoid passing formatted message bodies as shell arguments,
+// where backticks, $, and quotes would otherwise be interpreted by the shell
+// and corrupt the message.
 func resolveMessageText(cmd *cobra.Command, args []string, textArg int) (string, error) {
 	file, _ := cmd.Flags().GetString("file")
 
@@ -337,6 +338,8 @@ func resolveMessageText(cmd *cobra.Command, args []string, textArg int) (string,
 			return "", fmt.Errorf("reading message body from %s: %w", file, err)
 		}
 		return string(b), nil
+	case len(args) > textArg && args[textArg] == "-":
+		return readAllStdin()
 	case len(args) > textArg:
 		return args[textArg], nil
 	case stdinIsPiped():

cmd/message_test.go

@@ -0,0 +1,30 @@
+package cmd
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+func TestResolveMessageTextDashStdin(t *testing.T) {
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatal(err)
+	}
+	orig := os.Stdin
+	os.Stdin = r
+	defer func() { os.Stdin = orig }()
+
+	go func() {
+		w.WriteString("hello from stdin\n")
+		w.Close()
+	}()
+
+	got, err := resolveMessageText(messageSendCmd, []string{"D0AHB4FLY75", "-"}, 1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if strings.TrimSpace(got) != "hello from stdin" {
+		t.Fatalf("got %q, want stdin content", got)
+	}
+}