feat: add cli contract and local browser events

cmd/chub/main_test.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestRunCLIRejectsUnknownCommandWithStableCode(t *testing.T) {
+	var out bytes.Buffer
+	if code := runCLI([]string{"wat"}, &out, &out); code != 2 || !strings.Contains(out.String(), `"invalid_argument"`) {
+		t.Fatalf("code=%d output=%s", code, out.String())
+	}
+}