fix: sync DrKLO report selection support

internal/compat/android/report.go

@@ -0,0 +1,22 @@
+package android
+
+const clientType = "android"
+
+// OfferInitialMessageReportOptions preserves DrKLO's official channel-report
+// flow. DrKLO starts that flow with an empty message-id vector and only opens
+// its message selector after a chosen option receives MESSAGE_ID_REQUIRED.
+//
+// This exception is deliberately limited to the non-mutating first request:
+// a selected option, a comment, or any non-Android caller must still pass the
+// normal messages.report message-id validation.
+func OfferInitialMessageReportOptions(
+	client string,
+	messageIDCount int,
+	option []byte,
+	comment string,
+) bool {
+	return client == clientType &&
+		messageIDCount == 0 &&
+		len(option) == 0 &&
+		comment == ""
+}

internal/compat/android/report_test.go

@@ -0,0 +1,32 @@
+package android
+
+import "testing"
+
+func TestOfferInitialMessageReportOptions(t *testing.T) {
+	tests := []struct {
+		name           string
+		client         string
+		messageIDCount int
+		option         []byte
+		comment        string
+		want           bool
+	}{
+		{name: "android initial discovery", client: "android", want: true},
+		{name: "desktop keeps protocol error", client: "tdesktop"},
+		{name: "selected option requires messages", client: "android", option: []byte("spam")},
+		{name: "comment requires messages", client: "android", comment: "details"},
+		{name: "message ids use normal flow", client: "android", messageIDCount: 1},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := OfferInitialMessageReportOptions(
+				test.client,
+				test.messageIDCount,
+				test.option,
+				test.comment,
+			); got != test.want {
+				t.Fatalf("OfferInitialMessageReportOptions() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}