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)
+			}
+		})
+	}
+}

internal/rpc/channels_passive_stubs_rpc_test.go

@@ -449,6 +449,36 @@ func TestTDesktopPassiveChannelStubs(t *testing.T) {
 	if ok, err := r.onMessagesReportSpam(ownerCtx, inputPeerChannel(channel)); err != nil || !ok {
 		t.Fatalf("messages.reportSpam = ok %v err %v, want true nil", ok, err)
 	}
+	if _, err := r.onMessagesReport(ownerCtx, &tg.MessagesReportRequest{
+		Peer: inputPeerChannel(channel),
+	}); err == nil || !strings.Contains(err.Error(), "MESSAGE_ID_REQUIRED") {
+		t.Fatalf("desktop messages.report without ids err = %v, want MESSAGE_ID_REQUIRED", err)
+	}
+	androidReportOptions, err := r.onMessagesReport(
+		WithClientInfo(ownerCtx, ClientInfo{
+			Type:       ClientTypeAndroid,
+			AppVersion: "12.9.0 (69669) pbeta",
+		}),
+		&tg.MessagesReportRequest{Peer: inputPeerChannel(channel)},
+	)
+	if err != nil {
+		t.Fatalf("android messages.report initial options: %v", err)
+	}
+	if choices, ok := androidReportOptions.(*tg.ReportResultChooseOption); !ok || len(choices.Options) == 0 {
+		t.Fatalf("android messages.report initial options = %#v, want chooseOption", androidReportOptions)
+	}
+	if got := moderationReports.Reports(); len(got) != 1 {
+		t.Fatalf("android initial report option discovery persisted reports = %+v, want only earlier reportSpam", got)
+	}
+	if _, err := r.onMessagesReport(
+		WithClientInfo(ownerCtx, ClientInfo{Type: ClientTypeAndroid}),
+		&tg.MessagesReportRequest{
+			Peer:   inputPeerChannel(channel),
+			Option: []byte("spam"),
+		},
+	); err == nil || !strings.Contains(err.Error(), "MESSAGE_ID_REQUIRED") {
+		t.Fatalf("android selected report option without ids err = %v, want MESSAGE_ID_REQUIRED", err)
+	}
 	reportOptions, err := r.onMessagesReport(ownerCtx, &tg.MessagesReportRequest{
 		Peer: inputPeerChannel(channel),
 		ID:   []int{1},

internal/rpc/messages_reports.go

@@ -9,6 +9,7 @@ import (
 	"github.com/iamxvbaba/td/tg"
 	"github.com/iamxvbaba/td/tgerr"
 
+	compatandroid "telesrv/internal/compat/android"
 	"telesrv/internal/domain"
 )
 
@@ -52,6 +53,14 @@ func (r *Router) onMessagesReport(ctx context.Context, req *tg.MessagesReportReq
 		return nil, err
 	}
 	if len(req.ID) == 0 {
+		if compatandroid.OfferInitialMessageReportOptions(
+			string(ClientTypeFrom(ctx)),
+			len(req.ID),
+			req.Option,
+			req.Message,
+		) {
+			return reportResultForOption("")
+		}
 		return nil, tgerr.New(400, "MESSAGE_ID_REQUIRED")
 	}
 	if len(req.ID) > maxGetMessagesIDs || len(req.Option) > maxReportOptionLength || utf8.RuneCountInString(req.Message) > maxReportCommentLength {