fix: sync session membership routing fixes

internal/rpc/router_layer_binder_test.go

@@ -0,0 +1,82 @@
+package rpc
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"go.uber.org/zap/zaptest"
+
+	"github.com/gotd/td/bin"
+	"github.com/gotd/td/clock"
+	"github.com/gotd/td/tg"
+)
+
+type layerBinderCall struct {
+	rawAuthKeyID [8]byte
+	sessionID    int64
+	layer        int
+}
+
+// layerCaptureSessions 在 captureSessions 基础上实现可选的 ClientLayerBinder。
+type layerCaptureSessions struct {
+	captureSessions
+	layerMu    sync.Mutex
+	layerCalls []layerBinderCall
+}
+
+func (s *layerCaptureSessions) SetClientLayerForAuthKey(rawAuthKeyID [8]byte, sessionID int64, layer int) {
+	s.layerMu.Lock()
+	defer s.layerMu.Unlock()
+	s.layerCalls = append(s.layerCalls, layerBinderCall{rawAuthKeyID: rawAuthKeyID, sessionID: sessionID, layer: layer})
+}
+
+func (s *layerCaptureSessions) layerCallsSnapshot() []layerBinderCall {
+	s.layerMu.Lock()
+	defer s.layerMu.Unlock()
+	return append([]layerBinderCall(nil), s.layerCalls...)
+}
+
+// TestDispatchInvokeWithLayerPushesLayerToSessionBinder 验证 invokeWithLayer 在
+// Dispatch 入口把新观测的 layer 即时下推到连接层（ClientLayerBinder），且仅在
+// 首次观测或 layer 变化时下推——每条请求都带 wrapper 的客户端不会造成逐 RPC 下推。
+func TestDispatchInvokeWithLayerPushesLayerToSessionBinder(t *testing.T) {
+	sessions := &layerCaptureSessions{}
+	r := New(Config{DC: 2, IP: "127.0.0.1", Port: 2398}, Deps{Sessions: sessions}, zaptest.NewLogger(t), clock.System)
+	rawAuthKeyID := [8]byte{1, 2, 3, 4, 5, 6, 7, 8}
+	const sessionID = int64(42)
+
+	dispatchWithLayer := func(layer int) {
+		t.Helper()
+		var in bin.Buffer
+		req := &tg.InvokeWithLayerRequest{Layer: layer, Query: &tg.HelpGetConfigRequest{}}
+		if err := req.Encode(&in); err != nil {
+			t.Fatalf("encode: %v", err)
+		}
+		if _, err := r.Dispatch(context.Background(), rawAuthKeyID, sessionID, &in); err != nil {
+			t.Fatalf("dispatch layer %d: %v", layer, err)
+		}
+	}
+
+	dispatchWithLayer(225)
+	calls := sessions.layerCallsSnapshot()
+	if len(calls) != 1 {
+		t.Fatalf("layer binder calls = %d, want 1", len(calls))
+	}
+	if calls[0] != (layerBinderCall{rawAuthKeyID: rawAuthKeyID, sessionID: sessionID, layer: 225}) {
+		t.Fatalf("layer binder call = %+v", calls[0])
+	}
+
+	// 同 layer 重复 wrapper：不再下推。
+	dispatchWithLayer(225)
+	if calls := sessions.layerCallsSnapshot(); len(calls) != 1 {
+		t.Fatalf("layer binder calls after repeat = %d, want 1", len(calls))
+	}
+
+	// layer 变化：再次下推。
+	dispatchWithLayer(226)
+	calls = sessions.layerCallsSnapshot()
+	if len(calls) != 2 || calls[1].layer != 226 {
+		t.Fatalf("layer binder calls after change = %+v, want second call with layer 226", calls)
+	}
+}