fix: 上行分发前统一限速，send 不再单独扣桶

internal/app/message/rate.go

@@ -57,3 +57,11 @@ func (r *rateLimiter) allow(endpointID string, now time.Time) bool {
 	b.tokens--
 	return true
 }
+
+// AllowRequest 消耗该端 1 个请求令牌；允许则 true。rps<=0 时不限速。
+func (a *App) AllowRequest(endpointID string) bool {
+	if a == nil {
+		return true
+	}
+	return a.rates.allow(endpointID, a.now())
+}

internal/app/message/rate_test.go

@@ -0,0 +1,22 @@
+package message
+
+import (
+	"testing"
+)
+
+func TestAllowRequestBurstAndAckExemptBucket(t *testing.T) {
+	t.Parallel()
+	lim := defaultTestLimits()
+	lim.RequestsPerSecond = 50
+	lim.RequestBurst = 100
+	app, _ := openTestApp(t, lim)
+	allowed := 0
+	for i := 0; i < 150; i++ {
+		if app.AllowRequest("alice") {
+			allowed++
+		}
+	}
+	if allowed != 100 {
+		t.Fatalf("allowed=%d want 100 (burst)", allowed)
+	}
+}

internal/app/message/submit.go

@@ -21,9 +21,6 @@ func (a *App) Submit(ctx context.Context, senderID string, conn port.ConnInfo, r
 		return SubmitResult{}, errCode(protocol.CodeBadRequest, "invalid sender")
 	}
 	now := a.now()
-	if !a.rates.allow(senderID, now) {
-		return SubmitResult{}, errCode(protocol.CodeRateLimited, "request rate exceeded")
-	}
 
 	if err := req.Validate(a.protocolLimits()); err != nil {
 		return SubmitResult{}, err

internal/app/message/submit_test.go

@@ -371,16 +371,15 @@ SELECT kind FROM talk_grants WHERE sender_id=? AND target_id=?`, "bob", "alice")
 		app, db := openTestApp(t, lim)
 		insertEndpoint(t, db, "alice", "", 1, 0)
 		insertEndpoint(t, db, "bob", "", 1, 0)
+		if !app.AllowRequest("alice") || !app.AllowRequest("alice") {
+			t.Fatal("burst should allow first two")
+		}
+		if app.AllowRequest("alice") {
+			t.Fatal("third request should be rate limited")
+		}
 		ctx := context.Background()
 		if _, err := app.Submit(ctx, "alice", port.ConnInfo{}, baseSend("r1", "bob")); err != nil {
 			t.Fatal(err)
 		}
-		if _, err := app.Submit(ctx, "alice", port.ConnInfo{}, baseSend("r2", "bob")); err != nil {
-			t.Fatal(err)
-		}
-		_, err := app.Submit(ctx, "alice", port.ConnInfo{}, baseSend("r3", "bob"))
-		if protoCode(err) != protocol.CodeRateLimited {
-			t.Fatalf("want rate_limited got %v", err)
-		}
 	})
 }