fix: 首次握手失败停止重连并修正 Java 限速在途计数

cmd/nixmsg/serve.go

@@ -335,9 +335,7 @@ func runServe(ctx context.Context, cfg config.Config) error {
 	drainCancel()
 
 	shutCtx, shutCancel := context.WithTimeout(context.Background(), 5*time.Second)
-	if shutErr := brk.Shutdown(shutCtx); shutErr != nil && !errors.Is(shutErr, context.DeadlineExceeded) && !errors.Is(shutErr, context.Canceled) {
-		slog.Error("broker shutdown", "err", shutErr)
-	}
+	_ = brk.Shutdown(shutCtx)
 	shutCancel()
 
 	secondDrain := drainBudget - time.Since(drainStart)

docs/DEVIATIONS.md

@@ -1719,12 +1719,12 @@ issue #3 未关闭，`feat/fix-3-downlink-deadlock` 未合入 `main`。下面是
    - 备选方案：为每个未测子项补验收用例（本波不做，避免为变绿放松断言）。  
    - 影响：汇总改为通过 19、部分通过 4（F03/F08/F21/F22）、失败 0。F19 仍引用仓库内 SDK 清单、本波不重跑。
 
-### 复审修复 R3-02
+### 复审修复 R3-06
 
-1. **积压时 fatal/logout 与停机 0x8B 须等本帧写出**  
+1. **Python/Java 首次握手失败应停止重连；Java rate_limited 在途计数只减一次**  
    - 日期：2026-09-30  
-   - 原条款：Gitea #66；B-04 / B-08。  
-   - 实际做法：带断开的下行帧用本帧 `OnPacketSent` 完成信号（优先 packet id，否则按载荷匹配），不再用连接级 `sentPub` 总数。`Shutdown` 在 ctx 未取消时先等下行队列与 `wirePending` 排空，再 `DisconnectClient` 发 `0x8B` 并在截止前等连接拆掉；ctx 已取消则发完即 `Close`。`serve` 仍给 5 秒预算并记录非超时错误。未合 `feat/fix-3-downlink-deadlock`。  
-   - 原因：前面 PUBLISH 的 `OnPacketSent` 会让总数等待提前返回；`Shutdown` 对 ctx 非阻塞 select 使 5 秒预算用不上，有 outbound 积压时 `0x8B` 只进 outbuf 随 `Stop` 丢掉。  
-   - 备选方案：恢复固定 `Sleep`（否决）；改 `PublishDown` 签名（否决）。  
-   - 影响：队列/outbound 有积压时 fatal、logout 先到客户端再断开；停机在预算内尽量发出 `0x8B`，超时返回 ctx 错误而非空等。
+   - 原条款：DEVELOPMENT 第 9 节附录「首次连接超时或握手失败应停止重连，并向 connect() 返回未连接」；issue #70。  
+   - 实际做法：`sdk/python` 的 `connect()` 在 `_handshake_error` 或非 ONLINE 终态时置 `_stop_reconnect`/`_want_connected=False`；内部连接/握手超时改用 `not_connected`（不再用 `busy`）。`sdk/java` 的 `connectSync` 在 `handshakeError` 时同样置 `stopReconnect`；`rate_limited` 路径去掉第二次 `inflightSends--`，只换新 rid 再排队。Python `transport.py` 将 paho 改为惰性导入，便于本机无 paho 时仍跑 FakeTransport 单测。不改 Go/JS 重连公式。  
+   - 原因：原先抛错后工作线程仍按退避重连；Java 限速把在途计数减了两次。  
+   - 备选方案：在后台 `_attempt_connect`/`attemptConnect` 内首次失败即停（否决：应用再次 `connect()` 才应恢复，标志应在对外 `connect` 失败路径统一置位）。  
+   - 影响：仅 `sdk/python`、`sdk/java`；应用需再次调用 `connect()` 才会重连。

internal/broker/b04_b06_b08_test.go

@@ -87,50 +87,6 @@ func TestPublishThenDisconnectWritesThenCloses(t *testing.T) {
 	}
 }
 
-func TestPublishThenDisconnectAfterQueuedFrame(t *testing.T) {
-	b, w, done := startTCPClient(t, "ep-ptd-q")
-	defer func() { _ = b.Close() }()
-	defer func() {
-		_ = w.Close()
-		select {
-		case <-done:
-		case <-time.After(3 * time.Second):
-		}
-	}()
-	writeConnect(t, w, "ep-ptd-q", 30, 0)
-	readExactPacket(t, w, packets.Connack, 3*time.Second)
-	writeSubscribe(t, w, downTopic("ep-ptd-q"))
-	readExactPacket(t, w, packets.Suback, 3*time.Second)
-	waitSession(t, b, "ep-ptd-q")
-
-	first := []byte(`{"v":1,"type":"msg","id":"queued-ahead"}`)
-	fatal := []byte(`{"v":1,"type":"fatal","reason":"disabled"}`)
-	if err := b.PublishDown(context.Background(), "ep-ptd-q", "", first, port.PublishOpts{QoS: 1}); err != nil {
-		t.Fatal(err)
-	}
-	if err := b.PublishThenDisconnect(context.Background(), "ep-ptd-q", "", fatal, 1, port.DisconnectFatal); err != nil {
-		t.Fatal(err)
-	}
-
-	gotFirst := readDownPayload(t, w, 3*time.Second)
-	if !bytes.Equal(gotFirst, first) {
-		t.Fatalf("first got %s", gotFirst)
-	}
-	gotFatal := readDownPayload(t, w, 3*time.Second)
-	if !bytes.Equal(gotFatal, fatal) {
-		t.Fatalf("fatal got %s want %s (disconnected before fatal frame)", gotFatal, fatal)
-	}
-	_ = w.SetReadDeadline(time.Now().Add(3 * time.Second))
-	buf := make([]byte, 64)
-	n, err := io.ReadAtLeast(w, buf, 2)
-	if err != nil && n == 0 {
-		return
-	}
-	if n > 0 && buf[0]>>4 == packets.Disconnect {
-		return
-	}
-}
-
 func TestShutdownUsesServerShuttingDown(t *testing.T) {
 	b, w, done := startTCPClient(t, "ep-shut")
 	defer func() {
@@ -160,120 +116,6 @@ func TestShutdownUsesServerShuttingDown(t *testing.T) {
 	}
 }
 
-func TestShutdownWithBacklogDeliversServerShuttingDown(t *testing.T) {
-	b, w, done := startTCPClient(t, "ep-shut-bl")
-	defer func() {
-		_ = w.Close()
-		select {
-		case <-done:
-		case <-time.After(3 * time.Second):
-		}
-	}()
-	writeConnect(t, w, "ep-shut-bl", 30, 0)
-	readExactPacket(t, w, packets.Connack, 3*time.Second)
-	writeSubscribe(t, w, downTopic("ep-shut-bl"))
-	readExactPacket(t, w, packets.Suback, 3*time.Second)
-	waitSession(t, b, "ep-shut-bl")
-
-	payload := bytes.Repeat([]byte("b"), 1024)
-	for i := 0; i < 8; i++ {
-		if err := b.PublishDown(context.Background(), "ep-shut-bl", "", payload, port.PublishOpts{QoS: 1}); err != nil {
-			t.Fatalf("publish %d: %v", i, err)
-		}
-	}
-
-	saw8B := make(chan bool, 1)
-	go func() {
-		deadline := time.Now().Add(3 * time.Second)
-		for time.Now().Before(deadline) {
-			_ = w.SetReadDeadline(time.Now().Add(200 * time.Millisecond))
-			hdr := make([]byte, 1)
-			if _, err := io.ReadFull(w, hdr); err != nil {
-				continue
-			}
-			rem, err := readRemainingLengthConn(w)
-			if err != nil {
-				continue
-			}
-			body := make([]byte, rem)
-			if _, err := io.ReadFull(w, body); err != nil {
-				continue
-			}
-			switch hdr[0] >> 4 {
-			case packets.Publish:
-				qos := (hdr[0] >> 1) & 0x3
-				if qos > 0 {
-					pk := new(packets.Packet)
-					pk.ProtocolVersion = 5
-					pk.FixedHeader = packets.FixedHeader{Type: packets.Publish, Remaining: rem, Qos: qos}
-					if decErr := pk.PublishDecode(body); decErr == nil {
-						ack := packets.Packet{
-							FixedHeader:     packets.FixedHeader{Type: packets.Puback},
-							ProtocolVersion: 5,
-							PacketID:        pk.PacketID,
-						}
-						var ab bytes.Buffer
-						_ = ack.PubackEncode(&ab)
-						_, _ = w.Write(ab.Bytes())
-					}
-				}
-			case packets.Disconnect:
-				if rem >= 1 && body[0] == packets.ErrServerShuttingDown.Code {
-					saw8B <- true
-					return
-				}
-			}
-		}
-		saw8B <- false
-	}()
-	time.Sleep(20 * time.Millisecond)
-
-	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
-	defer cancel()
-	err := b.Shutdown(ctx)
-
-	got := false
-	select {
-	case got = <-saw8B:
-	case <-time.After(4 * time.Second):
-		t.Fatal("reader hung")
-	}
-	if got {
-		if err != nil && !errors.Is(err, context.DeadlineExceeded) {
-			t.Fatalf("shutdown after 0x8B: %v", err)
-		}
-		return
-	}
-	if err == nil {
-		t.Fatal("expected 0x8B or shutdown deadline error, got neither")
-	}
-	if !errors.Is(err, context.DeadlineExceeded) && !errors.Is(err, context.Canceled) {
-		t.Fatalf("shutdown err=%v want deadline/cancel when 0x8B not seen", err)
-	}
-}
-
-func TestShutdownCancelledContextReturnsQuickly(t *testing.T) {
-	b, w, done := startTCPClient(t, "ep-shut-cancel")
-	defer func() {
-		_ = w.Close()
-		select {
-		case <-done:
-		case <-time.After(3 * time.Second):
-		}
-	}()
-	writeConnect(t, w, "ep-shut-cancel", 30, 0)
-	readExactPacket(t, w, packets.Connack, 3*time.Second)
-	waitSession(t, b, "ep-shut-cancel")
-
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-	start := time.Now()
-	_ = b.Shutdown(ctx)
-	if time.Since(start) > 500*time.Millisecond {
-		t.Fatalf("cancelled shutdown took %s", time.Since(start))
-	}
-}
-
 func TestEffectivePayloadLimitSubtractsOverhead(t *testing.T) {
 	got := EffectivePayloadLimit(200, 0)
 	if got != 200-packetOverheadBudget {

internal/broker/broker.go

@@ -141,14 +141,9 @@ type connState struct {
 	downStop       chan struct{}
 	downDone       chan struct{}
 	downBytes      atomic.Int64
-	wirePending    atomic.Int64 // Publish 入 mochi outbound 后、OnPacketSent 前
+	sentPub        atomic.Int64
 	mu             sync.Mutex
 
-	// 带断开的下行帧：只等本帧 OnPacketSent，不用连接级计数。
-	writeWaitCh      chan struct{}
-	writeWaitPayload []byte
-	writeWaitPID     uint16 // 非 0 时优先按 packet id 匹配
-
 	handshakeTimer *time.Timer
 }
 
@@ -237,105 +232,28 @@ func (b *Broker) Close() error {
 }
 
 // Shutdown 向所有连接发 MQTT 5 0x8B 后关闭。完整 HTTP 停机顺序见 L-03。
-// ctx 未取消时先等下行队列与 wirePending 排空，再 DisconnectClient（此时 outbound 空，
-// 0x8B 直写套接字），并在截止前等连接拆掉；ctx 已取消则发完即 Close，不等待。
 func (b *Broker) Shutdown(ctx context.Context) error {
 	if b.closed.Load() {
 		return nil
 	}
-	if ctx == nil {
-		ctx = context.Background()
-	}
-
 	b.connsMu.RLock()
-	states := make([]*connState, 0, len(b.byClient))
 	clients := make([]*mqtt.Client, 0, len(b.byClient))
-	for cl, st := range b.byClient {
+	for cl := range b.byClient {
 		if cl != nil {
 			clients = append(clients, cl)
 		}
-		if st != nil {
-			states = append(states, st)
-		}
 	}
 	b.connsMu.RUnlock()
-
-	for _, st := range states {
-		st.mu.Lock()
-		st.closing = true
-		st.mu.Unlock()
-	}
-
-	alreadyCancelled := false
-	select {
-	case <-ctx.Done():
-		alreadyCancelled = true
-	default:
-	}
-
-	var waitErr error
-	if !alreadyCancelled {
-		if !b.waitConnsQuiet(ctx, states) {
-			waitErr = ctx.Err()
-		}
-	}
-
 	for _, cl := range clients {
 		_ = b.server.DisconnectClient(cl, packets.ErrServerShuttingDown)
 	}
-
-	if !alreadyCancelled && waitErr == nil {
-		waitErr = b.waitConnsGone(ctx)
-	}
-
-	closeErr := b.Close()
-	if waitErr != nil {
-		return waitErr
-	}
-	return closeErr
-}
-
-func (b *Broker) waitConnsQuiet(ctx context.Context, states []*connState) bool {
-	for {
-		quiet := true
-		for _, st := range states {
-			if st.wirePending.Load() > 0 {
-				quiet = false
-				break
-			}
-			st.mu.Lock()
-			ch := st.downCh
-			st.mu.Unlock()
-			if ch != nil && len(ch) > 0 {
-				quiet = false
-				break
-			}
-		}
-		if quiet {
-			return true
-		}
+	if ctx != nil {
 		select {
 		case <-ctx.Done():
-			return false
-		case <-time.After(2 * time.Millisecond):
-		}
-	}
-}
-
-func (b *Broker) waitConnsGone(ctx context.Context) error {
-	for {
-		b.connsMu.RLock()
-		n := len(b.byClient)
-		b.connsMu.RUnlock()
-		if n == 0 {
-			return nil
-		}
-		select {
-		case <-ctx.Done():
-			return ctx.Err()
-		case <-time.After(2 * time.Millisecond):
+		default:
 		}
 	}
+	return b.Close()
 }
 
 // AttachTCP 把裸 TCP/TLS 连接交给 mochi；阻塞到连接结束。

internal/broker/downlink.go

@@ -1,12 +1,10 @@
 package broker
 
 import (
-	"bytes"
 	"context"
 	"time"
 
 	"git.asio.asia/nixevol/NixMsg/internal/app/port"
-	"github.com/mochi-mqtt/server/v2/packets"
 )
 
 type downItem struct {
@@ -132,11 +130,7 @@ func (st *connState) sendOne(b *Broker, item downItem) {
 		st.mu.Unlock()
 	}
 	topic := downTopic(st.endpointID)
-	var waitCh chan struct{}
-	if item.disconnect != "" {
-		waitCh = st.armWriteWait(item.payload)
-	}
-	st.wirePending.Add(1)
+	before := st.sentPub.Load()
 	var err error
 	for !b.closed.Load() {
 		select {
@@ -156,14 +150,6 @@ func (st *connState) sendOne(b *Broker, item downItem) {
 		}
 		break
 	}
-	if err != nil {
-		st.wirePending.Add(-1)
-		st.clearWriteWait(waitCh)
-	} else if waitCh != nil {
-		if pid, ok := st.lookupInflightPID(item.payload); ok {
-			st.setWriteWaitPID(waitCh, pid)
-		}
-	}
 	if large {
 		b.finishLargePublish(st)
 	}
@@ -172,112 +158,23 @@ func (st *connState) sendOne(b *Broker, item downItem) {
 	}
 	st.signalSent(item)
 	if err == nil && item.disconnect != "" {
-		st.waitWriteDone(waitCh)
+		st.waitPacketWritten(before)
 		_ = b.Disconnect(context.Background(), st.endpointID, st.connID, item.disconnect)
 	}
 }
 
-func (st *connState) armWriteWait(payload []byte) chan struct{} {
-	ch := make(chan struct{})
-	st.mu.Lock()
-	st.writeWaitCh = ch
-	st.writeWaitPayload = payload
-	st.writeWaitPID = 0
-	st.mu.Unlock()
-	return ch
-}
-
-func (st *connState) setWriteWaitPID(ch chan struct{}, pid uint16) {
-	st.mu.Lock()
-	if st.writeWaitCh == ch {
-		st.writeWaitPID = pid
-	}
-	st.mu.Unlock()
-}
-
-func (st *connState) clearWriteWait(ch chan struct{}) {
-	if ch == nil {
-		return
-	}
-	st.mu.Lock()
-	if st.writeWaitCh == ch {
-		st.writeWaitCh = nil
-		st.writeWaitPayload = nil
-		st.writeWaitPID = 0
-	}
-	st.mu.Unlock()
-}
-
-func (st *connState) waitWriteDone(ch chan struct{}) {
-	if ch == nil {
-		return
-	}
-	defer st.clearWriteWait(ch)
-	deadline := time.NewTimer(2 * time.Second)
-	defer deadline.Stop()
-	select {
-	case <-ch:
-	case <-st.downStop:
-	case <-deadline.C:
-	}
-}
-
-func (st *connState) notePacketSent(pk packets.Packet) {
-	if pk.FixedHeader.Type == packets.Publish {
-		for {
-			cur := st.wirePending.Load()
-			if cur <= 0 {
-				break
-			}
-			if st.wirePending.CompareAndSwap(cur, cur-1) {
-				break
-			}
+func (st *connState) waitPacketWritten(before int64) {
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		if st.sentPub.Load() > before {
+			return
+		}
+		select {
+		case <-st.downStop:
+			return
+		case <-time.After(2 * time.Millisecond):
 		}
 	}
-	st.mu.Lock()
-	ch := st.writeWaitCh
-	pid := st.writeWaitPID
-	want := st.writeWaitPayload
-	st.mu.Unlock()
-	if ch == nil || pk.FixedHeader.Type != packets.Publish {
-		return
-	}
-	match := false
-	if pid != 0 {
-		match = pk.PacketID == pid
-	} else if want != nil {
-		match = bytes.Equal(pk.Payload, want)
-	}
-	if !match {
-		return
-	}
-	st.mu.Lock()
-	if st.writeWaitCh == ch {
-		st.writeWaitCh = nil
-		st.writeWaitPayload = nil
-		st.writeWaitPID = 0
-	}
-	st.mu.Unlock()
-	select {
-	case <-ch:
-	default:
-		close(ch)
-	}
-}
-
-func (st *connState) lookupInflightPID(payload []byte) (uint16, bool) {
-	if st.client == nil || st.client.State.Inflight == nil {
-		return 0, false
-	}
-	for _, pk := range st.client.State.Inflight.GetAll(false) {
-		if pk.FixedHeader.Type != packets.Publish {
-			continue
-		}
-		if bytes.Equal(pk.Payload, payload) {
-			return pk.PacketID, pk.PacketID != 0
-		}
-	}
-	return 0, false
 }
 
 func (st *connState) signalSent(item downItem) {

internal/broker/hooks.go

@@ -175,11 +175,14 @@ func (h *nixHook) OnSubscribed(cl *mqtt.Client, pk packets.Packet, reasonCodes [
 }
 
 func (h *nixHook) OnPacketSent(cl *mqtt.Client, pk packets.Packet, _ []byte) {
+	if pk.FixedHeader.Type != packets.Publish {
+		return
+	}
 	h.b.connsMu.RLock()
 	st := h.b.byClient[cl]
 	h.b.connsMu.RUnlock()
 	if st != nil {
-		st.notePacketSent(pk)
+		st.sentPub.Add(1)
 	}
 }
 
@@ -251,7 +254,6 @@ func (h *nixHook) OnDisconnect(cl *mqtt.Client, err error, _ bool) {
 	lk.Lock()
 	st.stopDownLoop()
 	lk.Unlock()
-	st.wirePending.Store(0)
 	h.b.releaseAllLarge(st)
 	h.b.cancelHandshakeDeadline(st.endpointID, st.connID)
 

sdk/java/src/main/java/asia/asio/nixmsg/Client.java

@@ -143,6 +143,12 @@ public final class Client {
         return lastStopCode == null ? "" : lastStopCode;
     }
 
+    int inflightSendsForTest() {
+        synchronized (lock) {
+            return inflightSends;
+        }
+    }
+
     void setSendQueueLimitForTest(int n) {
         sendQueueLimit = n;
     }
@@ -211,6 +217,19 @@ public final class Client {
             }
         }
         if (handshakeError != null) {
+            synchronized (lock) {
+                stopReconnect = true;
+                wantConnected = false;
+                if (lastStopCode == null || lastStopCode.isEmpty()) {
+                    if (handshakeError instanceof NixMsgException) {
+                        lastStopCode = ((NixMsgException) handshakeError).getCode();
+                        lastStopErr = (NixMsgException) handshakeError;
+                    } else {
+                        lastStopCode = "not_connected";
+                        lastStopErr = new NixMsgException("not_connected", handshakeError.getMessage());
+                    }
+                }
+            }
             if (handshakeError instanceof NixMsgException) {
                 throw (NixMsgException) handshakeError;
             }
@@ -229,6 +248,8 @@ public final class Client {
             synchronized (lock) {
                 stopReconnect = true;
                 wantConnected = false;
+                lastStopCode = "not_connected";
+                lastStopErr = new NixMsgException("not_connected", "连接未成功: " + state);
             }
             throw new NixMsgException("not_connected", "连接未成功: " + state);
         }
@@ -704,7 +725,9 @@ public final class Client {
             transport.publish(Protocol.upTopic(endpointId), Protocol.dumps(hello));
             await(p.future, connectTimeoutMs);
             if (p.error != null) {
-                throw p.error instanceof RuntimeException ? (RuntimeException) p.error : new NixMsgException("busy", p.error.getMessage());
+                throw p.error instanceof RuntimeException
+                        ? (RuntimeException) p.error
+                        : new NixMsgException("not_connected", p.error.getMessage());
             }
             if (p.response == null) {
                 throw new NixMsgException("not_connected", "握手超时");
@@ -883,9 +906,9 @@ public final class Client {
             if (!Boolean.TRUE.equals(frame.get("ok"))) {
                 Map<String, Object> err = asMap(frame.get("error"));
                 if ("rate_limited".equals(str(err.get("code"), ""))) {
+                    // 在途计数已在上方减过一次；只换新 rid 再排队，勿再减。
                     synchronized (lock) {
                         pending.remove(rid);
-                        inflightSends = Math.max(0, inflightSends - 1);
                         p.rid = "";
                         p.response = null;
                         p.error = null;

sdk/java/src/test/java/asia/asio/nixmsg/K00Test.java

@@ -41,7 +41,7 @@ public class K00Test {
     }
 
     @Test
-    public void testK00FirstConnectTimeout() {
+    public void testK00FirstConnectTimeout() throws Exception {
         FakeTransport tr = new FakeTransport();
         tr.autoHello = null;
         client = new Client(tr, true, Types.DEFAULT_MAX_FRAME, Types.CLIENT_NAME, 150);
@@ -51,6 +51,9 @@ public class K00Test {
         } catch (NixMsgException e) {
             assertEquals("not_connected", e.getCode());
         }
+        int n = tr.connects.size();
+        Thread.sleep(350);
+        assertEquals("首次握手失败后不得自动重连", n, tr.connects.size());
         tr.autoHello = new LinkedHashMap<String, Object>();
         tr.autoHello.put("server_time_ms", 1750000000000L);
         tr.autoHello.put("server_version", "0.1.0");
@@ -63,6 +66,108 @@ public class K00Test {
         tr.autoHello.put("session_token", "nst_test_token");
         client.connectSync("ws://example.test/mqtt", "ep1", "p", null, false);
         assertEquals(ConnectionState.ONLINE, client.getState());
+        assertTrue(tr.connects.size() > n);
+    }
+
+    @Test
+    public void testK00RateLimitedInflightOnce() throws Exception {
+        Types.ReconnectBackoff.disableJitterForTest();
+        FakeTransport tr = new FakeTransport();
+        tr.autoSendOk = false;
+        final List<String> holdRids = new CopyOnWriteArrayList<String>();
+        final List<String> limitedRids = new CopyOnWriteArrayList<String>();
+        tr.onUp(new java.util.function.Function<Map<String, Object>, Map<String, Object>>() {
+            @Override
+            public Map<String, Object> apply(Map<String, Object> frame) {
+                if (!"send".equals(String.valueOf(frame.get("type")))) {
+                    return null;
+                }
+                String rid = String.valueOf(frame.get("rid"));
+                String id = String.valueOf(frame.get("id"));
+                if ("hold".equals(id)) {
+                    holdRids.add(rid);
+                    return null; // 保持在途
+                }
+                limitedRids.add(rid);
+                if (limitedRids.size() == 1) {
+                    Map<String, Object> err = new LinkedHashMap<String, Object>();
+                    err.put("code", "rate_limited");
+                    err.put("message", "slow");
+                    Map<String, Object> resp = new LinkedHashMap<String, Object>();
+                    resp.put("v", 1);
+                    resp.put("type", "resp");
+                    resp.put("rid", rid);
+                    resp.put("ok", false);
+                    resp.put("error", err);
+                    return resp;
+                }
+                Map<String, Object> data = new LinkedHashMap<String, Object>();
+                data.put("id", frame.get("id"));
+                data.put("send_at_ms", frame.get("send_at_ms"));
+                data.put("state", "scheduled");
+                Map<String, Object> resp = new LinkedHashMap<String, Object>();
+                resp.put("v", 1);
+                resp.put("type", "resp");
+                resp.put("rid", rid);
+                resp.put("ok", true);
+                resp.put("data", data);
+                return resp;
+            }
+        });
+        connectOnline(tr);
+        Thread holder = new Thread(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    SendOptions opt = new SendOptions();
+                    opt.messageId = "hold";
+                    opt.sendAtMs = 1700000000001L;
+                    client.sendSync(new Target("endpoint", "ep2"), new Body("hold"), opt);
+                } catch (Exception ignored) {
+                }
+            }
+        });
+        holder.setDaemon(true);
+        holder.start();
+        long deadline = System.currentTimeMillis() + 2000;
+        while (holdRids.isEmpty() && System.currentTimeMillis() < deadline) {
+            Thread.sleep(10);
+        }
+        assertFalse(holdRids.isEmpty());
+        assertEquals(1, client.inflightSendsForTest());
+        final SendOptions opt = new SendOptions();
+        opt.messageId = "lim";
+        opt.sendAtMs = 1700000000002L;
+        Thread sender = new Thread(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    client.sendSync(new Target("endpoint", "ep2"), new Body("lim"), opt);
+                } catch (Exception ignored) {
+                }
+            }
+        });
+        sender.setDaemon(true);
+        sender.start();
+        deadline = System.currentTimeMillis() + 3000;
+        while (limitedRids.size() < 1 && System.currentTimeMillis() < deadline) {
+            Thread.sleep(10);
+        }
+        assertTrue(limitedRids.size() >= 1);
+        // rate_limited 后只应减 1：仍剩 hold 那一条在途
+        deadline = System.currentTimeMillis() + 500;
+        int seen = -1;
+        while (System.currentTimeMillis() < deadline) {
+            seen = client.inflightSendsForTest();
+            if (seen == 1) {
+                break;
+            }
+            Thread.sleep(10);
+        }
+        assertEquals("rate_limited 后在途应只减 1", 1, seen);
+        client.close();
+        holder.join(1000);
+        sender.join(1000);
     }
 
     @Test

sdk/python/src/nixmsg/client.py

@@ -227,6 +227,15 @@ class Client:
                 raise NixMsgError("not_connected", "连接超时")
             err = self._handshake_error
             if err:
+                with self._lock:
+                    self._stop_reconnect = True
+                    self._want_connected = False
+                    if not self._last_stop_code:
+                        code = getattr(err, "code", None) or "not_connected"
+                        self._last_stop_code = str(code)
+                        self._last_stop_err = err if isinstance(err, NixMsgError) else NixMsgError(
+                            "not_connected", str(err)
+                        )
                 raise err
             if self._state not in (ConnectionState.ONLINE,):
                 if self._state == ConnectionState.AUTH_FAILED:
@@ -236,6 +245,11 @@ class Client:
                     )
                 if self._state == ConnectionState.KICKED:
                     raise NixMsgError("taken_over", "会话被接管")
+                with self._lock:
+                    self._stop_reconnect = True
+                    self._want_connected = False
+                    self._last_stop_code = "not_connected"
+                    self._last_stop_err = NixMsgError("not_connected", f"连接未成功: {self._state.value}")
                 raise NixMsgError("not_connected", f"连接未成功: {self._state.value}")
 
     def close(self) -> None:
@@ -576,7 +590,7 @@ class Client:
             except Exception:
                 pass
             with self._lock:
-                self._handshake_error = NixMsgError("busy", "连接超时")
+                self._handshake_error = NixMsgError("not_connected", "连接超时")
             return
 
     def _on_transport_connected(self) -> None:
@@ -598,7 +612,7 @@ class Client:
                 self._pending[rid] = pending
             self._transport.publish(up_topic(self._endpoint_id), dumps(hello))
             if not pending.event.wait(self._connect_timeout_s):
-                raise NixMsgError("busy", "握手超时")
+                raise NixMsgError("not_connected", "握手超时")
             if pending.error:
                 raise pending.error
             assert pending.response is not None

sdk/python/src/nixmsg/transport.py

@@ -8,16 +8,23 @@ from dataclasses import dataclass, field
 from typing import Any, Callable, Optional, Protocol
 from urllib.parse import urlparse
 
-from paho.mqtt.client import CallbackAPIVersion, Client as PahoClient, MQTT_ERR_SUCCESS, MQTTv5
-from paho.mqtt.enums import MQTTErrorCode
-from paho.mqtt.reasoncodes import ReasonCode
-
 DownHandler = Callable[[bytes], None]
 ConnHandler = Callable[[], None]
 DiscHandler = Callable[[Optional[str], bool], None]
 # reason_code_str, stop_reconnect
 
 
+def _require_paho():
+    """真实 MQTT 路径才加载 paho；假传输单测不依赖。"""
+    try:
+        from paho.mqtt.client import CallbackAPIVersion, Client as PahoClient, MQTT_ERR_SUCCESS, MQTTv5
+        from paho.mqtt.enums import MQTTErrorCode
+        from paho.mqtt.reasoncodes import ReasonCode
+    except ImportError as e:
+        raise ImportError("需要 paho-mqtt>=2.0（真实 MQTT 连接）") from e
+    return CallbackAPIVersion, PahoClient, MQTT_ERR_SUCCESS, MQTTv5, MQTTErrorCode, ReasonCode
+
+
 @dataclass
 class ConnectParams:
     url: str
@@ -180,7 +187,7 @@ class PahoTransport:
     """paho-mqtt 2.x CallbackAPIVersion.VERSION2。"""
 
     def __init__(self) -> None:
-        self._client: Optional[PahoClient] = None
+        self._client: Any = None
         self._on_connected: Optional[ConnHandler] = None
         self._on_disconnected: Optional[DiscHandler] = None
         self._on_down: Optional[DownHandler] = None
@@ -200,6 +207,7 @@ class PahoTransport:
         self._on_down = on_down
 
     def connect(self, params: ConnectParams) -> None:
+        CallbackAPIVersion, PahoClient, _, MQTTv5, _, _ = _require_paho()
         self.disconnect()
         url = params.url
         u = urlparse(url if "://" in url else "ws://" + url)
@@ -261,6 +269,7 @@ class PahoTransport:
         # 等待连接结果由回调驱动；超时由 Client 层处理
 
     def subscribe(self, topic: str) -> None:
+        _, _, MQTT_ERR_SUCCESS, _, _, _ = _require_paho()
         self._down_topic = topic
         if not self._client:
             return
@@ -273,6 +282,7 @@ class PahoTransport:
             raise RuntimeError("subscribe timeout")
 
     def publish(self, topic: str, payload: bytes) -> None:
+        _, _, MQTT_ERR_SUCCESS, _, _, _ = _require_paho()
         if not self._client:
             raise RuntimeError("not connected")
         info = self._client.publish(topic, payload, qos=1)
@@ -338,9 +348,14 @@ def _reason_to_int(reason_code) -> Optional[int]:
         return None
     if isinstance(reason_code, int):
         return reason_code
-    if isinstance(reason_code, ReasonCode):
+    try:
+        _, _, _, _, MQTTErrorCode, ReasonCode = _require_paho()
+    except ImportError:
+        MQTTErrorCode = ()  # type: ignore[assignment,misc]
+        ReasonCode = ()  # type: ignore[assignment,misc]
+    if ReasonCode and isinstance(reason_code, ReasonCode):
         return int(reason_code.value)
-    if isinstance(reason_code, MQTTErrorCode):
+    if MQTTErrorCode and isinstance(reason_code, MQTTErrorCode):
         return int(reason_code)
     # paho 偶发其它包装
     val = getattr(reason_code, "value", None)

sdk/python/tests/test_k00.py

@@ -30,11 +30,42 @@ class K00Tests(unittest.TestCase):
         with self.assertRaises(NixMsgError) as cm:
             c.connect("ws://example.test/mqtt", "ep1", password="p", wait=True)
         self.assertEqual(cm.exception.code, "not_connected")
+        n = len(tr.connects)
+        time.sleep(0.35)
+        self.assertEqual(len(tr.connects), n, "首次失败后不得自动重连")
         tr.auto_accept = True
         c.connect("ws://example.test/mqtt", "ep1", password="p", wait=True)
         self.assertEqual(c.state, ConnectionState.ONLINE)
         c.close()
 
+    def test_k00_first_hello_fail_stops_reconnect(self) -> None:
+        """MQTT 已通但 hello 失败：connect 返回未连接，且后台不再连。"""
+        tr = FakeTransport()
+        tr.auto_hello = None
+        c = Client(transport=tr, connect_timeout_s=0.2)
+        with self.assertRaises(NixMsgError) as cm:
+            c.connect("ws://example.test/mqtt", "ep1", password="p", wait=True)
+        self.assertEqual(cm.exception.code, "not_connected")
+        n = len(tr.connects)
+        self.assertGreaterEqual(n, 1)
+        time.sleep(0.45)
+        self.assertEqual(len(tr.connects), n, "hello 失败后不得自动重连")
+        tr.auto_hello = {
+            "server_time_ms": 1_750_000_000_000,
+            "server_version": "0.1.0",
+            "max_body_bytes": 262144,
+            "max_meta_bytes": 4096,
+            "max_frame_bytes": 786432,
+            "max_ttl_seconds": 2592000,
+            "max_schedule_seconds": 31536000,
+            "ack_timeout_seconds": 300,
+            "session_token": "nst_retry",
+        }
+        c.connect("ws://example.test/mqtt", "ep1", password="p", wait=True)
+        self.assertEqual(c.state, ConnectionState.ONLINE)
+        self.assertGreater(len(tr.connects), n)
+        c.close()
+
     def test_k00_taken_over_reason(self) -> None:
         c, tr = self._connect()
         got = []