Avoid stuck MCP state after stream replacement

cmd/whasapo/main.go

@@ -200,6 +200,8 @@ func cmdPair() {
 
 func cmdServe() {
 	dbPath := getDBPath()
+	releaseLock := acquireServeLock()
+	defer releaseLock()
 
 	var err error
 	wa, err = whatsapp.NewClient(dbPath)
@@ -327,6 +329,20 @@ func cmdServe() {
 	}
 }
 
+func acquireServeLock() func() {
+	lockPath := filepath.Join(dataDir(), "serve.lock")
+	lock, err := os.OpenFile(lockPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0600)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "whasapo: another serve process is already running; close/restart your AI app or remove stale lock %s\n", lockPath)
+		os.Exit(1)
+	}
+	fmt.Fprintf(lock, "%d\n", os.Getpid())
+	lock.Close()
+	return func() {
+		os.Remove(lockPath)
+	}
+}
+
 // --- status command ---
 
 func cmdStatus() {

whatsapp/client.go

@@ -12,7 +12,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	_ "modernc.org/sqlite"
 	"go.mau.fi/whatsmeow"
 	"go.mau.fi/whatsmeow/proto/waE2E"
 	"go.mau.fi/whatsmeow/proto/waHistorySync"
@@ -22,6 +21,7 @@ import (
 	"go.mau.fi/whatsmeow/types/events"
 	waLog "go.mau.fi/whatsmeow/util/log"
 	"google.golang.org/protobuf/proto"
+	_ "modernc.org/sqlite"
 )
 
 // StoredMessage holds a message.
@@ -55,7 +55,7 @@ type ChatDetail struct {
 	Topic        string            `json:"topic,omitempty"`
 	Participants []ParticipantInfo `json:"participants,omitempty"`
 	CreatedAt    string            `json:"created_at,omitempty"`
-	MessageCount int              `json:"message_count"`
+	MessageCount int               `json:"message_count"`
 }
 
 // ParticipantInfo holds group participant info.
@@ -67,16 +67,17 @@ type ParticipantInfo struct {
 
 // Client wraps whatsmeow with persistent message storage.
 type Client struct {
-	WM        *whatsmeow.Client
-	Container *sqlstore.Container
-	db        *sql.DB
+	WM           *whatsmeow.Client
+	Container    *sqlstore.Container
+	db           *sql.DB
 	firstConn    chan struct{} // closed on first successful connection
 	ready        atomic.Bool
 	loggedOut    atomic.Bool
 	disconnectAt atomic.Int64 // unix timestamp of last disconnect, 0 if connected
 	names        map[string]string
 	namesMu      sync.RWMutex
 	mediaDir     string
+	reconnectMu  sync.Mutex
 }
 
 const dsn = "file:%s?_pragma=foreign_keys(1)&_pragma=journal_mode(WAL)&_pragma=busy_timeout(5000)"
@@ -235,6 +236,7 @@ func (c *Client) eventHandler(evt interface{}) {
 			// Only log on transition from connected → disconnected (debounce)
 			c.disconnectAt.Store(time.Now().Unix())
 			fmt.Fprintf(os.Stderr, "whasapo: disconnected, reconnecting...\n")
+			c.scheduleReconnect()
 		}
 	case *events.LoggedOut:
 		c.ready.Store(false)
@@ -244,6 +246,7 @@ func (c *Client) eventHandler(evt interface{}) {
 		c.ready.Store(false)
 		c.disconnectAt.Store(time.Now().Unix())
 		fmt.Fprintf(os.Stderr, "whasapo: connection replaced by another client\n")
+		c.scheduleReconnect()
 	case *events.HistorySync:
 		c.handleHistorySync(v.Data)
 	case *events.Message:
@@ -260,6 +263,33 @@ func (c *Client) eventHandler(evt interface{}) {
 	}
 }
 
+func (c *Client) scheduleReconnect() {
+	go func() {
+		c.reconnectMu.Lock()
+		defer c.reconnectMu.Unlock()
+		if c.loggedOut.Load() || c.ready.Load() {
+			return
+		}
+		for attempt := 1; attempt <= 6; attempt++ {
+			time.Sleep(time.Duration(attempt*2) * time.Second)
+			if c.loggedOut.Load() || c.ready.Load() {
+				return
+			}
+			if err := c.WM.Connect(); err != nil {
+				fmt.Fprintf(os.Stderr, "whasapo: reconnect attempt %d failed: %v\n", attempt, err)
+				continue
+			}
+			deadline := time.Now().Add(10 * time.Second)
+			for time.Now().Before(deadline) {
+				if c.ready.Load() {
+					return
+				}
+				time.Sleep(250 * time.Millisecond)
+			}
+		}
+	}()
+}
+
 func (c *Client) messageToStored(info types.MessageInfo, msg *waE2E.Message) StoredMessage {
 	text, mediaType := extractTextAndMedia(msg)
 	sm := StoredMessage{