fix(wecom): remove message-dedupe data races in bot/app channels

Centralize dedupe map access behind a mutex-safe helper and use it in both
WeCom bot and WeCom app channels to eliminate concurrent map access races while
preserving current dedupe behavior.

pkg/channels/wecom/app.go

@@ -607,23 +607,12 @@ func (c *WeComAppChannel) processMessage(ctx context.Context, msg WeComXMLMessag
 	// Message deduplication: Use msg_id to prevent duplicate processing
 	// As per WeCom documentation, use msg_id for deduplication
 	msgID := fmt.Sprintf("%d", msg.MsgId)
-	c.msgMu.Lock()
-	if c.processedMsgs[msgID] {
-		c.msgMu.Unlock()
+	if !markMessageProcessed(&c.msgMu, &c.processedMsgs, msgID, wecomMaxProcessedMessages) {
 		logger.DebugCF("wecom_app", "Skipping duplicate message", map[string]any{
 			"msg_id": msgID,
 		})
 		return
 	}
-	c.processedMsgs[msgID] = true
-	// Clean up old messages while still holding the lock to avoid a data race
-	// on len(). Reset the map but re-insert the current msgID so it remains
-	// deduplicated.
-	if len(c.processedMsgs) > 1000 {
-		c.processedMsgs = make(map[string]bool)
-		c.processedMsgs[msgID] = true
-	}
-	c.msgMu.Unlock()
 
 	senderID := msg.FromUserName
 	chatID := senderID // WeCom App uses user ID as chat ID for direct messages

pkg/channels/wecom/bot.go

@@ -330,23 +330,12 @@ func (c *WeComBotChannel) processMessage(ctx context.Context, msg WeComBotMessag
 
 	// Message deduplication: Use msg_id to prevent duplicate processing
 	msgID := msg.MsgID
-	c.msgMu.Lock()
-	if c.processedMsgs[msgID] {
-		c.msgMu.Unlock()
+	if !markMessageProcessed(&c.msgMu, &c.processedMsgs, msgID, wecomMaxProcessedMessages) {
 		logger.DebugCF("wecom", "Skipping duplicate message", map[string]any{
 			"msg_id": msgID,
 		})
 		return
 	}
-	c.processedMsgs[msgID] = true
-	// Clean up old messages while still holding the lock to avoid a data race
-	// on len(). Reset the map but re-insert the current msgID so it remains
-	// deduplicated.
-	if len(c.processedMsgs) > 1000 {
-		c.processedMsgs = make(map[string]bool)
-		c.processedMsgs[msgID] = true
-	}
-	c.msgMu.Unlock()
 
 	senderID := msg.From.UserID
 

pkg/channels/wecom/dedupe.go

@@ -0,0 +1,28 @@
+package wecom
+
+import "sync"
+
+const wecomMaxProcessedMessages = 1000
+
+// markMessageProcessed marks msgID as processed and returns false for duplicates.
+// All map reads/writes (including len) are protected by msgMu to avoid races.
+func markMessageProcessed(msgMu *sync.RWMutex, processedMsgs *map[string]bool, msgID string, maxEntries int) bool {
+	if maxEntries <= 0 {
+		maxEntries = wecomMaxProcessedMessages
+	}
+
+	msgMu.Lock()
+	defer msgMu.Unlock()
+
+	if (*processedMsgs)[msgID] {
+		return false
+	}
+	(*processedMsgs)[msgID] = true
+
+	// Keep the newest message marker when rotating to bound memory growth.
+	if len(*processedMsgs) > maxEntries {
+		*processedMsgs = map[string]bool{msgID: true}
+	}
+
+	return true
+}