chore: optimize agent-panel metrics communication (#352)

go-backend/internal/http/handler/handler.go

@@ -1234,6 +1234,21 @@ func nullableNullInt64(v sql.NullInt64) interface{} {
 	return nil
 }
 
+// flowCryptoCache caches AES crypto instances by secret to avoid per-request SHA256+GCM init.
+var flowCryptoCache sync.Map
+
+func getOrCreateFlowCrypto(secret string) *security.AESCrypto {
+	if v, ok := flowCryptoCache.Load(secret); ok {
+		return v.(*security.AESCrypto)
+	}
+	c, err := security.NewAESCrypto(secret)
+	if err != nil {
+		return nil
+	}
+	flowCryptoCache.Store(secret, c)
+	return c
+}
+
 func readAndDecryptFlowBody(body io.ReadCloser, secret string) (string, error) {
 	defer body.Close()
 	raw, err := io.ReadAll(body)
@@ -1254,8 +1269,8 @@ func readAndDecryptFlowBody(body io.ReadCloser, secret string) (string, error) {
 		return text, nil
 	}
 
-	crypto, err := security.NewAESCrypto(secret)
-	if err != nil {
+	crypto := getOrCreateFlowCrypto(secret)
+	if crypto == nil {
 		return text, nil
 	}
 	plain, err := crypto.Decrypt(wrap.Data)