feat(modules): 帮助中心、工单、工作流与多渠道接入

补齐 FAQ、帮助中心、工单、可视化工作流及 Telegram/WhatsApp/Slack 等渠道模块。

backend/app/api/webhooks/common.py

@@ -0,0 +1,42 @@
+"""
+Copyright 2024-2026 ReplyPier
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+"""
+
+from app.core.redis import get_redis
+from app.core.logger import get_logger
+
+logger = get_logger(__name__)
+
+# Platforms redeliver webhooks on slow acks/timeouts; remember processed
+# message ids long enough to absorb every retry cycle.
+DEDUPE_TTL_SECONDS = 60 * 60
+
+
+def is_duplicate_message(channel_type: str, external_message_id: str) -> bool:
+    """Atomically claim an inbound message id (Redis SETNX). Returns True when
+    the message was already processed. Without Redis, dedupe is skipped —
+    single-process deployments rarely see retries fast enough to matter."""
+    if not external_message_id:
+        return False
+    try:
+        redis_client = get_redis()
+        if redis_client is None:
+            return False
+        key = f"channel_dedupe:{channel_type}:{external_message_id}"
+        claimed = redis_client.set(key, "1", nx=True, ex=DEDUPE_TTL_SECONDS)
+        return not claimed
+    except Exception as e:
+        logger.error(f"Dedupe check failed (processing anyway): {e}")
+        return False