diff --git a/src/api/blackboard_routes.py b/src/api/blackboard_routes.py
index 028aa44..0eb6ab6 100644
--- a/src/api/blackboard_routes.py
+++ b/src/api/blackboard_routes.py
@@ -119,12 +119,20 @@ async def create_task(project_id: str, body: Dict[str, Any]):
         desc = body.get("description", "") or ""
         title = await _generate_title(desc) or ((desc[:30] + "…") if len(desc) > 30 else (desc or "新军令"))
 
+    # #04: assignee 由 @mention 推断
+    description_text = body.get("description") or ""
+    description_mentions = _extract_mentions(description_text)
+    assignee = description_mentions[0] if description_mentions else None
+    # 兼容：显式传 assignee 且无 @mention 时保留（deprecated）
+    if not assignee and body.get("assignee"):
+        assignee = body.get("assignee")
+
     task = Task(
         id=task_id, title=title,
         description=body.get("description"),
         task_type=body.get("task_type", "coding"),
         priority=body.get("priority", 5),
-        assignee=body.get("assignee"),
+        assignee=assignee,
         assigned_by=body.get("assigned_by", "user"),
         depends_on=json.dumps(body["depends_on"]) if "depends_on" in body else None,
         parent_task=body.get("parent_task"),
@@ -288,24 +296,27 @@ async def get_comments(project_id: str, task_id: str,
 async def add_comment(project_id: str, task_id: str, body: Dict[str, Any]):
     bb = _bb(project_id)
     mentions_raw = body.get("mentions")
-    cid = bb.add_comment(task_id, body["author"], body["body"],
+    comment_body = body["body"]
+
+    # #04: 自动从 body 提取 @mention，与显式传的 mentions 取并集
+    auto_mentions = _extract_mentions(comment_body)
+    if isinstance(mentions_raw, str):
+        try:
+            explicit_mentions = json.loads(mentions_raw)
+        except Exception:
+            explicit_mentions = []
+    elif isinstance(mentions_raw, list):
+        explicit_mentions = mentions_raw
+    else:
+        explicit_mentions = []
+    merged_mentions = list(set(explicit_mentions + auto_mentions))
+
+    cid = bb.add_comment(task_id, body["author"], comment_body,
                           comment_type=body.get("comment_type", "general"),
-                          mentions=mentions_raw)
-    # v2.9 #01: 写入 mention_queue
-    if mentions_raw:
-        if isinstance(mentions_raw, str):
-            import json as _json
-            try:
-                mentions_list = _json.loads(mentions_raw)
-            except Exception:
-                mentions_list = []
-        elif isinstance(mentions_raw, list):
-            mentions_list = mentions_raw
-        else:
-            mentions_list = []
-        if mentions_list:
-            bb.record_mentions(cid, task_id, mentions_list)
-    return {"ok": True, "comment_id": cid}
+                          mentions=merged_mentions)
+    if merged_mentions:
+        bb.record_mentions(cid, task_id, merged_mentions)
+    return {"ok": True, "comment_id": cid, "mentions": merged_mentions}
 
 
 # --- Outputs ---