fix(db): AGENT_SEED 全局固定 id 种子冲突 — 智能体幂等播种

新增 _add_agent(按 (id,user_id,port) 已存在则跳过)，base 路径/_ensure_extra_demo_users/
_ensure_port_agents 三处统一调用；修复多用户/多端口复用固定 agent id 触发唯一冲突。
验证：临时库 migrate+seed 完整通过且重跑幂等(pine 已灌入)。

app/infrastructure/seed.py

@@ -255,6 +255,20 @@ DEMO_USERS = [
 ]
 
 
+async def _add_agent(session: AsyncSession, seed: dict, user_id: str, port: str | None, now: str) -> None:
+    """幂等播种单个智能体：按 (id,user_id,port) 已存在则跳过（修全局固定 id 多用户/端口填重）。"""
+    key = (seed["id"], user_id, port)
+    if await session.get(Agent, key) is not None:
+        return
+    session.add(
+        Agent(id=seed["id"], user_id=user_id, port=port, name=seed["name"],
+              description=seed["description"], language=seed.get("language", "zh"),
+              model_name=seed.get("model_name", ""), deletable=seed.get("deletable", True),
+              use_fixed_soul=seed.get("use_fixed_soul", False),
+              created_at=now, updated_at=now)
+    )
+
+
 async def seed_data(session: AsyncSession) -> None:
     """幂等种子：仅当 roles 表为空时写入全部基础数据；身份与 OPC 业务始终补种。"""
     now = utcnow_iso()
@@ -317,19 +331,9 @@ async def seed_data(session: AsyncSession) -> None:
                 status="active", token_version=0, created_at=now, updated_at=now,
             )
         )
-        # 为每个用户播种默认 + QA 智能体
+        # 为每个用户播种默认 + QA 智能体（幂等按 (id,user_id,port=null) 防重）
         for seed in AGENT_SEED:
-            session.add(
-                Agent(
-                    id=seed["id"], user_id=uid, name=seed["name"],
-                    description=seed["description"],
-                    language=seed.get("language", "zh"),
-                    model_name=seed.get("model_name", ""),
-                    deletable=seed.get("deletable", True),
-                    use_fixed_soul=seed.get("use_fixed_soul", False),
-                    created_at=now, updated_at=now,
-                )
-            )
+            await _add_agent(session, seed, uid, None, now)
 
     await _seed_operator_business(session, now)
     await _seed_opc_business(session, now)
@@ -989,15 +993,7 @@ async def _ensure_extra_demo_users(session: AsyncSession, now: str) -> None:
             )
         )
         for seed in AGENT_SEED:
-            session.add(
-                Agent(
-                    id=seed["id"], user_id=uid, name=seed["name"],
-                    description=seed["description"], language=seed.get("language", "zh"),
-                    model_name=seed.get("model_name", ""), deletable=seed.get("deletable", True),
-                    use_fixed_soul=seed.get("use_fixed_soul", False),
-                    created_at=now, updated_at=now,
-                )
-            )
+            await _add_agent(session, seed, uid, None, now)
 
 
 async def _seed_ecosystem(session: AsyncSession, now: str) -> None:
@@ -1049,17 +1045,7 @@ async def _ensure_port_agents(session: AsyncSession, now: str) -> None:
             (await session.execute(select(Agent.id).where(Agent.user_id == user_id, Agent.port == port))).scalars()
         )
         for seed in AGENT_SEED:
-            if seed["id"] in existing_ids:
-                continue  # 已存在，跳过（幂等，避免 (id,user_id,port) 唯一冲突）
-            session.add(
-                Agent(
-                    id=seed["id"], user_id=user_id, port=port, name=seed["name"],
-                    description=seed["description"], language=seed.get("language", "zh"),
-                    model_name=seed.get("model_name", ""), deletable=seed.get("deletable", True),
-                    use_fixed_soul=seed.get("use_fixed_soul", False),
-                    created_at=now, updated_at=now,
-                )
-            )
+            await _add_agent(session, seed, user_id, port, now)
 
 
 async def _seed_org_members(session: AsyncSession, now: str) -> None: