diff --git a/backend/app/services/agent_runtime.py b/backend/app/services/agent_runtime.py
index 8ef65ee..1e54e39 100644
--- a/backend/app/services/agent_runtime.py
+++ b/backend/app/services/agent_runtime.py
@@ -114,8 +114,8 @@ async def run(self, db, model_type, name: str, args: dict,
                 )
                 return f"权限不足：工具 {name} 需 {allowed_roles} 角色", True
         tool_args = dict(args) if isinstance(args, dict) else {}
-        # tenant 是运行时保留参数，LLM/用户参数无权指定或覆盖。
-        for reserved in ("tenant", "tenant_id", "tenantId"):
+        # tenant/creator 是运行时保留参数，LLM/用户参数无权指定或覆盖。
+        for reserved in ("tenant", "tenant_id", "tenantId", "creator"):
             tool_args.pop(reserved, None)
         if ctx is not None:
             tenant = str(ctx.get("tenant") or "default").strip() or "default"
@@ -131,6 +131,17 @@ async def run(self, db, model_type, name: str, args: dict,
             if not tenant_aware:
                 return f"工具 {name} 未声明租户隔离能力，已拒绝调用", True
             tool_args["tenant"] = tenant
+            # creator 同理取登录态：防 LLM 幻觉/注入伪造开票人（如 _t_create_ticket）。
+            username = str(ctx.get("username") or "").strip()
+            if username:
+                try:
+                    creator_aware = any(
+                        parameter.name == "creator" for parameter in parameters
+                    )
+                except (TypeError, ValueError):
+                    creator_aware = False
+                if creator_aware:
+                    tool_args["creator"] = username
         error = False
         _tool_t0 = time.perf_counter()
         try:
diff --git a/tests/test_agent_tools.py b/tests/test_agent_tools.py
index 7224cdb..f434c67 100644
--- a/tests/test_agent_tools.py
+++ b/tests/test_agent_tools.py
@@ -76,3 +76,49 @@ def test_registry_flag_on(monkeypatch):
     reg = svc.build_default_registry()
     assert reg.get("create_ticket") is not None
     assert reg.get("submit_ticket") is not None
+
+
+def test_creator_reserved_injected_from_ctx(monkeypatch):
+    """creator 是运行时保留参数：LLM args 里的 creator 被剥掉，注入登录态用户名。"""
+    from app.services.agent_runtime import Tool, ToolRegistry
+
+    seen = {}
+
+    async def fake_audit(*args, **kwargs):
+        return None
+
+    async def handler(db, model_type, task="", tenant=None, creator=""):
+        seen.update(creator=creator, tenant=tenant)
+        return "ok"
+
+    monkeypatch.setattr(
+        "app.services.agent_tool_audit_service.log_tool_call", fake_audit,
+    )
+    registry = ToolRegistry()
+    registry.register(Tool("fake_create", "d", {}, handler))
+    result, error = asyncio.run(registry.run(
+        None, None, "fake_create",
+        {"task": "x", "creator": "spoofed"},
+        ctx={"username": "alice", "tenant": "t1"},
+    ))
+    assert error is False and result == "ok"
+    assert seen == {"creator": "alice", "tenant": "t1"}
+
+
+def test_creator_stripped_without_ctx(monkeypatch):
+    """无登录态（老链路 ctx=None）：creator 一律剥掉，落 handler 默认空串。"""
+    from app.services.agent_runtime import Tool, ToolRegistry
+
+    seen = {}
+
+    async def handler(db, model_type, task="", creator=""):
+        seen.update(creator=creator)
+        return "ok"
+
+    registry = ToolRegistry()
+    registry.register(Tool("fake_create", "d", {}, handler))
+    result, error = asyncio.run(registry.run(
+        None, None, "fake_create", {"task": "x", "creator": "spoofed"},
+    ))
+    assert error is False and result == "ok"
+    assert seen == {"creator": ""}