fix(mcp): add auth interceptor with channel user_id and keep header propagation to mcp tools (#3294)

* 修复channel中的user_id传递到interceptor中的bug, mcp可通过header传递user_id到mcp工具

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(channel,mcp,gateway): normalize channel user_id and add regression tests

Normalize external channel user ids into filesystem-safe runtime context while preserving raw channel_user_id, and document gateway user_id propagation semantics. Add regression coverage for channel user_id context mapping, gateway user_id precedence/internal-role behavior, and MCP interceptor header forwarding via meta.headers.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(auth,mcp): harden user id normalization and header handling

Increase sanitized user-id digest suffix to 16 hex chars, replace internal system role magic string with a shared constant, and harden MCP header forwarding with Mapping type checks. Add regression tests for empty channel user_id handling, unsupported header types, and updated digest length behavior.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: zhongli <335302680@qq.com>
Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/test_channels.py

@@ -1787,6 +1787,51 @@ class TestChannelManager:
         _run(go())
 
 
+class TestResolveRunParamsUserId:
+    """Regression for PR #3294: channel identity must reach ``run_context``
+    while staying safe for user-scoped filesystem buckets.
+    """
+
+    def _manager(self):
+        from app.channels.manager import ChannelManager
+
+        bus = MessageBus()
+        store = ChannelStore(path=Path(tempfile.mkdtemp()) / "store.json")
+        return ChannelManager(bus=bus, store=store)
+
+    def test_safe_user_id_is_passed_through(self):
+        manager = self._manager()
+        msg = InboundMessage(channel_name="telegram", chat_id="c", user_id="123456", text="hi")
+
+        _, _, run_context = manager._resolve_run_params(msg, "thread-1")
+
+        assert run_context["user_id"] == "123456"
+        assert run_context["channel_user_id"] == "123456"
+
+    def test_unsafe_user_id_is_normalized_but_raw_preserved(self):
+        from deerflow.config.paths import make_safe_user_id
+
+        manager = self._manager()
+        raw = "user@example.com"
+        msg = InboundMessage(channel_name="feishu", chat_id="c", user_id=raw, text="hi")
+
+        _, _, run_context = manager._resolve_run_params(msg, "thread-1")
+
+        assert run_context["user_id"] == make_safe_user_id(raw)
+        assert run_context["user_id"] != raw
+        assert run_context["channel_user_id"] == raw
+
+    @pytest.mark.parametrize("raw_user_id", ["", None])
+    def test_empty_or_none_user_id_is_not_injected(self, raw_user_id):
+        manager = self._manager()
+        msg = InboundMessage(channel_name="feishu", chat_id="c", user_id=raw_user_id, text="hi")
+
+        _, _, run_context = manager._resolve_run_params(msg, "thread-1")
+
+        assert "user_id" not in run_context
+        assert "channel_user_id" not in run_context
+
+
 # ---------------------------------------------------------------------------
 # ChannelService tests
 # ---------------------------------------------------------------------------