diff --git a/tests/test_eda_router_contract.py b/tests/test_eda_router_contract.py
index 425eb16..08d4e1f 100644
--- a/tests/test_eda_router_contract.py
+++ b/tests/test_eda_router_contract.py
@@ -56,8 +56,29 @@ class EdaRouterPinsContractTest(unittest.TestCase):
         self.assertEqual(link.dst_pin, "in")
         self.assertEqual(link.xsection, "metal_1")
         self.assertEqual(link.width, 5)
+        self.assertEqual(link.bundle, "output_bus")
         self.assertEqual(link.points[1], {"x": 50.0, "y": 0.0})
 
+    def test_loader_accepts_explicit_link_route_group_metadata(self):
+        from mxpic_router.eda_loader import parse_cell_dict
+
+        spec = parse_cell_dict({
+            "name": "cell_a",
+            "bundles": {
+                "output_bus": {
+                    "links": [{
+                        "from": "inst_a:out",
+                        "to": "inst_b:in",
+                        "route_group": "stage_1",
+                    }]
+                }
+            }
+        })
+
+        link = spec.bundles["output_bus"].links[0]
+        self.assertEqual(link.bundle, "output_bus")
+        self.assertEqual(link.route_group, "stage_1")
+
     def test_port_element_creates_named_io_pins_and_inside_route_pins(self):
         from mxpic_router.builder import _register_element_pins
         from mxpic_router.eda_loader import parse_cell_dict
@@ -529,6 +550,105 @@ class EdaRouterPinsContractTest(unittest.TestCase):
         lstarts = [call[1]["Lstart"] for call in FakeRoute.calls if call[0] == "sbend_p2p"]
         self.assertEqual(lstarts, [50.0, 50.0])
 
+    def test_sbend_lstart_spacing_handles_same_source_mmi_fanout(self):
+        from mxpic_router.builder import _route_bundle_links
+        from mxpic_router.eda_loader import LinkSpec
+
+        class FakePin:
+            def __init__(self, x, y, angle):
+                self.x = x
+                self.y = y
+                self.a = angle
+
+        class FakeRoute:
+            calls = []
+
+            def __init__(self, **kwargs):
+                pass
+
+            def sbend_p2p(self, **kwargs):
+                self.calls.append(("sbend_p2p", kwargs))
+                return self
+
+            def put(self):
+                self.calls.append(("put", {}))
+
+        FakeRoute.calls = []
+        links = [
+            LinkSpec(src_inst="MMI_1", src_pin="b1", dst_inst="port_1", dst_pin="port_1_io2", width=0.7, radius=10),
+            LinkSpec(src_inst="MMI_1", src_pin="b2", dst_inst="port_1", dst_pin="port_1_io1", width=0.7, radius=10),
+        ]
+        pin_map = {
+            ("MMI_1", "b1"): FakePin(1963.1, -1931.15, 0),
+            ("port_1", "port_1_io2"): FakePin(2047.2, -2056.3, 180),
+            ("MMI_1", "b2"): FakePin(1963.1, -1939.85, 0),
+            ("port_1", "port_1_io1"): FakePin(2047.2, -2066.3, 180),
+        }
+
+        _route_bundle_links(links, pin_map, FakeRoute, [])
+
+        lstarts = [call[1]["Lstart"] for call in FakeRoute.calls if call[0] == "sbend_p2p"]
+        self.assertEqual(lstarts, [21.4, 10.7])
+
+    def test_sbend_lstart_spacing_keeps_separate_route_stages_ordered(self):
+        from mxpic_router.builder import _route_bundle_links
+        from mxpic_router.eda_loader import LinkSpec
+
+        class FakePin:
+            def __init__(self, x, y, angle):
+                self.x = x
+                self.y = y
+                self.a = angle
+
+        class FakeRoute:
+            calls = []
+
+            def __init__(self, **kwargs):
+                pass
+
+            def sbend_p2p(self, **kwargs):
+                self.calls.append(("sbend_p2p", kwargs))
+                return self
+
+            def put(self):
+                self.calls.append(("put", {}))
+
+        FakeRoute.calls = []
+        links = [
+            LinkSpec(src_inst="r1", src_pin="en1", dst_inst="r5", dst_pin="ep1", width=40, radius=10),
+            LinkSpec(src_inst="r2", src_pin="en1", dst_inst="r6", dst_pin="ep1", width=40, radius=10),
+            LinkSpec(src_inst="r3", src_pin="en1", dst_inst="r7", dst_pin="ep1", width=40, radius=10),
+            LinkSpec(src_inst="r4", src_pin="en1", dst_inst="r8", dst_pin="ep1", width=40, radius=10),
+            LinkSpec(src_inst="r6", src_pin="en1", dst_inst="port", dst_pin="io3", width=40, radius=10),
+            LinkSpec(src_inst="r5", src_pin="en1", dst_inst="port", dst_pin="io4", width=40, radius=10),
+            LinkSpec(src_inst="r7", src_pin="en1", dst_inst="port", dst_pin="io2", width=40, radius=10),
+            LinkSpec(src_inst="r8", src_pin="en1", dst_inst="port", dst_pin="io1", width=40, radius=10),
+        ]
+        pin_map = {
+            ("r1", "en1"): FakePin(0, 40, 0),
+            ("r5", "ep1"): FakePin(100, 70, 180),
+            ("r2", "en1"): FakePin(0, 30, 0),
+            ("r6", "ep1"): FakePin(100, 60, 180),
+            ("r3", "en1"): FakePin(0, 20, 0),
+            ("r7", "ep1"): FakePin(100, 50, 180),
+            ("r4", "en1"): FakePin(0, 10, 0),
+            ("r8", "ep1"): FakePin(100, 40, 180),
+            ("r6", "en1"): FakePin(100, 60, 0),
+            ("port", "io3"): FakePin(200, 30, 180),
+            ("r5", "en1"): FakePin(100, 70, 0),
+            ("port", "io4"): FakePin(200, 40, 180),
+            ("r7", "en1"): FakePin(100, 50, 0),
+            ("port", "io2"): FakePin(200, 20, 180),
+            ("r8", "en1"): FakePin(100, 40, 0),
+            ("port", "io1"): FakePin(200, 10, 180),
+        }
+
+        _route_bundle_links(links, pin_map, FakeRoute, [])
+
+        lstarts = [call[1]["Lstart"] for call in FakeRoute.calls if call[0] == "sbend_p2p"]
+        self.assertEqual(lstarts[:4], [50.0, 100.0, 150.0, 200.0])
+        self.assertEqual(lstarts[4:], [150.0, 200.0, 100.0, 50.0])
+
     def test_route_backend_falls_back_to_nazca_interconnect_when_forge_is_absent(self):
         import mxpic_router.builder as builder