Fix risk group assignments on DC-BB and BB cross-site links

Two bugs fixed:
1. DC-BB links (FADU↔BB, XSW↔BB) had no risk_groups — correlated
   failures didn't affect DC-BB connectivity. Now each link carries
   plane_site, plane_group, and device-index-across-PG risk groups
   from its BB endpoint.
2. BB cross-site links lacked device-index risk groups. Now each
   link carries pg_G_idx_D_abc1 and pg_G_idx_D_xyz1 from both
   endpoints. Links went from 4 to 6 risk groups.

Full audit confirmed all other topology aspects match spec.
430 tests pass.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Andrey Golovanov

netlab/autoresearch/scenario_generator.py

@@ -516,6 +516,7 @@ def _build_bb_cross_site_links(config: DcBbScenarioConfig) -> list[dict]:
     """
     links: list[dict] = []
     for pl in range(1, config.bb_planes + 1):
+        pg = (pl - 1) // 4 + 1
         for a in range(1, config.bb_devices_per_plane + 1):
             for x in range(1, config.bb_devices_per_plane + 1):
                 for path in ["path_a", "path_b"]:
@@ -527,9 +528,11 @@ def _build_bb_cross_site_links(config: DcBbScenarioConfig) -> list[dict]:
                             "cost": 10,
                             "risk_groups": [
                                 path,
-                                f"plane_group_{(pl - 1) // 4 + 1}",
+                                f"plane_group_{pg}",
                                 f"plane_{pl}_site_abc1",
                                 f"plane_{pl}_site_xyz1",
+                                f"pg_{pg}_idx_{a}_abc1",
+                                f"pg_{pg}_idx_{x}_xyz1",
                             ],
                             "attrs": {
                                 "link_type": "bb_cross_site",
@@ -582,13 +585,21 @@ def _build_dc_bb_links(config: DcBbScenarioConfig) -> list[dict]:
         for dr, dc in dc_devs:
             fadu_name = f"abc1/fadu/hgrid{dr + 1}/idx{dc + 1}"
             for br, bc in bb_devs:
-                bb_name = f"bb/abc1/plane{br + 1}/dev{bc + 1}"
+                bb_plane = br + 1
+                bb_dev = bc + 1
+                bb_name = f"bb/abc1/plane{bb_plane}/dev{bb_dev}"
+                pg = (bb_plane - 1) // 4 + 1
                 links.append(
                     {
                         "source": fadu_name,
                         "target": bb_name,
                         "capacity": config.dc_bb_link_capacity,
                         "cost": 5,
+                        "risk_groups": [
+                            f"plane_{bb_plane}_site_abc1",
+                            f"plane_group_{pg}",
+                            f"pg_{pg}_idx_{bb_dev}_abc1",
+                        ],
                         "attrs": {"link_type": "dc_bb", "side": "abc1"},
                     }
                 )
@@ -609,13 +620,21 @@ def _build_dc_bb_links(config: DcBbScenarioConfig) -> list[dict]:
             # dr = device index within plane, dc = plane index
             xsw_name = f"xyz1/xsw/plane{dc + 1}/dev{dr + 1}"
             for br, bc in bb_devs:
-                bb_name = f"bb/xyz1/plane{br + 1}/dev{bc + 1}"
+                bb_plane = br + 1
+                bb_dev = bc + 1
+                bb_name = f"bb/xyz1/plane{bb_plane}/dev{bb_dev}"
+                pg = (bb_plane - 1) // 4 + 1
                 links.append(
                     {
                         "source": xsw_name,
                         "target": bb_name,
                         "capacity": config.dc_bb_link_capacity,
                         "cost": 5,
+                        "risk_groups": [
+                            f"plane_{bb_plane}_site_xyz1",
+                            f"plane_group_{pg}",
+                            f"pg_{pg}_idx_{bb_dev}_xyz1",
+                        ],
                         "attrs": {"link_type": "dc_bb", "side": "xyz1"},
                     }
                 )

tests/autoresearch/test_bb_links.py

@@ -84,9 +84,9 @@ class TestRiskGroups:
     """Verify risk group assignments."""
 
     def test_risk_group_structure(self, default_links):
-        """Every link has exactly 4 risk groups."""
+        """Every link has exactly 6 risk groups."""
         for link in default_links:
-            assert len(link["risk_groups"]) == 4
+            assert len(link["risk_groups"]) == 6
 
     def test_risk_group_contents(self, default_links):
         """Spot-check a specific link's risk groups."""
@@ -106,6 +106,8 @@ def test_risk_group_contents(self, default_links):
             "plane_group_1",
             "plane_1_site_abc1",
             "plane_1_site_xyz1",
+            "pg_1_idx_1_abc1",
+            "pg_1_idx_1_xyz1",
         ]
 
     def test_plane_group_mapping(self, default_links):
@@ -145,6 +147,31 @@ def test_16_plane_groups_total(self, default_links):
         assert len(groups) == 16
         assert groups == {f"plane_group_{g}" for g in range(1, 17)}
 
+    def test_device_index_risk_groups_present(self, default_links):
+        """Each link includes pg_G_idx_D_abc1 and pg_G_idx_D_xyz1."""
+        for link in default_links:
+            src_dev = int(link["source"].split("/")[-1].replace("dev", ""))
+            tgt_dev = int(link["target"].split("/")[-1].replace("dev", ""))
+            pl = link["attrs"]["plane"]
+            pg = (pl - 1) // 4 + 1
+            assert f"pg_{pg}_idx_{src_dev}_abc1" in link["risk_groups"]
+            assert f"pg_{pg}_idx_{tgt_dev}_xyz1" in link["risk_groups"]
+
+    def test_device_index_spot_check(self, default_links):
+        """Spot-check: plane7 dev2->dev3 link should have pg_2_idx_2_abc1, pg_2_idx_3_xyz1."""
+        target = None
+        for link in default_links:
+            if (
+                link["source"] == "bb/abc1/plane7/dev2"
+                and link["target"] == "bb/xyz1/plane7/dev3"
+                and link["attrs"]["path"] == "path_a"
+            ):
+                target = link
+                break
+        assert target is not None
+        assert "pg_2_idx_2_abc1" in target["risk_groups"]
+        assert "pg_2_idx_3_xyz1" in target["risk_groups"]
+
 
 # ---------------------------------------------------------------------------
 # Link attributes

tests/autoresearch/test_dc_bb_links.py

@@ -95,6 +95,101 @@ def test_side_values(self, default_links):
         sides = {lk["attrs"]["side"] for lk in default_links}
         assert sides == {"abc1", "xyz1"}
 
+    def test_all_links_have_risk_groups(self, default_links):
+        for lk in default_links:
+            assert "risk_groups" in lk, (
+                f"Link {lk['source']}->{lk['target']} missing risk_groups"
+            )
+            assert len(lk["risk_groups"]) == 3
+
+
+# ---------------------------------------------------------------------------
+# Risk group assignments on DC-BB links
+# ---------------------------------------------------------------------------
+
+
+class TestDcBbRiskGroups:
+    """Verify risk group assignments derived from BB endpoint."""
+
+    def test_abc1_link_has_plane_site_group(self, default_links):
+        """ABC1 DC-BB links include plane_P_site_abc1 from BB endpoint."""
+        abc1 = [lk for lk in default_links if lk["attrs"]["side"] == "abc1"]
+        for lk in abc1:
+            # Extract plane from target name bb/abc1/plane{P}/dev{D}
+            parts = lk["target"].split("/")
+            plane = int(parts[2].replace("plane", ""))
+            expected_rg = f"plane_{plane}_site_abc1"
+            assert expected_rg in lk["risk_groups"], (
+                f"{lk['target']}: expected {expected_rg} in {lk['risk_groups']}"
+            )
+
+    def test_xyz1_link_has_plane_site_group(self, default_links):
+        """XYZ1 DC-BB links include plane_P_site_xyz1 from BB endpoint."""
+        xyz1 = [lk for lk in default_links if lk["attrs"]["side"] == "xyz1"]
+        for lk in xyz1:
+            parts = lk["target"].split("/")
+            plane = int(parts[2].replace("plane", ""))
+            expected_rg = f"plane_{plane}_site_xyz1"
+            assert expected_rg in lk["risk_groups"], (
+                f"{lk['target']}: expected {expected_rg} in {lk['risk_groups']}"
+            )
+
+    def test_abc1_link_has_plane_group(self, default_links):
+        """ABC1 DC-BB links include plane_group_G from BB endpoint's plane."""
+        abc1 = [lk for lk in default_links if lk["attrs"]["side"] == "abc1"]
+        for lk in abc1:
+            parts = lk["target"].split("/")
+            plane = int(parts[2].replace("plane", ""))
+            pg = (plane - 1) // 4 + 1
+            expected_rg = f"plane_group_{pg}"
+            assert expected_rg in lk["risk_groups"]
+
+    def test_abc1_link_has_device_index_group(self, default_links):
+        """ABC1 DC-BB links include pg_G_idx_D_abc1 from BB endpoint."""
+        abc1 = [lk for lk in default_links if lk["attrs"]["side"] == "abc1"]
+        for lk in abc1:
+            parts = lk["target"].split("/")
+            plane = int(parts[2].replace("plane", ""))
+            dev = int(parts[3].replace("dev", ""))
+            pg = (plane - 1) // 4 + 1
+            expected_rg = f"pg_{pg}_idx_{dev}_abc1"
+            assert expected_rg in lk["risk_groups"]
+
+    def test_xyz1_link_has_device_index_group(self, default_links):
+        """XYZ1 DC-BB links include pg_G_idx_D_xyz1 from BB endpoint."""
+        xyz1 = [lk for lk in default_links if lk["attrs"]["side"] == "xyz1"]
+        for lk in xyz1:
+            parts = lk["target"].split("/")
+            plane = int(parts[2].replace("plane", ""))
+            dev = int(parts[3].replace("dev", ""))
+            pg = (plane - 1) // 4 + 1
+            expected_rg = f"pg_{pg}_idx_{dev}_xyz1"
+            assert expected_rg in lk["risk_groups"]
+
+    def test_spot_check_specific_abc1_link(self, default_links):
+        """Spot-check: FADU->bb/abc1/plane7/dev2 should have specific risk groups."""
+        abc1 = [lk for lk in default_links if lk["attrs"]["side"] == "abc1"]
+        target_links = [lk for lk in abc1 if lk["target"] == "bb/abc1/plane7/dev2"]
+        assert len(target_links) > 0, "No links to bb/abc1/plane7/dev2"
+        for lk in target_links:
+            assert lk["risk_groups"] == [
+                "plane_7_site_abc1",
+                "plane_group_2",
+                "pg_2_idx_2_abc1",
+            ]
+
+    def test_spot_check_specific_xyz1_link(self, default_links):
+        """Spot-check: XSW->bb/xyz1/plane7/dev3 should have specific risk groups."""
+        xyz1 = [lk for lk in default_links if lk["attrs"]["side"] == "xyz1"]
+        target_links = [lk for lk in xyz1 if lk["target"] == "bb/xyz1/plane7/dev3"]
+        assert len(target_links) > 0, "No links to bb/xyz1/plane7/dev3"
+        for lk in target_links:
+            assert lk["risk_groups"] == [
+                "plane_7_site_xyz1",
+                "plane_group_2",
+                "pg_2_idx_3_xyz1",
+            ]
+
 
 # ---------------------------------------------------------------------------
 # Node name validity

tests/autoresearch/test_risk_groups.py

@@ -7,6 +7,7 @@
 from netlab.autoresearch.scenario_generator import (
     DcBbScenarioConfig,
     _build_bb_cross_site_links,
+    _build_dc_bb_links,
     _build_risk_groups,
 )
 
@@ -227,6 +228,49 @@ def test_plane_site_names_in_links(self, default_config):
         defined_ps = {g["name"] for g in groups if g["attrs"]["type"] == "plane_site"}
         assert ps_names.issubset(defined_ps)
 
+    def test_device_index_groups_referenced_by_bb_links(self, default_config):
+        """All 128 device_index_across_planes groups are referenced by BB cross-site links."""
+        groups = _build_risk_groups(default_config)
+        defined_di = {
+            g["name"]
+            for g in groups
+            if g["attrs"]["type"] == "device_index_across_planes"
+        }
+        links = _build_bb_cross_site_links(default_config)
+        referenced_di = {
+            rg for link in links for rg in link["risk_groups"] if rg.startswith("pg_")
+        }
+        assert defined_di == referenced_di
+
+    def test_device_index_groups_referenced_by_dc_bb_links(self, default_config):
+        """DC-BB links reference device_index_across_planes groups."""
+        groups = _build_risk_groups(default_config)
+        defined_di = {
+            g["name"]
+            for g in groups
+            if g["attrs"]["type"] == "device_index_across_planes"
+        }
+        links = _build_dc_bb_links(default_config)
+        referenced_di = {
+            rg for link in links for rg in link["risk_groups"] if rg.startswith("pg_")
+        }
+        # DC-BB links reference a subset (only one site per link)
+        assert referenced_di.issubset(defined_di)
+        assert len(referenced_di) > 0
+
+    def test_all_dc_bb_link_risk_groups_defined(self, default_config):
+        """Every risk group referenced by DC-BB links exists in the risk group list."""
+        groups = _build_risk_groups(default_config)
+        group_names = {g["name"] for g in groups}
+        links = _build_dc_bb_links(default_config)
+        referenced = set()
+        for link in links:
+            referenced.update(link.get("risk_groups", []))
+        missing = referenced - group_names
+        assert not missing, (
+            f"Risk groups referenced by DC-BB links but not defined: {missing}"
+        )
+
 
 # ---------------------------------------------------------------------------
 # Custom config