Fix e2e fixture: use Table=off + manual routes to avoid wg-quick conflict

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/e2e/wg/test_cell_to_cell_routing.py

@@ -234,10 +234,14 @@ def wg_setup(tmp_path_factory):
 
     # --- Write wg-quick config on the test runner ---
     conf_path = str(tmp_path / f'{IFACE_NAME}.conf')
+    # Table=off: let wg-quick create the interface without managing routes.
+    # We add routes manually below so that existing host routes (added by
+    # ensure_cell_subnet_routes) don't conflict with wg-quick's route additions.
     conf = (
         f'[Interface]\n'
         f'PrivateKey = {privkey}\n'
         f'Address = {test_peer_ip}/32\n'
+        f'Table = off\n'
         f'\n'
         f'[Peer]\n'
         f'PublicKey = {cell2_pubkey}\n'
@@ -253,6 +257,10 @@ def wg_setup(tmp_path_factory):
     up_r = _run(['sudo', 'wg-quick', 'up', conf_path], timeout=15)
     assert up_r.returncode == 0, f'wg-quick up failed: {up_r.stderr}\n{up_r.stdout}'
 
+    # --- Add routes manually (replace is idempotent, handles pre-existing routes) ---
+    for subnet in allowed_ips.split(','):
+        _run(['sudo', 'ip', 'route', 'replace', subnet.strip(), 'dev', IFACE_NAME], timeout=5)
+
     time.sleep(3)
 
     yield {