fix(mcp): stop infra_stop false positive on decorative equals banners

Line-anchor conflict-marker detection in check_mid_merge and MCP startup
so mcp_discoverability.py RELOAD_INSTRUCTIONS banners no longer block
reviewer capability resolution. Share python_bytes_have_conflict_markers
between mcp_server startup scan and role_session_router mid-merge checks.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

tests/test_health.py

@@ -5,6 +5,7 @@ import unittest
 from unittest.mock import patch
 
 import role_session_router
+from role_session_router import python_bytes_have_conflict_markers
 from mcp_server import gitea_route_task_session, gitea_resolve_task_capability
 
 _HEALTH_SUBPROCESS_TIMEOUT_SEC = 30
@@ -80,6 +81,20 @@ class TestMCPHealth(unittest.TestCase):
             with self.assertRaises(unittest.SkipTest):
                 _health_test_python()
 
+    def test_conflict_marker_helper_ignores_decorative_equals_border(self):
+        sample = b'banner = """\n===========================================\n"""\n'
+        self.assertFalse(python_bytes_have_conflict_markers(sample))
+
+    def test_conflict_marker_helper_detects_real_markers(self):
+        sample = (
+            b"<" * 7 + b" HEAD\n"
+            b"print('hello')\n"
+            b"=" * 7 + b"\n"
+            b"print('world')\n"
+            b">" * 7 + b" main\n"
+        )
+        self.assertTrue(python_bytes_have_conflict_markers(sample))
+
     def test_startup_conflict_detection(self):
         # Create a Python file with conflict markers constructed dynamically
         with open(self.temp_file, "w") as f: