diff --git a/hermes_logging.py b/hermes_logging.py
index 4de9619a97..a2f786f9bb 100644
--- a/hermes_logging.py
+++ b/hermes_logging.py
@@ -669,6 +669,17 @@ def _add_rotating_handler(
     )
     if log_filter is not None:
         handler.addFilter(log_filter)
+    # Routing already on (a second home adopted earlier): a component log added now —
+    # ``mode="gateway"`` after the fact — must route too, or it takes every home's records.
+    routers = [h for h in _queued_file_handlers if isinstance(h, _ProfileRoutingFileHandler)]
+    if routers:
+        homes: set[Path] = set()
+        for router in routers:
+            homes.add(router._default_home)
+            homes.update(router._profile_homes)
+        routed = _ProfileRoutingFileHandler(handler, sorted(homes))
+        _quietly(handler.close)
+        handler = routed
     # Queue, not ``addHandler``: the rotation-lock wait never runs on the caller's thread.
     _register_queued_handler(handler)
 
diff --git a/tests/test_hermes_logging.py b/tests/test_hermes_logging.py
index ca0813ca97..14afc5e0fb 100644
--- a/tests/test_hermes_logging.py
+++ b/tests/test_hermes_logging.py
@@ -196,6 +196,30 @@ class TestSetupLogging:
         assert (profile_home / "logs" / "agent.log").read_text().count("once please") == 1
         assert "once please" not in (hermes_home / "logs" / "agent.log").read_text()
 
+    def test_a_component_log_added_after_routing_is_routed_too(self, hermes_home, tmp_path):
+        """setup_logging(mode="gateway") for an already-known home AFTER a second home turned
+        routing on: gateway.log must be a routed writer, not a bare handler taking every home."""
+        from hermes_constants import reset_hermes_home_override, set_hermes_home_override
+
+        profile_home = tmp_path / "profile-b"
+        profile_home.mkdir()
+        hermes_logging.setup_logging(hermes_home=hermes_home)
+        hermes_logging.setup_logging(hermes_home=profile_home)
+        hermes_logging.setup_logging(hermes_home=hermes_home, mode="gateway")
+
+        logger = logging.getLogger("gateway.run.routed-component-test")
+        token = set_hermes_home_override(profile_home)
+        try:
+            logger.info("gw-b")
+        finally:
+            reset_hermes_home_override(token)
+        logger.info("gw-a")
+        hermes_logging.flush_log_queue()
+
+        a_log = (hermes_home / "logs" / "gateway.log").read_text()
+        assert "gw-a" in a_log and "gw-b" not in a_log
+        assert "gw-b" in (profile_home / "logs" / "gateway.log").read_text()
+