docs(run_agent): clarify why F401 re-exports stay

run_agent.py

@@ -65,6 +65,10 @@ from hermes_constants import get_hermes_home
 
 # OpenAI lazy proxy + safe stdio + proxy URL helpers — see agent/process_bootstrap.py.
 # `OpenAI` is re-exported here so `patch("run_agent.OpenAI", ...)` in tests works.
+# The other `# noqa: F401` re-exports below cover names accessed via
+# `mock.patch("run_agent.<X>")`, `from run_agent import <X>` in production
+# siblings, or the `_ra().<X>` indirection in agent/system_prompt.py — none
+# of which ruff's in-module usage scan can see.
 from agent.process_bootstrap import (
     OpenAI,  # noqa: F401  # re-exported for tests that mock.patch("run_agent.OpenAI")
     _SafeWriter,  # noqa: F401  # re-exported for tests that `from run_agent import _SafeWriter`