docs: add inline comment explaining deferred agent imports

Author: mwbrooks

slack_bolt/context/async_context.py

@@ -207,6 +207,8 @@ async def handle_mention(agent):
             `AsyncBoltAgent` instance
         """
         if "agent" not in self:
+            # Deferred import: AsyncBoltAgent is only imported at runtime when accessed,
+            # avoiding unnecessary loading when the agent property is never used.
             from slack_bolt.agent.async_agent import AsyncBoltAgent
 
             self["agent"] = AsyncBoltAgent(

slack_bolt/context/context.py

@@ -208,6 +208,8 @@ def handle_mention(agent):
             `BoltAgent` instance
         """
         if "agent" not in self:
+            # Deferred import: BoltAgent is only imported at runtime when accessed,
+            # avoiding unnecessary loading when the agent property is never used.
             from slack_bolt.agent.agent import BoltAgent
 
             self["agent"] = BoltAgent(