fix(context): scale replay cap with context window

nanobot/agent/loop.py

@@ -57,7 +57,11 @@ from nanobot.session.goal_state import (
     sustained_goal_active,
 )
 from nanobot.session.keys import UNIFIED_SESSION_KEY, session_key_for_channel
-from nanobot.session.manager import DEFAULT_REPLAY_MAX_MESSAGES, Session, SessionManager
+from nanobot.session.manager import (
+    Session,
+    SessionManager,
+    replay_max_messages_for_context,
+)
 from nanobot.utils.document import extract_documents, reference_non_image_attachments
 from nanobot.utils.helpers import image_placeholder_text
 from nanobot.utils.helpers import truncate_text as truncate_text_fn
@@ -201,7 +205,7 @@ class AgentLoop:
         timezone: str | None = None,
         session_ttl_minutes: int = 0,
         consolidation_ratio: float = 0.5,
-        max_messages: int = DEFAULT_REPLAY_MAX_MESSAGES,
+        max_messages: int = 0,
         hooks: list[AgentHook] | None = None,
         unified_session: bool = False,
         disabled_skills: list[str] | None = None,
@@ -292,8 +296,11 @@ class AgentLoop:
             llm_wall_timeout_for_session=lambda sk: runner_wall_llm_timeout_s(self.sessions, sk),
         )
         self._unified_session = unified_session
+        self._explicit_max_messages = max_messages > 0
         self._max_messages = (
-            max_messages if max_messages > 0 else DEFAULT_REPLAY_MAX_MESSAGES
+            max_messages
+            if self._explicit_max_messages
+            else replay_max_messages_for_context(self.context_window_tokens)
         )
         self._running = False
         self._mcp_servers = mcp_servers or {}
@@ -422,6 +429,7 @@ class AgentLoop:
         self.runner.provider = provider
         self.subagents.set_provider(provider, model)
         self.consolidator.set_provider(provider, model, context_window_tokens)
+        self._sync_replay_max_messages()
         self._provider_signature = snapshot.signature
         if publish_update and self._runtime_model_publisher is not None:
             self._runtime_model_publisher(
@@ -435,6 +443,10 @@ class AgentLoop:
             )
         logger.info("Runtime model switched for next turn: {} -> {}", old_model, model)
 
+    def _sync_replay_max_messages(self) -> None:
+        if not self._explicit_max_messages:
+            self._max_messages = replay_max_messages_for_context(self.context_window_tokens)
+
     def _refresh_provider_snapshot(self) -> None:
         if self._provider_snapshot_loader is None:
             return