Persist API chat lifetime and add cleanup job

Validate and persist API chat lifetime: lifetime_hours is validated as a positive number and stored in the AgentContext data, and context.last_message is set using UTC. Removed the in-class threading-based cleanup state and old _cleanup_expired_chats method. Introduced a new job-loop extension (extensions/python/job_loop/_20_cleanup_expired_api_chats.py) that periodically scans AgentContext instances and removes expired API chats (using persist_chat.remove_chat) in a UTC-aware manner. Added tests (tests/test_api_chat_lifetime.py) to verify lifetime persistence and that the job loop removes expired chats.

extensions/python/job_loop/_20_cleanup_expired_api_chats.py

@@ -0,0 +1,63 @@
+from datetime import datetime, timedelta, timezone
+from typing import Any
+
+from agent import AgentContext
+from helpers import persist_chat
+from helpers.extension import Extension
+from helpers.print_style import PrintStyle
+from helpers.state_monitor_integration import mark_dirty_all
+
+
+CHECK_INTERVAL = timedelta(hours=1)
+LIFETIME_KEY = "lifetime_hours"
+
+
+class CleanupExpiredApiChats(Extension):
+    _last_check: datetime | None = None
+
+    async def execute(self, data: dict[str, Any] | None = None, **kwargs):
+        now = datetime.now(timezone.utc)
+        if type(self)._last_check and now - type(self)._last_check < CHECK_INTERVAL:
+            return
+        type(self)._last_check = now
+
+        removed = 0
+        for context in list(AgentContext.all()):
+            lifetime_hours = context.get_data(LIFETIME_KEY)
+            if lifetime_hours is None:
+                continue
+
+            try:
+                lifetime = timedelta(hours=float(lifetime_hours))
+            except (TypeError, ValueError):
+                PrintStyle.error(
+                    f"Invalid chat lifetime for {context.id}: {lifetime_hours}"
+                )
+                continue
+
+            if lifetime <= timedelta(0) or context.is_running():
+                continue
+
+            last_message = _as_utc(context.last_message)
+            if now - last_message <= lifetime:
+                continue
+
+            try:
+                context.reset()
+                AgentContext.remove(context.id)
+                persist_chat.remove_chat(context.id)
+                removed += 1
+                PrintStyle().print(f"Cleaned up expired API chat: {context.id}")
+            except Exception as e:
+                PrintStyle.error(f"Failed to cleanup expired API chat {context.id}: {e}")
+
+        if removed:
+            mark_dirty_all(reason="job_loop.CleanupExpiredApiChats")
+
+
+def _as_utc(value: datetime | None) -> datetime:
+    if value is None:
+        return datetime.fromtimestamp(0, timezone.utc)
+    if value.tzinfo is None:
+        return value.replace(tzinfo=timezone.utc)
+    return value.astimezone(timezone.utc)