fix(webui): keep idle compaction out of session recency

tests/agent/test_auto_compact.py

@@ -8,6 +8,7 @@ from unittest.mock import AsyncMock, MagicMock
 import pytest
 
 from nanobot.agent.loop import AgentLoop
+from nanobot.agent.memory import LAST_COMPACTED_AT_META
 from nanobot.bus.events import InboundMessage
 from nanobot.bus.queue import MessageBus
 from nanobot.command import CommandContext
@@ -88,10 +89,11 @@ def _make_fake_compact(
     async def _fake_compact(key: str, max_suffix: int = 8) -> str:
         state["count"] += 1
         session = loop.sessions.get_or_create(key)
+        compacted_at = datetime.now().isoformat()
 
         tail = list(session.messages[session.last_consolidated:])
         if not tail:
-            session.updated_at = datetime.now()
+            session.metadata[LAST_COMPACTED_AT_META] = compacted_at
             loop.sessions.save(session)
             return ""
 
@@ -111,7 +113,7 @@ def _make_fake_compact(
         archive_msgs = result.dropped[result.already_consolidated_count:]
 
         if not archive_msgs and not kept:
-            session.updated_at = datetime.now()
+            session.metadata[LAST_COMPACTED_AT_META] = compacted_at
             loop.sessions.save(session)
             return ""
 
@@ -132,7 +134,7 @@ def _make_fake_compact(
 
         session.messages = kept
         session.last_consolidated = 0
-        session.updated_at = datetime.now()
+        session.metadata[LAST_COMPACTED_AT_META] = compacted_at
         loop.sessions.save(session)
         return s
 
@@ -1021,14 +1023,14 @@ class TestProactiveAutoCompact:
         await self._run_check_expired(loop)
         assert _fake_compact.state["count"] == 1
 
-        # Second tick: should NOT re-schedule (updated_at is fresh after clear)
+        # Second tick: should NOT re-schedule (maintenance timestamp is fresh)
         await self._run_check_expired(loop)
         assert _fake_compact.state["count"] == 1  # Still 1, not re-scheduled
         await loop.close_mcp()
 
     @pytest.mark.asyncio
-    async def test_empty_skip_refreshes_updated_at_prevents_reschedule(self, tmp_path):
-        """Empty session skip refreshes updated_at, preventing immediate re-scheduling."""
+    async def test_empty_skip_records_compaction_prevents_reschedule(self, tmp_path):
+        """Empty session skip records maintenance, preventing immediate re-scheduling."""
         loop = _make_loop(tmp_path, session_ttl_minutes=15)
         session = loop.sessions.get_or_create("cli:test")
         session.updated_at = datetime.now() - timedelta(minutes=20)
@@ -1036,11 +1038,11 @@ class TestProactiveAutoCompact:
 
         loop.consolidator.compact_idle_session = _make_fake_compact(loop)
 
-        # First tick: skips (no messages), refreshes updated_at
+        # First tick: skips (no messages), records compaction metadata
         await self._run_check_expired(loop)
         assert "cli:test" not in loop.auto_compact._summaries
 
-        # Second tick: should NOT re-schedule because updated_at is fresh
+        # Second tick: should NOT re-schedule because maintenance metadata is fresh
         await self._run_check_expired(loop)
         assert "cli:test" not in loop.auto_compact._summaries
         await loop.close_mcp()