feat: redesign memory system — two-layer architecture with grep-based retrieval

nanobot/agent/memory.py

@@ -1,109 +1,30 @@
 """Memory system for persistent agent memory."""
 
 from pathlib import Path
-from datetime import datetime
 
-from nanobot.utils.helpers import ensure_dir, today_date
+from nanobot.utils.helpers import ensure_dir
 
 
 class MemoryStore:
-    """
-    Memory system for the agent.
-    
-    Supports daily notes (memory/YYYY-MM-DD.md) and long-term memory (MEMORY.md).
-    """
-    
+    """Two-layer memory: MEMORY.md (long-term facts) + HISTORY.md (grep-searchable log)."""
+
     def __init__(self, workspace: Path):
-        self.workspace = workspace
         self.memory_dir = ensure_dir(workspace / "memory")
         self.memory_file = self.memory_dir / "MEMORY.md"
-    
-    def get_today_file(self) -> Path:
-        """Get path to today's memory file."""
-        return self.memory_dir / f"{today_date()}.md"
-    
-    def read_today(self) -> str:
-        """Read today's memory notes."""
-        today_file = self.get_today_file()
-        if today_file.exists():
-            return today_file.read_text(encoding="utf-8")
-        return ""
-    
-    def append_today(self, content: str) -> None:
-        """Append content to today's memory notes."""
-        today_file = self.get_today_file()
-        
-        if today_file.exists():
-            existing = today_file.read_text(encoding="utf-8")
-            content = existing + "\n" + content
-        else:
-            # Add header for new day
-            header = f"# {today_date()}\n\n"
-            content = header + content
-        
-        today_file.write_text(content, encoding="utf-8")
-    
+        self.history_file = self.memory_dir / "HISTORY.md"
+
     def read_long_term(self) -> str:
-        """Read long-term memory (MEMORY.md)."""
         if self.memory_file.exists():
             return self.memory_file.read_text(encoding="utf-8")
         return ""
-    
+
     def write_long_term(self, content: str) -> None:
-        """Write to long-term memory (MEMORY.md)."""
         self.memory_file.write_text(content, encoding="utf-8")
-    
-    def get_recent_memories(self, days: int = 7) -> str:
-        """
-        Get memories from the last N days.
-        
-        Args:
-            days: Number of days to look back.
-        
-        Returns:
-            Combined memory content.
-        """
-        from datetime import timedelta
-        
-        memories = []
-        today = datetime.now().date()
-        
-        for i in range(days):
-            date = today - timedelta(days=i)
-            date_str = date.strftime("%Y-%m-%d")
-            file_path = self.memory_dir / f"{date_str}.md"
-            
-            if file_path.exists():
-                content = file_path.read_text(encoding="utf-8")
-                memories.append(content)
-        
-        return "\n\n---\n\n".join(memories)
-    
-    def list_memory_files(self) -> list[Path]:
-        """List all memory files sorted by date (newest first)."""
-        if not self.memory_dir.exists():
-            return []
-        
-        files = list(self.memory_dir.glob("????-??-??.md"))
-        return sorted(files, reverse=True)
-    
+
+    def append_history(self, entry: str) -> None:
+        with open(self.history_file, "a", encoding="utf-8") as f:
+            f.write(entry.rstrip() + "\n\n")
+
     def get_memory_context(self) -> str:
-        """
-        Get memory context for the agent.
-        
-        Returns:
-            Formatted memory context including long-term and recent memories.
-        """
-        parts = []
-        
-        # Long-term memory
         long_term = self.read_long_term()
-        if long_term:
-            parts.append("## Long-term Memory\n" + long_term)
-        
-        # Today's notes
-        today = self.read_today()
-        if today:
-            parts.append("## Today's Notes\n" + today)
-        
-        return "\n\n".join(parts) if parts else ""
+        return f"## Long-term Memory\n{long_term}" if long_term else ""