fix(memory): prune encoded Dream sessions

nanobot/agent/memory.py

@@ -16,7 +16,7 @@ from typing import TYPE_CHECKING, Any, Callable, Iterator
 from loguru import logger
 
 from nanobot.runtime_context import public_history_messages
-from nanobot.session.manager import Session
+from nanobot.session.manager import Session, SessionManager
 from nanobot.utils.gitstore import GitStore
 from nanobot.utils.helpers import (
     ensure_dir,
@@ -31,7 +31,6 @@ from nanobot.utils.helpers import (
 from nanobot.utils.prompt_templates import render_template
 
 if TYPE_CHECKING:
-    from nanobot.session.manager import SessionManager
     from nanobot.utils.llm_runtime import LLMRuntime
 
 # ---------------------------------------------------------------------------
@@ -705,12 +704,15 @@ class MemoryStore:
     def prune_dream_sessions(sessions_dir: Path, *, keep: int = 10) -> None:
         """Remove the oldest Dream session files, keeping only the N most recent.
 
-        Only files matching ``dream_*.jsonl`` are considered. Non-dream session
-        files are never touched.
+        Only current base64url-encoded Dream session keys are considered.
+        Non-dream session files are never touched.
         """
-        dream_files = sorted(
-            sessions_dir.glob("dream_*.jsonl"), key=lambda p: p.stat().st_mtime,
-        )
+        dream_files = []
+        for path in sessions_dir.glob("*.jsonl"):
+            decoded_key = SessionManager._decode_storage_key(path.stem)
+            if decoded_key is not None and decoded_key.startswith("dream:"):
+                dream_files.append(path)
+        dream_files.sort(key=lambda p: p.stat().st_mtime)
         if len(dream_files) <= keep:
             return