feat: add embedding-aware graph query interfaces and parallel retrieval (#212)

* feat: add log timer for presstest

* fix: session pool error

* feat: can choose whether return embedding in some graph db functions

* fix: log

* feat: change system prompts

Author: CaralHsi

src/memos/graph_dbs/base.py

@@ -70,15 +70,27 @@ def edge_exists(self, source_id: str, target_id: str, type: str) -> bool:
 
     # Graph Query & Reasoning
     @abstractmethod
-    def get_node(self, id: str) -> dict[str, Any] | None:
+    def get_node(self, id: str, include_embedding: bool = False) -> dict[str, Any] | None:
         """
         Retrieve the metadata and content of a node.
         Args:
             id: Node identifier.
+            include_embedding: with/without embedding
         Returns:
             Dictionary of node fields, or None if not found.
         """
 
+    @abstractmethod
+    def get_nodes(self, id: str, include_embedding: bool = False) -> dict[str, Any] | None:
+        """
+        Retrieve the metadata and memory of a list of nodes.
+        Args:
+            ids: List of Node identifier.
+            include_embedding: with/without embedding
+        Returns:
+        list[dict]: Parsed node records containing 'id', 'memory', and 'metadata'.
+        """
+
     @abstractmethod
     def get_neighbors(
         self, id: str, type: str, direction: Literal["in", "out", "both"] = "out"
@@ -163,7 +175,9 @@ def get_by_metadata(self, filters: list[dict[str, Any]]) -> list[str]:
         """
 
     @abstractmethod
-    def get_structure_optimization_candidates(self, scope: str) -> list[dict]:
+    def get_structure_optimization_candidates(
+        self, scope: str, include_embedding: bool = False
+    ) -> list[dict]:
         """
         Find nodes that are likely candidates for structure optimization:
         - Isolated nodes, nodes with empty background, or nodes with exactly one child.
@@ -205,7 +219,7 @@ def clear(self) -> None:
         """
 
     @abstractmethod
-    def export_graph(self) -> dict[str, Any]:
+    def export_graph(self, include_embedding: bool = False) -> dict[str, Any]:
         """
         Export the entire graph as a serializable dictionary.
 
@@ -221,3 +235,16 @@ def import_graph(self, data: dict[str, Any]) -> None:
         Args:
             data: A dictionary containing all nodes and edges to be loaded.
         """
+
+    @abstractmethod
+    def get_all_memory_items(self, scope: str, include_embedding: bool = False) -> list[dict]:
+        """
+        Retrieve all memory items of a specific memory_type.
+
+        Args:
+            scope (str): Must be one of 'WorkingMemory', 'LongTermMemory', or 'UserMemory'.
+            include_embedding: with/without embedding
+
+        Returns:
+            list[dict]: Full list of memory items under this scope.
+        """