Correct Answer: B
Explanation:
The application incorrectly combines short-term conversational memory and long-term semantic memory within a single vector retrieval mechanism.
Short-term memory must preserve the sequence of messages, recent user statements, intermediate decisions, and tool interactions within an active session.
Semantic vector retrieval does not guarantee chronological completeness. It retrieves information based on relevance scores, potentially omitting earlier conversation details that remain essential for the current interaction.
Furthermore, storing all users' conversation summaries in a shared index without appropriate access boundaries can cause unrelated information to appear in generated responses.
Option B separates these responsibilities.
A session-scoped short-term buffer maintains the active conversation context, preserving continuity across turns. A separate persistent vector store retains durable information such as confirmed preferences, customer-specific facts, and significant decisions that should remain accessible across sessions.
Databricks provides this architectural distinction through Agent Sessions and Agent Memory, both of which can use Lakebase-backed persistence.
Option A improves retrieval isolation but continues using semantic search as the primary mechanism for session continuity. Option C does not properly distinguish durable memory from session history. Option D continues accumulating redundant summaries and increases retrieval overhead.
Production implementations should also enforce user-scoped access controls, bounded session histories, and relevance-based long-term memory retrieval.
Official Databricks reference: Agent memory and sessions, Agent sessions, and Agent state and memory.