Letta AI's background agent that runs alongside Claude Code, watching sessions and building persistent memory to inject contextual guidance before each prompt — without ever blocking the main agent or writing to disk. The system uses Letta's memory engine to accumulate codebase patterns, developer preferences, bug history, and project context across sessions. Three operation modes (whisper, full, off) allow flexible configuration. The subconscious actively explores the codebase using Read, Grep, and Glob tools, and optionally supports two-way communication for explicit memory queries.