Agent Estate Wiki

Mnemosyne

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tagsmemory, mnemosyne, backend

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Mnemosyne

Purpose

Primary agent memory store for Hermes.

Current Configuration

  • Provider: mnemosyne
  • Enabled: true
  • Auto sleep: true
  • Default scope: session
  • Memory char limit: 5000
  • User char limit: 3000
  • Vector type: int8
  • Profile isolation: true
  • Shared surface read: true
  • Shared surface path: data/shared/mnemosyne.db
  • Skip contexts: cron, flush, subagent, background, skill_loop
  • Reflect max calls per session: 3
  • Sync roles: user
  • Flush every: 6 turns
  • Embedding model: BAAI/bge-small-en-v1.5 (384 dims)
  • Embeddings via API: false (local fastembed)

Database Stats (2026-08-02)

TableRowsNotes
working_memory1,476Active memories
episodic_memory458Consolidated summaries
memory_embeddings158Only working memories — 0 episodic
memory (legacy)2,181Old table, not migrated
vec_working159Vector index rows
Shared surface0Empty — cross-agent sharing not functional

Known Issues

Vector embedding coverage gap

  • Only 159/1,476 working memories (10.8%) have vector embeddings
  • 0/458 episodic memories have embeddings
  • Semantic search (mnemosyne_recall) falls back to FTS5 keyword matching for ~90% of working and 100% of episodic memories
  • This means recall quality is degraded — vector similarity can only search a tiny fraction of the memory store
  • Root cause: The embedding pipeline (fastembed) never processed the bulk of memories. The vec_working table was rebuilt once (Jul 18) but only captured 159 rows.
  • Fix needed: Backfill embeddings for all working and episodic memories. This requires running the embedding pipeline across the full dataset.

Profile isolation chosen over shared surface

|- The ops profile was enabled with mnemosyne on 2026-08-02 |- Decision: profile_isolation: true was set on ops, giving each profile its own independent memory bank — zero cross-contamination |- data/shared/mnemosyne.db exists with 0 rows; cross-profile sharing is intentionally unused |- This means Tusk (ops) and Rhino (default) do not share memories, which is the desired behaviour |- Config in ~/.hermes/profiles/ops/config.yaml: memory.mnemosyne.profile_isolation: true, allow_tool_override: false, shared_surface_read: false |- Verified end-to-end on 2026-08-02: memory writes land correctly in both profiles independently

Legacy table not migrated

  • 2,181 rows in the old memory table are not in the new working_memory/episodic_memory system
  • These are only accessible via the legacy memory tool, not via mnemosyne_recall

Known Management Jobs

  • Mnemosyne Auto-Consolidate every 30m — script: consolidate_mnemosyne.sh, mode: no-agent
  • Mnemosyne DB Backup weekly Sunday 03:00 — script: mnemosyne-backup.sh, mode: no-agent
  • Mnemosyne Health Monitor every 12h — skill: mnemosyne-operations, reports only on exception
  • Mnemosyne Watchdog every 15m — script: mnemosyne-watchdog.py, mode: no-agent

History and Evidence

  • 2026-08-01 incident: Automatic conversational capture was broken by stringified structured YAML, especially sync_roles: "['user']". Fixed by rewriting with native YAML types. See 2026-08-01-mnemosyne-capture-failure.
  • 2026-08-01 cleanup: Legacy always-injected memory reduced from 8,013 bytes to 4,998 bytes (memory) and 2,958 bytes (user).
  • 2026-07-29 incident: memory.mnemosyne.tools: None caused schema loading warnings. Fixed by removing the line. See 2026-07-29-mnemosyne-relay.
  • 2026-07-29 relay scope corruption: RuntimeError: scope handle is not at the top of the stack — 3 occurrences, self-resolved.

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