Consolidation gate

The paper “Useful Memories Become Faulty” (arXiv:2605.12978) shows that LLMs lose 54% of previously-solved problems after blind consolidation sweeps. The reason is that raw episodic memory is often more useful than the merged summary, but consolidation pipelines have no way to tell which is which.

Mnemosyne’s solution is gated consolidation. Every candidate cluster must pass six conditions or the merge is skipped.

The six conditions

A cluster of similar memories is merged only if all apply:

1. Memory Worth < 0.5 for every member
   (don't merge memories that are clearly useful as-is)

2. Cluster size ≥ 3
   (don't merge pairs — too aggressive)

3. No member was recalled in the last 14 days
   (recently active memories shouldn't be disturbed)

4. No member has worth confidence > 0.7
   (uncertain memories need more data, not merging)

5. Semantic similarity ≥ 0.85
   (only merge memories that are truly redundant — tighter than
   v1.x's 0.75 default)

6. No admin override (manual lock-out during sensitive windows)

If any condition fails, the gate logs the reason and tries the next cluster.

Post-merge validation

After a merge runs, the gate replays the last 10 recall queries that would have hit any of the merged members:

Replay recent recalls → measure result quality delta
If quality drops → ROLLBACK
Restore from mnemo_fact_archive
Log rollback for the health snapshot

The rollback path is real — mnemo_fact_archive (migration 0029) was built specifically so merges are reversible.

What never gets consolidated

• Episodes. Immutable evidence. Facts derived from an episode can be consolidated; the episode itself stays.
• Pinned memories. Explicit user intent overrides everything.
• Anything tagged worth_canonical. Promoted by worth gravity, exempt from merging.

Why this matters for adoption

Every other memory system on the market consolidates blindly. Letta does it. Zep does it. Mem0 does it. Cognee does it. The downstream effect is the same: after a few weeks of operation, the agent’s answers get worse without anyone knowing why.

The consolidation gate is the most undervalued feature in Mnemosyne. It’s the difference between memory that strengthens with time and memory that decays into mush.