---
id: ai-memory-layers
area: ai
level: 3
title: "Artefact — Memory in two layers · Engram and Headroom"
claim: "Memory is split by purpose — Engram stores what should persist and Headroom keeps what should not persist out of the context window."
confidence: running
period: "2020–"
tech: [Engram, Headroom, SQLite, JEV]
metrics: [{label: "memory layers", value: 2}]
artefacts: []
public: true
last_verified: 2026-10-26
tags: [ai, memory, context, artefact]
---

# Artefact — Memory in two layers · Engram and Headroom

**Status: stub.** A redacted session handoff and a before-and-after context measurement land in Phase 7.

## What the artefact is

Engram is local-first storage for curated summaries, decisions, prompts and session handoffs in SQLite, so a conversation can be resumed in any project; it is integrated with JEV for fast compaction. Headroom is token control: it strips, cleanses and analyses code and logs before they reach the model, compressing rather than truncating.

## What it proves

Two distinct problems recognised as two — persistence and window economy — instead of one tool asked to do both.

## When it is delivered

Phase 7. Both tools are part of Sam's own workflow; they are deliberately not part of the public assistant, which is stateless by decision (see `reference/decisions.md` D11).