Memory Lean

memory-lean

Long-term memory for AI coding agents that doesn't burn the context window.

A knowledge graph your agent searches cheaply, and a web UI where you can see and edit all of it.

Quick start · Web UI · How it works · Tools · Setup for 12 agents · Contributing

memory-lean is an MCP server that gives Claude Code, Codex, Cursor, MiMo Code and any other MCP client a memory that lasts between sessions: which projects exist, what depends on what, which version shipped, what is still pending, and which rules were learned the hard way. It is a drop-in replacement for the reference memory server (@modelcontextprotocol/server-memory), with the same file and tool names, but its answers are about 40 times smaller.

Highlights

About 40× smaller answers. Search returns a ranked list of names and the lines that matched, not every entity in full, so the agent can afford to check its memory before every task.

A web UI for people. See the whole graph grouped by type, follow relations, and add, edit or delete anything. Agent writes show up live.

Drop-in replacement. Same memory.jsonl file and the same nine tools as the reference server. Switch in, and switch back whenever you like.

Works with every agent. Copy-paste setup for Claude Code, MiMo Code, Codex, Cursor, Copilot, Gemini CLI, Zed, JetBrains and more, plus the instructions that teach the agent to use it.

Stays small by itself. Short facts, a cap per entity, and an archive for the overflow, so the graph never grows into a wall of text.

Private and safe. Plain local files, daily backups, a write lock for parallel sessions, and no network access. One server file, zero dependencies.

The numbers

Measured on a real graph of 237 entities, 355 relations and 1,160 facts (tokens ≈ characters ÷ 4):

A narrow search that matches one or two entities saves less, because there is little to trim. To measure your own graph, run node tools/bench.mjs from a clone; it is read-only and prints sizes, never content.

Quick start

Claude Code: install the plugin. It adds the server, the instructions as a skill, a short reminder at the start of each session, and /memory-ui.

/plugin marketplace add zamansheikh/memory-lean

/plugin install memory-lean@memory-lean

Any other agent: add the server to its MCP config, then give it the instructions.

{

"mcpServers": { "memory": { "command": "npx", "args": ["-y", "memory-lean"] } } }

npx -y memory-lean --protocol >> AGENTS.md   # into the rules file your agent reads

Just looking? Open the web UI on a made-up example graph:

npx -y memory-lean --ui --demo

Setup for each agent

The graph is created on the first write at ~/.claude/memory-graph/memory.jsonl, whichever agent writes it, so all your agents share one memory. Set MEMORY_FILE_PATH to keep it somewhere else.

Web UI

npx -y memory-lean --ui

This opens your memory in the browser. Everything an agent can do, you can do here:

• Explore. Each type gets its own bubble. Click an entity to highlight everything it connects to, drag nodes to arrange them, and scroll to zoom. Search matches names, types and facts.
• Edit. Add, edit and delete facts, rename an entity or change its type, add and remove relations, create and delete entities, and restore archived facts. Every change passes the same checks as the agents' tools.
• Watch. Changes your agents make appear within two seconds.
• Spot problems. The overview lists pending work, the most connected entities, and anything over budget, which is also marked on the graph.

Follow the connections. Select an entity to see its facts and relations. Find anything. Search names, types and facts at once.

Edit in place. With the same 300-character limit the agents have. Light or dark. It follows your system, or pick one.

The page runs on your machine only (127.0.0.1) and needs the one-time key in the link it prints, so other websites cannot read or change your memory. Nothing is uploaded anywhere.

How it works

Search, then open

The reference server answers a search with every matching entity in full, as pretty-printed JSON. memory-lean answers with a ranked list of names and the lines that matched:

> search_nodes { "query": "deploy" }

57 match "deploy", top 10 shown (narrow the query or raise limit). open_nodes for full entities.

• shop-backend [service] 12 obs, 6 rel › 2026-03-02: deployed 2.4.0 to production › deploy with scripts/release.sh, never by hand
• PENDING shop-backend 2.4.0 [pending] 2 obs, 3 rel › …mobile apps still call the old endpoint until the deploy of 2.4.0 reaches them

The agent then opens only what it needs:

> open_nodes { "names": ["shop-backend"] }

shop-backend [service] (3 archived)

• NestJS API behind api.example.com
• 2026-03-02: deployed 2.4.0 to production

relations

shop-app -talks_to-> shop-backend PENDING shop-backend 2.4.0 -blocks-> shop-app

Why it stays lean

How it keeps your data safe

Tools

| archived_observations | Lists what was archived for an entity, optionally filtered, and restores chosen fa