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):

Call	Reference server	memory-lean
read_graph	~77,800 tokens	~2,000 tokens	40× smaller
search_nodes, average of 5 common words	~31,000 tokens	~770 tokens	40× smaller

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

Agent	Server config	Instructions
Claude Code	plugin	included in the plugin
Xiaomi MiMo Code	mimocode.jsonc	skill or AGENTS.md
opencode	opencode.json	AGENTS.md
OpenAI Codex CLI	codex mcp add	AGENTS.md
Cursor	.cursor/mcp.json	AGENTS.md or a rule
VS Code (Copilot)	.vscode/mcp.json	copilot-instructions.md
Gemini CLI	settings.json	GEMINI.md
Windsurf	mcp_config.json	a rule
Cline	cline_mcp_settings.json	.clinerules/
Zed	settings.json	AGENTS.md or .rules
JetBrains IDEs	AI Assistant settings	a rule or guidelines
Claude Desktop	claude_desktop_config.json	project instructions

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

Limit	What it means
Small answers	search_nodes returns at most 10 names with snippets, read_graph returns an index of names, and only open_nodes returns full entities.
Short facts	An observation longer than 300 characters is rejected, with a message telling the agent to split it or put the detail in the repo.
A cap per entity	An entity keeps 15 observations. Past that, the oldest dated ones move to archive/<entity>.md. Nothing is deleted: they can be listed and restored, and undated facts (the identity facts) always stay.
Search that narrows	Every word must match somewhere in the entity, so adding a word narrows the result. The reference server looks for the query as one exact phrase.

How it keeps your data safe

Safeguard	What it means
Safe to share	Writers take a lock file, so several agent sessions can use one graph without overwriting each other. Every write replaces the file atomically.
Daily backups	A copy goes to backups/ once a day; the last 7 are kept.
Damaged lines are kept	A line that cannot be read is moved to memory.jsonl.unreadable on the next write and reported, never silently dropped.
Plain files	The graph is JSON lines, archives are Markdown, backups are copies. You can read, grep and edit all of it by hand.

Tools

Tool	What it returns
search_nodes	Ranked list of entity names with counts and up to two matching snippets each. Every word must match the name, type, an observation, or the type of a relation touching the entity.
open_nodes	The full entities you name, as compact text, with every relation touching them and their archive count. Unknown names come back with "did you mean" suggestions.
read_graph	An index: entity names grouped by type, with observation counts. Never the observations.
create_entities	Creates entities; existing names are skipped.
create_relations	Creates relations between existing entities; duplicates are skipped.
add_observations	Adds facts to an entity, enforcing the length limit and the per-entity cap.
delete_observations	Removes observations by exact text.
delete_relations	Removes specific relations.
delete_entities	Removes entities and every relation touching them.
rename_entity	Renames an entity, keeping its observations, relations and archive. Not in the reference server.
archived_observations	Lists what was archived for an entity, optionally filtered, and restores chosen facts. Not in the reference server.

The three read tools are marked read-only, so clients that support it can run them without asking.

Command line

Command	What it does
memory-lean	Runs the MCP server over stdio. This is what agents start.
memory-lean --ui [port]	Opens the web UI. --no-open only prints the link; --demo uses a throwaway copy of a made-up graph.
memory-lean --protocol	Prints the agent instructions, ready to append to AGENTS.md, CLAUDE.md or GEMINI.md.
memory-lean --skill <dir>	Writes the same instructions as an Agent Skill into <dir>/memory-graph.
memory-lean --lint	Reports what in the graph is over budget. Read-only.
memory-lean --compact	Backs up the graph, then moves overflow observations to the archive.
memory-lean --version	Prints the version.

With npx, put npx -y in front: npx -y memory-lean --ui.

Teach your agent to use it

A memory server only helps if the agent reads it before working and writes to it when something changes. docs/AGENT-PROTOCOL.md is a ready-made set of instructions: what to look up at the start of a task, what to record, how to name things, and what never to store. The Claude Code plugin includes it. For every other agent, one command installs it:

npx -y memory-lean --protocol >> AGENTS.md     # into a rules file: always on
npx -y memory-lean --skill .agents/skills      # as an Agent Skill: loaded when relevant

Adjust the entity types and names in it to your own work.

Coming from the reference memory server

Point MEMORY_FILE_PATH at your existing memory.jsonl and swap the command. The file format is identical, so you can switch back at any time. Existing observations longer than 300 characters are kept as they are; only new writes are checked. To see what is over budget, and optionally fix it:

npx -y memory-lean --lint      # report only
npx -y memory-lean --compact   # back up, then move overflow to archive/

Settings

All optional, set as environment variables on the server:

Variable	Default	Meaning
MEMORY_FILE_PATH	~/.claude/memory-graph/memory.jsonl	Where the graph lives
MEMORY_OBS_MAX_CHARS	300	Longest observation accepted
MEMORY_OBS_MAX	15	Observations per entity before the oldest dated ones are archived
MEMORY_SEARCH_LIMIT	10	Default number of search results
MEMORY_BACKUPS_KEPT	7	Daily backups kept

FAQ

Is my memory sent anywhere?

No. The server reads and writes local files and makes no network requests. The web UI listens on 127.0.0.1 only. Keep the graph out of git, and never store passwords, keys or tokens in it: record where a secret lives, not its value.

Can several agents or sessions share one graph?

Yes. Every write takes a lock, re-reads the file and replaces it atomically, so parallel sessions (and the web UI) do not overwrite each other.

Why plain text search instead of embeddings?

It needs no model, no index and no dependencies, and an agent's queries are mostly names it already knows. Good entity names matter more than clever queries.

What happens to old facts?

When an entity passes 15 facts, the oldest dated ones move to archive/<entity>.md next to the graph. archived_observations, or the Archive section in the web UI, lists and restores them.

Roadmap

• Claude Code plugin with the server, a skill and /memory-ui
• Setup guides for 12 agents
• rename_entity and archive restore
• A web UI to explore and edit the graph
• Listed in the official MCP registry
• Listed in the Claude Code plugin directory
• Search across the archived facts of every entity
• Undo in the web UI

Contributing

Ideas, bug reports and pull requests are welcome. The server is one file with no dependencies, the web UI is one HTML file, and npm test runs in a few seconds, so a first change is quick to make. CONTRIBUTING.md has the layout, the ground rules and a list of good first contributions.

If memory-lean saves you tokens, a ⭐ helps other people find it.

Support

memory-lean is free and MIT licensed. If it is useful to you, you can support the work:

Author

Created and maintained by Zaman Sheikh at Silifton.

Built on the file format and tool names of the Model Context Protocol reference memory server.

License

MIT © 2026 Zaman Sheikh. Free to use, change and share, including commercially; keep the copyright notice.