jevmem

Say it once. jevmem saves the decisions, rules and failed approaches from your Claude Code chats to JEVMEM.md in your repo, and brings the relevant ones back next session. Before Claude runs a command or edits a file, it checks the call against your saved rules. It is open source (MIT), built on TypeSafe AI's Jev, in Anthropic's Claude plugin directory and on the MCP Registry. Since 0.7.4 it saves from Cursor chats the same way, as a Cursor plugin since 0.7.6, and it works with Codex and Claude Desktop over MCP.

In Anthropic's Claude plugin directory · On the MCP Registry · Open source, MIT

The docs site, one page per question: avinash-jetwani.github.io/jevmem

https://github.com/user-attachments/assets/c8a7eced-c427-4ef6-85f2-124eb34ad291

Why

Each Claude Code session starts with a fresh context, so what you decided last week lives in last week's chat. A CLAUDE.md file helps if you keep it up to date. jevmem keeps a file like it up to date for you, as you work.

In numbers

In real Claude Code sessions on three small test projects, with jevmem and without it:

• Claude followed the project's earlier decisions: in 66 of 72 sessions with jevmem, 28 of 72 without (about 9 in 10, against 4 in 10).
• Tried a change the project forbids: in 0 of 18 sessions with jevmem, against 10 of 18 without.
• Repeated an approach that had already failed: in 0 of 15, against 3 of 15.
• Saving: about 18 cents per 1,000 messages and about a fifth of a second to decide, in the background: Claude doesn't wait for it.
• Bringing lines back: about a third to half a second on each prompt, which Claude waits for; the time and the cost grow with the file.
• To be fair: a CLAUDE.md you keep up to date by hand did about as well (67 of 72), and better on one convention nothing in the prompt points at (3 of 3 against 0 of 3). jevmem keeps a file like it up to date for you, and since 0.7.1 marks such rules always-on, so they reach every session: 18 of 18 on six held-out tasks written for that gap, against 14 of 18 with 0.7.0.

My own test sets, each number from one run; none is an independent benchmark. Method and results

How it works

You chat as usual. When you decide something, jevmem writes it as one line in a file in your repo, and brings the right lines back next session.

1. You decide something in a chat: "We use Postgres."
2. jevmem asks Jev by TypeSafe AI, a model that answers yes/no questions with probabilities, whether it's worth keeping.
3. If it is, jevmem writes one line to JEVMEM.md in your repo.
4. Next session, the lines that matter for your prompt go back to Claude.

Change your mind, and the old line is crossed out: kept for history, not sent to Claude. Your team gets the same file through git.

jevmem keeps decisions, rules, bugs, to-dos and dead ends (an approach that was tried and failed, with the reason).

- [superseded] We'll use SQLite as the primary store for now. → id:cuasaq
- [decision] Switch the primary store to Postgres 16.
- [constraint] Node 20 is the minimum supported version, and CI runs Node 20 and 22.

Each line also carries a comment with its id, time and confidence, left out above. The full lines:

- [superseded] We'll use SQLite as the primary store for now. → id:cuasaq  <!-- id:21ycba ts:2026-09-26T13:46:34.703Z conf:1.00 by:cuasaq -->
- [decision] Switch the primary store to Postgres 16.  <!-- id:cuasaq ts:2026-09-26T13:46:35.240Z conf:1.00 -->
- [constraint] Node 20 is the minimum supported version, and CI runs Node 20 and 22.  <!-- id:tollba ts:2026-09-26T13:46:35.763Z conf:0.90 -->

Real lines from 0.5.7's default writer, which 0.5.8 to 0.5.10 did not change (the run, 2026-09-26). It kept one sentence of each turn: the Postgres turn also said "SQLite locks up under concurrent writes", and that reason was left out. Since 0.6.0 the line is made from the sentences Jev picks, the one that states the memory and the one that gives its reason (What's new). With writer set, an OpenAI or Anthropic model condenses the whole turn instead.

Does it work?

In 72 real Claude Code sessions for each setup, Claude acted on the saved line about as often with jevmem as with the same lines in a hand-written CLAUDE.md, and in fewer than half the sessions with neither.

So jevmem did about as well as a hand-written CLAUDE.md, without you writing it. CLAUDE.md did better on a convention nothing in the prompt points at (3 of 3 against 0 of 3), measured on 0.6, where jevmem brought a line back only for a prompt it bears on. Since 0.7.1 jevmem marks a rule every change must follow always-on and sends it at the start of every session: on six held-out tasks written for that gap, Claude followed the convention in 14 of 18 sessions with 0.7.0 and 18 of 18 with 0.7.1, as with the same lines in a hand-kept CLAUDE.md (what's new, limits). How the sessions were run, and every row: the benchmark page.

The guard

Before Claude runs a command or edits a file, jevmem checks it against your saved rules. If one might break, Claude Code asks you first:

jevmem: this may break a saved rule: "Never commit .env files" (JEVMEM.md)

On a test of 274 tool calls, a set the guard was not tuned on, it caught 66 of 68 rule breaks and asked about 3 or 4 of the 206 calls that broke no rule (one run each on 0.6.0 and 0.6.1). It's a backstop, not a sandbox: it looks at the words a rule and a call share. Since 0.7.0, jevmem trust lets a rule you added by hand block a call in the guard's block mode, not only ask about it. How the guard works.

Side pane

A pane beside your Claude Code chat shows what jevmem just did: the memory lines it gave Claude for your prompt, what its guard said about a command, and the line it saved from the turn, each with why, wrong and forget buttons. The two that change JEVMEM.md ask first; a rule is retired in a terminal only. It reads three local files and sends nothing anywhere.

/plugin install jevmem-pane@jevmem

It is a second plugin from the jevmem marketplace (the jevmem plugin itself still ships no code), for Claude Code 2.1.299 or newer; it opens on its own in a terminal 144 columns wide or wider and in the desktop app's Code tab, and /jevmem opens or closes it anywhere. What each block shows, and what was measured: docs/pane.md.

Install

You need a TypeSafe API key, which jevmem's requests are billed to, and Claude Code 2.1.273 or later.

1. In the Claude app: Plugins → Discover → jevmem → Add.
2. Install the CLI the plugin runs:

   npm install -g jevmem
   

3. In your project's folder, finish the setup in one go (it asks for your key without showing it, turns jevmem on in that folder, and checks the setup):

   jevmem setup
   

Start Claude Code in that project. If you start it before the setup is done, the plugin says once what is left; jevmem doctor checks the setup any time.

From the jevmem marketplace:

npm install -g jevmem
claude plugin marketplace