LTM: A JSON Protocol for Portable Agent Memory

If you use Claude across multiple editors or machines, you've likely hit the context portability wall: your CLAUDE.md doesn't follow you to Cursor, Cursor rules don't transfer to Codex, and nothing survives a model or OS switch. Existing "agent memory" tools are mostly markdown files you manually groom or vendor-locked stores. A new open-source project called ltm takes a different approach: a small JSON protocol called the Core Memory Packet, plus a CLI and server to move packets around.

How It Works

At the end of a session, the agent calls ltm save. At the start of the next session, ltm resume pulls in the dossier on the current obstacle—regardless of model, harness, or machine. A packet contains five required fields and is typically 2 to 5 KB:

Goal: what you're trying to achieve
Decisions locked in: constraints that shaped the code
What you've already tried: dead ends and rejected approaches
Next step: what to do next

The commit log already carries the work that went fine. LTM focuses on what agents can't reconstruct from a repo: dead ends and constraints that never appear in code.

Key Design Decisions

Model, harness, and machine agnostic: a packet written by Claude on macOS reads fine for Codex on Linux, or for a teammate on their machine. The protocol is the product; CLI and server are reference implementations.
Token-efficient: a 2–5 KB packet at session start is cheaper than letting the agent re-explore the codebase to rediscover what was already tried and rejected.
Self-host or managed hub: same protocol either way. One Go binary, SQLite on disk, runs on a low-end VPS.
Redaction is load-bearing: every packet is scanned before leaving the machine. AWS keys, GitHub tokens, JWTs, private keys, absolute paths, Slack and Stripe tokens—all blocked by default. Secrets don't travel.
MCP support out of the box: Claude Code, Cursor, Zed, Codex, etc. can call save and resume as tools without ever typing an ID.
Intent is portable, configuration isn't: packets never carry CLAUDE.md, skills, prompts, or tool setup—those stay local.

Try It Without Signing Up

You can see what a resume looks like immediately: ltm example --resume runs the full flow against a sample packet and drops the resume block on your clipboard.