USRCP — User Context Protocol

Structured user state that follows you across AI tools. Local-first. Open source. AES-256-GCM encrypted, and you hold the key.

You told Claude Desktop your stack on Tuesday. On Wednesday, Cursor doesn't know. Thursday, Codex asks again. Every AI tool you use has its own memory, or none.

USRCP is a local, encrypted SQLite ledger that any MCP-aware tool can read and write. One install, one passphrase, and every tool shares the same structured user state — your timezone, your stack, your projects, your preferences.

Registers with Claude Desktop, Cursor, Continue, Cline, and terminal agents (Claude Code, Codex CLI, Copilot CLI, Aider, OpenCode, Antigravity). Captures structured activity from GitHub, Linear, Obsidian, Claude Code sessions, and Google Calendar — plus an experimental conversation-capture set.

brew install frank-bot07/usrcp/usrcp
usrcp init

→ See it work: the cross-editor demo, or prove the claim on your own machine in one command — node scripts/cross-client-proof.mjs (writes state as one editor, reads it as another, then scans the raw DB to show it's all ciphertext). → Apache 2.0 · 600+ tests · threat model in docs/SECURITY.md

What USRCP is not. USRCP is not a semantic memory layer. It doesn't do vector search, embeddings, or fuzzy conversational recall. If you ask "what did I tell you about my anxiety meds last week?" USRCP won't find that unless you stored it as a structured fact. For fuzzy recall over chat transcripts, use Mem0 or Zep — they solve a different problem. See What USRCP is vs. isn't below.

Protocol Stack

┌─────────────────────────────────┐
│         Agent Layer             │  ← ACP (Agent-to-Agent)
├─────────────────────────────────┤
│         Model Layer             │  ← MCP (Model Context Protocol)
├─────────────────────────────────┤
│     >>> USRCP <<<               │  ← Structured User State (THIS PROTOCOL)
├─────────────────────────────────┤
│         User / Client           │
└─────────────────────────────────┘

Related MCP server: memory-arbiter-mcp

What USRCP is vs. isn't

USRCP is the right choice when:

• You need identity, preferences, or project state to flow between Claude Desktop, Cursor, Continue, Cline, etc.

• You're in a regulated industry (health, finance, legal) where a memory provider seeing plaintext is a non-starter.

• You want users to own the encryption key, not the memory vendor.

Semantic memory (Mem0/Zep) is the right choice when:

• You want fuzzy recall over free-form chat history.

• You're building a consumer product where "remind me what I said about X" is the core feature.

• The user trusts the memory provider with plaintext.

The two are complementary, not competitive. Nothing stops an agent from using both.

vs OpenMemory MCP (Mem0)

Mem0 shipped OpenMemory MCP in early 2026 — a local-first MCP server that shares memory across Cursor / Claude / Windsurf / Cline. Closest neighbor on positioning. The differentiation is real but tight:

Same broad goal (cross-tool memory you control); different shape of "memory" and a much smaller install footprint here. Worth using both if your workflow wants structured state and semantic chat recall.

vs vendor-built memory (Claude Memory, ChatGPT Memory, Cursor Memory)

The 2026 vendor surfaces — Claude Memory, ChatGPT Memory, Gemini personalization — solve the cross-session problem within one vendor. USRCP solves it across vendors. If you only use Claude (or only ChatGPT), the vendor's built-in memory is probably enough. The day you add a second tool, USRCP starts paying for itself: the structured user state you typed once is there in every MCP-aware client, and the encryption key stays with you instead of the vendor.

Cursor users specifically: native @memories was removed in v2.1.x. USRCP is one way to fill that gap that also bonus-shares the memory with the rest of your stack.

Quickstart

Install

npm (recommended) — the usrcp CLI + encrypted ledger:

npm install -g usrcp        # the `usrcp` command + local ledger
# …or run without installing:
npx usrcp init

No native build, no compiler, no postinstall — usrcp uses Node's built-in SQLite (node:sqlite), so npm install just works on any npm (including npm 12+, whose allowScripts default blocks native build scripts). Requires Node ≥ 22.5 (Node 24+ recommended).

Homebrew (macOS / Linux) — alternative for the core CLI:

brew install frank-bot07/usrcp/usrcp

The CLI ships with the inline adapters (terminal, mcp-agent, openclaw). Capture adapters install as their own packages, then you configure each with the setup wizard:

# structured-state adapters:
npm install -g usrcp-github   # or usrcp-linear, usrcp-obsidian, usrcp-claude-code, usrcp-google-calendar
usrcp setup --adapter=github

# experimental conversation-capture set:
npm install -g usrcp-slack    # or usrcp-discord, usrcp-telegram, usrcp-imessage, usrcp-gmail
usrcp setup --adapter=slack

See the Adapters table for the full list (the Chrome extension and VS Code viewer ship separately — see their package READMEs).

From source — for contributing or running unreleased changes:

git clone https://github.com/frank-bot07/usrcp.git
# Build the protocol core first — usrcp-local's build compiles it.
cd usrcp/packages/usrcp-core && npm install && npm run build
cd ../usrcp-local && npm install && npm run build && npm link

First run

# Interactive init — prompts for passphrase by default
usrcp init

# Non-interactive:
usrcp init --passphrase "your secret phrase"       # passphrase mode
usrcp init --dev                                     # dev mode (key on disk)

# Start the server
usrcp serve

In passphrase mode, init offers to store the passphrase in the OS keychain (macOS Keychain / Linux Secret Service); pass --keychain / --no-keychain to decide non-interactively. With a keychain entry present, MCP clients auto-start the server with no plaintext passphrase in any config file. Manage the entry anytime:

usrcp keychain store    # add/replace (verifies the passphrase unlocks this ledger first)
usrcp keychain status   # show backend + whether an entry exists
usrcp keychain clear    # remove it

# Prefer no keychain? The env var path still works:
USRCP_PASSPHRASE="your secret phrase" usrcp serve

init creates ~/.usrcp/users/<slug>/ with an encrypted SQLite ledger and writes the MCP server entry to Claude Desktop's config:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Linux: ~/.config/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

Single-user is the default and what every shared-machine consideration in the rest of this README assumes. If two people use the same OS account (or you run multiple identities side by side), see Multiple users on one machine below — each user gets an independent ledger and passphrase under a --user=<name> slug.

Adding capture adapters

Adapters watch a source (a GitHub org, an Obsidian vault, a Linear workspace, etc.) and append the activity you authored into the same ledger your local MCP server reads from. Install the adapter's package, then run the setup wizard to configure it:

npm install -g usrcp-linear          # install the adapter you want
usrcp setup --adapter=linear         # configure it (validates credentials, picks scope)
# or, to browse what's installed:
usrcp setup                          # interactive picker

See the Adapters tables below for the full list.

Multiple users on one machine

usrcp init --user=frank
usrcp init --user=jess
usrcp serve --user=frank   # or rely on --user in the registered MCP entry
usrcp users                # list available slugs

Each user gets an independent ledger, passphrase, and MCP server entry.

Passphrase mode and terminal agents

If you initialized USRCP in passphrase mode (usrcp init with the default), the MCP server needs the passphrase to decrypt the ledger. The terminal-adapter register() writes only command + args to each agent's config — it never bakes the passphrase in.

Recommended: the OS keychain. One command covers every agent — shell-launched and GUI alike — with nothing in plaintext on disk:

usrcp keychain store

The server checks USRCP_PASSPHRASE, then --passphrase, then the keychain, so existing setups keep working unchanged. (Windows: keychain support isn't wired up yet — use the env-var paths below.)

Env-var alternatives, if you'd rather not use the keychain:

• Shell-launched agents (claude-code, codex, copilot-cli, aider, opencode) — add to ~/.zshrc / ~/.bashrc and restart your shell:

  export USRCP_PASSPHRASE="your secret phrase"

• GUI/IDE-launched agents (cursor, cline, continue, antigravity) do not inherit shell environment. Either add an env block under the usrcp server entry in the agent's config file (JSON for Cursor/Cline/Continue, TOML for Codex), or set a system-wide GUI env on macOS with launchctl setenv USRCP_PASSPHRASE "..." (persists until reboot; use a ~/Library/LaunchAgents/ plist for permanence).

Treat any config file you bake the passphrase into as a secret — it sits in plaintext on disk and is the weakest link in an otherwise-encrypted setup. This is exactly what usrcp keychain store exists to avoid.

The wizard prints this same guidance after registration, so you can also re-run usrcp setup or usrcp adapter add terminal --targets=<list> for a reminder.

Capture Adapters

Adapters are independent processes that read from a source and append events to the local ledger via the same encrypted-at-rest pipeline as the MCP server. Each adapter handles its own auth, idempotency, and cursor persistence.

Structured-state adapters

These are the headline adapters: they capture genuinely structured dev/work state — issues, PRs, notes, calendar events, coding-session context — the kind of data USRCP's schema and exact-keyword search are built for.

Alongside these, the inline adapters that ship with the brew CLI (terminal, mcp-agent, openclaw) wire the same structured state into terminal agents and agent harnesses — see Editor & CLI Integrations and Agent harness integrations. The VS Code viewer browses the resulting ledger read-only.

Conversation capture adapters (experimental)

These adapters capture messages you send — in iMessage, Slack, Discord, Telegram, Gmail, or on claude.ai — into the encrypted ledger. Be clear-eyed about the trade: search over captured messages is exact-keyword only, with no semantic recall, which is the weakest retrieval model for free-form chat (see What USRCP is vs. isn't). If conversational memory is your primary need, Mem0 or Zep are better tools for that job. These adapters exist for users who want specific structured facts pulled from their conversations to live under their own key, not for fuzzy recall over chat history.

Install an adapter's package (npm install -g usrcp-<value>), then configure it with usrcp setup --adapter=<value> (e.g. npm i -g usrcp-linear && usrcp setup --adapter=linear). Run usrcp setup alone for an interactive picker over the adapters you've installed.

All adapters write under a configurable domain (default matches the source name) and use stable, source-side IDs as idempotency keys, so re-polling or re-watching the same window cannot double-write. Capture-only adapters do not reply; bot adapters reply only to explicit @usrcp / /usrcp mentions and answer using the same ledger the user sees.

Agent harness integrations

These adapters expose USRCP's tools to a third-party AI agent harness. They don't capture new events on their own — capture from external surfaces (Discord, Slack, iMessage, etc.) still goes through the dedicated capture adapters above. Install the harness first, then run the USRCP setup route.

Ledger viewers

Read-only clients that browse the encrypted ledger via a local usrcp serve subprocess. No network calls; the viewer never sees plaintext outside the host process.

Cross-device sync

usrcp-cloud is the hosted ledger for syncing the local SQLite store across devices. It only ever sees ciphertext — encryption happens client-side under the user's passphrase before push, and decryption happens client-side after pull. The server cannot read your data.

MCP Tools (12)

What's Encrypted

All your content. Every field that carries what you said, did, or stored is ciphertext at rest. What stays in the clear is structural metadata — opaque identifiers and timestamps that reveal when, never what. An attacker reading the SQLite file sees:

The same rule holds in the other tables: in active_projects, the content fields (name, domain, status, summary) are enc: ciphertext; the project_id you choose is stored as an HMAC (with the original encrypted in project_ref_enc), and only last_touched (a timestamp) stays plaintext. No field that holds user content is ever stored in the clear.

In passphrase mode, no key file exists on disk. The key is derived via scrypt on startup and zeroed on shutdown.

Each adapter's test suite includes a ciphertext-at-rest check: it captures real activity, then opens the SQLite file with raw better-sqlite3 and asserts no plaintext markers (titles, bodies, URLs, IDs) appear in any encrypted column.

Security Architecture

• AES-256-GCM encryption at rest for all content fields

• Domain-scoped keys via HKDF-SHA256 — coding key cannot decrypt health data

• scrypt passphrase derivation (N=131072, r=8, p=2) — key never on disk

• HMAC domain pseudonyms — domain names are opaque identifiers

• Blind index search with n-gram tokens and noise injection

• Encrypted audit log — access patterns are ciphertext

• Atomic key rotation — re-encrypts all data in a single transaction

• secure_delete pragma — SQLite zero-fills deleted pages

• Master key zeroed on process shutdown

• Scope enforcement — agents registered with a --scope flag see only the domains they're authorized for; usrcp_status and timeline queries filter accordingly

Full model in docs/SECURITY.md.

Editor & CLI Integrations

USRCP works with any MCP-compatible client. The usrcp init wizard registers the server entry for editor clients:

Register with multiple clients at once: usrcp init --client=claude,cursor or --client=all.

For terminal-based MCP-aware CLI agents (Claude Code, Cursor CLI, Codex, Copilot CLI, Cline, Continue, Aider, Antigravity, OpenCode), a single wizard wires them all up:

usrcp setup --adapter=terminal

No external accounts or bot tokens required — every terminal session in those agents gets cross-platform memory through the same local ledger.

All clients share the same local ledger per user.

Other Consumers

• usrcp-hermes — Python memory-provider plugin for Hermes Agent. Adds USRCP as a memory backend so Hermes runs share state with Claude Code, Cursor, etc. Thin wrapper — ledger logic stays in TypeScript.

Project Structure

usrcp/
├── spec/
│   └── PROTOCOL.md                  # Protocol specification
├── schemas/                          # JSON schemas (get_state, append_event, handshake)
├── docs/
│   ├── SECURITY.md                   # Security & privacy model
│   └── INTEGRATIONS/                 # MCP client integration guides
├── strategy/                         # GTM, pitch, positioning
├── packages/
│   ├── usrcp-core/                   # Framework-agnostic protocol core (ledger, crypto, encryption, pairing, rotation, scope)
│   ├── usrcp-local/                  # Local MCP server + CLI
│   ├── usrcp-cloud/                  # Hosted ledger for ciphertext-only sync
│   ├── usrcp-discord/                # Discord capture+reader adapter
│   ├── usrcp-extension/              # Chrome extension (claude.ai capture)
│   ├── usrcp-hermes/                 # Hermes Agent memory plugin (Python)
│   ├── usrcp-imessage/               # iMessage capture+reader (macOS)
│   ├── usrcp-linear/                 # Linear issues + comments capture
│   ├── usrcp-obsidian/               # Obsidian vault capture
│   ├── usrcp-slack/                  # Slack capture+reader
│   └── usrcp-telegram/               # Telegram capture+reader
└── sdk/                              # Legacy prototype (Jan-Feb 2026); not the reference impl

The legacy sdk/ was a pre-protocol exploration — see sdk/README.md for the historical context. New work should target the usrcp-core ledger directly.

Tests

Current snapshot (per-package npm test):

Plus a Python suite in usrcp-hermes (pytest).

Run a package's suite with npm test from inside its directory. Cross-package prebuild/pretest hooks build usrcp-core (and other siblings) first so types stay in sync. Coverage spans: ledger CRUD, crypto roundtrips, tamper detection, domain isolation, audit log, ULID, pruning, multi-user isolation, optimistic concurrency, schemaless facts, scope enforcement (all in usrcp-core); sync push/pull, Ed25519 signed-request auth (usrcp-local/usrcp-cloud); and per-adapter capture/idempotency/ciphertext-at-rest checks.

Business Model

Open-source protocol (Apache 2.0). The reference implementation is free and local-first. Revenue comes from the hosted ledger — cross-device sync, team ledgers, compliance-grade audit features — all operating on ciphertext only.

The wedge isn't "every AI-using human." It's security-conscious developers and regulated enterprises who can't adopt an AI state store that phones a third party with plaintext. See strategy/PITCH.md and strategy/GTM.md for the full positioning.

License

Apache 2.0