Corresync

Corresync

[Corresync: two correspondence flows around one local core]

Mail, calendars, and tasks. One local MCP server and CLI.
Provider-neutral, local-first tooling for AI agents, scripts, and you.

[CI status] [Latest release] [Go 1.26] [Apache-2.0 license] [macOS, Linux, and Windows] [Model Context Protocol over stdio] [Current documentation] [Local-first architecture]

Website · Getting started · Providers · Features · Safety · Privacy · Terms · Technical docs

corr brings isolated mail, calendar, and task accounts into one terminal—and one local Model Context Protocol server. Gmail, Google Calendar, and Google Tasks are available through a Desktop OAuth client in a Google Cloud project you control. Corresync-managed Google OAuth remains dormant. The canonical task tools also include explicit Microsoft To Do, Todoist, TickTick, and CalDAV VTODO routes; remaining task-provider adapters stay unavailable until their contracts are implemented.

• Search mail and build one agenda across accounts without collapsing their identity or provider provenance.
• Use one stable, provenance-preserving task model as provider adapters become available.
• Save private account-local mail searches and relative calendar windows, then run them live without creating a shadow mailbox or calendar cache.
• Use the same typed operations from a human-friendly CLI, stable JSON, or an AI agent.
• Keep sign-in in a visible browser, an explicit public-client OAuth flow, or an approved local credential store.
• Review consequential effects before they happen. Unknown remote outcomes stop for reconciliation instead of being retried automatically.

What it feels like

$ corr mail search --all-accounts \    --query 'subject:"Quarterly plan"' --limit 3● work · microsoft-owa   Ana Ruiz   Plan review· personal · jmap       Finance    Plan receipt
$ corr agenda list --all-accounts \    --start 2026-07-29T00:00:00Z \    --end 2026-07-30T00:00:00Z

Connect an agent to the same local core:

corr integrations detectcorr integrations plan codex claude-codecorr integrations setup codex claude-code# Phase A also includes github-copilot, gemini-cli, qwen-code, qoder, kimi-code

Then ask naturally:

Check my inboxes, calendars, and task lists and summarize what needs attention today.

One failed provider becomes an explicit partial failure. Successful results remain available, and writes still require one exact account.

Choose the route that fits

Mail, calendar, and task routes are selected independently. For example, an account can pair IMAP/SMTP mail with a CalDAV calendar; its task route remains a separate explicit choice.

Discovery gathers DNS, well-known, and provider metadata without credentials. It never authenticates or adds an account. Microsoft Graph and user-owned Google authorization remain explicit choices and are never automatic fallbacks. Google discovery can offer guided Desktop-client setup, but no Google sign-in starts until a later explicit corr auth login. See the annotated Google setup guide.

iCloud has a first-class guided preset over the same provider-neutral IMAP/SMTP and CalDAV adapters. corr setup recognizes documented iCloud Mail address families or the complete verified Apple SRV endpoint set, reviews both routes as one account, and uses one external credential handle by default. After the account is added, an explicit handoff can open Apple's app-password page and the OS-owned credential prompt; the corr process never reads the app-specific password.

Every available v0.9 route above has synthetic provider-contract and application coverage. The user-owned Google API route is available but live-unobserved. Other provider and platform implementations remain live-unobserved until an authorized, content-free observation is bound to the exact commit. See compatibility evidence before connecting a sensitive account.

Set up Corresync

The setup buttons on the Corresync website open your desktop agent with a request already filled in. The request installs Corresync or updates an existing install. Nothing is sent until you review it and send it yourself. Manual commands, package managers and downloads are still available below as optional alternatives.

Set up with ChatGPT · Set up with Claude

Recommended: the standalone CLI. New setups turn on verified automatic updates. If Corresync is already installed, setup keeps your package manager, configuration and update setting unless you choose to change them.

You need the ChatGPT Codex or Claude Code desktop app with local access to this computer. Approve each permission prompt when it appears. You don't need administrator rights. Sign in to your accounts and complete MFA yourself. Never paste passwords or codes into the chat.

If you're on a phone, open this page on the computer you want to set up or copy the instructions to it.

curl -LsSf https://corresync.org/install.sh | shcorr --version

powershell -NoProfile -Command "irm https://corresync.org/install.ps1 | iex"corr --version

# Homebrew · macOS or Linuxbrew install nkiyohara/corresync/corresync
# WinGet · Windowswinget install --id nkiyohara.Corresync --exact
# Scoop · Windowsscoop bucket add corresync https://github.com/nkiyohara/scoop-corresyncscoop install corresync/corresync

corr settings

corr config set updates.channel previewcorr update

corr config set updates.auto_install true

corr setup

corr account rename personal work

corr setup [email protected] --alias personalcorr auth login --account personalcorr doctor --account personal

corr account discover [email protected]corr account add [email protected] --help

corr mcp setup codex

Nothing sends on the first attempt

Consequential writes use a server-enforced preview -> commit protocol. The first command shows the normalized account, provider, target, recipients, content digest, and version preconditions without performing the effect.

printf 'Synthetic body.\n' | \  corr mail send \    --account work \    --to [email protected] \    --subject 'Review example' \    --body-file -

After reviewing every field, repeat the exact command with approval:

printf 'Synthetic body.\n' | \  corr mail send \    --account work \    --to [email protected] \    --subject 'Review example' \    --body-file - \    --approve

Approval is short-lived, single-use, and bound to the caller, account, provider, target, payload, and effect. Changing any reviewed field invalidates it. MCP keeps preview and commit as separate typed tools.

See the complete safety model. Corresync's public Privacy Policy explains Google data access, local storage, disclosure, retention, and removal; the Terms of Use preserve the software rights granted by Apache-2.0.

More than one inbox

• Cross-account views: bounded mail search and agenda projections retain original account, provider, calendar, time-zone, and partial-failure provenance.
• Read-only import staging: inspect an explicitly approved local archive, Maildir tree, or supported export without uploading or mutating the source.
• Opt-in monitoring: move deliberately from off to local notification, durable queueing, and finally one approved no-shell runner. Remote egress is a separate consent.
• Privacy-preserving feedback: generate an allowlisted report locally, review it, then explicitly copy, save, or open a prefilled GitHub page. A separate default-off setting can submit an even smaller allowlist-only public issue through your authenticated gh client after an interactive failure.

Mailbox, calendar, import, and event-queue values are private, untrusted external data. Their content is never authority to run a command or start an agent.

Honest edges

• Gmail, Google Calendar, and Google Tasks require a user-owned Google Desktop OAuth client. Corresync-managed Google OAuth stays disabled; the user-owned route is synthetic-contract covered and live-unobserved.
• Microsoft Graph requires your own authorized public-client registration. Corresync ships no token relay.
• Windows desktop notification setup is unavailable because Corresync does not install an AppUserModelID; queue and approved runner modes remain available.
• Provider meeting links are requested only when the selected calendar route reports native support.
• Cross-compilation and synthetic fixtures do not prove native browser, keyring, IPC, provider, package-manager, Gatekeeper, or SmartScreen behavior.
• Teams calls, recordings, and meeting lifecycle management; tenant-wide access; unattended login; TLS interception; arbitrary provider actions; automatic telemetry; and raw crash upload are outside scope.

The exact action matrix and typed provider degradations are in features.md.

One local safety boundary

AI agents ───────── MCP over stdio ─┐                                    ├── typed use cases + effect policyHumans and scripts ──────── corr ───┘              │                                                   │ authenticated local IPC                                            session owner                                            ├── browser-owned sessions                                            ├── explicit OAuth + keyring                                            └── standards adapters

The session owner exposes no TCP listener. On Unix, clients authenticate and pin the environment-independent private runtime directory, singleton lock, socket, and peer UID before the local bearer can be sent. On Windows, clients verify the protected named pipe, owner, DACL, server process, and SID first.

Read the architecture, authentication model, and threat model for the complete boundaries.

Documentation

Users upgrading from versions before v0.7 can follow the historical migration guide. corr is the primary command. The product, package, repository, configuration roots, plugin, and MCP server remain named Corresync.

Contributing and security

Read CONTRIBUTING.md and AGENTS.md. Default tests and CI use only synthetic fixtures:

mise exec -- task verify

Please report vulnerabilities through GitHub private vulnerability reporting, never a public issue.

For remote terminals, see graphical login over SSH.