Corresync

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

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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 detect
corr integrations plan codex claude-code
corr 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.

From install to a first read

Prefer a guided page? Follow getting started on the website.

1. Install

The official standalone installers are the shortest path on every platform. They select the latest stable release, verify its archive and candidate binary, install for the current user without elevation, and leave account setup untouched.

macOS and Linux

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

Windows PowerShell

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

Review install.sh or install.ps1 before running it if you prefer. Package managers remain fully supported alternatives:

# Homebrew · macOS or Linux
brew install nkiyohara/corresync/corresync

# WinGet · Windows
winget install --id nkiyohara.Corresync --exact

# Scoop · Windows
scoop bucket add corresync https://github.com/nkiyohara/scoop-corresync
scoop install corresync/corresync

Direct archives, native Linux packages, version pinning, checksums, and Sigstore provenance are in the installation guide. The guided website keeps the same copy-paste choices visible for people who do not use GitHub regularly.

Claude Desktop users can also install the platform-universal .mcpb from the latest release. The bundle runs the same verified corr mcp serve binary locally over stdio; it does not deploy Corresync or relay mailbox data. Install the CLI first for the explicit account setup and sign-in steps below, then open or drag the .mcpb into Claude Desktop.

Stay current

Interactive commands make a quiet, cached release check at startup. If an update exists, Corresync shows the exact command for your installation: corr update for the standalone build, or the matching Homebrew, Scoop, or WinGet command. Package-managed files are never changed by Corresync.

Stable releases are selected by default. Standalone users who want signed release candidates can choose the preview channel interactively:

corr settings

The equivalent copy-paste commands for scripts are:

corr config set updates.channel preview
corr update

Switch back with corr config set updates.channel stable; Corresync never downgrades the running binary. Preview releases do not enter package-manager catalogs.

Standalone users can opt in to verified automatic installation:

corr config set updates.auto_install true

It never runs during MCP tool calls, configuration changes, daemon work, JSON output, pipes, or other non-interactive paths. The current command continues normally and the new binary is active on the next corr start.