Corresync

corr brings isolated mail, calendar, and task accounts into one terminal—and one local Model Context Protocol server. Gmail, Google Calendar, and Google Tasks support are coming soon after Google OAuth approval. The canonical task tools include explicit Microsoft To Do, Todoist, TickTick, and CalDAV VTODO routes; the Google Tasks code is present but disabled, and 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.

• 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.

Related MCP server: multi-mail-mcp

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 managed Google authorization remain explicit choices and are never automatic fallbacks. Google discovery does not add an account while Corresync awaits approval for its official Google OAuth application. No Google sign-in starts. For now, connect Gmail, Calendar, and Tasks through Google's official Workspace MCP servers (Developer Preview).

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 or staged v0.8 route above has synthetic provider-contract and application coverage. The Gmail API route included in RC builds is disabled and live-unobserved. Other v0.8 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.

2. Add and sign in to your account

corr setup

The guided setup derives a resumable preflight from current local state, optionally installs shell completion at a displayed user-local path, and then performs credential-free account discovery. It previews the selected mail/calendar/task routes and adds an account only after confirmation. Authentication or external-credential access remains a separate choice. The same run can add more accounts, select several detected agent hosts, preview their independent local integration plans, apply only one confirmed plan, and verify each result. Re-running corr setup skips healthy work and offers the missing or repairable steps.

Run corr settings to open the same account wizard; sign in to, rename, select, or remove accounts; and manage updates, safety, and browser sign-in from an arrow-key form. Its Setup guide entry resumes the complete coordinator instead of maintaining another implementation. The top-level Accounts category contains Add account and the configured account list; selecting an account opens only actions for that account. Removal previews the local data it deletes and asks for confirmation; removing the default first asks which remaining account should replace it. Each choice also displays the equivalent command, so the interactive flow teaches the direct CLI. Set CORRESYNC_ACCESSIBLE=true for line-oriented screen-reader prompts; type :cancel to leave an input step safely. The direct rename form remains:

corr account rename personal work

Scripts and advanced users retain the deterministic form:

corr setup you@example.com --alias personal
corr auth login --account personal
corr doctor --account personal

The direct setup ADDRESS form creates the same provider-neutral, secret-free local configuration, performs credential-free discovery, and adds only an automatically selectable first-party route. It never opens a sign-in page. Authentication is a separate, account-specific action.

If no route can be selected safely—or if you want an API or standards route— inspect the evidence and choose the exact provider settings:

corr account discover reader@example.invalid
corr account add reader@example.invalid --help

For Gmail, Google Calendar, and Google Tasks, the integration is included but disabled while Corresync's production OAuth application awaits approval. Account addition, browser sign-in, keyring access, and Google API traffic remain blocked. Until the route opens in a separate approved release, use Google's official Workspace MCP setup with your agent. It is currently a Google Developer Preview and has its own Google Cloud and OAuth setup requirements.

Before installing, the optional provider compatibility checker can classify public evidence for an address. The browser sends only the domain after the @ in a request body; it never sends the local part, persists the address, or starts sign-in. The public service uses only a fixed DNS resolver and returns no raw DNS record. Skip it whenever you prefer and run corr account discover ADDRESS locally.

Account addition does not authenticate. OAuth routes require a public-client registration you are authorized to use. Standards routes use a keyring entry or explicitly approved helper reference. Passwords and tokens never enter config.toml. See account and provider configuration. The Outlook Web route opens a dedicated visible profile only during the later auth login; SSO, MFA, Conditional Access, and organization notices remain inside the provider-owned flow.

3. Connect an agent

corr mcp setup codex

Use corr mcp --help for Claude Code, GitHub Copilot CLI, Gemini CLI, Qwen Code, Qoder, Kimi Code CLI, and generic stdio clients. Corresync exposes 45 narrow tools and two read-only monitor resources; there is no HTTP, SSE, remote MCP endpoint, or hosted relay.

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 reader@example.invalid \
    --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 reader@example.invalid \
    --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 code is included in RC builds, but Corresync's production Google OAuth application is awaiting approval. The route is disabled and starts no Google sign-in; use Google's official Workspace MCP in the meantime.

• 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 chat, channels, 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 policy
Humans 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.