Corresync
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Local-first MCP for provider-neutral mail and calendars with isolated accounts and guarded writes.
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- nkiyohara
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Setup
Install Corresync in your MCP client (Claude Desktop, Cursor, Windsurf, and others).
Repository: https://github.com/nkiyohara/corresync
Follow the installation instructions in the repository README, then restart your MCP client.
Mail, calendars, and tasks. One local MCP server and CLI.
Provider-neutral, local-first tooling for AI agents, scripts, and you.
Website·Getting started·Providers·Features·Safety·Privacy·Terms·Technical docs
corrbrings isolated mail, calendar, and task accounts into one terminal—and one localModel Context Protocolserver. 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.
$ 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
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.
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 explicitcorr auth login. See theannotated Google setup guide.
iCloud has a first-class guided preset over the same provider-neutral IMAP/SMTP and CalDAV adapters.corr setuprecognizes 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; thecorrprocess 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 remainlive-unobserveduntil an authorized, content-free observation is bound to the exact commit. Seecompatibility evidencebefore connecting a sensitive account.
Prefer a guided page? Followgetting started on the website.
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.
curl -LsSf https://corresync.org/install.sh | sh corr --version
powershell -NoProfile -Command "irm https://corresync.org/install.ps1 | iex" corr --version
Reviewinstall.shorinstall.ps1before 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 theinstallation guide. Theguided websitekeeps the same copy-paste choices visible for people who do not use GitHub regularly.
Claude Desktop users can also install the platform-universal.mcpbfrom the[latest release. The bundle runs the same verifiedcorr mcp servebinary 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.mcpbinto Claude Desktop.
Interactive commands make a quiet, cached release check at startup. If an update exists, Corresync shows the exact command for your installation:corr updatefor 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:
The equivalent copy-paste commands for scripts are:
corr config set updates.channel preview corr update
Switch back withcorr 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 nextcorrstart.
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-runningcorr setupskips healthy work and offers the missing or repairable steps.
After choosing a connection route, the wizard presents a service checklist. For a Microsoft account, Outlook Mail and Calendar are preselected and can be changed independently; Microsoft To Do is an optional, explicit Graph authorization. Teams messaging is shown as coming soon while the v0.9 release gate is closed and cannot be selected, persisted, or opened. Discovery is only route evidence: it never proves that any checked service is enabled for the account, and it never triggers a Graph fallback.
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