Local-first CLI and MCP server for unified email, calendar, and tasks
Unify messages, calendars, and tasks across accounts from a local command line using Corresync's CLI and MCP server, built for terminal workflows and agent access. Developed by Naoki Kiyohara, the utility targets developers and power users who manage multiple Gmail, Outlook, iCloud, and IMAP/CalDAV accounts. It offers guarded write previews, local credential storage, and direct provider connections, letting terminal-oriented professionals search mail, build agendas, and grant AI agents controlled access without sending credentials off the machine.
What the tool actually does for multi-account workflows
Corresync aggregates separate identities without merging them. It connects to Gmail, Outlook, Microsoft 365, iCloud, and IMAP/SMTP for mail, plus Google Calendar, Outlook calendar, and CalDAV for events, and syncs tasks from Microsoft To Do, Google Tasks, and Todoist. The CLI exposes these sources through the corr command, and the MCP server surfaces the same data to AI agents, so searches and agenda builds span accounts while preserving each account's original identity.
How it behaves on a running system and during operations
Local-first architecture keeps network paths simple and direct. Corresync communicates with providers from the desktop rather than using a hosted relay, and stores credentials in the system keyring. Write actions are guarded: the tool produces an exact preview of consequential changes and requires explicit approval before committing, which reduces the risk of accidental sends or deletions when the CLI or an MCP client requests modifications.
Safety, agent integration, and technical accessibility
MCP support makes controlled agent access explicit and auditable. As an MCP server, the app integrates with agents such as Claude Code, Cursor, and GitHub Copilot CLI, giving those clients contextual access to mail and calendars. The CLI-first workflow privileges terminal users and developers; non-terminal users will need to learn the corr command set. The guarded-write model and local credential handling address common safety concerns for automated agents accessing personal data.
Practical pick for terminal-oriented professionals, with a single caveat
Corresync suits developers and power users who need unified, local control over multiple mailboxes and calendars and who accept a command-line workflow. It enforces safer automation through guarded previews and keeps credentials in the system keyring, which supports secure agent access. The main trade-off is the CLI-first design, which demands comfort with terminal commands for full productivity rather than offering a purely graphical experience.
