About Sessyn

Sessyn is the workspace-sync tool we wanted ourselves: a way to keep everything about a developer workspace consistent across the machines we trust — without uploading source code to yet another cloud-storage service.

The problem

Git handles the source. iCloud and Dropbox handle photos and documents. But the things that make a developer machine actually yours — .env files, editor settings, keybindings, snippets, local scratch databases, half-written scripts — fall through every crack: they're either gitignored on purpose or they're personal, and you end up re-creating them from memory each time you spin up a new box.

What Sessyn does differently

• Client-side AES-256-GCM — files are encrypted before they leave your machine.
• Zero-knowledge coordinator — the VPS only sees ciphertext + metadata for routing, never your file contents in the clear.
• Direct peer transfer — once the WebSocket is brokered, files move machine-to-machine; the coordinator gets out of the way.
• Three-way reconciliation — workspace generations + per-machine checkpoints prevent the "stale push wipes my recent work" problem.

The stack

• VS Code extension (TypeScript)
• Coordinator: TypeScript / Node, deployed to a hardened VPS
• Auth: Google OAuth + JWT (jwks-rsa verification)
• Transport: wss:// (TLS 1.3) plus a per-pair shared secret
• Crypto: AES-256-GCM with per-file IVs, ECDH-derived keys