One Workspace.
Every Device.

1 Installation

Install Sessyn directly from the VS Code Marketplace:

Or install from the command line:

You can also install from the VS Code Marketplace website, or download a .vsix file from GitHub Releases for offline installation.

2 First-Time Setup

When you first open VS Code after installing Sessyn, you'll see a welcome notification prompting you to set up workspace sync.

The setup wizard walks you through three steps:

• Authenticate — Sign in with your GitHub or Microsoft account. Sessyn uses OAuth to verify your identity; your credentials are never stored on the server.
• Configure workspace — Enter a name for this machine (e.g., "Work MacBook") and select the workspace path to sync.
• Set passphrase — Create a passphrase used to derive your encryption keys. This passphrase is never sent to the server. “Remember on this device” stores the derived workspace key securely in VS Code and your OS keychain.

3 Syncing Your Workspace

After setup, Sessyn connects to the sync server via WebSocket for real-time updates.

To sync manually, click the Sync Now button in the Machines sidebar, or run Sessyn: Sync Now from the command palette (Cmd+Shift+P).

What happens during a sync:

• Sessyn scans your workspace and computes SHA-256 hashes for each file
• Only metadata (file paths + hashes) is sent to the server — never raw file content
• The server compares metadata and returns what's changed
• Changed files are encrypted on your machine with AES-256-GCM, then uploaded
• New files from other machines are downloaded and decrypted locally

Real-time updates: When another machine pushes changes, you'll get a notification:

Safety features:

• Mass-delete protection — If a sync would delete >50% of your files, you must explicitly confirm
• Conflict resolution UI — If the same file changed on two machines, you get a per-file prompt: Keep Local, Keep Remote, Keep Both, or Diff & Decide
• Side-by-side diff — "Diff & Decide" opens VS Code's native diff editor so you can visually compare remote vs local before choosing
• Pre-write safety — Before overwriting a local file during sync, Sessyn re-hashes it to make sure you haven't edited it since the compare step
• Quarantine auto-cleanup — When remote deletes would remove local files, backups are quarantined. Quarantine files older than 30 days are automatically pruned each sync
• Chunked resume — Interrupted uploads and downloads resume from the last completed encrypted chunk instead of restarting the whole file

4 Conflict Resolution

When the same file is modified on two machines before syncing, Sessyn detects the conflict and gives you full control over how to resolve it.

Resolution options (prompted per file):

Pre-write safety: Before overwriting a local file, Sessyn re-hashes it to verify you haven't made edits since the compare step. If the file changed, it's skipped instead of silently overwritten.

Quarantine: When a remote sync would delete a local file, the file is quarantined (backed up) instead of removed. Quarantine backups older than 30 days are automatically pruned at the start of each sync.

5 Machine Trust

Every machine that syncs your workspace must be explicitly trusted. Each generates a unique keypair at setup time (Ed25519 on desktop, ECDSA P-256 on web) and signs every sync request. The server verifies signatures against the registered public key.

Trust states:

6 Configuring .syncignore

Sessyn creates a .syncignore file in your workspace root. It uses standard .gitignore syntax to control which files are synced.

To edit your ignore list, run Sessyn: Manage Ignore List from the command palette, or just open .syncignore directly.

Commands Reference

All commands are accessible via the VS Code command palette (Cmd+Shift+P / Ctrl+Shift+P):

Status Bar

Sessyn shows its current state in the bottom-left of VS Code's status bar. Click it to open the Machines sidebar.

Troubleshooting

"Sessyn: Offline" and won't connect

• Run Sessyn: Reconnect from the command palette
• Check your internet connection
• Run Sessyn: Show Status for detailed diagnostics

"Auth Expired" in status bar

• Sessyn auto-heals expired sessions — it will silently refresh your token or re-authenticate via OAuth
• If auto-heal fails, run Sessyn: Reconnect to manually trigger re-authentication
• If rate-limited (429), the extension auto-retries with progressive backoff — no action needed
• As a last resort, use Fresh Start in Settings to clear all local data and re-run setup

Machine stuck in "Pending"

• A new machine needs to be approved from an already-trusted machine
• Your first machine is auto-trusted — additional machines need approval
• Open the Machines sidebar on your trusted machine and approve the pending device

File conflicts

• When the same file is modified on two machines before syncing, Sessyn detects the conflict automatically
• You'll be prompted per file: Keep Local, Keep Remote, Keep Both, or Diff & Decide
• "Diff & Decide" opens a side-by-side diff editor so you can compare versions before choosing
• "Keep Both" saves the remote version alongside your local file as filename.remote.ext

Generate a diagnostic report

This generates a JSON file with connection state, auth info, and sync history. All secrets are automatically redacted.

Changelog

Release history pulled directly from GitHub Releases.