Sessyn

Securely sync your full developer workspace between trusted machines.

Sessyn syncs everything Git can't — .env files, certificates, local configs, API keys, database files, SSH keys, notes, and anything else in your workspace.

All files are encrypted client-side with AES-256-GCM before leaving your machine. The server is a temporary encrypted relay that never sees your plaintext data.

Works on all VS Code platforms — macOS, Linux, Windows (including ARM64), and vscode.dev / github.dev.

Why Sessyn?

You work across multiple machines. Git handles your code — but what about everything else?

Your .env files with API keys and database URLs
SSL certificates and private keys
Local configuration that's different per-project
Notes, scratch files, and work-in-progress that isn't committed yet

Sessyn fills that gap. One command, fully encrypted, workspace-to-workspace.

Features

🔐 End-to-End Encryption

AES-256-GCM with HKDF-derived subkeys. Argon2id key derivation. HMAC-SHA256 manifest integrity. The server never sees your data.

🔄 Real-Time Sync

WebSocket connection shows machine status (online/offline/syncing). Trigger sync manually or watch it happen in real time.

📁 Selective Sync

Use .syncignore (gitignore syntax) to control exactly what syncs. By default, everything syncs — add exclusions as needed.

🧪 Recovery Tools

Run a local smoke test, inspect the recovery dashboard, repair stuck local sync state, or apply reusable sync profiles without leaving VS Code.

🔀 Git-Aware

Detects when machines have diverged on Git history and prompts you to resolve gaps before syncing workspace files.

📤 File Transfers

Right-click any file → Send to Machine to push individual files to a specific machine without a full sync.

⚡ Conflict Resolution

Automatic detection of conflicting changes between machines with guided resolution.

🔑 Multi-Account Auth

🛡️ Zero-Trust Architecture

Server is untrusted — never sees passphrases, keys, or plaintext
Secrets stored in VS Code SecretStorage only — never in files or logs
Encrypted blobs auto-deleted within 2 hours
AAD binds ciphertext to workspace, machine, file path, and version

Getting Started

Open the command palette (Cmd+Shift+P / Ctrl+Shift+P)
Run Sessyn: Setup Wizard
Sign in with GitHub or Microsoft
Name your machine and choose a workspace folder
Set an encryption passphrase (use the same one on all machines)
Sync!

Commands

Command	Description
`Sessyn: Setup Wizard`	First-time setup — auth, machine, workspace, passphrase
`Sessyn: Sync Now`	Trigger a manual sync
`Sessyn: View Machines`	Refresh the machine list
`Sessyn: Review Changes`	Review incoming changes before applying
`Sessyn: Sync Untracked Files`	Review and sync only gitignored or untracked files
`Sessyn: Open Settings`	Open extension settings panel
`Sessyn: Manage Ignore List`	Edit `.syncignore`
`Sessyn: Apply Sync Profile`	Apply a managed `.syncignore` profile
`Sessyn: Show Status`	Open the recovery dashboard
`Sessyn: Run Smoke Test`	Verify auth, connection, encryption, and workspace readiness
`Sessyn: Repair Sync State`	Clear resumable sync state and cached file index
`Sessyn: Send to Machine...`	Send a file to a specific machine
`Update Extension Remotely`	Ask another connected machine to update and reload
`Update, Reload & Sync Remotely`	Remotely update a machine, reload it, run a smoke test, and start syncing
`Run Smoke Test Remotely`	Ask another connected machine to run its smoke test
`Sessyn: Export Diagnostics`	Export redacted diagnostics for support
`Sessyn: Reconnect`	Force reconnect to server
`Sessyn: Sign In Again`	Re-authenticate if your session expired
`Sessyn: Check for Updates`	Check for new extension versions
`Sessyn: Forget Local Secrets`	Wipe all locally stored secrets

.syncignore

Sessyn syncs everything by default. Use .syncignore with gitignore syntax to exclude files:

# Always excluded automatically:
.git/
.DS_Store
node_modules/

# Add your own:
*.log
build/
dist/
.cache/

You can also apply built-in sync profiles from the command palette to manage the generated section of .syncignore for common cases like build-output-heavy workspaces, dotfiles-only sync, or secrets-only sync.

Security Model

Layer	Implementation
Encryption	AES-256-GCM with HKDF-derived subkeys
Key Derivation	Argon2id (PBKDF2-SHA256 fallback on web)
Integrity	HMAC-SHA256 with replay protection
Request Signing	Ed25519 (desktop) / ECDSA P-256 (web) — per-machine keypairs
Anti-Tampering	AAD binds ciphertext to workspace + machine + path + version
Secret Storage	VS Code SecretStorage API only
Server Trust	Zero — server never sees plaintext
Data Retention	Encrypted blobs auto-deleted within 2 hours
PQ Readiness	All symmetric crypto quantum-safe; ML-DSA-87 ready when available

Sessyn Sync

Aegyrix