Private multi-machine continuity · Beta

Pick up the exact session on another machine.

C3Sync synchronizes native coding-agent sessions and the working-tree state attached to them across machines you own. It is end-to-end encrypted, agent-agnostic, self-hosted, and designed to catch up after a machine has been offline. A guided setup wizard stands up the hub and first device in one sitting.

Join the beta waitlist Read sync docs

C3Sync / Event fabricBeta · Linux

Machine / A

WORKSTATION

agent: codex

head: E106

online

Sealed hub

Ciphertext only

Machine / B

LAPTOP

agent: claude

head: E103

catching up

Encrypted event journal3 pending → peer B

E104SESSION+ 3 turnsSEALED

E105TREE7 filesSEALED

E106RESTOREanchor 9f2aREADY

Supported beta

Linux

Relay

Self-hosted

Hub visibility

Ciphertext only

Sync / Sessions

Native sessions, not exported transcripts.

C3Sync reads each agent’s on-disk session format and writes it back natively on peers, so the agent’s own resume command works on the next machine.

Native session mergePeer caught up

MACHINE / A

codex resume

E218user

E219tool

E220agent

MACHINE / B

claude resume

E218user

E219tool

E220agent

native

MERGEappend-only · no transcript conversionREADY

01Claude Code, Codex, OpenCode, and Pi
02Append-only session merge
03Durable offline catch-up

Sync / File state

The working tree stays attached to the turn.

Every captured agent turn can carry the exact uncommitted file state that existed at that moment, with git-aware protection against stale committed history. Commit and push on one machine, and the others fast-forward automatically — unrelated WIP untouched.

Working-tree timelineSnapshot E220

E218

3 files

anchor

E219

7 files

captured

E220

5 files

current

+ src/session/restore.ts

+ tests/restore.test.ts

− src/session/legacy.ts

· .env ignored

Conflict guard

A losing edit is written beside the file, never silently discarded.

file.c3sync-conflict

01Untracked files included, .gitignore respected
02Commit-aware auto-pull on machine switch
03Conflict sidecars preserve the losing version

Sync / Trust

The hub routes data it cannot read.

Payloads are sealed on enrolled devices before they reach the NATS JetStream hub. TLS pinning, per-device credentials, and explicit revocation protect access. The same hub also powers C3 Mobile — in an isolated account that can never read sync data.

Read the documented trust model before exposing services remotely.

Zero-knowledge relayKeys local

Device / A

SEAL ✓

9F 2A
C1 7E
44 B0

Device / B

OPEN ✓

Hub visibility

YES

route

YES

device id

content

XChaCha20-Poly1305epoch / 04

01XChaCha20-Poly1305 payload sealing
02Balanced PAKE device enrollment
03Epoch-based key rotation after revocation

C3Sync / Early access

Be first in the control room.

Join the waitlist for beta access, platform availability, and the setup path for your machines.