Cosyncing: Control DeepSeek Harness and other agents on your phone Cosyncing, a new open-source tool, lets users synchronize and control coding agents such as DeepSeek Harness and Claude Code from a phone or desktop via a local broker, with no hosted service. The broker runs on the agent's machine, serving a web client that groups sessions by project and supports read-only observation or takeover, with support for six agents including experimental adapters for Kimi Code and DeepSeek Harness. The tool requires Tailscale for cross-device use and Bun 1.3.8 or newer, and is installed via npm. From CLI to GUI, live and in sync Website https://cosyncing.com/ · Install install · Client client · Docs /cosyncing/cosyncing/blob/main/docs/README.md · Contributing /cosyncing/cosyncing/blob/main/docs/CONTRIBUTING.md · 简体中文 /cosyncing/cosyncing/blob/main/README.zh-CN.md Synchronize and control your agents — from CLI to GUI, from desktop to phone. Pick up right where you left off, anywhere. cosyncing keeps your coding agents in sync across your own network. The broker runs on the machine where your agents work. It watches their sessions and serves a client that shows each one — grouped by project, with its transcript, diffs, commands, and any prompt waiting on you. Read a session, answer a prompt, or take over. No account to create, no hosted service between the client and the broker. One protocol covers all six. Per-agent control differs, and Claude Code sessions open read-only until you take over. See supported-agent setup /cosyncing/cosyncing/blob/main/docs/supported agents/README.md for versions and installation, and adapter support /cosyncing/cosyncing/blob/main/docs/protocol/adapter-support.md for the capability matrix. Foreground clients can join the same broker-owned Codex or Pi Drive session without starting a second native Resume. Claude Code keeps its Observe/Take-over flow on another client, while OpenCode keeps its shared-live behavior. Background Observe connections stay read-only. Experimental: Two provisional adapters are available to source contributors, both talking to a local server rather than a CLI. Kimi Code /cosyncing/cosyncing/blob/main/docs/supported agents/kimi.md observes every session on a kimi web server read-only, drives the ones cosyncing created — prompts, approvals, model selection — and takes over the ones it did not, explicitly. DeepSeek Harness /cosyncing/cosyncing/blob/main/docs/supported agents/dsh.md connects to a dsh web host and gives active foreground clients a shared transcript and control surface, with model and reasoning-effort selection, permission presets, the host's own slash commands, and image attachments. General file attachments are not supported — the host accepts image content only — and background resident subscriptions and some message presentation remain follow-up work. Neither needs a rollout flag, and neither needs a terminal left open: an installed cosyncing service starts a host when none is running, restarts one that crashes, and stops the one it started. A host you started yourself is never stopped, replaced, or reconfigured, and setup names both hosts before you agree to manage them. Install DeepSeek Harness globally with npm install -g @deepseek-ai/dsh — cosyncing looks for dsh on your PATH, so an npx -only install can be talked to but never started or version-checked. See supported-agent setup /cosyncing/cosyncing/blob/main/docs/supported agents/README.md for both hosts. Supported cross-device use requires Tailscale https://tailscale.com/ on the server and client devices. The server requires Bun https://bun.sh 1.3.8 or newer to run cosyncing and Node.js/npm to install and update it. Tokdash https://github.com/JingbiaoMei/tokdash is optional but strongly recommended for quota tracking and warnings. See installation prerequisites /cosyncing/cosyncing/blob/main/docs/installation/prerequisites.md for Linux and macOS commands, WSL notes, and Tokdash setup. The package contains one JavaScript application bundle and the web client. Supported broker hosts are Linux x64, Linux arm64, and Apple Silicon macOS; on Windows, run the broker inside WSL. Before setup, install only the agents you use; see agent setup and PATH preflight /cosyncing/cosyncing/blob/main/docs/supported agents/README.md preflight . Install the current release: npm install --global cosyncing Open a new login shell, then configure the service: cosyncing setup After setup, use cosy as the shorthand for cosyncing cosy restart cosy doctor cosy status cosy pair setup inspects the machine, shows exactly what it will change, and applies the whole plan or none of it. It copies the broker to ~/.cosyncing/bin/cosyncing , installs a user service that runs that copy with your Bun, and prints your broker URL. The broker refuses to start until setup has committed. To update, let npm replace the global package, then re-run setup so cosyncing copies the new application into its managed service and reconciles the installation: npm update --global cosyncing cosy setup cosy update reports this package-manager-owned update path; it does not run npm or modify the global package. cosy pair prints a five-minute, one-use QR code. Scan it from a client to grant that device access; cosy devices list lists paired devices, and cosy devices revoke