DeepSeek Harness

DeepSeek Harness — `dsh` — is the open-source agent harness released by DeepSeek in August 2026, and its defining idea is radical composability: everything is a plugin. The model provider, the sandbox, the tool set, session storage, the Web UI, and even the agent loop itself are all plugins loaded into a Cordis-based runtime (Cordis is a composable-plugin framework from the cordiverse project). Any layer can be replaced or extended without forking the harness. You can try it in seconds — `npx @deepseek-ai/dsh web` starts a local-first Web UI on port 3080 — and it also runs headless for automation. Plugins declare a `dsh.bundle` manifest and install with a single command into a named profile (`dsh plugin --profile web add <plugin-name>`), and they can come from npm packages, GitHub repositories, tarballs, or local directories. The ecosystem response has been explosive: the official repository passed 179,000 GitHub stars in its first week, and the community `dsh-plugin` topic grew past 6,000 repositories in that same week, spanning model routers, memory systems, cost meters, IM integrations, full IDE workbenches, and desktop-pet skins. Multiple community catalogs (DSH Get, dsh-suite, several awesome lists) index thousands of plugins, and in-app plugin stores exist as plugins themselves. It is currently a developer preview — the README states plainly that there will be compatibility-breaking changes — and there is no official curated plugin store yet, so third-party plugins (which are executable code) need manual vetting. For developers who want an open-source, local-first, deeply hackable coding agent with native DeepSeek V4-generation model access at extremely low API prices, dsh is the most consequential entrant since Claude Code.