harness-sdk.

The React client for agent harnesses. Bring Claude Code, Codex, or deepagents—keep one useChat-shaped API.

pnpm add harness-sdk
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Claude CodeCodexdeepagents
01Familiar by design

Messages, status, sendMessage, stop.

02Resumes by default

Snapshots, ordered commands, cumulative acks.

03Durable on Python

Pinned objects keep agent state alive.