AI BriefingVercel durable-harness supports log-based turn resumption on function failure
·2026.10.27 21:00
Key point
Vercel has released durable-harness, which allows coding agent turns to continue via logs.
Details
- Vercel released durable-harness, a TypeScript adapter that records coding agent turns for Claude Code, Codex, OpenCode, Pi, fx, and others in durable logs, enabling new functions to read the logs and resume turns upon function failure, on October 19, 2026
- The npm version 0.0.1-beta.6 is in the experimental stage and requires Node.js 22 or higher (24 when integrated with Agent Runs); completed model and tool calls read only the results from the logs without re-execution, preventing duplicate token costs
- Claude Code and Codex require execution exclusively in Vercel Sandbox, including self-hosting, as CLI state isolation cannot be guaranteed, while Pi, fx, and OpenCode can run the harness in developer functions
- Self-hosting via Postgres World is at the reference implementation level, lacking support for authentication and encryption, and there are current limitations regarding Vercel Queues, where chat route requests execute for a maximum of 60 seconds before switching to queue routes
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