Vercel releases durable-harness package to make coding agent harnesses resumable after crashes
Vercel announced durable-harness, an open source package of adapters and utilities that let existing agent harnesses (including Pi, OpenCode, Codex, and Claude Code) store their sessions in the Workflow SDK's durable World backend. It records each model and tool call intent and outcome to a durable log, and backstops turns with a queue message so a new function can resume an interrupted turn.
Why it matters
Agent runs that take minutes or hours can lose completed work on a timeout, crash, or dropped connection. A durable log lets builders resume turns without repeating finished model and tool calls, and lets them watch sessions in traces that show where a turn resumed.
Who should care
Developers running always-on coding agents, teams building agent-powered apps on open-source harnesses, and engineers building their own harness products.
What you can do
Read the durable-harness setup guide for your harness and wrap an existing long-running agent task in it, then mark each tool as safe or never to control retry behavior after a crash.