Durable Harness

Durable Harness is a coding-agent workflow tool that runs durable agents on a Workflow SDK environment.

This software runs coding-agent tools such as Pi, OpenCode, fx, Claude Code, and Codex as durable agents on a Workflow SDK environment. Each session operates as a workflow run where conversations, turns, model calls, and tool calls are recorded in an event log. This design allows crashes to resume from the log on another machine and prevents unsafe tool execution repetitions. Developers can install it in a Next.js application, use virtual workspaces or Vercel Sandboxes for security, and deploy it locally or on Vercel.

Durable Harness at a glance

Best for: Software engineer
Runs on: Web, CLI, self-hosted, open source
Pricing: Free
Released: October 2026
Category: AI coding tool
Website: github.com/vercel-labs/durable-harness

Key features

Runs coding agents as durable workflows
Logs conversations and tool calls
Resumes crashed sessions from logs
Prevents duplicate tool execution
Supports virtual workspaces for tools
Runs Claude Code and Codex in Vercel Sandboxes

Use it for

Running durable coding agents
Recovering interrupted agent sessions
Executing agent commands in sandboxed environments

Alternatives to Durable Harness

HarnessRouter — One API to manage agent runtimes, sandboxes, and execution lifecycles.
Claude Code Harness — Enforces a disciplined delivery loop with verification gates and safety checks.
Better Harness — Gathers project evidence and turns concrete gaps into prioritized findings.
Harness Meta-Skill — Generates specialized agent teams and skills for Claude Code from a single prompt.
Repository Harness — It prepares software repositories for safe coding agent integration.
LongHorizon Harness — Maintains durable task state and executes reliable, verifiable workflows over many hours.
Harness Engineering — Improves agent output by shaping the environment with context and tools.
Exo Harness — Separates trusted state and security from agent logic for safe execution.
Agent Skills — Encodes senior-engineer workflows and quality gates into 24 skills.
DeepSeek Harness — Builds on a plugin architecture to organize documents, analyze tables, and write code.
Browser Harness — Agents edit their own helper scripts mid-task to improve task completion.
Runway — Control Claude Code and Codex sessions on local or cloud machines from any phone.

All Durable Harness alternatives