$ find your agent harness

An early (2023-era) open-source background agent that turned labeled GitHub issues into pull requests by planning, coding and opening a PR asynchronously; the original bot is effectively sunset — the repo README redirects to the company's pivot into a proprietary JetBrains AI plugin (autocomplete + in-IDE agent, $10-60/mo) using Sweep's own LLMs, so the background-agent product itself is legacy.

The original 'AI software engineer': a cloud VM agent that plans, codes, tests and opens PRs from Slack/web/API, now spanning a whole product line (Devin cloud, Devin Desktop nee Windsurf, CLI) with ACU consumption billing ($2.00-2.25/ACU, Core $20 entry, Team $500/mo) and Cognition's own SWE-1.6 model alongside frontier models.

OpenAI's delegation-first coding agent whose cloud mode runs each task in an isolated no-internet-by-default sandbox with the repo cloned, opens PRs, does automatic PR code review on GitHub and takes tasks from ChatGPT/Slack, bundled into ChatGPT Plus/Pro/Business with rolling credit-based billing since April 2026 (the CLI companion is open source, the cloud service is not).

Anthropic's cloud-hosted Claude Code at claude.ai/code: each session gets an isolated Anthropic-managed VM with the GitHub repo cloned and limited default network access, supports parallel steerable sessions across repos with automatic PR creation, sessions persist after browser close and are monitorable from the Claude mobile app; bundled with Pro/Max/Team/Enterprise plans (research preview).

Google's asynchronous coding agent that clones your GitHub repo into a secure cloud VM, plans and executes tasks (bug fixes, tests) and returns PRs; free tier of 15 tasks/day with higher quotas bundled into Google AI Pro/Ultra, Gemini 3.1 Pro/3 Flash under the hood, curated MCP connections (Linear, Supabase, Neon, Context7) added Feb 2026 and an alpha REST API for Slack/Linear-driven automation.

GitHub's fully autonomous background worker: assign it a GitHub Issue and it works in a GitHub Actions-powered sandbox and delivers a draft PR, with MCP server support, custom .agent.md agents, agentic code review that hands fixes back to the agent, and (since Feb 2026) the ability to assign the same issue to Claude, Codex and Copilot simultaneously and pick the best PR; available on Pro through Enterprise with AI-credit billing from June 2026.

YC-backed autonomous software engineer that picks up tickets from GitHub/Jira/Linear and opens tested PRs end-to-end across CLI, desktop, VS Code and cloud, distinguished by its own in-house Lumen model family (including on-device Scout and air-gapped sovereign variants for regulated industries like HSBC/NatWest/BAE) and the April 2026 'Swarm' feature for parallel long-horizon agents; credit-based seats at $20 (Hobby) and $200 (Professional).

Launched GA June 30 2026, these are pipeline-native reasoning agents for the software-delivery stage (between code and production) rather than code authoring: every pipeline step can run as an agent governed by existing enterprise deployment controls, with an LLM Gateway enforcing policy on prompts, distinct auditable AI identities, per-agent/per-pipeline model switching, and a marketplace of Harness-managed and community agents.

Cursor's fire-and-forget mode (formerly Background Agents): agents run in isolated cloud Ubuntu VMs — since Feb 2026 with a full desktop and browser for 'computer use' UI verification — clone the repo onto their own branch, work multi-repo in parallel, report back to the IDE/web/Slack/Teams/iOS app, and open PRs, with Dockerfile-configurable environments, scoped secrets, and a headless Background Agent API.

Always-on 'daemon' agents defined in Markdown files that work proactively across GitHub, Linear and Slack without prompts — reviewing PRs, opening fix PRs, triaging bugs, syncing docs — positioned as the follow-through layer that keeps work moving after other coding agents create it; runs on Charlie's V2 durable runtime with worker orchestration and a devbox that includes a real Playwright browser for validating UI flows before opening a PR.

Enterprise-focused 'Droids' platform ($1.5B valuation after April 2026 Series C): autonomous agents that execute refactors, migrations and incident investigations end-to-end across CLI, desktop, SDK and remote 'Droid Computers' cloud workloads, with both local and cloud background agents on the $20 Pro tier and adoption at Nvidia, Adobe, Morgan Stanley and MongoDB; notably model-agnostic across frontier providers.