$ find your agent harness

Open-source (Rust, BSD-3) Codex-native personal agent platform whose defining trait is a hardware-isolated microVM per agent — Firecracker on Linux, Hyper-V on Windows, not just a container — wrapped in zero-trust controls: 'Pipelock' keeps secrets and credentials out of an agent's reach and an egress-allowlist proxy governs outbound traffic. Agents are authored, validated and launched entirely from Codex in-repo ('everything is a skill'), build their own capability-gated WASM tools at runtime, persist memory in a shared knowledge graph, and can run always-on via cron-style schedules and heartbeats.

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.

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.