Agent-Driven E2E Testing with Cypress: A Practical Guide to Harness Engineering with Cursor Subagents

Teams have done end-to-end testing deliberately for years: exploring the app, writing tests from what they see, fixing failures in focused sessions. That's skilled work, not guesswork. The hard part is usually organizational. Knowledge sits in people's heads or scattered across chat histories and tickets. What you see on a live screen is tough to describe clearly to whoever writes the automated test. Each new flow forces everyone to reload the same context from scratch. Agent-driven development doesn't replace that judgment. It packages skilled work into narrow roles (explore, implement, execute, repair) with clear inputs and outputs. Quality builds over time instead of starting from zero every sprint. This approach mirrors harness engineering: the system around the agents that makes them reliable, not just capable. What Is a Harness, and Why Does It Matter? The term "harness" has emerged as shorthand for everything in an AI agent system except the model itself. Put simply: Agent = Mod