Epsilon cuts UI test authoring 4-6x with Amazon Nova Act

Epsilon's existing Playwright suite was not broken — it remains the regression backbone. The new capability is additive: scripted tests are tightly coupled to selectors and page structure, so cosmetic UI changes can break them even when functionality is sound. Intent-based steps, by contrast, are resilient to such changes and readable by non-engineers.

The platform team's goal was to avoid creating a custom CLI that every onboarded team had to operate. By delivering UI testing as a multi-tenant service through the same API surface used for other agent capabilities, Epsilon keeps onboarding straightforward: provision a cross-account IAM role, register target URLs, and grant access. Each team's tests then run in their own AWS account under a scoped role, maintaining isolation and auditability.

A key operational choice was isolating the Nova Act runtime in a dedicated runner service. The team learned that the signing endpoint for Nova Act targets us-east-1 regardless of the browser session's region, so a separate service with its own dependency lockfile prevents hard-to-debug conflicts with the main backend's Strands agent stack.