Summary

Background

The testing skill did not explicitly warn against starting e2e before a workspace build had fully completed. That made it easy to hit missing built artifacts such as packages/core/dist/rstestSuppressWarnings.cjs during e2e runs.

Implementation

• Added guidance to prefer pnpm build before e2e when a change can affect multiple packages.
• Added explicit rules to wait for build completion, avoid overlapping build and e2e sessions, and treat missing built artifacts as incomplete-build failures.
• Added a reminder to verify expected artifacts exist before retrying e2e when build completion is uncertain.

User Impact

Developers following the testing skill are less likely to trigger false e2e failures caused by incomplete package builds.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).