[Error-Zhang]

Summary

• inject the height controller from explicit source instead of runtime Function#toString output
• execute that exact embedded source in unit tests
• preserve shrink, deduplication, feedback freeze, and hard-cap behavior across minified production builds

Verification

• npm run check
• minified Vite preview: iframe/body/scrollHeight settle at 352px
• minified viewport-feedback fixture stops at 720px with internal scrollHeight 856px