Chart.js responsive resize limits across major versions

Goal: Zero‑downtime migration of a small application to Chart.js 4.x

The application currently renders several charts using Chart.js 3.x with responsive resizing enabled. The migration must preserve the visual consistency of the charts while avoiding any layout thrashing or visual glitches during the live switch. Constraints include the fact that Chart.js 4.x introduces a new global registry and altered default scale configurations, which may affect the internal ResizeObserver logic that drives responsive resizing.

Because the responsive feature is a documented capability that relies on the library’s resize handling, it is unclear whether the same behavior and performance characteristics will hold after upgrading. The migration plan also needs to consider how the new tree‑shakable ES module entry points might change the bundle size and initial render time.

What are the documented limits of Chart.js’s responsive resizing between versions 3.x and 4.x? Are there any breaking changes in the options or default scales that can alter the automatic resize thresholds? How can a live application switch to the new version without triggering layout thrashing or visual flicker during the transition?