The TrendChart layout effect has no deps and dispatched setEdges on every
render. Steady state survived via React's same-value eager bailout, but a
granularity switch genuinely flips the fades (narrow turn chart has no
overflow), and the programmatic scrollLeft assignment fires an async scroll
event whose dispatch leaves the fiber with pending lanes — the eager
bailout is skipped, every commit's effect enqueues yet another update, and
the queue grows without bound until React #185 (maximum update depth)
throws and the slot's error boundary blanks the tab.
Mirror the fades in a ref and never dispatch when the values are unchanged,
killing the cascade at the source instead of relying on bailout internals.
The real-React repro now emulates layout well enough to catch this class:
scrollWidth follows the bar count and programmatic scrolls dispatch an
async scroll event, so the old code crashes the test and the fix passes.
bowenliang123
9c0adb5dcc