Async loaders per route, resolved before the transition commits.
Reproduce the stale loader deterministically. Navigate A→B→C with controlled latencies so that
B resolves last. If your reproduction is "click fast", you have observed the bug, not reproduced
it.
Implement three fixes: render-time guard, navigation sequence number, AbortController.
Rank them. Then answer the question that separates seniority: which is correct when the loader
has a server side effect?
Ship abort plus sequence guard, and explain why cancellation alone is insufficient.