Rust, TypeScript and Python receivers evicted the stalest fragment set
when the pending bound was reached, including sets whose fragments had
already been acknowledged. The sender never resends an acknowledged
fragment, so the frame was lost while the sender saw it delivered.
Eviction now picks the stalest set holding no reliable fragment. When
every pending set is reliable the packet is refused, as every other
refusal is. A conforming sender keeps at most 32 reliable packets in
flight against a bound of 64 sets, so it cannot reach the refusal.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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