The pending-fragment bound evicted the first non-reliable set in insertion
order in TypeScript and Python, so a set actively receiving could be the
victim. Rust already took the least recently touched set. TS and Python now
track a per-set touch counter and match Rust. A test in each runtime pins the
scenario: bound full, the oldest set receives another fragment, a new set
forces one eviction, and the oldest set still completes.
Session receive in all three runtimes now documents that a refusal error ends
the session and the caller must end it, since the refused sequence is already
recorded and would be acknowledged.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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