Implement MSC3871: Gappy timelines - indicate `gaps` in `/messages`#18873

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madlittlemods/msc3871-gappy-timeline

Commits on Aug 28, 2025

First stab at `gaps` in `/messages`
MadLittleMods
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Commits on Aug 29, 2025

Commits on Sep 2, 2025

Picking backfill points: `current_depth` should be padded for approximate comparisons
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