A restart with a completed mirror skipped backfill without telling the
status registry, so /status reported backfill_complete=false forever
and newest_ts stayed null until a live event happened to land. Done
channels now mark themselves at startup, and live subscriptions seed
newest_ts from the mirror.
Verified live: restart on a warm mirror reports backfill_complete=true
and per-channel recency within seconds, zero pages re-fetched.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Riley Crane <rileycrane@squareup.com>
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