Edge Cache and CDN Platform · View 17 of 29 · 5 · Runtime

A PoP Returns — Reconcile Before Serving

A PoP that was away while purges happened catches up from the log before it announces, or throws its cache away logically if the gap is too old.

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Reconciliation is in the MVP, not Phase 2 as the requirement suggests. With the invalidation log already a replayable stream, it is a replay from a sequence number. Shipping purge without it would ship a purge that can silently fail to happen.
The PoP stays withdrawn until the agent confirms both the invalidation position and the configuration bundle. pop-guard does not announce a PoP that is behind on either.
A gap older than the log is not partly replayed. Every property's generation number is bumped, which turns every stored object into a miss. That is expensive and always correct.

Replaying a nine-hour gap of about 1,300 records takes seconds. The 30-day retention covers the 14-day longest tolerated absence with margin.

A PoP that returns without its tag tables, for example after an NVMe failure, has lost its position. The agent treats a missing table as a gap older than the log.