Decide how OLN detects that a linked external page has drifted enough to re-verify, handles link rot, and bounds the cost of monitoring verified ties.
Why this matters
Entry 028's lifecycle re-evaluates a tie when its external target changes. That implies OLN watches content it does not host:
- Drift detection — snapshot the target at verification time, then detect meaningful change (content hash / fetched-text diff) so re-scoring compares against the original proof.
- Link rot — detect dead, redirected, or hijacked targets and route them to quarantine.
- Trigger model and cadence — event-driven where signals exist, plus a scheduled sweep; batch vs runtime split per Entry 022.
- Cost envelope — this is the expensive part. Crawling, storage of snapshots, and re-inference per verified tie must stay bounded as the link corpus grows; cache and make re-scoring replayable.
- Evidence retention — keep the verification-time snapshot so a quarantine decision is auditable and reversible.