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Journey — A Rotation Owner Closes a Gap Nine Days Before DST

A US/Eastern rotation hands over at 02:30 local, a time that does not exist on the spring-forward night. The platform finds it nine days out, not when a page falls through.

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Rotation owner platform-db · US/Eastern Goal — No hour without a responder Trigger — Gap warning for the spring-forward night Done when — Covered, verified, provable later 1 · Warned 2 · Inspect 3 · Override 4 · Verify 5 · The night ◆ moment of truth 6 · Prove What they do Reads the gap warning Opens coverage preview Adds a 01:00–04:00 override Reads the snapshot diff Sleeps Answers who was on call System behind it Gap detector · 14 d Resolved timeline Override layer Second resolver Snapshot · 72 h ahead Schedule audit How it feels Confident Unsure Anxious Where it hurts 02:30 does not exist Four layers deep Will anyone be paged? What the platform gives Warned 9 days early Shown in local time Override beats all layers Two resolvers agree Nothing computed live Answer from the record Journey — A Rotation Owner Closes a Gap Nine Days Before DST v 1.0 · owner Reliability Architecture · date 2026-09

The moment of truth

  • The night itself. The owner is asleep and has to trust that nothing about the clock change will be computed live. It is not: the buckets for that night were materialised and verified by two independent resolvers 72 hours earlier.
  • If the gap had not been fixed, a page in that hour would not have paused. It would have fallen straight to the escalation policy's final step (view 34).

Decisions it relies on

  • Gap detection looks 14 days ahead every hour and warns the owner, not the on-call responder (ADR-15).
  • Overrides are a layer that wins over every layer beneath it, time-bounded, and recorded with actor and effective window (ADR-14).
  • Unverified contact methods do not count as coverage, so a gap can exist on a rotation that looks full on paper.

Target

  • Every gap in the next 14 days surfaced to its owner before it is reached. Coverage change visible to paging within 60 seconds at p99.
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Solution Architecture v1.0 · Reliability Architecture · 2026-09 · 34 views · open source, fully on-premises06-journey-close-a-coverage-gap-before-dst