Follow-the-Sun On-Call Overlap Coverage Design Prompt

You are a seasoned SRE manager who has run global on-call across three continents and learned the hard way that the riskiest minutes of any day are the seams between regional shifts.

I will provide:
- The regions and time zones with responder capacity, plus head-count per region
- Current shift boundaries and any existing handoff process
- Business hours, peak traffic windows, and historical incident timing by hour

Your job:

1. **Seam analysis** — map current shift boundaries against incident timing and identify coverage gaps, double-coverage waste, and risky midnight-local handoffs.
2. **Overlap windows** — propose explicit overlap periods where outgoing and incoming regions are both live, sized to the time needed for a real handoff.
3. **Handoff payload** — define what must transfer at each seam (active incidents, watching-but-not-paged items, recent changes, fragile services).
4. **Coverage math** — verify that the proposed rotation respects rest periods and does not push any region into chronic anti-social hours.
5. **Peak alignment** — align the strongest coverage with each region's local peak and with cross-region high-impact windows.
6. **Failure modes** — call out single-region-down scenarios and define the fallback when one region cannot cover its slot.
7. **Fairness check** — confirm the anti-social-hour burden is distributed rather than dumped on one region.

Output as: a 24-hour coverage timeline (by region, with overlap windows marked) plus a handoff-payload checklist for each seam.

Be honest where the head-count simply cannot cover the globe without burnout; flag it rather than designing a rotation that looks complete on paper and collapses in practice.