Guides

Field verification guide

Use SwiftProof to verify that field agents actually visited the sites they reported visiting.

Use cases

Insurance assessors confirming property inspections
Lenders verifying SME business premises before disbursement
Telcos confirming installation site visits
Utilities confirming meter reading visits
Compliance officers signing off on physical audits

Integration pattern

Create a chain when a field visit is scheduled. The agent confirms on-site by opening the link — SwiftProof captures their GPS to verify they were actually at the location.

schedule-visit.js
const chain = await sp.chains.create({
  title: `Site visit — \${site.address}`,
  metadata: {
    siteId: site.id,
    agentId: agent.id,
    visitType: 'pre-disbursement-inspection',
  },
  actors: [
    { event: 'arrived',   actor: agent.name },
    { event: 'inspected', actor: agent.name },
    { event: 'departed',  actor: agent.name },
  ],
  expires_in_hours: 24,
});

// Send to agent before the visit
await sendSMS(agent.phone,
  `Your visit confirmation links for \${site.address}: \${chain.handoffs[0].confirmation_url}`);

Verifying location accuracy

After the agent confirms, verify the chain and compare the captured GPS coordinates against the expected site location.

verify-visit.js
function distanceKm(a, b) {
  // Haversine formula
  const R = 6371;
  const dLat = (b.lat - a.lat) * Math.PI / 180;
  const dLng = (b.lng - a.lng) * Math.PI / 180;
  const x = Math.sin(dLat/2) ** 2 +
    Math.cos(a.lat * Math.PI/180) * Math.cos(b.lat * Math.PI/180) *
    Math.sin(dLng/2) ** 2;
  return R * 2 * Math.atan2(Math.sqrt(x), Math.sqrt(1 - x));
}

const proof = await sp.chains.verify(chainId);
const arrival = proof.trail.find(s => s.event === 'arrived');
const dist = distanceKm(arrival.coordinates, site.coordinates);

if (dist > 0.1) { // More than 100m from site
  flagForReview('Agent confirmed too far from site', dist);
}