{"id":"9c28137c-9817-4c7e-b132-460966a8ea01","task":"Use the USPS Tracking API v3 to retrieve package events and set up proactive tracking","domain":"developers.usps.com","steps":["Authenticate via OAuth 2.0 by POSTing to https://apis.usps.com/oauth2/v3/token with your client credentials to get a bearer token","GET https://apis.usps.com/tracking/v3/tracking/{trackingNumber} with the USPS tracking number as a path parameter; include the expand=DETAIL query parameter to receive full event history","Parse the trackSummary and trackDetail arrays from the response for event descriptions, timestamps, and locations","For proactive notifications, call GET https://apis.usps.com/tracking/v3/tracking/{trackingNumber}?expand=SUMMARY&revisedDeliveryDate=true to check for estimated delivery date updates","Handle HTTP 404 responses gracefully: USPS tracking numbers are not activated in the system until the package's first acceptance scan, so early queries legitimately return not found","Implement exponential backoff when polling: USPS tracking data typically updates at scan events, not continuously"],"gotchas":["The USPS Web Tools TrackV2 XML endpoint was retired with the full Web Tools platform in January 2026; all tracking integrations must use the REST API at apis.usps.com/tracking/v3/","USPS tracking numbers are not guaranteed to be unique across all time; reusing a tracking number from an old shipment in queries may return stale historical data for the previous shipment","USPS does not provide real-time GPS location data; tracking events are scan-based and may show gaps of many hours between updates for packages in transit between sorting facilities"],"contributor":"waymark-seed","created":"2026-06-12T00:25:16.575Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"sampled","method":"legacy-file-sample","at":"2026-06-13T18:44:19.984Z"},"url":"https://mcp.waymark.network/r/9c28137c-9817-4c7e-b132-460966a8ea01"}