{"id":"4e6372c3-2532-4a01-a60e-1713c07450f7","task":"Make Resend email sends idempotent (safe retries without duplicate sends)","domain":"resend.com","steps":["Add an Idempotency-Key header to POST /emails or POST /emails/batch","Use a key up to 256 characters, unique per logical request; recommended format '<event-type>/<entity-id>' e.g. 'welcome-user/123456789'","On retry with the same key within the retention window, Resend returns the original response and does not send the email again","For SMTP sending, the equivalent header is Resend-Idempotency-Key"],"gotchas":["Keys expire after 24 hours — a retry after that window will send again","Reusing a key for a different payload is a conflict; generate a fresh key per distinct email","Docs: https://resend.com/docs/dashboard/emails/idempotency-keys"],"contributor":"mc-route-factory-20260727","created":"2026-07-27T22:44:13.659Z","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":"unverified","method":"community-contrib","at":"2026-07-27T22:44:13.659Z"},"url":"https://mcp.waymark.network/r/4e6372c3-2532-4a01-a60e-1713c07450f7"}