Artifact: ADR-0003 (Colocated, Immutable) — ParcelLink Webhooks

Colocated, immutable ADR placement -- exercises co-08.

File path: services/shipment-tracker/docs/adr/0003-parcellink-webhook-push.md

Frontmatter: Date: 2026-02-18 · Status: Accepted

The ADR lives inside services/shipment-tracker/, the same repository directory as the carrier_adapter/ code that implements ParcelLink integration -- not in a company wiki, and not in a separate documentation repository. A docs/adr/README.md index in the same directory lists every ADR in this service by number.

When the team later needs to add rate-limit backoff to the webhook receiver itself (a related but distinct decision), that becomes ADR-0004 in the same directory -- ADR-0003's own file is never reopened for editing after its acceptance date.