Laboratory Service — Sync Contract

Status: populated Owner: TBD Last updated: 2026-04-18 Companion: Service Template · 03 platform-services · 02 DDD

1. Per-Aggregate Conflict Policy

Aggregate / Entity	Conflict policy	Rationale
`Accession`	`server_authoritative`	State machine transitions are strictly ordered; client cannot win a conflict
`Specimen`	`server_authoritative`	Chain-of-custody integrity requires server to be the single truth
`LabResult` (draft)	`server_authoritative`	Only one technologist owns a result at a time; optimistic lock via `version`
`LabResult` (verified/released)	`append_only`	Corrections create new versions; prior versions are immutable
`ResultAcknowledgment`	`append_only`	Acks are additive facts; cannot be retracted
`TestCatalogItem`	`server_authoritative`	Admin-only mutations; no client-side write expected
`CriticalValuePolicy`	`server_authoritative`	Admin-only; safety policy must be authoritative

Laboratory service is deployed at facility level and requires network connectivity to the platform hub for:

Offline degradation rules:

Accession creation and result entry may proceed offline using locally cached test catalog.
Terminology validation is flagged terminology_validated=false and re-validated on reconnect.
Release to chart is queued and executed when platform connectivity is restored; the outbox pattern handles this.
Critical alerts are buffered in the outbox and delivered as soon as NATS connection is re-established.

All mutable rows include a version column. Concurrent updates use:

UPDATE lab_results
SET status = $newStatus, version = version + 1, updated_at = NOW()
WHERE id = $id AND version = $expectedVersion;

If 0 rows updated → 409 CONFLICT returned to client.