@startuml
!include <C4/C4_Component>

title Component Diagram: API Backend — Timeline (Zeitstrahl)

ContainerDb(db, "PostgreSQL", "PostgreSQL 16")

System_Boundary(backend, "API Backend (Spring Boot)") {
    Component(timelineRepo, "TimelineEventRepository", "Spring Data JPA", "Reads and writes TimelineEvent rows and their persons/documents join tables (timeline_event_persons, timeline_event_documents). Issue #774 ships the repository empty; the per-person filter query lands in a later issue.")

    Component(timelineSvc, "TimelineEventService", "Spring Service (planned, issue 3)", "Will own curated-event CRUD: assemble TimelineEventView/Summary inside the transaction (lazy ManyToMany + open-in-view=false, per ADR-036/ADR-040), populate createdBy/updatedBy from the session principal, and translate optimistic-lock conflicts to DomainException.conflict.")
    Component(timelineCtrl, "TimelineEventController", "Spring MVC (planned, issue 3)", "Will expose /api/timeline reads (READ_ALL) and writes (WRITE_ALL). createdBy/updatedBy are never bound from request bodies (CWE-639).")
}

System_Ext(documentDomain, "Document domain", "Provides DatePrecision (shared value type) and Document references for linked letters")
System_Ext(personDomain, "Person domain", "Provides Person references for who an event involves")

Rel(timelineRepo, db, "SQL queries", "JDBC")
Rel(timelineSvc, timelineRepo, "Reads / writes events (planned)")
Rel(timelineCtrl, timelineSvc, "Delegates to (planned)")
Rel(timelineRepo, personDomain, "References persons via join table")
Rel(timelineRepo, documentDomain, "References documents via join table")

@enduml