# ADR-044 — Relationship dates become LocalDate + DatePrecision; relationships become editable

**Status:** Accepted
**Date:** 2026-06-14
**Issue:** #837 (Zeitstrahl milestone; deferred follow-up to #773 / ADR-039)

## Context

`PersonRelationship` stored its span as `Integer fromYear`/`toYear`. A wedding could
never be more precise than `1923`, while `Person` (ADR-039), `Document`, and
`TimelineEvent` already carry full `DatePrecision`. Relationships also supported only
create + delete: fixing a wrong type, a wrong person, or adding a date learned later
meant deleting and re-creating the edge — losing `createdAt`. A `notes` column existed
that no form set and nothing displayed.

V78 replaces the two integer columns with `from_date`/`to_date` (`DATE`, nullable) plus
`from_date_precision`/`to_date_precision` (`VARCHAR(16) NOT NULL DEFAULT 'UNKNOWN'`),
backfilling existing years as `YYYY-01-01` at `YEAR` precision — exactly the V76 / ADR-039
pattern applied to the relationship edge. A new `PUT /api/persons/{id}/relationships/{relId}`
makes relationships editable, and `notes` is activated end to end.

## Decisions

### 1. Mirror ADR-039 verbatim for the relationship edge

`DatePrecision` is imported cross-domain from `document/` (ADR-039 §1 — value-type
sharing, not a layering breach). The precision columns are NOT NULL default `UNKNOWN`,
guarded by five named CHECK constraints (`chk_relationship_from_coherence`,
`chk_relationship_to_coherence`, `chk_relationship_date_order`,
`chk_relationship_{from,to}_precision_values`). `RelationshipService.validateRelationshipDates`
enforces the same rules first, so the user gets a structured 400
(`INVALID_DATE_PRECISION` for coherence, the new `INVALID_RELATIONSHIP_DATES` for a
`toDate < fromDate` order violation) instead of a constraint-violation 500. The form
offers only **DAY / MONTH / YEAR**; storage still accepts all seven values, and a
stored non-offered precision seeds the edit select as `YEAR` (ADR-039 §2).

### 2. Update re-runs every create invariant

An edit can violate the same invariants as a create, so `updateRelationship` re-runs
all of them: self-relation (`VALIDATION_ERROR`), date coherence + order, reverse
`PARENT_OF` (`CIRCULAR_RELATIONSHIP`), and the `(person, relatedPerson, type)` unique
constraint via `saveAndFlush` (`DUPLICATE_RELATIONSHIP`). Editing into a family type
flags both endpoints as family members (additive; never auto-unflags). The directed
orientation is preserved per viewpoint — whichever endpoint `{personId}` already holds
on the row stays put — so a `PARENT_OF` edge remains parent→child whether edited from
either person's page.

### 3. No optimistic locking (`@Version`)

`PersonRelationship` gains no `@Version`; the edit is last-write-wins, matching the
person edit form. This is a single-writer family archive, and it avoids the managed-
`setVersion` pitfall (a `setVersion` on a managed entity is silently ignored by
Hibernate — see the integration-test note in #496-era work). If concurrent curation
ever becomes real, add `@Version` plus an explicit client-version compare then.

### 4. IDOR / anti-enumeration: ownership mismatch is 404, for PUT **and** DELETE

A `{relId}` that does not belong to `{personId}` returns 404 `RELATIONSHIP_NOT_FOUND`
(a shared `loadOwnedRelationship` helper), so a curator cannot probe relationship ids
belonging to people they cannot see. This **aligns `deleteRelationship`** from its
former 403 to 404 in the same change, so the two mutating endpoints behave identically
on the same mismatch.

### 5. Derived marriage events gain precision for free

`TimelineEventService.buildMarriageEvents` now sources the Heirat date from the
`SPOUSE_OF` row's `from_date` + `from_date_precision` (previously
`LocalDate.of(fromYear, 1, 1)` at hard-coded `YEAR`). A DAY-precision wedding now
surfaces the exact day on the Zeitstrahl. `RelationshipInferenceService` is unchanged
— it is time-ignorant and never read the year fields.

### 6. `relationshipDates.ts` lives in `$lib/person/`, no new boundary

`formatRelationshipDateRange` mirrors `personLifeDates.ts` and delegates entirely to the
already-tested `formatDocumentDate` (zero new precision logic). It sits in `$lib/person/`
next to `personLifeDates.ts`; its only cross-domain import is `formatDocumentDate` from
`$lib/shared/utils/`, which the existing `person → shared` rule in `eslint.config.js`
already permits — **no new eslint boundary rule is added**.

## Consequences

- V78 is one-way (columns dropped) and is **not** rolling-deploy-safe — the running JAR
  maps `from_year` until redeploy. Deploy order: **stop old JAR → run Flyway V78 →
  start new JAR**. Rollback = targeted `pg_restore -t person_relationships` from the
  pre-deploy dump (see `docs/DEPLOYMENT.md` §8). No maintenance window needed
  (single-writer archive).
- Relationships are fully editable (type, related person, dates, notes) and the read
  view shows the date range + notes.
- `RelationshipDTO` drops `fromYear`/`toYear` for `fromDate`/`fromDatePrecision`/
  `toDate`/`toDatePrecision`; the `personBirthYear`/`relatedPersonBirthYear` derived
  fields are unaffected (ADR-039 §3).
