List a child of several families of a parent once (#1502)

A child in two families of the same parent, such as a child whose
mother remarried, appeared twice in the descendant and hourglass charts,
with everything below them doubled. The child is now listed once, from
their primary parent family if it is one of the parent's families.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/charts/model/FamilyGraph.js

@@ -94,18 +94,33 @@ export class FamilyGraph {
   }
 
   // Returns the person's children in all families where they are a parent,
-  // each with its `handle` and its `relation` to this parent
+  // each with its `handle` and its `relation` to this parent. A child in
+  // several of these families, such as a child of a parent who remarried, is
+  // listed once, from their primary parent family if it is one of them and
+  // otherwise from the first.
   childRelations(handle) {
-    return this.partnerFamilies(handle).flatMap(family => {
+    const entries = this.partnerFamilies(handle).flatMap(family => {
       const isFather = family.father_handle === handle
       if (!isFather && family.mother_handle !== handle) {
         return []
       }
       return (family.child_ref_list || []).map(childRef => ({
+        family,
         handle: childRef.ref,
         relation: (isFather ? childRef.frel : childRef.mrel) || 'Birth',
       }))
     })
+    const chosen = new Map()
+    for (const entry of entries) {
+      const primary = this.person(entry.handle)?.extended?.primary_parent_family
+        ?.handle
+      if (!chosen.has(entry.handle) || entry.family.handle === primary) {
+        chosen.set(entry.handle, entry)
+      }
+    }
+    return entries
+      .filter(entry => chosen.get(entry.handle) === entry)
+      .map(({handle: child, relation}) => ({handle: child, relation}))
   }
 
   // Returns the handles of the person's children in all families where they

test/unit/familyGraph.test.js

@@ -82,6 +82,38 @@ describe('FamilyGraph', () => {
     })
   })
 
+  it('lists a child in several families of the parent once', () => {
+    // M had G with an unknown father, then married S, who took G in
+    const fFirst = family('fFirst', '', 'M', [childRef('G')])
+    const fSecond = family('fSecond', 'S', 'M', [
+      childRef('H'),
+      childRef('G', 'Stepchild', 'Birth'),
+    ])
+    const people = (...families) => [
+      {handle: 'M', extended: {families}},
+      {handle: 'S', extended: {families: [fSecond]}},
+      {handle: 'G', extended: {primary_parent_family: fFirst}},
+    ]
+    // From the primary parent family, wherever it is in the family list
+    expect(
+      new FamilyGraph(people(fSecond, fFirst)).childRelations('M')
+    ).toEqual([
+      {handle: 'H', relation: 'Birth'},
+      {handle: 'G', relation: 'Birth'},
+    ])
+    expect(
+      new FamilyGraph(people(fFirst, fSecond)).childRelations('S')
+    ).toEqual([
+      {handle: 'H', relation: 'Birth'},
+      {handle: 'G', relation: 'Stepchild'},
+    ])
+    // From the first family for a child who was not fetched
+    const unfetched = new FamilyGraph([
+      {handle: 'M', extended: {families: [fSecond, fFirst]}},
+    ])
+    expect(unfetched.children('M')).toEqual(['H', 'G'])
+  })
+
   it('returns no children for a person without families', () => {
     expect(graph.children('S')).toEqual([])
     expect(graph.children('X')).toEqual([])