Add collision detection for family overlaps and second line labels

Major changes:
- Implement intelligent collision detection and resolution for complex
  family structures (divorce/remarriage scenarios)
- Rewrite generation assignment with constraint propagation algorithm
  to ensure spouses are always in the same generation
- Add FamilyUnit concept for grouping parents and children
- Add second line label support with custom text, birth year, death year,
  and age display options

Files modified:
- PedigreeLayout.ts: Add collision detection, family units, and improved
  generation assignment
- types.ts: Add FamilyUnit interface and extend PersonMetadata
- useD3Pedigree.ts: Render second line labels
- PropertyPanel.tsx: Add UI for editing second line labels
- PropertyPanel.module.css: Add styles for inline form groups

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/PedigreeCanvas/hooks/useD3Pedigree.ts

@@ -446,7 +446,7 @@ function renderPersons(
         .attr('fill', 'none');
     }
 
-    // Label (positioned just below the symbol, above connection lines)
+    // Label line 1 (positioned just below the symbol, above connection lines)
     if (options.showLabels && person.metadata.label) {
       personGroup
         .append('text')
@@ -472,8 +472,49 @@ function renderPersons(
         .attr('fill', '#666')
         .text(person.id);
     }
+
+    // Label line 2 (subtitle/additional info)
+    const line2Text = buildSecondLineText(person);
+    if (options.showLabels && line2Text) {
+      personGroup
+        .append('text')
+        .attr('class', 'person-label-line2')
+        .attr('x', 0)
+        .attr('y', options.symbolSize / 2 + 30)
+        .attr('text-anchor', 'middle')
+        .attr('font-size', '10px')
+        .attr('font-family', 'sans-serif')
+        .attr('fill', '#666')
+        .text(line2Text);
     }
   }
+}
+
+/**
+ * Build the second line text from person metadata
+ */
+function buildSecondLineText(person: Person): string {
+  const parts: string[] = [];
+  const meta = person.metadata;
+
+  // Custom text first
+  if (meta.label2) {
+    parts.push(meta.label2);
+  }
+
+  // Year/age info
+  if (meta.showBirthYear && meta.birthYear) {
+    parts.push(`b.${meta.birthYear}`);
+  }
+  if (meta.showDeathYear && meta.deathYear) {
+    parts.push(`d.${meta.deathYear}`);
+  }
+  if (meta.showAge && meta.age !== undefined) {
+    parts.push(`${meta.age}y`);
+  }
+
+  return parts.join(' ');
+}
 
 function renderGenerationLabels(
   group: d3.Selection<SVGGElement, unknown, null, undefined>,

src/components/PropertyPanel/PropertyPanel.module.css

@@ -112,3 +112,46 @@
   color: #999;
   font-style: italic;
 }
+
+.inlineGroup {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 6px;
+}
+
+.inlineGroup:last-child {
+  margin-bottom: 0;
+}
+
+.inlineLabel {
+  display: flex;
+  align-items: center;
+  gap: 4px;
+  font-size: 13px;
+  cursor: pointer;
+  min-width: 70px;
+}
+
+.inlineLabel input[type="checkbox"] {
+  width: 14px;
+  height: 14px;
+  cursor: pointer;
+}
+
+.smallInput {
+  width: 70px;
+  padding: 5px 8px;
+  border: 1px solid #ddd;
+  border-radius: 4px;
+  font-size: 13px;
+}
+
+.smallInput:focus {
+  outline: none;
+  border-color: #2196F3;
+}
+
+.smallInput::placeholder {
+  color: #aaa;
+}

src/components/PropertyPanel/PropertyPanel.tsx

@@ -50,6 +50,18 @@ export function PropertyPanel() {
     });
   };
 
+  const handleLabel2Change = (label2: string) => {
+    updatePerson(selectedPerson.id, {
+      metadata: { ...selectedPerson.metadata, label2 },
+    });
+  };
+
+  const handleMetadataChange = (key: keyof typeof selectedPerson.metadata, value: unknown) => {
+    updatePerson(selectedPerson.id, {
+      metadata: { ...selectedPerson.metadata, [key]: value },
+    });
+  };
+
   return (
     <div className={styles.panel}>
       <div className={styles.header}>
@@ -68,6 +80,72 @@ export function PropertyPanel() {
         />
       </div>
 
+      <div className={styles.section}>
+        <div className={styles.sectionTitle}>Label Line 2</div>
+        <input
+          type="text"
+          className={styles.input}
+          value={selectedPerson.metadata.label2 ?? ''}
+          onChange={(e) => handleLabel2Change(e.target.value)}
+          placeholder="Second line text..."
+        />
+      </div>
+
+      <div className={styles.section}>
+        <div className={styles.sectionTitle}>Birth/Death/Age</div>
+        <div className={styles.inlineGroup}>
+          <label className={styles.inlineLabel}>
+            <input
+              type="checkbox"
+              checked={selectedPerson.metadata.showBirthYear ?? false}
+              onChange={(e) => handleMetadataChange('showBirthYear', e.target.checked)}
+            />
+            Birth
+          </label>
+          <input
+            type="number"
+            className={styles.smallInput}
+            value={selectedPerson.metadata.birthYear ?? ''}
+            onChange={(e) => handleMetadataChange('birthYear', e.target.value ? parseInt(e.target.value) : undefined)}
+            placeholder="Year"
+          />
+        </div>
+        <div className={styles.inlineGroup}>
+          <label className={styles.inlineLabel}>
+            <input
+              type="checkbox"
+              checked={selectedPerson.metadata.showDeathYear ?? false}
+              onChange={(e) => handleMetadataChange('showDeathYear', e.target.checked)}
+            />
+            Death
+          </label>
+          <input
+            type="number"
+            className={styles.smallInput}
+            value={selectedPerson.metadata.deathYear ?? ''}
+            onChange={(e) => handleMetadataChange('deathYear', e.target.value ? parseInt(e.target.value) : undefined)}
+            placeholder="Year"
+          />
+        </div>
+        <div className={styles.inlineGroup}>
+          <label className={styles.inlineLabel}>
+            <input
+              type="checkbox"
+              checked={selectedPerson.metadata.showAge ?? false}
+              onChange={(e) => handleMetadataChange('showAge', e.target.checked)}
+            />
+            Age
+          </label>
+          <input
+            type="number"
+            className={styles.smallInput}
+            value={selectedPerson.metadata.age ?? ''}
+            onChange={(e) => handleMetadataChange('age', e.target.value ? parseInt(e.target.value) : undefined)}
+            placeholder="Age"
+          />
+        </div>
+      </div>
+
       <div className={styles.section}>
         <div className={styles.sectionTitle}>Sex</div>
         <div className={styles.buttonGroup}>

src/core/layout/PedigreeLayout.ts

@@ -9,7 +9,7 @@
  * 4. Handle special cases (consanguinity, twins)
  */
 
-import type { Pedigree, Person, Relationship, LayoutOptions, LayoutNode } from '@/core/model/types';
+import type { Pedigree, Person, Relationship, LayoutOptions, LayoutNode, FamilyUnit } from '@/core/model/types';
 
 export const DEFAULT_LAYOUT_OPTIONS: LayoutOptions = {
   nodeWidth: 50,
@@ -46,86 +46,188 @@ export class PedigreeLayout {
     // Step 1: Assign generations
     const generations = this.assignGenerations(pedigree);
 
-    // Step 2: Sort within each generation
+    // Step 2: Build family units and find shared persons (multiple marriages)
-    const sortedGenerations = this.sortGenerations(generations, pedigree);
+    const familyUnits = this.buildFamilyUnits(pedigree);
+    const sharedPersons = this.findSharedPersons(familyUnits);
 
-    // Step 3: Calculate positions
+    // Calculate minimum widths for family units
+    for (const unit of familyUnits) {
+      unit.minWidth = this.calculateFamilyUnitWidth(unit);
+    }
+
+    // Step 3: Sort within each generation (with family unit awareness)
+    const sortedGenerations = this.sortGenerationsWithFamilyUnits(
+      generations,
+      pedigree,
+      familyUnits,
+      sharedPersons
+    );
+
+    // Step 4: Calculate initial positions
     this.calculatePositions(sortedGenerations, pedigree, result);
 
-    // Step 4: Center the layout
+    // Step 5: Adjust parent positions to be centered above children
+    // This is important for newly added parents
+    this.adjustParentPositions(sortedGenerations, result, pedigree);
+
+    // Step 6: Adjust children positions to be centered under parents
+    this.adjustChildrenPositions(sortedGenerations, result, pedigree);
+
+    // Step 7: Resolve collisions for all generations
+    const genKeys = Array.from(generations.keys()).sort((a, b) => a - b);
+    for (const gen of genKeys) {
+      // Multiple passes to ensure all collisions are resolved
+      let maxIterations = 10;
+      while (this.detectCollisions(result, gen) && maxIterations > 0) {
+        this.resolveCollisions(result, gen);
+        maxIterations--;
+      }
+    }
+
+    // Step 8: Center the layout
     this.centerLayout(result);
 
     return result;
   }
 
+  /**
+   * Sort generations with family unit awareness
+   */
+  private sortGenerationsWithFamilyUnits(
+    generations: Map<number, Person[]>,
+    pedigree: Pedigree,
+    familyUnits: FamilyUnit[],
+    sharedPersons: Map<string, FamilyUnit[]>
+  ): Map<number, Person[]> {
+    const sorted = new Map<number, Person[]>();
+
+    for (const [gen, persons] of generations) {
+      // Filter family units and shared persons for this generation
+      const genFamilyUnits = familyUnits.filter(u => u.generation === gen);
+      const genSharedPersons = new Map<string, FamilyUnit[]>();
+      for (const [personId, units] of sharedPersons) {
+        const person = pedigree.persons.get(personId);
+        if (person && person.generation === gen) {
+          genSharedPersons.set(personId, units);
+        }
+      }
+
+      const sortedGen = this.sortGenerationWithFamilyUnits(
+        persons,
+        pedigree,
+        genFamilyUnits,
+        genSharedPersons
+      );
+      sorted.set(gen, sortedGen);
+    }
+
+    return sorted;
+  }
+
   /**
    * Assign generation numbers to each person using BFS from founders
+   * Ensures spouses are always in the same generation
    */
   private assignGenerations(pedigree: Pedigree): Map<number, Person[]> {
     const generations = new Map<number, Person[]>();
     const personGenerations = new Map<string, number>();
     const persons = Array.from(pedigree.persons.values());
 
-    // Find founders (no parents in pedigree)
+    // Step 1: Calculate the minimum generation for each person based on parents
-    const founders = persons.filter(p => !p.fatherId && !p.motherId);
+    // A person's generation must be at least (max parent generation + 1)
+    const minGeneration = new Map<string, number>();
 
-    // BFS from founders
+    const calculateMinGeneration = (personId: string, visited: Set<string>): number => {
-    const queue: Array<{ person: Person; generation: number }> = [];
+      if (visited.has(personId)) return minGeneration.get(personId) ?? 0;
+      visited.add(personId);
 
-    for (const founder of founders) {
+      const person = pedigree.persons.get(personId);
-      queue.push({ person: founder, generation: 0 });
+      if (!person) return 0;
-      personGenerations.set(founder.id, 0);
-    }
 
-    while (queue.length > 0) {
+      let minGen = 0;
-      const { person, generation } = queue.shift()!;
-
-      // Add to generation map
-      if (!generations.has(generation)) {
-        generations.set(generation, []);
-      }
-      if (!generations.get(generation)!.find(p => p.id === person.id)) {
-        generations.get(generation)!.push(person);
-      }
-
-      // Process children
-      for (const childId of person.childrenIds) {
-        const child = pedigree.persons.get(childId);
-        if (child && !personGenerations.has(childId)) {
-          const childGen = generation + 1;
-          personGenerations.set(childId, childGen);
-          queue.push({ person: child, generation: childGen });
-        }
-      }
-
-      // Ensure spouses are in the same generation
-      for (const spouseId of person.spouseIds) {
-        const spouse = pedigree.persons.get(spouseId);
-        if (spouse && !personGenerations.has(spouseId)) {
-          personGenerations.set(spouseId, generation);
-          queue.push({ person: spouse, generation: generation });
-        }
-      }
-    }
-
-    // Handle disconnected individuals
-    for (const person of persons) {
-      if (!personGenerations.has(person.id)) {
-        // Try to infer from children or parents
-        let gen = 0;
 
+      // Check parents
       if (person.fatherId) {
-          const fatherGen = personGenerations.get(person.fatherId);
+        const fatherMin = calculateMinGeneration(person.fatherId, visited);
-          if (fatherGen !== undefined) {
+        minGen = Math.max(minGen, fatherMin + 1);
-            gen = fatherGen + 1;
+      }
+      if (person.motherId) {
+        const motherMin = calculateMinGeneration(person.motherId, visited);
+        minGen = Math.max(minGen, motherMin + 1);
+      }
+
+      minGeneration.set(personId, minGen);
+      return minGen;
+    };
+
+    // Calculate minimum generation for all persons
+    for (const person of persons) {
+      calculateMinGeneration(person.id, new Set());
+    }
+
+    // Step 2: Propagate minimum generations through spouse relationships
+    // Spouses must be in the same generation, so take the maximum
+    let changed = true;
+    while (changed) {
+      changed = false;
+      for (const person of persons) {
+        const currentMin = minGeneration.get(person.id) ?? 0;
+        for (const spouseId of person.spouseIds) {
+          const spouseMin = minGeneration.get(spouseId) ?? 0;
+          if (spouseMin > currentMin) {
+            minGeneration.set(person.id, spouseMin);
+            changed = true;
+          } else if (currentMin > spouseMin) {
+            minGeneration.set(spouseId, currentMin);
+            changed = true;
+          }
+        }
       }
     }
 
-        personGenerations.set(person.id, gen);
+    // Step 3: Propagate to children (children must be at least parent gen + 1)
-        if (!generations.has(gen)) {
+    changed = true;
-          generations.set(gen, []);
+    while (changed) {
+      changed = false;
+      for (const person of persons) {
+        const parentGen = minGeneration.get(person.id) ?? 0;
+        for (const childId of person.childrenIds) {
+          const childMin = minGeneration.get(childId) ?? 0;
+          if (childMin <= parentGen) {
+            minGeneration.set(childId, parentGen + 1);
+            changed = true;
           }
-        generations.get(gen)!.push(person);
+        }
+      }
+      // Also propagate spouse constraints after updating children
+      for (const person of persons) {
+        const currentMin = minGeneration.get(person.id) ?? 0;
+        for (const spouseId of person.spouseIds) {
+          const spouseMin = minGeneration.get(spouseId) ?? 0;
+          if (spouseMin !== currentMin) {
+            const maxGen = Math.max(spouseMin, currentMin);
+            minGeneration.set(person.id, maxGen);
+            minGeneration.set(spouseId, maxGen);
+            changed = true;
+          }
+        }
+      }
+    }
+
+    // Step 4: Normalize generations to start from 0
+    const allGens = Array.from(minGeneration.values());
+    const minGen = allGens.length > 0 ? Math.min(...allGens) : 0;
+
+    for (const [personId, gen] of minGeneration) {
+      const normalizedGen = gen - minGen;
+      personGenerations.set(personId, normalizedGen);
+
+      if (!generations.has(normalizedGen)) {
+        generations.set(normalizedGen, []);
+      }
+      const person = pedigree.persons.get(personId);
+      if (person && !generations.get(normalizedGen)!.find(p => p.id === personId)) {
+        generations.get(normalizedGen)!.push(person);
       }
     }
 
@@ -251,9 +353,7 @@ export class PedigreeLayout {
         person.y = y;
       }
     }
-
+    // Note: adjustChildrenPositions is now called separately in layout()
-    // Second pass: adjust children to center under parents
-    this.adjustChildrenPositions(generations, result, pedigree);
   }
 
   /**
@@ -274,8 +374,101 @@ export class PedigreeLayout {
     return null;
   }
 
+  /**
+   * Adjust parent positions to be centered above their children
+   */
+  private adjustParentPositions(
+    generations: Map<number, Person[]>,
+    positions: Map<string, LayoutNode>,
+    pedigree: Pedigree
+  ): void {
+    const genKeys = Array.from(generations.keys()).sort((a, b) => a - b);
+
+    // Process from bottom to top (children first, then parents)
+    for (let i = genKeys.length - 1; i >= 0; i--) {
+      const gen = genKeys[i];
+      const persons = generations.get(gen) ?? [];
+
+      // Track which persons have been processed as part of a couple
+      const processedAsCouple = new Set<string>();
+
+      for (const person of persons) {
+        if (processedAsCouple.has(person.id)) continue;
+
+        // Find children of this person
+        if (person.childrenIds.length === 0) continue;
+
+        const childNodes = person.childrenIds
+          .map(id => positions.get(id))
+          .filter((n): n is LayoutNode => n !== undefined);
+
+        if (childNodes.length === 0) continue;
+
+        // Calculate center of children
+        const childXs = childNodes.map(n => n.x);
+        const childCenter = (Math.min(...childXs) + Math.max(...childXs)) / 2;
+
+        // Get spouse if any (must be in same generation and share children)
+        const spouse = person.spouseIds
+          .map(id => pedigree.persons.get(id))
+          .find(s => {
+            if (!s || s.generation !== person.generation) return false;
+            // Check if they share children
+            return s.childrenIds.some(cid => person.childrenIds.includes(cid));
+          });
+
+        const parentNode = positions.get(person.id);
+        if (!parentNode) continue;
+
+        if (spouse) {
+          processedAsCouple.add(spouse.id);
+          const spouseNode = positions.get(spouse.id);
+          if (spouseNode) {
+            // Calculate current parent center
+            const parentCenter = (parentNode.x + spouseNode.x) / 2;
+            const offset = childCenter - parentCenter;
+
+            // Apply offset (collision will be resolved later)
+            const safeOffset = this.calculateSafeOffset([person, spouse], offset, positions, gen);
+            if (Math.abs(safeOffset) > 0) {
+              parentNode.x += safeOffset;
+              person.x = parentNode.x;
+              spouseNode.x += safeOffset;
+              spouse.x = spouseNode.x;
+            } else if (Math.abs(offset) > 0) {
+              // If safe offset is 0, try moving everything including colliding nodes
+              parentNode.x += offset;
+              person.x = parentNode.x;
+              spouseNode.x += offset;
+              spouse.x = spouseNode.x;
+            }
+          }
+        } else {
+          // Single parent - center directly
+          const offset = childCenter - parentNode.x;
+          const safeOffset = this.calculateSafeOffset([person], offset, positions, gen);
+          if (Math.abs(safeOffset) > 0) {
+            parentNode.x += safeOffset;
+            person.x = parentNode.x;
+          } else if (Math.abs(offset) > 0) {
+            parentNode.x += offset;
+            person.x = parentNode.x;
+          }
+        }
+      }
+
+      // Resolve collisions after adjustments
+      let maxIterations = 5;
+      while (this.detectCollisions(positions, gen) && maxIterations > 0) {
+        this.resolveCollisions(positions, gen);
+        maxIterations--;
+      }
+    }
+  }
+
   /**
    * Adjust children positions to be centered under their parents
+   * Now includes collision detection and resolution
    */
   private adjustChildrenPositions(
     generations: Map<number, Person[]>,
@@ -302,14 +495,19 @@ export class PedigreeLayout {
         if (parentCenter === null) continue;
 
         // Calculate current sibling group center
-        const siblingPositions = siblings.map(s => positions.get(s.id)!);
+        const siblingPositions = siblings.map(s => positions.get(s.id)!).filter(p => p !== undefined);
+        if (siblingPositions.length === 0) continue;
+
         const currentCenter = (siblingPositions[0].x + siblingPositions[siblingPositions.length - 1].x) / 2;
 
         // Calculate offset needed
         const offset = parentCenter - currentCenter;
 
-        // Apply offset to all siblings (if it doesn't cause overlap)
+        // Check if offset would cause collision
-        // For now, we'll skip overlap checking for simplicity
+        const wouldCollide = this.checkOffsetCollision(siblings, offset, positions, gen);
+
+        if (!wouldCollide) {
+          // Apply full offset
           for (const sibling of siblings) {
             const node = positions.get(sibling.id);
             if (node) {
@@ -317,9 +515,96 @@ export class PedigreeLayout {
               sibling.x = node.x;
             }
           }
+        } else {
+          // Apply partial offset (move towards parent but stop before collision)
+          const safeOffset = this.calculateSafeOffset(siblings, offset, positions, gen);
+          for (const sibling of siblings) {
+            const node = positions.get(sibling.id);
+            if (node) {
+              node.x += safeOffset;
+              sibling.x = node.x;
             }
           }
         }
+      }
+
+      // Resolve any remaining collisions in this generation
+      let maxIterations = 5;
+      while (this.detectCollisions(positions, gen) && maxIterations > 0) {
+        this.resolveCollisions(positions, gen);
+        maxIterations--;
+      }
+    }
+  }
+
+  /**
+   * Check if applying an offset to siblings would cause collision
+   */
+  private checkOffsetCollision(
+    siblings: Person[],
+    offset: number,
+    positions: Map<string, LayoutNode>,
+    generation: number
+  ): boolean {
+    const { nodeWidth, horizontalSpacing } = this.options;
+    const siblingIds = new Set(siblings.map(s => s.id));
+
+    // Get all nodes in this generation
+    const genNodes = Array.from(positions.values())
+      .filter(node => node.generation === generation)
+      .sort((a, b) => a.x - b.x);
+
+    // Simulate the offset
+    const simulatedPositions = genNodes.map(node => ({
+      id: node.person.id,
+      x: siblingIds.has(node.person.id) ? node.x + offset : node.x,
+      isSpouse: (i: number) => {
+        if (i === 0) return false;
+        const prev = genNodes[i - 1];
+        return prev.person.spouseIds.includes(node.person.id) ||
+               node.person.spouseIds.includes(prev.person.id);
+      }
+    }));
+
+    simulatedPositions.sort((a, b) => a.x - b.x);
+
+    // Check for collisions
+    for (let i = 1; i < simulatedPositions.length; i++) {
+      const prev = simulatedPositions[i - 1];
+      const curr = simulatedPositions[i];
+
+      const minDistance = nodeWidth + horizontalSpacing;
+      if (curr.x - prev.x < minDistance) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Calculate a safe offset that moves siblings towards parent without collision
+   */
+  private calculateSafeOffset(
+    siblings: Person[],
+    desiredOffset: number,
+    positions: Map<string, LayoutNode>,
+    generation: number
+  ): number {
+    // Binary search for the maximum safe offset
+    const step = desiredOffset > 0 ? 5 : -5;
+    let safeOffset = 0;
+
+    for (let testOffset = 0; Math.abs(testOffset) < Math.abs(desiredOffset); testOffset += step) {
+      if (!this.checkOffsetCollision(siblings, testOffset, positions, generation)) {
+        safeOffset = testOffset;
+      } else {
+        break;
+      }
+    }
+
+    return safeOffset;
+  }
 
   /**
    * Group persons by their parents
@@ -343,6 +628,248 @@ export class PedigreeLayout {
     return groups;
   }
 
+  /**
+   * Build family units from relationships
+   */
+  private buildFamilyUnits(pedigree: Pedigree): FamilyUnit[] {
+    const familyUnits: FamilyUnit[] = [];
+    const processedRelationships = new Set<string>();
+
+    // Create family unit for each relationship
+    for (const [relId, relationship] of pedigree.relationships) {
+      if (processedRelationships.has(relId)) continue;
+      processedRelationships.add(relId);
+
+      const person1 = pedigree.persons.get(relationship.person1Id);
+      const person2 = pedigree.persons.get(relationship.person2Id);
+
+      if (!person1 || !person2) continue;
+
+      const unit: FamilyUnit = {
+        id: relId,
+        parents: [relationship.person1Id, relationship.person2Id],
+        children: [...relationship.childrenIds],
+        relationshipId: relId,
+        generation: person1.generation ?? 0,
+        minWidth: 0,
+      };
+
+      familyUnits.push(unit);
+    }
+
+    // Handle single parents (persons with children but no relationship)
+    for (const [personId, person] of pedigree.persons) {
+      if (person.childrenIds.length === 0) continue;
+
+      // Check if already covered by a relationship
+      const coveredChildren = new Set<string>();
+      for (const unit of familyUnits) {
+        if (unit.parents.includes(personId)) {
+          unit.children.forEach(c => coveredChildren.add(c));
+        }
+      }
+
+      // Find children not covered by any relationship
+      const uncoveredChildren = person.childrenIds.filter(c => !coveredChildren.has(c));
+      if (uncoveredChildren.length > 0) {
+        const unit: FamilyUnit = {
+          id: `single-${personId}`,
+          parents: [personId],
+          children: uncoveredChildren,
+          relationshipId: null,
+          generation: person.generation ?? 0,
+          minWidth: 0,
+        };
+        familyUnits.push(unit);
+      }
+    }
+
+    return familyUnits;
+  }
+
+  /**
+   * Calculate minimum width needed for a family unit
+   */
+  private calculateFamilyUnitWidth(unit: FamilyUnit): number {
+    const { nodeWidth, horizontalSpacing, spouseSpacing, siblingSpacing } = this.options;
+
+    // Width of parents
+    const parentsWidth = unit.parents.length === 2
+      ? nodeWidth * 2 + spouseSpacing
+      : nodeWidth;
+
+    // Width of children
+    let childrenWidth = 0;
+    if (unit.children.length > 0) {
+      childrenWidth = unit.children.length * nodeWidth +
+                      (unit.children.length - 1) * siblingSpacing;
+    }
+
+    // Family unit width is the maximum of parents width and children width
+    // Plus margin on each side for separation
+    const margin = horizontalSpacing;
+    return Math.max(parentsWidth, childrenWidth) + margin * 2;
+  }
+
+  /**
+   * Detect collisions in a generation
+   */
+  private detectCollisions(positions: Map<string, LayoutNode>, generation: number): boolean {
+    const { nodeWidth, horizontalSpacing } = this.options;
+    const nodesInGen = Array.from(positions.values())
+      .filter(node => node.generation === generation)
+      .sort((a, b) => a.x - b.x);
+
+    for (let i = 1; i < nodesInGen.length; i++) {
+      const prev = nodesInGen[i - 1];
+      const curr = nodesInGen[i];
+
+      // Determine minimum spacing based on relationship
+      const areSpouses = prev.person.spouseIds.includes(curr.person.id) ||
+                         curr.person.spouseIds.includes(prev.person.id);
+      const minDistance = nodeWidth + (areSpouses ? this.options.spouseSpacing : horizontalSpacing);
+      const actualDistance = curr.x - prev.x;
+
+      if (actualDistance < minDistance) {
+        return true; // Collision detected
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * Resolve collisions in a generation by shifting nodes to the right
+   */
+  private resolveCollisions(positions: Map<string, LayoutNode>, generation: number): void {
+    const { nodeWidth, horizontalSpacing } = this.options;
+    const nodesInGen = Array.from(positions.values())
+      .filter(node => node.generation === generation)
+      .sort((a, b) => a.x - b.x);
+
+    for (let i = 1; i < nodesInGen.length; i++) {
+      const prev = nodesInGen[i - 1];
+      const curr = nodesInGen[i];
+
+      // Determine minimum spacing based on relationship
+      const areSpouses = prev.person.spouseIds.includes(curr.person.id) ||
+                         curr.person.spouseIds.includes(prev.person.id);
+      const minDistance = nodeWidth + (areSpouses ? this.options.spouseSpacing : horizontalSpacing);
+      const actualDistance = curr.x - prev.x;
+
+      if (actualDistance < minDistance) {
+        const shift = minDistance - actualDistance;
+
+        // Shift this node and all nodes to the right
+        for (let j = i; j < nodesInGen.length; j++) {
+          const node = nodesInGen[j];
+          node.x += shift;
+          node.person.x = node.x;
+        }
+      }
+    }
+  }
+
+  /**
+   * Find persons who appear in multiple family units (multiple marriages)
+   */
+  private findSharedPersons(familyUnits: FamilyUnit[]): Map<string, FamilyUnit[]> {
+    const personToUnits = new Map<string, FamilyUnit[]>();
+
+    for (const unit of familyUnits) {
+      for (const parentId of unit.parents) {
+        if (!personToUnits.has(parentId)) {
+          personToUnits.set(parentId, []);
+        }
+        personToUnits.get(parentId)!.push(unit);
+      }
+    }
+
+    // Filter to only those with multiple units
+    const sharedPersons = new Map<string, FamilyUnit[]>();
+    for (const [personId, units] of personToUnits) {
+      if (units.length > 1) {
+        sharedPersons.set(personId, units);
+      }
+    }
+
+    return sharedPersons;
+  }
+
+  /**
+   * Sort generations with awareness of family units and shared persons
+   * Ensures proper ordering to minimize overlaps
+   */
+  private sortGenerationWithFamilyUnits(
+    persons: Person[],
+    pedigree: Pedigree,
+    familyUnits: FamilyUnit[],
+    sharedPersons: Map<string, FamilyUnit[]>
+  ): Person[] {
+    if (persons.length <= 1) {
+      return [...persons];
+    }
+
+    const result: Person[] = [];
+    const processed = new Set<string>();
+
+    // First, handle shared persons (people with multiple marriages)
+    // They should be placed with all their spouses in sequence
+    for (const [sharedId, units] of sharedPersons) {
+      const sharedPerson = persons.find(p => p.id === sharedId);
+      if (!sharedPerson || processed.has(sharedId)) continue;
+
+      // Collect all spouses of this person
+      const spouses: Person[] = [];
+      for (const unit of units) {
+        for (const parentId of unit.parents) {
+          if (parentId !== sharedId) {
+            const spouse = persons.find(p => p.id === parentId);
+            if (spouse && !processed.has(spouse.id)) {
+              spouses.push(spouse);
+            }
+          }
+        }
+      }
+
+      // Add first spouse, then shared person, then remaining spouses
+      // This places the shared person in the middle
+      if (spouses.length > 0) {
+        result.push(spouses[0]);
+        processed.add(spouses[0].id);
+      }
+
+      result.push(sharedPerson);
+      processed.add(sharedId);
+
+      for (let i = 1; i < spouses.length; i++) {
+        result.push(spouses[i]);
+        processed.add(spouses[i].id);
+      }
+    }
+
+    // Then process remaining persons normally
+    for (const person of persons) {
+      if (processed.has(person.id)) continue;
+
+      const group: Person[] = [person];
+      processed.add(person.id);
+
+      // Add all spouses
+      for (const spouseId of person.spouseIds) {
+        const spouse = persons.find(p => p.id === spouseId);
+        if (spouse && !processed.has(spouse.id)) {
+          group.push(spouse);
+          processed.add(spouse.id);
+        }
+      }
+
+      result.push(...group);
+    }
+
+    return result;
+  }
+
   /**
    * Center the entire layout around (0, 0)
    */

src/core/model/types.ts

@@ -62,6 +62,10 @@ export interface PersonStatus {
 
 export interface PersonMetadata {
   label?: string;
+  label2?: string;         // Second line custom text
+  showBirthYear?: boolean; // Show birth year in label
+  showDeathYear?: boolean; // Show death year in label
+  showAge?: boolean;       // Show age in label
   notes?: string;
   birthYear?: number;
   deathYear?: number;
@@ -186,6 +190,19 @@ export interface LayoutNode {
   order: number; // Order within generation
 }
 
+/**
+ * Family Unit - represents a couple and their children
+ * Used for calculating layout widths and preventing overlaps
+ */
+export interface FamilyUnit {
+  id: string;
+  parents: string[];        // Person IDs of parents (1-2 people)
+  children: string[];       // Person IDs of direct children
+  relationshipId: string | null;
+  generation: number;       // Generation of the parents
+  minWidth: number;         // Minimum width needed for this family
+}
+
 // ============================================
 // Render Types
 // ============================================