Add a family

1. Define semantic input. Add program/<kind>.ts with strict Zod objects, unique identity checks, reference validation, and cycle checks where needed.
2. Define the plugin. Add families/<kind>.ts using defineFamily().
3. Normalize. Convert every node, relation, and group to GraphIR; never parse facts from display labels.
4. Select placement. Return a configured shared strategy or a cohesive bespoke placer that still emits the common Placement shape.
5. Define notation. Map every finite style key to shared caps, dashes, and a legend label.
6. Register built-ins. Add the definition to BUILT_IN_FAMILIES, or use an isolated custom FamilyRegistry outside the built-in catalogue.
7. Create fixtures. Hand-author realistic easy, medium, and hard programs.
8. Verify visually. Run the family harness, inspect all PNGs, then run the complete gate.

A family is intentionally small

export const exampleFamily = defineFamily({
  kind: 'example',
  schema: exampleProgramSchema,
  orthogonalEdges: true,
  normalize(program) {
    return { title: program.title, nodes: [], relations: [], groups: [] };
  },
  placement() {
    return { strategy: 'layered', config: { direction: 'RIGHT' } };
  },
  notation(styleKey) {
    return NOTATION[styleKey];
  },
});

If the definition needs to import routing, labels, icons, colours, or the harness, the responsibility is in the wrong layer.