ref: make isFamilyType a TypeSchemaIndex method

The family-root predicate belongs to the index that resolves it: replaces
mkIsFamilyType in the TypeScript profile writer and the byte-identical
inline copy in the Python naming utils.

Author: ryukzak

CLAUDE.md

@@ -286,7 +286,7 @@ Single-element slices (`max: 1`) keep the existing single-item API.
 
 When a reference target is a family type (e.g. `Resource`, `DomainResource`), the generated type uses `Reference<string /* Resource */>` instead of `Reference<"Resource">`. This makes narrower profile references like `Reference<"Patient">` assignable to the base type field.
 
-Detection uses `mkIsFamilyType(tsIndex)` which checks `schema.typeFamily.resources.length > 0`.
+Detection uses `tsIndex.isFamilyType` which checks `schema.typeFamily.resources.length > 0`.
 
 ### Slice Field Validation
 

src/api/writer-generator/python/naming-utils.ts

@@ -133,13 +133,8 @@ export const pyReferenceTypeParam = (
     tsIndex: TypeSchemaIndex,
 ): string | undefined => {
     if (!field.reference || field.reference.resource.length === 0) return undefined;
-    const isFamilyType = (ref: TypeIdentifier): boolean => {
-        const schema = tsIndex.resolveType(ref);
-        if (!schema || !("typeFamily" in schema)) return false;
-        return (schema.typeFamily?.resources?.length ?? 0) > 0;
-    };
     const resolved = field.reference.resource.map((ref) => tsIndex.findLastSpecializationByIdentifier(ref));
-    if (resolved.some(isFamilyType)) return undefined;
+    if (resolved.some(tsIndex.isFamilyType)) return undefined;
     const names = [...new Set(resolved.map((ref) => ref.name))];
     return `Literal[${names.map((n) => JSON.stringify(n)).join(", ")}]`;
 };

src/api/writer-generator/typescript/profile.ts

@@ -119,14 +119,6 @@ const tryPromoteChoice = (
     promotedChoices.add(choiceName);
 };
 
-export const mkIsFamilyType =
-    (tsIndex: TypeSchemaIndex) =>
-    (ref: TypeIdentifier): boolean => {
-        const schema = tsIndex.resolveType(ref);
-        if (!schema || !("typeFamily" in schema)) return false;
-        return (schema.typeFamily?.resources?.length ?? 0) > 0;
-    };
-
 export const collectProfileFactoryInfo = (
     tsIndex: TypeSchemaIndex,
     snapshot: SnapshotProfileTypeSchema,
@@ -139,7 +131,7 @@ export const collectProfileFactoryInfo = (
     const fields = snapshot.fields;
     const promotedChoices = new Set<string>();
     const resolveRef = tsIndex.findLastSpecializationByIdentifier;
-    const isFamilyType = mkIsFamilyType(tsIndex);
+    const isFamilyType = tsIndex.isFamilyType;
 
     if (isResourceIdentifier(snapshot.base)) {
         autoFields.push({ name: "resourceType", value: JSON.stringify(snapshot.base.name) });

src/api/writer-generator/typescript/writer.ts

@@ -42,7 +42,7 @@ import {
     tsProfileModuleFileName,
     tsResourceName,
 } from "./name";
-import { generateProfileClass, generateProfileImports, generateProfileIndexFile, mkIsFamilyType } from "./profile";
+import { generateProfileClass, generateProfileImports, generateProfileIndexFile } from "./profile";
 import { resolveFieldTsType } from "./utils";
 
 export const resolveTsAssets = (fn: string) => resolveGeneratorAsset(import.meta.url, "typescript", fn);
@@ -475,7 +475,7 @@ export class TypeScript extends Writer<TypeScriptOptions> {
                 });
             });
         } else if (isSpecializationTypeSchema(schema)) {
-            const isFamilyType = mkIsFamilyType(tsIndex);
+            const isFamilyType = tsIndex.isFamilyType;
             this.cat(`${tsModuleFileName(schema.identifier)}`, () => {
                 this.generateDisclaimer();
                 this.generateDependenciesImports(tsIndex, schema);

src/typeschema/utils.ts

@@ -353,6 +353,7 @@ export type TypeSchemaIndex = {
     hierarchy: (schema: TypeSchema) => TypeSchema[];
     findLastSpecialization: (schema: TypeSchema) => TypeSchema;
     findLastSpecializationByIdentifier: (id: TypeIdentifier) => TypeIdentifier;
+    isFamilyType: (id: TypeIdentifier) => boolean;
     flatProfile: (schema: ProfileTypeSchema) => ProfileTypeSchema;
     constrainedChoice: (
         pkgName: PkgName,
@@ -588,6 +589,15 @@ export const mkTypeSchemaIndex = (
         return findLastSpecialization(resolved).identifier;
     };
 
+    /** True when `id` resolves to a family root — a specialization with concrete
+     *  resource descendants (e.g. Resource, DomainResource), where a reference
+     *  target admits any member of the family. */
+    const isFamilyType = (id: TypeIdentifier): boolean => {
+        const schema = resolveType(id);
+        if (!schema || !("typeFamily" in schema)) return false;
+        return (schema.typeFamily?.resources?.length ?? 0) > 0;
+    };
+
     /** Resolve the permitted choice variants monotonically through the profile hierarchy.
      *  Each profile's constraints (restated declaration, declared instances, exclusions)
      *  intersect with the inherited permitted set, so a child profile can never
@@ -859,6 +869,7 @@ export const mkTypeSchemaIndex = (
         hierarchy,
         findLastSpecialization,
         findLastSpecializationByIdentifier,
+        isFamilyType,
         flatProfile,
         constrainedChoice,
         sliceChoiceVariants,