fix(protocol): keep Swift array item types stable

scripts/protocol-gen-swift.ts

@@ -80,12 +80,54 @@ function safeName(name: string) {
 
 // filled later once schemas are loaded
 const schemaNameByObject = new Map<object, string>();
+const schemaNameBySignature = new Map<string, string>();
+const duplicateSchemaSignatures = new Set<string>();
 
-function swiftType(schema: JsonSchema, required: boolean): string {
+function stableJson(value: unknown): unknown {
+  if (Array.isArray(value)) {
+    return value.map(stableJson);
+  }
+  if (value && typeof value === "object") {
+    const record = value as Record<string, unknown>;
+    return Object.fromEntries(
+      Object.keys(record)
+        .toSorted()
+        .map((key) => [key, stableJson(record[key])]),
+    );
+  }
+  return value;
+}
+
+function schemaSignature(schema: JsonSchema): string {
+  return JSON.stringify(stableJson(schema));
+}
+
+function registerNamedSchema(name: string, schema: JsonSchema): void {
+  schemaNameByObject.set(schema as object, name);
+  const signature = schemaSignature(schema);
+  if (duplicateSchemaSignatures.has(signature)) {
+    return;
+  }
+  if (schemaNameBySignature.has(signature)) {
+    schemaNameBySignature.delete(signature);
+    duplicateSchemaSignatures.add(signature);
+    return;
+  }
+  schemaNameBySignature.set(signature, name);
+}
+
+function namedSchema(schema: JsonSchema, allowStructuralFallback = false): string | undefined {
+  return (
+    schemaNameByObject.get(schema as object) ??
+    (allowStructuralFallback ? schemaNameBySignature.get(schemaSignature(schema)) : undefined)
+  );
+}
+
+function swiftType(schema: JsonSchema, required: boolean, allowStructuralNamed = false): string {
   const t = schema.type;
   const isOptional = !required;
   let base: string;
-  const named = schemaNameByObject.get(schema as object);
+  const named = namedSchema(schema, allowStructuralNamed);
   if (named) {
     base = named;
   } else if (t === "string") {
@@ -97,7 +139,7 @@ function swiftType(schema: JsonSchema, required: boolean): string {
   } else if (t === "boolean") {
     base = "Bool";
   } else if (t === "array") {
-    base = `[${swiftType(schema.items ?? { type: "Any" }, true)}]`;
+    base = `[${swiftType(schema.items ?? { type: "Any" }, true, true)}]`;
   } else if (schema.enum) {
     base = "String";
   } else if (schema.patternProperties) {
@@ -214,7 +256,7 @@ async function generate() {
   const definitions = Object.entries(ProtocolSchemas) as Array<[string, JsonSchema]>;
 
   for (const [name, schema] of definitions) {
-    schemaNameByObject.set(schema as object, name);
+    registerNamedSchema(name, schema);
   }
 
   const parts: string[] = [];