checkpoint

Author: jonathantneal

src/loader/merge.ts

@@ -39,45 +39,48 @@ export const mergeFormats = (formats: Format[], root?: RawObject, inheritedType?
 		return ownType ?? inheritedType;
 	};
 
-	// ── Define a lazy getter for every key ────────────────────────────────────
+	// ── Define a self-memoizing getter for every key ─────────────────────────
+	// On first access the getter computes the value, overwrites itself with a
+	// plain data property, and is never called again. After a single traversal
+	// the object is indistinguishable from a regular {}.
 	for (const key of keys) {
 		Object.defineProperty(merged, key, {
 			get(): unknown {
 				// $type: own value, or fall back to the inherited type.
-				if (key === "$type") return getNodeType();
-
-				const subFormats: RawObject[] = [];
-				let leafValue: unknown;
-				let hasLeaf = false;
-
-				for (const format of formats) {
-					const val = (format as RawObject)[key];
-					if (val === undefined) continue;
-
-					if (isPlainObject(val)) {
-						subFormats.push(val);
-					} else {
-						// A later leaf (primitive or array) wins; reset sub-objects.
-						subFormats.length = 0;
-						leafValue = val;
-						hasLeaf = true;
+				let value: unknown = key === "$type" ? getNodeType() : undefined;
+
+				if (value === undefined && key !== "$type") {
+					const subFormats: RawObject[] = [];
+					let leafValue: unknown;
+					let hasLeaf = false;
+
+					for (const format of formats) {
+						const val = (format as RawObject)[key];
+						if (val === undefined) continue;
+
+						if (isPlainObject(val)) {
+							subFormats.push(val);
+						} else {
+							// A later leaf (primitive or array) wins; reset sub-objects.
+							subFormats.length = 0;
+							leafValue = val;
+							hasLeaf = true;
+						}
 					}
-				}
-
-				if (subFormats.length > 0) {
-					// Pass along the current node's effective type so children can inherit it.
-					return mergeFormats(subFormats as Format[], effectiveRoot, getNodeType());
-				}
 
-				if (hasLeaf) {
-					// Resolve DTCG alias strings in $value lazily against the merged root.
-					if (key === "$value" && isAlias(leafValue)) {
-						return resolveAlias(leafValue, effectiveRoot);
+					if (subFormats.length > 0) {
+						// Pass along the current node's effective type so children can inherit it.
+						value = mergeFormats(subFormats as Format[], effectiveRoot, getNodeType());
+					} else if (hasLeaf) {
+						// Resolve DTCG alias strings in $value lazily against the merged root.
+						value = key === "$value" && isAlias(leafValue) ? resolveAlias(leafValue, effectiveRoot) : leafValue;
 					}
-					return leafValue;
 				}
 
-				return undefined;
+				// Replace this getter with the computed value so the object becomes
+				// a plain data property after first access.
+				Object.defineProperty(this, key, { value, enumerable: true, configurable: true });
+				return value;
 			},
 			enumerable: true,
 			configurable: true,