修复了2个bug

lib/seedream/layer-composition.ts

@@ -26,3 +26,16 @@ export type SeedreamLayerComposition = {
 };
 
 export type SeedreamLayerDraft = Pick<SeedreamLayerComposition, "baseAssetId" | "baseVisible" | "layers">;
+
+export function hasCompleteSeedreamLayerMetadata(records: unknown[], outputCount: number): boolean {
+  if (!Number.isInteger(outputCount) || outputCount < 2 || records.length !== outputCount) return false;
+  const indices = records.map((value) => {
+    if (!value || typeof value !== "object" || Array.isArray(value)) return undefined;
+    const raw = (value as Record<string, unknown>).z_index;
+    const index = typeof raw === "number" ? raw : typeof raw === "string" && raw.trim() ? Number(raw) : Number.NaN;
+    return Number.isInteger(index) && index >= 0 ? index : undefined;
+  });
+  if (indices.some((index) => index === undefined)) return false;
+  const numericIndices = indices as number[];
+  return numericIndices.includes(0) && new Set(numericIndices).size === numericIndices.length;
+}