fix(imports): tolerate a UTF-8 BOM in uploaded Trakt JSON

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

packages/core/src/imports/parsers.ts

@@ -424,6 +424,11 @@ function addTraktDocument(agg: TraktAggregate, json: unknown): void {
   }
 }
 
+/** JSON.parse that tolerates a leading UTF-8 BOM (as Blob.json() does). */
+function parseJsonText(text: string): unknown {
+  return JSON.parse(text.charCodeAt(0) === 0xfeff ? text.slice(1) : text);
+}
+
 /**
  * Parse an uploaded Trakt export: Trakt's official ZIP (watched-history-*.json,
  * ratings-*.json, lists-watchlist.json, …), any single JSON file from it, or the
@@ -447,7 +452,7 @@ export async function parseTraktExport(file: Blob): Promise<ParseResult> {
       const name = entry.entryName.split("/").pop() ?? entry.entryName;
       if (!name.toLowerCase().endsWith(".json")) continue;
       try {
-        addTraktDocument(agg, JSON.parse(entry.getData().toString("utf-8")));
+        addTraktDocument(agg, parseJsonText(entry.getData().toString("utf-8")));
       } catch {
         log.debug(`Skipping unreadable Trakt export entry: ${entry.entryName}`);
       }
@@ -455,7 +460,7 @@ export async function parseTraktExport(file: Blob): Promise<ParseResult> {
   } else {
     let json: unknown;
     try {
-      json = JSON.parse(buf.toString("utf8"));
+      json = parseJsonText(buf.toString("utf8"));
     } catch {
       throw new Error("Invalid JSON file");
     }

packages/core/test/import-parsers.test.ts

@@ -1362,6 +1362,18 @@ describe("parseTraktExport", () => {
     );
   });
 
+  test("accepts a JSON file with a UTF-8 byte-order mark", async () => {
+    const bytes = new Uint8Array([
+      0xef,
+      0xbb,
+      0xbf,
+      ...new TextEncoder().encode(JSON.stringify(historyItems)),
+    ]);
+    const result = await parseTraktExport(new Blob([bytes], { type: "application/json" }));
+    expect(result.data.movies).toHaveLength(1);
+    expect(result.data.episodes).toHaveLength(1);
+  });
+
   test("skips an unparsable JSON entry inside the ZIP", async () => {
     const zip = createZip({
       "watched-history-1.json": JSON.stringify(historyItems),