[skip ci] Initial commit — CodexBar Mobile Expo app

lib/fileReader.ts

@@ -0,0 +1,34 @@
+import * as DocumentPicker from "expo-document-picker";
+import { File } from "expo-file-system/next";
+import type { CodexAuth } from "@/types/codex";
+
+export async function pickAndReadCodexAuth(): Promise<CodexAuth> {
+  const result = await DocumentPicker.getDocumentAsync({
+    type: "application/json",
+    copyToCacheDirectory: true,
+  });
+
+  if (result.canceled) {
+    throw new Error("PICKER_CANCELLED");
+  }
+
+  const { uri } = result.assets[0];
+  const file = new File(uri);
+  const text = file.text();
+
+  let parsed: Record<string, unknown>;
+  try {
+    parsed = JSON.parse(text);
+  } catch {
+    throw new Error("INVALID_JSON");
+  }
+
+  const accessToken = parsed["accessToken"] as string | undefined;
+  const accountId = parsed["accountId"] as string | undefined;
+
+  if (!accessToken || typeof accessToken !== "string") {
+    throw new Error("MISSING_ACCESS_TOKEN");
+  }
+
+  return { accessToken, accountId };
+}