Function processUploadedFiles

packages/studio-server/src/routes/files.ts:1496–1578

(
  formData: FormData,
  targetDir: string,
  projectDir: string,
)

// ── Upload file processing ──────────────────────────────────────────────────

async function processUploadedFiles(
  formData: FormData,
  targetDir: string,
  projectDir: string,
): Promise<{
  uploaded: string[];
  skipped: string[];
  invalid: Array<{ name: string; reason: string }>;
}> {
  const MAX_UPLOAD_BYTES = 500 * 1024 * 1024; // 500 MB per file
  const uploaded: string[] = [];
  const skipped: string[] = [];
  const invalid: Array<{ name: string; reason: string }> = [];

  // @types/node v25 narrows the ambient `FormData.entries()` to
  // `[string, string]` in workspaces where another dep declares an
  // `onmessage` global (it trips the worker branch of v25's conditional
  // File type). At runtime the value is still `File | string` — cast the
  // iterator so the rest of this block keeps type-checking on every
  // bun-install layout (hoisted on Windows surfaces this; isolated on
  // Linux happens to keep v24 in scope).
  type FileLike = {
    readonly name: string;
    readonly size: number;
    arrayBuffer(): Promise<ArrayBuffer>;
  };
  const entries = formData.entries() as unknown as Iterable<[string, FileLike | string]>;

  // Derive the subdirectory prefix from targetDir relative to projectDir
  const subDir = targetDir === projectDir ? "" : targetDir.slice(projectDir.length + 1);

  for (const [, value] of entries) {
    if (typeof value === "string") continue;

    // Strip path separators — browsers may include directory components
    const name = value.name.split("/").pop()?.split("\\").pop() ?? "";
    if (!name || name.includes("\0") || name.includes("..")) continue;

    // Reject individual files that exceed the size limit
    if (value.size > MAX_UPLOAD_BYTES) {
      skipped.push(name);
      continue;
    }

    const destPath = resolve(targetDir, name);
    if (!isSafePath(projectDir, destPath)) continue;

    // Don't overwrite — append (2), (3), etc.
    let finalPath = destPath;
    let finalName = name;
    if (existsSync(finalPath)) {
      // Handle dotfiles correctly: .gitignore → ext="", base=".gitignore"
      const dotIdx = name.indexOf(".", name.startsWith(".") ? 1 : 0);
      const ext = dotIdx > 0 ? name.slice(dotIdx) : "";
      const base = dotIdx > 0 ? name.slice(0, dotIdx) : name;
      let n = 2;
      const MAX_COPY_INDEX = 10000;
      while (n < MAX_COPY_INDEX && existsSync(resolve(targetDir, `${base} (${n})${ext}`))) n++;