const { data, error } = await supabase.storage
  .from("documents")
  .createSignedUrl("user-123/report.pdf", 60);

if (error) throw error;

const md = await fetch("https://api.markpdf.tech/convert/from-url", {
  method: "POST",
  headers: {
    "x-api-key": process.env.FLASH_MD_API_KEY!,
    "content-type": "application/json"
  },
  body: JSON.stringify({
    url: data.signedUrl,
    filename: "report.pdf",
    mode: "fast"
  })
}).then((r) => r.text());