diff --git a/src/app/(app)/orders/[id]/page.tsx b/src/app/(app)/orders/[id]/page.tsx
index ef0c60a..afb5a25 100644
--- a/src/app/(app)/orders/[id]/page.tsx
+++ b/src/app/(app)/orders/[id]/page.tsx
@@ -36,6 +36,7 @@ import {
   RefreshCw,
   History,
   Send,
+  Paperclip,
 } from "lucide-react";
 import {
   Dialog,
@@ -108,6 +109,13 @@ export default function OrderDetailPage({ params }: { params: Promise<{ id: stri
   // build a non-misleading body, so the textarea is disabled until
   // the count is resolved.
   const [sendMessageLoading, setSendMessageLoading] = useState(false);
+  // Additional attachments (supplier quote, drawing, NDA, etc.) sent
+  // alongside the PO PDF. PB stores these as file tokens in
+  // `po.additional_attachments`; the modal reads them on open and
+  // writes back via the upload/delete routes.
+  const [attachments, setAttachments] = useState<string[]>([]);
+  const [attachmentsLoading, setAttachmentsLoading] = useState(false);
+  const [attachmentUploading, setAttachmentUploading] = useState(false);
   const [loading, setLoading] = useState(true);
   const [deleteOpen, setDeleteOpen] = useState(false);
 
@@ -331,6 +339,12 @@ export default function OrderDetailPage({ params }: { params: Promise<{ id: stri
       toast.error("Couldn't load line count for preview; check the PO before sending.");
     } finally {
       setSendMessageLoading(false);
+      // Seed the attachments list from the PO record that just opened
+      // the modal. PB returns a multi-file field as either an array
+      // or (for legacy single-file rows) a bare string — normalise
+      // to string[] so the rest of the modal can treat it uniformly.
+      const rawAtt = po.additional_attachments ?? [];
+      setAttachments(Array.isArray(rawAtt) ? rawAtt : rawAtt ? [rawAtt] : []);
     }
   };
 
@@ -402,6 +416,58 @@ export default function OrderDetailPage({ params }: { params: Promise<{ id: stri
     }
   };
 
+  // ─── Additional attachments handlers ──────────────────────────
+  // Upload one or more files to `po.additional_attachments` via the
+  // dedicated route. We refresh `attachments` from each successful
+  // response so the list always reflects the canonical PB state.
+  const uploadAttachments = async (files: FileList | null) => {
+    if (!sendPo || !files || files.length === 0) return;
+    setAttachmentUploading(true);
+    try {
+      for (const file of Array.from(files)) {
+        const fd = new FormData();
+        fd.append("file", file);
+        const res = await fetch(
+          `/api/v1/purchase-orders/${sendPo.id}/attachments/upload`,
+          { method: "POST", body: fd },
+        );
+        if (!res.ok) {
+          const body = await res.json().catch(() => ({}));
+          toast.error(
+            `Upload failed for ${file.name}: ${body.error ?? res.status}`,
+          );
+          continue;
+        }
+        const data = (await res.json()) as { attachments: string[] };
+        setAttachments(data.attachments ?? []);
+      }
+    } finally {
+      setAttachmentUploading(false);
+    }
+  };
+
+  // Remove a single attachment by its PB token. The token is what
+  // appears in `additional_attachments[]`; it may differ from the
+  // operator's original filename because PB slug-normalises on disk.
+  const removeAttachment = async (token: string) => {
+    if (!sendPo) return;
+    setAttachmentUploading(true);
+    try {
+      const res = await fetch(
+        `/api/v1/purchase-orders/${sendPo.id}/attachments/${encodeURIComponent(token)}`,
+        { method: "DELETE" },
+      );
+      if (!res.ok) {
+        toast.error("Couldn't remove attachment");
+        return;
+      }
+      const data = (await res.json()) as { attachments: string[] };
+      setAttachments(data.attachments ?? []);
+    } finally {
+      setAttachmentUploading(false);
+    }
+  };
+
   // Order-level "Complete" — derived from items, not stored anywhere.
   const complete = isOrderComplete(items);
 
@@ -1100,6 +1166,59 @@ export default function OrderDetailPage({ params }: { params: Promise<{ id: stri
                   : `${sendMessage.length}/2000`}
               </p>
             </div>
+            <div className="space-y-2 rounded-md border p-3">
+              <div className="flex items-center justify-between">
+                <div>
+                  <p className="text-sm font-medium">Additional attachments</p>
+                  <p className="text-xs text-muted-foreground">
+                    Files sent alongside the PO PDF (supplier quotes, drawings, etc.).
+                  </p>
+                </div>
+                <label className="inline-flex cursor-pointer items-center gap-1.5 rounded-md border bg-background px-2 py-1 text-xs hover:bg-accent">
+                  <Paperclip className="h-3 w-3" />
+                  {attachmentUploading ? "Uploading…" : "Attach files"}
+                  <input
+                    type="file"
+                    multiple
+                    className="hidden"
+                    onChange={(e) => uploadAttachments(e.target.files)}
+                    disabled={attachmentUploading}
+                  />
+                </label>
+              </div>
+              {attachments.length === 0 ? (
+                <p className="text-xs text-muted-foreground">No additional files attached.</p>
+              ) : (
+                <ul className="space-y-1">
+                  {attachments.map((token) => (
+                    <li
+                      key={token}
+                      className="flex items-center justify-between gap-2 rounded border bg-muted/30 px-2 py-1 text-xs"
+                    >
+                      <a
+                        href={sendPo ? `/api/v1/files/purchase_orders/${sendPo.id}/${encodeURIComponent(token)}` : "#"}
+                        target="_blank"
+                        rel="noopener noreferrer"
+                        className="truncate text-foreground hover:underline"
+                      >
+                        {token}
+                      </a>
+                      <Button
+                        type="button"
+                        variant="ghost"
+                        size="icon"
+                        className="h-5 w-5 text-muted-foreground hover:text-destructive"
+                        onClick={() => removeAttachment(token)}
+                        disabled={attachmentUploading}
+                        aria-label={`Remove ${token}`}
+                      >
+                        <Trash2 className="h-3 w-3" />
+                      </Button>
+                    </li>
+                  ))}
+                </ul>
+              )}
+            </div>
             {sendPo?.status === "mail_failed" && sendPo?.email_error && (
               <div className="rounded-md border border-destructive/30 bg-destructive/5 px-3 py-2 text-xs text-destructive">
                 <span className="font-medium">Previous failure:</span>{" "}