Add re-analyse button and POST /documents/{id}/reprocess endpoint

Resets status to pending, clears error_message, and re-enqueues the
background AI extraction task. Button is disabled while the document
is already pending or processing; returns 409 in that case from the API.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/client.ts

@@ -170,6 +170,9 @@ export const updateDocumentTags = (id: string, tags: string[]) =>
 export const updateDocumentTitle = (id: string, title: string) =>
   api.patch<DocumentOut>(`/documents/${id}/title`, { title }).then((r) => r.data);
 
+export const reprocessDocument = (id: string) =>
+  api.post<DocumentOut>(`/documents/${id}/reprocess`).then((r) => r.data);
+
 export const assignCategory = (docId: string, catId: string) =>
   api.post(`/documents/${docId}/categories/${catId}`);
 

frontend/src/pages/DocumentsPage.tsx

@@ -13,6 +13,7 @@ import {
   assignCategory,
   removeCategory,
   updateDocumentTitle,
+  reprocessDocument,
   type DocumentOut,
   type CategoryOut,
   type DocumentListParams,
@@ -225,6 +226,11 @@ function DocumentRow({
     },
   });
 
+  const reprocessMut = useMutation({
+    mutationFn: () => reprocessDocument(doc.id),
+    onSuccess: () => qc.invalidateQueries({ queryKey: ["documents"] }),
+  });
+
   const handleAcceptSuggestion = (name: string, existing: CategoryOut | undefined) => {
     if (existing) {
       assignMut.mutate({ catId: existing.id });
@@ -276,6 +282,22 @@ function DocumentRow({
         >
           Download
         </button>
+        <button
+          onClick={(e) => {
+            e.stopPropagation();
+            reprocessMut.mutate();
+          }}
+          disabled={reprocessMut.isPending || doc.status === "pending" || doc.status === "processing"}
+          style={{
+            fontSize: 12,
+            cursor: reprocessMut.isPending || doc.status === "pending" || doc.status === "processing" ? "default" : "pointer",
+            color: "#2a7ae2",
+            opacity: reprocessMut.isPending || doc.status === "pending" || doc.status === "processing" ? 0.5 : 1,
+          }}
+          title="Re-run AI analysis on this document"
+        >
+          {reprocessMut.isPending ? "…" : "Re-analyse"}
+        </button>
         <button
           onClick={(e) => {
             e.stopPropagation();