diff --git a/src/pages/auth/PlatformAdminPage.tsx b/src/pages/auth/PlatformAdminPage.tsx
index 89c5240..60f3f12 100644
--- a/src/pages/auth/PlatformAdminPage.tsx
+++ b/src/pages/auth/PlatformAdminPage.tsx
@@ -102,6 +102,17 @@ const PlatformAdminPage: React.FC = () => {
                 </Grid>
             )}
 
+            <Alert severity="warning" sx={{ mb: 3 }}>
+                <Typography variant="subtitle2" sx={{ fontWeight: 700 }}>Destructive reset scope: exam-corpus</Typography>
+                <Typography variant="body2">
+                    The <strong>exam-corpus</strong> reset is not limited to public papers. It wipes the entire
+                    exam-marker subsystem: public corpus/eb_* data, cc.examboards storage, templates, template
+                    layouts, questions, boundaries, response areas, marking batches, student submissions, and
+                    mark entries. Use it only when you intend to rebuild all exam-marker data; it does not reset
+                    schools, users, or timetable data.
+                </Typography>
+            </Alert>
+
             <Typography variant="subtitle2" sx={{ mb: 1 }}>Schools ({loading ? '…' : schools.length})</Typography>
 
             {loading ? (