diff --git a/frontend/src/api/client.ts b/frontend/src/api/client.ts
index bbbc35d..3a71857 100644
--- a/frontend/src/api/client.ts
+++ b/frontend/src/api/client.ts
@@ -431,9 +431,18 @@ export async function reviewCheckpoint(checkpointId: string): Promise<import('..
 
 // ── Delete endpoints ─────────────────────────────────────────────────────────
 
-/** Delete a space and cascade to all its checkpoints, sessions, and turns. */
-export async function deleteRepo(repoId: string): Promise<void> {
-  return requestV2<void>(`/repos/${repoId}`, { method: 'DELETE' });
+/**
+ * Delete a space and cascade to all its checkpoints, sessions, and turns.
+ * The backend refuses with 409 unless force=true is passed for a space that
+ * still holds checkpoints, so callers must confirm with the user first, then
+ * pass { force: true }.
+ */
+export async function deleteRepo(
+  repoId: string,
+  opts?: { force?: boolean },
+): Promise<void> {
+  const qs = opts?.force ? '?force=true' : '';
+  return requestV2<void>(`/repos/${repoId}${qs}`, { method: 'DELETE' });
 }
 
 /**
diff --git a/frontend/src/pages/WorkspaceOverviewPage.tsx b/frontend/src/pages/WorkspaceOverviewPage.tsx
index aa19270..981f471 100644
--- a/frontend/src/pages/WorkspaceOverviewPage.tsx
+++ b/frontend/src/pages/WorkspaceOverviewPage.tsx
@@ -430,7 +430,10 @@ export function WorkspaceOverviewPage() {
           body="This will permanently delete the space, all of its checkpoints, sessions, and turns. This cannot be undone."
           onClose={() => setDeleteTarget(null)}
           onConfirm={async () => {
-            await deleteRepo(deleteTarget.id);
+            // force=true: the ConfirmDeleteModal above is the user's
+            // explicit confirmation, which the backend's non-empty
+            // delete guard requires.
+            await deleteRepo(deleteTarget.id, { force: true });
             setDeleteTarget(null);
             await refreshWorkspace();
           }}