diff --git a/src/routes/collections.$collectionId.tsx b/src/routes/collections.$collectionId.tsx
index 3e61d2d..73714a0 100644
--- a/src/routes/collections.$collectionId.tsx
+++ b/src/routes/collections.$collectionId.tsx
@@ -272,6 +272,39 @@ function CollectionDetailRoute() {
     else refreshTasks();
   };
 
+  const closeCollection = async () => {
+    if (!collection) return;
+    if (!confirm("Close this collection? Open tasks will be hidden but data is preserved. You can reopen anytime.")) return;
+    setClosingBusy(true);
+    const { error } = await supabase
+      .from("collections")
+      .update({ status: "closed", closed_at: new Date().toISOString().slice(0, 10) })
+      .eq("id", collection.id);
+    setClosingBusy(false);
+    if (error) {
+      toast.error("Could not close", { description: error.message });
+      return;
+    }
+    toast.success("Collection closed");
+    setReload((r) => r + 1);
+  };
+
+  const reopenCollection = async () => {
+    if (!collection) return;
+    setClosingBusy(true);
+    const { error } = await supabase
+      .from("collections")
+      .update({ status: "late_notice", closed_at: null })
+      .eq("id", collection.id);
+    setClosingBusy(false);
+    if (error) {
+      toast.error("Could not reopen", { description: error.message });
+      return;
+    }
+    toast.success("Collection reopened");
+    setReload((r) => r + 1);
+  };
+
   if (loading) {
     return (
       <ProtectedLayout>