cap get_loose_ends todo output + add ack_todos_until bulk-clear (#2944)

hive-agent/src/todo_server.rs

@@ -202,6 +202,7 @@ fn dispatch(
         } => clear_todo(store, &subsystem, key.as_deref(), all),
         Request::ListTodos { subsystem } => list_todos(store, subsystem.as_deref()),
         Request::MarkTodoDone { id } => mark_todo_done(store, id),
+        Request::MarkTodosDoneUntil { up_to } => mark_todos_done_until(store, up_to),
         Request::StoreReminder {
             message,
             timing,
@@ -417,6 +418,21 @@ fn mark_todo_done(store: &Todos, id: i64) -> Response {
     }
 }
 
+/// `MarkTodosDoneUntil` handler: bulk-acks every un-acked todo id at or
+/// below `up_to` — the escape hatch for a backlog too large to triage
+/// one-by-one (see `Todos::mark_done_until`'s doc for why it's needed).
+fn mark_todos_done_until(store: &Todos, up_to: i64) -> Response {
+    match store.mark_done_until(up_to) {
+        Ok(count) => {
+            tracing::debug!(up_to, count, "todo bulk mark-done");
+            Response::Acked {
+                count: u64::try_from(count).unwrap_or(0),
+            }
+        }
+        Err(e) => err(&e),
+    }
+}
+
 /// `Request::Compact` handler: gate on context usage, then queue the same
 /// deferred `compact_pending` flag the operator's `/compact` button sets.
 /// Mirrors `hive-agent::web_ui::actions::post_compact` but reachable from