end

    pub fn end(n: Node) void {
        if (noop_impl) {
            assert(n.index == .none);
            return;
        }
        const index = n.index.unwrap() orelse return;
        const io = global_progress.io;
        const parent_ptr = parentByIndex(index);
        if (@atomicLoad(Node.Parent, parent_ptr, .monotonic).unwrap()) |parent_index| {
            _ = @atomicRmw(u32, &storageByIndex(parent_index).completed_count, .Add, 1, .monotonic);
            @atomicStore(Node.Parent, parent_ptr, .unused, .monotonic);

            if (storageByIndex(index).getIpcIndex()) |ipc_index| {
                const file = global_progress.ipc_files[ipc_index.slot];
                const ipc = @atomicRmw(
                    Ipc,
                    &global_progress.ipc[ipc_index.slot],
                    .And,
                    .{ .locked = true, .valid = false, .generation = std.math.maxInt(Ipc.Generation) },
                    .release,
                );
                assert(ipc.valid and ipc.generation == ipc_index.generation);
                if (!ipc.locked) file.close(io);
            }

            const freelist = &global_progress.node_freelist;
            var old_freelist = @atomicLoad(Freelist, freelist, .monotonic);
            while (true) {
                @atomicStore(Node.OptionalIndex, freelistNextByIndex(index), old_freelist.head, .monotonic);
                old_freelist = @cmpxchgWeak(
                    Freelist,
                    freelist,
                    old_freelist,
                    .{ .head = index.toOptional(), .generation = old_freelist.generation +% 1 },
                    .release, // ensure a matching `start` sees the freelist link written above
                    .monotonic, // our write above is irrelevant if we need to retry
                ) orelse {
                    // We won the race.
                    return;
                };
            }
        } else {
            if (global_progress.update_worker) |*worker| worker.cancel(io) catch {};
            for (&global_progress.ipc, &global_progress.ipc_files) |ipc, ipc_file| {
                assert(!ipc.locked or !ipc.valid); // missing call to end()
                if (ipc.locked or ipc.valid) ipc_file.close(io);
            }
        }
    }