diff --git a/modules/services.nix b/modules/services.nix
index ce2f961..aaf50c1 100644
--- a/modules/services.nix
+++ b/modules/services.nix
@@ -123,12 +123,22 @@
     partOf = [ "graphical-session.target" ];
     after = [ "graphical-session.target" ];
     wantedBy = [ "graphical-session.target" ];
-    # stasis runs the configured actions as `sh -lc`, so those resolve through
-    # /etc/profile and need nothing here beyond a shell to start. niri, pactl
-    # and notify-send it spawns directly, past the shell, and pactl is why
-    # pulseaudio appears at all — it stays off systemPackages, see
-    # modules/desktop.nix.
-    path = with pkgs; [ bashNonInteractive niri pulseaudio libnotify ];
+    # Every binary a configured action names has to be listed here. stasis does
+    # not run the actions through a login shell, so /etc/profile never applies
+    # and nothing resolves via /run/current-system/sw/bin. A missing binary is
+    # silent: the spawn fails, stasis logs the action as started, sees the
+    # immediate exit, treats the step as finished and stops there — which is how
+    # swaylock was absent for the whole idle chain while `niri msg` worked.
+    # pactl is why pulseaudio appears at all — it stays off systemPackages, see
+    # modules/desktop.nix. brightnessctl is for the laptop's brightness step.
+    path = with pkgs; [
+      bashNonInteractive
+      niri
+      pulseaudio
+      libnotify
+      swaylock
+      brightnessctl
+    ];
     serviceConfig = {
       Type = "simple";
       ExecStart = "${lib.getExe pkgs.stasis}";