Decide how to log out by what the session is, not what is installed

The power menu's Log Out ran `uwsm stop` whenever the uwsm binary existed --
which is always, since Panama installs it. In a plain "Hyprland" session there
is no uwsm unit to stop, so the command failed and the button silently did
nothing. Nor is `uwsm check is-active` the test: it reads
graphical-session.target, which the plain session also activates. The one
thing unique to a managed session is uwsm's own compositor unit,
wayland-wm@*.service, so that is now what chooses between stopping the unit
and asking the compositor to exit. A new contract pins the decision -- and
checks the script line rather than the file, because the comment explaining
the wrong tests has to be allowed to name them.

Claude-Session: https://claude.ai/code/session_01Epx9ZC1gwm81K3jm9x9CKh

config/dot/quickshell/modules/powermenu/PowerMenu.qml

@@ -31,10 +31,15 @@ PanelWindow {
 
     property int currentIndex: 0
 
-    // The session is uwsm-managed, so logging out means stopping the uwsm unit
-    // rather than killing the compositor; the hyprctl branch is only there for
-    // a session started without it.
-    readonly property string logoutScript: 'if command -v uwsm >/dev/null 2>&1; then exec uwsm stop; else exec hyprctl dispatch "hl.dsp.exit()"; fi'
+    // A uwsm-managed session logs out by stopping the uwsm unit; a plain
+    // "Hyprland" session must ask the compositor to exit instead. The branch
+    // used to test merely that the uwsm BINARY existed -- but uwsm is always
+    // installed here, so in a plain session `uwsm stop` found no unit to
+    // stop, failed, and the button did nothing. Nor is `uwsm check is-active`
+    // the test: it only checks graphical-session.target, which the plain
+    // session also reaches. What only the managed session has is uwsm's own
+    // compositor unit, wayland-wm@*.service, so that is what decides.
+    readonly property string logoutScript: 'if systemctl --user list-units --no-legend --state=active "wayland-wm@*.service" 2>/dev/null | grep -q .; then exec uwsm stop; else exec hyprctl dispatch "hl.dsp.exit()"; fi'
 
     readonly property var entries: [
         {

tests/quickshell/powermenu-contract

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+# The power menu's Log Out, in both kinds of session.
+#
+# Logging out means `uwsm stop` in a uwsm-managed session and a compositor
+# exit in a plain one -- and the script has to tell the two apart by what the
+# SESSION is, not by what is installed. It once branched on the uwsm binary
+# existing; uwsm is always installed here, so in a plain session `uwsm stop`
+# found no unit to stop, failed, and the button silently did nothing. The only
+# thing unique to the managed session is uwsm's own compositor unit.
+
+set -uo pipefail
+
+repo_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/../.." && pwd)"
+menu="$repo_dir/config/dot/quickshell/modules/powermenu/PowerMenu.qml"
+
+fail() {
+    printf 'powermenu contract: %s\n' "$1" >&2
+    exit 1
+}
+
+[[ -r "$menu" ]] || fail "$menu is missing"
+
+# The script itself, not the file: the comment above it names the wrong
+# tests while explaining them, and a contract must not fail over prose.
+script_line="$(rg -N 'logoutScript:' "$menu" | head -1)"
+[[ -n "$script_line" ]] || fail 'the logout script is gone'
+
+# The branch condition is the session's own unit, nothing weaker.
+grep -Fq 'wayland-wm@*.service' <<<"$script_line" \
+    || fail 'logout does not decide by the uwsm compositor unit'
+grep -Fq 'command -v uwsm' <<<"$script_line" \
+    && fail 'logout branches on the uwsm binary existing, which is true in both kinds of session'
+# `uwsm check is-active` is the tempting wrong test: it reads
+# graphical-session.target, which the plain session also activates.
+grep -Fq 'uwsm check is-active' <<<"$script_line" \
+    && fail 'logout branches on is-active, which the plain session also passes'
+
+# Both destinations survive.
+grep -Fq 'uwsm stop' <<<"$script_line" \
+    || fail 'a managed session has no way to stop its unit'
+grep -Fq 'hl.dsp.exit()' <<<"$script_line" \
+    || fail 'a plain session has no way to exit the compositor'
+
+printf 'powermenu contract: ok\n'