Track the power profile through Quickshell instead of polling busctl (#15027)

* Track the power profile through Quickshell instead of polling busctl

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Recover the power profile when the daemon was down at shell start

Addresses Codex review: Quickshell never attaches its PowerProfiles listener if the daemon failed at startup. One-off reads on startup, power source changes and an IPC refresh from omarchy-powerprofiles-set cover that, still with no timer.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Don't let a stale power profile read win over a change signal or drop a refresh

Addresses Codex re-review: a busctl read in flight could overwrite a newer PowerProfiles signal, and refreshes requested while a read ran were dropped.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* Test power profile transitions and stale reads as behavior, not source text

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

shell/plugins/services/battery/BatteryModel.js

@@ -19,10 +19,32 @@ function shouldWarnLowBattery(device, onBattery, dischargingState, threshold, al
   }
 }
 
+function parseActiveProfile(text) {
+  // busctl --json=short prints {"type":"s","data":"balanced"}; an empty or
+  // malformed reply (daemon not running) reads as no active profile.
+  try {
+    return String(JSON.parse(text).data || "").trim()
+  } catch (e) {
+    return ""
+  }
+}
+
+function profileAfterRead(current, replyText, signalsAtStart, signalsNow) {
+  // A change signal that arrived during the read is newer than its reply.
+  return signalsAtStart === signalsNow ? parseActiveProfile(replyText) : current
+}
+
+function isPowerSaverOnBattery(onBattery, profile) {
+  return !!onBattery && profile === "power-saver"
+}
+
 if (typeof module !== "undefined") {
   module.exports = {
     batteryPercentage: batteryPercentage,
     isDischarging: isDischarging,
-    shouldWarnLowBattery: shouldWarnLowBattery
+    shouldWarnLowBattery: shouldWarnLowBattery,
+    parseActiveProfile: parseActiveProfile,
+    profileAfterRead: profileAfterRead,
+    isPowerSaverOnBattery: isPowerSaverOnBattery
   }
 }