Keep fans when closed on AC power

ChillMac/App/AppSettings.swift

@@ -76,6 +76,8 @@ final class AppSettings: ObservableObject {
     @AppStorage("batterySaverThreshold") var batterySaverThreshold = 20  // percent
     @AppStorage("forcePerformanceOnBattery") var forcePerformanceOnBattery = false
     @AppStorage("keepFansOnScreenSleep") var keepFansOnScreenSleep = false
+    /// When on AC, keep fans through display sleep / lock (clamshell while awake). Does not keep the Mac awake.
+    @AppStorage("keepFansClosedOnPower") var keepFansClosedOnPower = false
     @AppStorage("showFPS") var showFPS = false
 
     static let popoverMinHeight: CGFloat = 400

ChillMac/App/DiagnosticExporter.swift

@@ -28,6 +28,7 @@ struct SettingsSnapshot: Codable {
     let batterySaverThreshold: Int
     let useFahrenheit: Bool
     let keepFansOnScreenSleep: Bool
+    let keepFansClosedOnPower: Bool
 }
 
 // MARK: - Exporter
@@ -56,7 +57,8 @@ enum DiagnosticExporter {
                 batterySaverEnabled: settings.batterySaverEnabled,
                 batterySaverThreshold: settings.batterySaverThreshold,
                 useFahrenheit: settings.useFahrenheit,
-                keepFansOnScreenSleep: settings.keepFansOnScreenSleep
+                keepFansOnScreenSleep: settings.keepFansOnScreenSleep,
+                keepFansClosedOnPower: settings.keepFansClosedOnPower
             ),
             sleepIntervals: logger.sleepIntervalsSnapshot(),
             history: logger.snapshot()

ChillMac/Fan/DisplaySleepFanPolicy.swift

@@ -0,0 +1,30 @@
+import Foundation
+
+enum DisplaySleepFanPolicy {
+    /// Whether screen sleep / lock should leave fans under app control.
+    /// `keepClosedOnPower` only applies when on AC; `keepOnScreenSleep` is power-agnostic.
+    static func shouldKeepFansThroughDisplaySleep(
+        keepClosedOnPower: Bool,
+        keepOnScreenSleep: Bool,
+        onAC: Bool
+    ) -> Bool {
+        if keepClosedOnPower && onAC { return true }
+        return keepOnScreenSleep
+    }
+
+    /// Whether `NSWorkspace.willSleepNotification` should force fans back to auto.
+    ///
+    /// Lid close often posts willSleep after screensDidSleep. This must use the same keep
+    /// decision so a keep preference is not undone by resetting fans on willSleep.
+    static func shouldResetFansOnSystemWillSleep(
+        keepClosedOnPower: Bool,
+        keepOnScreenSleep: Bool,
+        onAC: Bool
+    ) -> Bool {
+        !shouldKeepFansThroughDisplaySleep(
+            keepClosedOnPower: keepClosedOnPower,
+            keepOnScreenSleep: keepOnScreenSleep,
+            onAC: onAC
+        )
+    }
+}

ChillMac/Fan/FanMonitor.swift

@@ -121,6 +121,17 @@ final class FanMonitor: ObservableObject {
     }
 
     @objc private func handleSleep() {
+        let shouldReset = DisplaySleepFanPolicy.shouldResetFansOnSystemWillSleep(
+            keepClosedOnPower: AppSettings.shared.keepFansClosedOnPower,
+            keepOnScreenSleep: AppSettings.shared.keepFansOnScreenSleep,
+            onAC: PowerSource.isOnAC
+        )
+        if !shouldReset {
+            // Lid-close often posts willSleep after screensDidSleep. Do not undo a keep decision
+            // by forcing fans back to auto — especially keepClosedOnPower + AC.
+            NSLog("FanMonitor: system willSleep — keeping fans active (user preference)")
+            return
+        }
         NSLog("FanMonitor: system going to sleep — resetting fans to auto")
         systemAsleep = true
         resetAllFansToAuto()
@@ -133,7 +144,11 @@ final class FanMonitor: ObservableObject {
     }
 
     @objc private func handleScreenSleep() {
-        if AppSettings.shared.keepFansOnScreenSleep {
+        if DisplaySleepFanPolicy.shouldKeepFansThroughDisplaySleep(
+            keepClosedOnPower: AppSettings.shared.keepFansClosedOnPower,
+            keepOnScreenSleep: AppSettings.shared.keepFansOnScreenSleep,
+            onAC: PowerSource.isOnAC
+        ) {
             NSLog("FanMonitor: screen sleep — keeping fans active (user preference)")
             return
         }
@@ -149,7 +164,11 @@ final class FanMonitor: ObservableObject {
     }
 
     @objc private func handleScreenLocked() {
-        if AppSettings.shared.keepFansOnScreenSleep {
+        if DisplaySleepFanPolicy.shouldKeepFansThroughDisplaySleep(
+            keepClosedOnPower: AppSettings.shared.keepFansClosedOnPower,
+            keepOnScreenSleep: AppSettings.shared.keepFansOnScreenSleep,
+            onAC: PowerSource.isOnAC
+        ) {
             NSLog("FanMonitor: screen locked — keeping fans active (user preference)")
             return
         }

ChillMac/Fan/PowerSource.swift

@@ -0,0 +1,16 @@
+import Foundation
+import IOKit.ps
+
+enum PowerSource {
+    /// Injectable seam for unit tests. Production default reads IOPS providing type.
+    static var providingType: () -> String? = {
+        guard let blob = IOPSCopyPowerSourcesInfo()?.takeRetainedValue(),
+              let type = IOPSGetProvidingPowerSourceType(blob)?.takeUnretainedValue() as String?
+        else { return nil }
+        return type
+    }
+
+    static var isOnAC: Bool {
+        providingType() == kIOPSACPowerValue
+    }
+}

ChillMac/Views/SettingsView.swift

@@ -285,6 +285,32 @@ struct SettingsView: View {
                 }
                 .padding(.horizontal, 14)
                 .padding(.vertical, 10)
+
+                Divider().padding(.leading, 52)
+
+                HStack {
+                    Image(systemName: "laptopcomputer.and.arrow.down")
+                        .font(.system(size: 16))
+                        .foregroundColor(theme.textTertiary)
+                        .frame(width: 24)
+                    VStack(alignment: .leading, spacing: 2) {
+                        Text("Keep Fans When Closed on Power")
+                            .font(.system(size: 13, weight: .medium))
+                            .foregroundColor(theme.textPrimary)
+                        Text("On AC only — for clamshell while awake. Does not force the Mac to stay awake.")
+                            .font(.system(size: 11))
+                            .foregroundColor(theme.textQuaternary)
+                    }
+                    Spacer()
+                    Toggle(isOn: $settings.keepFansClosedOnPower) {
+                        EmptyView()
+                    }
+                    .toggleStyle(.switch)
+                    .controlSize(.small)
+                    .tint(.orange)
+                }
+                .padding(.horizontal, 14)
+                .padding(.vertical, 10)
             }
             .background(theme.cardBg)
             .cornerRadius(12)