fix(icc): keep the night light state, prune names without a control, use a 0 sentinel

Fifth review round.

- `SaveICCConfig` replaces `SaveConfig` on the three ICC paths (apply, remove,
  set-temp). Writing the daemon's whole config persisted the night light fields
  it happens to hold in memory: with the night light on, applying a profile
  stored `"Enabled": true`, and since the shell only ever sends
  `wayland.gamma.setEnabled` when the mode is on, turning it off afterwards (an
  in-memory change on the daemon side, no write) left that `true` on disk — after
  log out/in the daemon came up driving the schedule while the UI showed night
  mode off, with no way to resync short of a toggle. The ICC save now reads the
  file and rewrites only `iccProfiles`/`outputTemps`, so the fields the shell
  owns stay as they are.
- `removeOutputByRegistryName` resolved the output from `m.outputs`, which only
  has entries once the gamma controls exist. On a default install (night light
  off, no profile, no override) no control is ever created, so a disconnected
  monitor kept its `outputNames`/`outputRegNames` entries for the life of the
  daemon: `dms icc status`/`listOutputs` listed monitors that were gone, and both
  maps grew with every dock/undock cycle. The object ID is resolved from
  `m.outputRegNames` (populated for every `wl_output`), the name entries are
  dropped before the output state is looked up, and a state that is known without
  a registry name still falls back to matching its own.
- The Display Config temperature row used `7000` as its fallback for an output
  with no override. `publishICCState` only copies entries with `temp != 0`, so
  the value is absent rather than `0` for an unconfigured output: the card claimed
  "7000K" while the daemon drove the night light or neutral, and a user who
  deliberately set 7000K got the "no override" colouring because the highlight
  tested `!== 7000`. The sentinel is `0` now, which is what the `Default` label
  branches and the "is overridden" tests were written against.

Covered by TestSaveICCConfigKeepsNightLightFields (the previous commit brings the
night light back on after a restart), TestManager_RemoveOutputByRegistryNameWithoutControl
(the previous commit keeps an unplugged monitor listed) and the existing
TestManager_RemoveOutputByRegistryNamePrunesNames.

core/internal/server/wayland/manager.go

@@ -398,34 +398,49 @@ func (m *Manager) removeAvailableOutput(o *wlclient.Output) {
 // removeOutputByRegistryName tears down the state of an output that left the
 // compositor (unplugged or asleep). Only the wayland actor goroutine calls it.
 func (m *Manager) removeOutputByRegistryName(registryName uint32) {
-	var foundID uint32
+	// Resolve the object ID from the registry name map: both name maps are
+	// populated for every wl_output, whether or not a gamma control exists for
+	// it, while m.outputs only has entries once the controls exist. On a default
+	// install (night light off, no profile, no override) no control is ever
+	// created, and the name entries still have to go with the output.
+	foundID, found := m.outputIDForRegistryName(registryName)
+
 	var foundOut *outputState
-	m.outputs.Range(func(id uint32, out *outputState) bool {
-		if out.registryName == registryName {
-			foundID = id
+	if found {
+		if out, ok := m.outputs.Load(foundID); ok {
 			foundOut = out
-			return false
 		}
-		return true
-	})
-	if foundOut == nil {
+	} else {
+		// An output whose name never arrived is only known through its state.
+		m.outputs.Range(func(id uint32, out *outputState) bool {
+			if out.registryName == registryName {
+				foundID, foundOut, found = id, out, true
+				return false
+			}
+			return true
+		})
+	}
+	if !found {
 		return
 	}
-	if foundOut.gammaControl != nil {
-		foundOut.gammaControl.(*wlr_gamma_control.ZwlrGammaControlV1).Destroy()
-		foundOut.gammaControl = nil
-	}
-	m.removeAvailableOutput(foundOut.output)
-	if foundOut.output != nil && !foundOut.output.IsZombie() {
-		_ = foundOut.output.Release()
-	}
-	m.outputs.Delete(foundID)
-	// The name entries have to go with the output: they are what
-	// `dms icc status`/`listOutputs` report, and a rebound wl_output reusing a
-	// released object ID would otherwise attach the previous monitor's profile
-	// from the stale name.
+
+	// The name entries go first: they are what `dms icc status`/`listOutputs`
+	// report, and a rebound wl_output reusing a released object ID would
+	// otherwise attach the previous monitor's profile from the stale name.
 	m.outputNames.Delete(foundID)
 	m.outputRegNames.Delete(foundID)
+
+	if foundOut != nil {
+		if foundOut.gammaControl != nil {
+			foundOut.gammaControl.(*wlr_gamma_control.ZwlrGammaControlV1).Destroy()
+			foundOut.gammaControl = nil
+		}
+		m.removeAvailableOutput(foundOut.output)
+		if foundOut.output != nil && !foundOut.output.IsZombie() {
+			_ = foundOut.output.Release()
+		}
+		m.outputs.Delete(foundID)
+	}
 	m.publishICCState()
 
 	hasOutputs := false
@@ -438,6 +453,21 @@ func (m *Manager) removeOutputByRegistryName(registryName uint32) {
 	}
 }
 
+// outputIDForRegistryName maps a wl_output registry name back to the object ID
+// it was announced with.
+func (m *Manager) outputIDForRegistryName(registryName uint32) (uint32, bool) {
+	var foundID uint32
+	var found bool
+	m.outputRegNames.Range(func(id, name uint32) bool {
+		if name == registryName {
+			foundID, found = id, true
+			return false
+		}
+		return true
+	})
+	return foundID, found
+}
+
 func (m *Manager) outputStillValid(out *outputState) bool {
 	switch {
 	case out == nil:
@@ -1583,8 +1613,9 @@ func (m *Manager) ApplyICC(outputName, iccPath string) error {
 	savedConfig := cloneConfig(m.config)
 	m.configMutex.Unlock()
 
-	// Save to disk
-	if err := SaveConfig(savedConfig); err != nil {
+	// Save to disk. Only the ICC fields are written: the night light fields in
+	// this config belong to the shell, not to the daemon.
+	if err := SaveICCConfig(savedConfig.ICCProfiles, savedConfig.OutputTemps); err != nil {
 		log.Warnf("icc: failed to save config: %v", err)
 	}
 
@@ -1614,7 +1645,7 @@ func (m *Manager) RemoveICC(outputName string) error {
 	savedConfig := cloneConfig(m.config)
 	m.configMutex.Unlock()
 
-	if err := SaveConfig(savedConfig); err != nil {
+	if err := SaveICCConfig(savedConfig.ICCProfiles, savedConfig.OutputTemps); err != nil {
 		log.Warnf("icc: failed to save config: %v", err)
 	}
 
@@ -1733,7 +1764,7 @@ func (m *Manager) SetOutputTemp(outputName string, temp int) error {
 	savedConfig := cloneConfig(m.config)
 	m.configMutex.Unlock()
 
-	if err := SaveConfig(savedConfig); err != nil {
+	if err := SaveICCConfig(savedConfig.ICCProfiles, savedConfig.OutputTemps); err != nil {
 		log.Warnf("icc: failed to save config: %v", err)
 	}
 

core/internal/server/wayland/manager_test.go

@@ -671,6 +671,26 @@ func TestManager_ControlStateReuseKeepsAttachedICC(t *testing.T) {
 	assert.Zero(t, fresh.outputTemp)
 }
 
+// A wl_output that has no gamma control (the default install: night light off,
+// no profile, no override) exists only in the name maps. It still has to
+// disappear from listOutputs/status once it is gone, or every dock/undock cycle
+// leaves another monitor in maps that live as long as the daemon.
+func TestManager_RemoveOutputByRegistryNameWithoutControl(t *testing.T) {
+	m := &Manager{}
+	m.outputNames.Store(9, "HDMI-A-1")
+	m.outputRegNames.Store(9, 77)
+
+	assert.Equal(t, []string{"HDMI-A-1"}, m.ListOutputs())
+
+	m.removeOutputByRegistryName(77)
+
+	assert.Empty(t, m.ListOutputs(), "a monitor with no control must not stay listed")
+	_, nameStored := m.outputNames.Load(9)
+	assert.False(t, nameStored, "the name entry should be gone")
+	_, regStored := m.outputRegNames.Load(9)
+	assert.False(t, regStored, "the registry name entry should be gone")
+}
+
 // The status payload is what the settings UI shows for a profile, so the
 // descriptive metadata has to be carried through.
 func TestManager_GetICCStatusDescribesProfile(t *testing.T) {

core/internal/server/wayland/types.go

@@ -276,6 +276,22 @@ func SaveConfig(cfg Config) error {
 	return os.WriteFile(path, data, 0o644)
 }
 
+// SaveICCConfig stores the ICC profiles and the per-output temperatures, leaving
+// every other field of the file as it is on disk.
+//
+// The night light fields are owned by the shell: the daemon only reads them at
+// boot and writes them in memory when the shell calls setEnabled/setTemperature,
+// so writing its copy back would persist whatever the night light happened to be
+// doing when an ICC change was made (for example `"Enabled": true` while the
+// user had since turned it off), and the shell only sends setEnabled when the
+// mode is on, so the state would silently come back after a session restart.
+func SaveICCConfig(iccProfiles map[string]string, outputTemps map[string]int) error {
+	cfg := LoadConfig()
+	cfg.ICCProfiles = iccProfiles
+	cfg.OutputTemps = outputTemps
+	return SaveConfig(cfg)
+}
+
 func (c *Config) Validate() error {
 	if c.LowTemp < 1000 || c.LowTemp > 10000 {
 		return errdefs.ErrInvalidTemperature

core/internal/server/wayland/types_test.go

@@ -3,6 +3,8 @@ package wayland
 import (
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestConfigValidate(t *testing.T) {
@@ -410,3 +412,36 @@ func TestStateChanged(t *testing.T) {
 		})
 	}
 }
+
+// The night light fields in wayland.json belong to the shell: the daemon reads
+// them at boot and the shell pushes changes through IPC, so an ICC change must
+// not write the daemon's copy of them back to disk. Otherwise applying a profile
+// while the night light happens to be on persists "Enabled": true, and the mode
+// comes back after a session restart with no way to resync from the UI.
+func TestSaveICCConfigKeepsNightLightFields(t *testing.T) {
+	t.Setenv("XDG_CONFIG_HOME", t.TempDir())
+
+	onDisk := Config{
+		Enabled:  true,
+		LowTemp:  3000,
+		HighTemp: 6000,
+		Gamma:    1.1,
+		Contrast: 1.0,
+		Outputs:  []string{},
+	}
+	if err := SaveConfig(onDisk); err != nil {
+		t.Fatalf("SaveConfig: %v", err)
+	}
+
+	if err := SaveICCConfig(map[string]string{"DP-1": "/tmp/dp1.icc"}, map[string]int{"DP-1": 7000}); err != nil {
+		t.Fatalf("SaveICCConfig: %v", err)
+	}
+
+	got := LoadConfig()
+	assert.True(t, got.Enabled, "the night light state on disk must survive an ICC write")
+	assert.Equal(t, 3000, got.LowTemp)
+	assert.Equal(t, 6000, got.HighTemp)
+	assert.Equal(t, 1.1, got.Gamma)
+	assert.Equal(t, map[string]string{"DP-1": "/tmp/dp1.icc"}, got.ICCProfiles)
+	assert.Equal(t, map[string]int{"DP-1": 7000}, got.OutputTemps)
+}

quickshell/Modules/Settings/DisplayConfig/OutputCard.qml

@@ -516,13 +516,16 @@ StyledRect {
             leftPadding: 0
             topPadding: Theme.spacingS
 
-            property int currentTemp: ICCService.outputTemps[root.outputName] !== undefined ? ICCService.outputTemps[root.outputName] : 7000
+            // 0 is "no override": the daemon only publishes an entry for an
+            // output that has one, and the night light temperature is not this
+            // value, so a fallback of 7000K would claim a setting nobody made.
+            property int currentTemp: ICCService.outputTemps[root.outputName] !== undefined ? ICCService.outputTemps[root.outputName] : 0
             property bool editing: false
 
             DankIcon {
                 name: "thermostat"
                 size: 18
-                color: colorTempRow.currentTemp !== 7000 ? Theme.primary : Theme.surfaceVariantText
+                color: colorTempRow.currentTemp !== 0 ? Theme.primary : Theme.surfaceVariantText
                 anchors.verticalCenter: parent.verticalCenter
             }
 
@@ -550,7 +553,7 @@ StyledRect {
                 text: colorTempRow.editing ? (Math.round(tempSlider.value) + "K") : (colorTempRow.currentTemp === 0 ? I18n.tr("Default", "Default") : (colorTempRow.currentTemp + "K"))
                 font.pixelSize: Theme.fontSizeSmall
                 font.weight: Font.Medium
-                color: colorTempRow.currentTemp !== 7000 && colorTempRow.currentTemp !== 0 ? Theme.primary : Theme.surfaceText
+                color: colorTempRow.currentTemp !== 0 ? Theme.primary : Theme.surfaceText
                 anchors.verticalCenter: parent.verticalCenter
             }