core: improve how DMS handles multiple-sessions under the same user

core/cmd/dms/server_client.go

@@ -101,6 +101,13 @@ func getServerSocketPath() string {
 		runtimeDir = os.TempDir()
 	}
 
+	if parentPID, ok := sessionParentPID(os.Getenv("WAYLAND_DISPLAY")); ok {
+		sessionSock := filepath.Join(runtimeDir, fmt.Sprintf("danklinux-%d.sock", parentPID))
+		if _, err := os.Stat(sessionSock); err == nil {
+			return sessionSock
+		}
+	}
+
 	entries, err := os.ReadDir(runtimeDir)
 	if err != nil {
 		return filepath.Join(runtimeDir, "danklinux.sock")

core/cmd/dms/shell.go

@@ -101,14 +101,23 @@ func getPIDFilePath() string {
 	return filepath.Join(getRuntimeDir(), fmt.Sprintf("danklinux-%d.pid", os.Getpid()))
 }
 
+func getSessionFilePath() string {
+	return filepath.Join(getRuntimeDir(), fmt.Sprintf("danklinux-%d.session", os.Getpid()))
+}
+
 func writePIDFile(childPID int) error {
 	pidFile := getPIDFilePath()
+	if display := os.Getenv("WAYLAND_DISPLAY"); display != "" {
+		if err := os.WriteFile(getSessionFilePath(), []byte(display), 0o644); err != nil {
+			log.Warnf("Failed to write session file: %v", err)
+		}
+	}
 	return os.WriteFile(pidFile, []byte(strconv.Itoa(childPID)), 0o644)
 }
 
 func removePIDFile() {
-	pidFile := getPIDFilePath()
-	os.Remove(pidFile)
+	os.Remove(getPIDFilePath())
+	os.Remove(getSessionFilePath())
 }
 
 func getAllDMSPIDs() []int {
@@ -390,9 +399,11 @@ func killShell() {
 	}
 
 	for _, entry := range entries {
-		if strings.HasPrefix(entry.Name(), "danklinux-") && strings.HasSuffix(entry.Name(), ".pid") {
-			pidFile := filepath.Join(dir, entry.Name())
-			os.Remove(pidFile)
+		if !strings.HasPrefix(entry.Name(), "danklinux-") {
+			continue
+		}
+		if strings.HasSuffix(entry.Name(), ".pid") || strings.HasSuffix(entry.Name(), ".session") {
+			os.Remove(filepath.Join(dir, entry.Name()))
 		}
 	}
 }
@@ -609,7 +620,7 @@ func parseTargetsFromIPCShowOutput(output string) ipcTargets {
 
 func buildQsIPCBaseArgs() ([]string, error) {
 	cmdArgs := []string{"ipc"}
-	switch pid, ok := getFirstDMSPID(); {
+	switch pid, ok := getSessionDMSPID(); {
 	case ok:
 		cmdArgs = append(cmdArgs, "--pid", strconv.Itoa(pid))
 	default:
@@ -710,6 +721,64 @@ func getFirstDMSPID() (int, bool) {
 	return 0, false
 }
 
+func sessionParentPID(display string) (int, bool) {
+	if display == "" {
+		return 0, false
+	}
+
+	dir := getRuntimeDir()
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return 0, false
+	}
+
+	for _, entry := range entries {
+		name := entry.Name()
+		if !strings.HasPrefix(name, "danklinux-") || !strings.HasSuffix(name, ".session") {
+			continue
+		}
+
+		data, err := os.ReadFile(filepath.Join(dir, name))
+		if err != nil || strings.TrimSpace(string(data)) != display {
+			continue
+		}
+
+		parentStr := strings.TrimSuffix(strings.TrimPrefix(name, "danklinux-"), ".session")
+		parentPID, err := strconv.Atoi(parentStr)
+		if err != nil {
+			continue
+		}
+
+		return parentPID, true
+	}
+
+	return 0, false
+}
+
+func getSessionDMSPID() (int, bool) {
+	parentPID, ok := sessionParentPID(os.Getenv("WAYLAND_DISPLAY"))
+	if !ok {
+		return getFirstDMSPID()
+	}
+
+	data, err := os.ReadFile(filepath.Join(getRuntimeDir(), fmt.Sprintf("danklinux-%d.pid", parentPID)))
+	if err != nil {
+		return getFirstDMSPID()
+	}
+
+	pid, err := strconv.Atoi(strings.TrimSpace(string(data)))
+	if err != nil {
+		return getFirstDMSPID()
+	}
+
+	proc, err := os.FindProcess(pid)
+	if err != nil || proc.Signal(syscall.Signal(0)) != nil {
+		return getFirstDMSPID()
+	}
+
+	return pid, true
+}
+
 func runShellIPCCommand(args []string) {
 	if len(args) == 0 {
 		printIPCHelp()

core/internal/matugen/matugen.go

@@ -122,6 +122,10 @@ func (o *Options) ColorsOutput() string {
 	return filepath.Join(o.StateDir, "dms-colors.json")
 }
 
+func (o *Options) colorsStaging() string {
+	return o.ColorsOutput() + ".tmp"
+}
+
 func (o *Options) ShouldSkipTemplate(name string) bool {
 	if o.SkipTemplates == "" {
 		return false
@@ -134,6 +138,38 @@ func (o *Options) ShouldSkipTemplate(name string) bool {
 	return false
 }
 
+func acquireMatugenLock(stateDir string) (*os.File, error) {
+	f, err := os.OpenFile(filepath.Join(stateDir, "matugen.lock"), os.O_CREATE|os.O_RDWR, 0o644)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open matugen lock: %w", err)
+	}
+
+	deadline := time.Now().Add(45 * time.Second)
+	for {
+		switch err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX|syscall.LOCK_NB); err {
+		case nil:
+			return f, nil
+		case syscall.EWOULDBLOCK:
+			if time.Now().After(deadline) {
+				f.Close()
+				return nil, fmt.Errorf("timed out waiting for matugen lock")
+			}
+			time.Sleep(100 * time.Millisecond)
+		default:
+			f.Close()
+			return nil, fmt.Errorf("failed to lock matugen: %w", err)
+		}
+	}
+}
+
+func releaseMatugenLock(f *os.File) {
+	if f == nil {
+		return
+	}
+	_ = syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
+	f.Close()
+}
+
 func Run(opts Options) error {
 	if opts.StateDir == "" {
 		return fmt.Errorf("state-dir is required")
@@ -167,6 +203,12 @@ func Run(opts Options) error {
 		return fmt.Errorf("failed to create state dir: %w", err)
 	}
 
+	lock, err := acquireMatugenLock(opts.StateDir)
+	if err != nil {
+		return err
+	}
+	defer releaseMatugenLock(lock)
+
 	log.Infof("Building theme: %s %s (%s)", opts.Kind, opts.Value, opts.Mode)
 
 	changed, buildErr := buildOnce(&opts)
@@ -188,6 +230,8 @@ func Run(opts Options) error {
 }
 
 func buildOnce(opts *Options) (bool, error) {
+	defer os.Remove(opts.colorsStaging())
+
 	cfgFile, err := os.CreateTemp("", "matugen-config-*.toml")
 	if err != nil {
 		return false, fmt.Errorf("failed to create temp config: %w", err)
@@ -275,10 +319,16 @@ func buildOnce(opts *Options) (bool, error) {
 		}
 	}
 
-	newColors, _ := os.ReadFile(opts.ColorsOutput())
+	newColors, err := os.ReadFile(opts.colorsStaging())
+	if err != nil {
+		return false, fmt.Errorf("matugen did not produce colors output: %w", err)
+	}
 	if bytes.Equal(oldColors, newColors) && len(oldColors) > 0 {
 		return false, nil
 	}
+	if err := os.Rename(opts.colorsStaging(), opts.ColorsOutput()); err != nil {
+		return false, fmt.Errorf("failed to commit colors output: %w", err)
+	}
 
 	if opts.ColorsOnly {
 		return true, nil
@@ -346,7 +396,7 @@ func buildMergedConfig(opts *Options, cfgFile *os.File, tmpDir string) error {
 input_path = '%s/matugen/templates/dank.json'
 output_path = '%s'
 
-`, opts.ShellDir, opts.ColorsOutput())
+`, opts.ShellDir, opts.colorsStaging())
 
 	if opts.ColorsOnly {
 		return nil

core/internal/matugen/matugen_test.go

@@ -437,7 +437,7 @@ func TestBuildMergedConfigColorsOnly(t *testing.T) {
 
 	content := string(output)
 	assert.Contains(t, content, "[templates.dank]")
-	assert.Contains(t, content, "output_path = '"+filepath.Join(opts.StateDir, "dms-colors.json")+"'")
+	assert.Contains(t, content, "output_path = '"+opts.colorsStaging()+"'")
 	assert.NotContains(t, content, "[templates.gtk]")
 	assert.False(t, strings.Contains(content, "output_path = 'CONFIG_DIR/"), "colors-only config should not emit app template outputs")
 }

quickshell/Common/Theme.qml

@@ -104,6 +104,8 @@ Singleton {
     signal matugenCompleted(string mode, string result)
     property var matugenColors: ({})
     property var _pendingGenerateParams: null
+    property int _colorsRetryCount: 0
+    property double _lastGenerateMs: 0
 
     property bool themeModeAutomationActive: false
     property bool dmsServiceWasDisconnected: true
@@ -1771,6 +1773,7 @@ Singleton {
         if (!matugenAvailable || isGreeterMode)
             return;
 
+        _lastGenerateMs = Date.now();
         _pendingGenerateParams = true;
         _themeGenerateDebounce.restart();
     }
@@ -2217,6 +2220,7 @@ Singleton {
         }
 
         onLoaded: {
+            _colorsRetryCount = 0;
             if (currentTheme === dynamic)
                 colorsFileLoadFailed = false;
             parseAndLoadColors();
@@ -2227,14 +2231,28 @@ Singleton {
         }
 
         onLoadFailed: function (error) {
-            if (currentTheme === dynamic) {
-                log.warn("Dynamic colors file load failed, marking for regeneration");
-                colorsFileLoadFailed = true;
-                const isGreeterMode = (typeof SessionData !== "undefined" && SessionData.isGreeterMode);
-                if (!isGreeterMode && matugenAvailable && rawWallpaperPath) {
-                    log.debug("Matugen available, triggering immediate regeneration");
-                    generateSystemThemesFromCurrentTheme();
-                }
+            if (currentTheme !== dynamic)
+                return;
+
+            if (SessionData.isGreeterMode)
+                return;
+
+            if (workerRunning) {
+                colorsReloadRetry.restart();
+                return;
+            }
+
+            if (_colorsRetryCount < 3) {
+                _colorsRetryCount++;
+                colorsReloadRetry.restart();
+                return;
+            }
+
+            colorsFileLoadFailed = true;
+            const stale = Date.now() - _lastGenerateMs > 5000;
+            if (matugenAvailable && rawWallpaperPath && stale) {
+                log.debug("Dynamic colors unrecoverable, regenerating");
+                generateSystemThemesFromCurrentTheme();
             }
         }
 
@@ -2243,6 +2261,13 @@ Singleton {
         }
     }
 
+    Timer {
+        id: colorsReloadRetry
+        interval: 150
+        repeat: false
+        onTriggered: dynamicColorsFileView.reload()
+    }
+
     IpcHandler {
         target: "theme"