kept data: the list names a leftover by the app that binds it through HDD_PATH, never the file browser (R-692, found live on 9202)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

controller/internal/stacks/kept.go

@@ -244,11 +244,19 @@ func overlaps(a, b string) bool {
 func (m *Manager) ownerOf(drive, abs string) (string, string) {
 	var cands []Stack
 	for _, st := range m.GetStacks() {
-		if st.ComposePath == "" {
+		if st.ComposePath == "" || st.Protected {
+			continue
+		}
+		// v0.274.0 (found live on 9202): only an app whose definition binds its drive folder THROUGH
+		// ${HDD_PATH} can own one. The file browser's own compose binds every kept folder by its absolute
+		// path (the read-only view), and matched first — the list named romm's and paperless's leftovers
+		// "Filebrowser". Pinned by TestKept_OwnerIsNeverTheFileBrowser.
+		if b, err := os.ReadFile(st.ComposePath); err != nil || !strings.Contains(string(b), "${HDD_PATH}") {
 			continue
 		}
 		for _, p := range ParseComposeHDDMounts(st.ComposePath, drive) {
-			if filepath.Clean(p) == abs {
+			// the folder itself, or one inside it (paperless binds appdata/paperless/media and …/export)
+			if c := filepath.Clean(p); c == abs || strings.HasPrefix(c, abs+string(filepath.Separator)) {
 				cands = append(cands, st)
 				break
 			}