File manager

Visiting file urls ending with "/" enters internal file manager.

When the current tab is internal file manager, visiting file url for a file shows the content of the file, long pressing button "🕔" -> Editor loads line-based editor for the file. If the file does not exist, saving creates a new file.

Running any command with address bar with the format "d::command line:" to execute "command line" in the current folder of the internal file manager. Ex:
"d::touch a.txt:" to create a new file a.txt.
"d::mkdir subdir:" to create a new folder names "subdir".
"d::mv old new:" to rename the file "old" to be "new".