wezterm/docs/config/lua/pane/get_title.md

pane:get_title()

Since: nightly builds only

Returns the title of the pane. This will typically be wezterm by default but can be modified by applications that send OSC 1 (Icon/Tab title changing) and/or OSC 2 (Window title changing) escape sequences.

The value returned by this method is the same as that used to display the tab title if this pane were the only pane in the tab; if OSC 1 was used to set a non-empty string then that string will be returned. Otherwise the value for OSC 2 will be returned.

Note that on Microsoft Windows the default behavior of the OS level PTY is to implicitly send OSC 2 sequences to the terminal as new programs attach to the console.