Use OSC 9;4 to report progress in window title

Motivation

When I use Claude Code it often takes multiple minutes to come up with a solution. While waiting I often do other work. Currently I have to regularly switch back to Claude Code to check its progress, to see if it has finished.

Proposed solution

Many terminal emulators support OSC 9;4 VT100/ANSI control sequences to show progress indicators in the window title. Examples include ConEmu, Kitty or Windows Terminal:
!Image

I think it would be useful if Claude Code used this functionality to notify me of progress, or at least completion, of the current process.

Implementation details

Applications can report:

• Relative progress (0-1)
• Indeterminate state

Here's some hopefully useful documentation of the features outlining the options in detail, and how to use them.