/add doesn't immediately update the list of files in the session

[pjcreath]

Issue

Steps to reproduce:

1. /add filename
2. Note that the new file hasn't been added to the file list above the prompt.
3. Press Enter.
4. Note that the new file name is now listed.

/drop immediately updates, apparently via a SwitchCoder exception. Should /add be doing the same, or is there a better way to update the list immediately?

Version and model info

Aider v0.88.28