renameApp() killed the old process with .kill() but didn't wait for it
to actually exit before restarting on the same port. The OS still had
the port bound, causing the new process to fail with "port is taken".
Additionally, the old process's exit handler would fire after the rename
and corrupt the app's state—releasing the new process's port, setting
state to 'invalid', and nullifying the proc reference.
Fix by:
- Making renameApp async and awaiting proc.exited before proceeding
- Guarding the exit handler to bail out when a newer process has taken over
https://claude.ai/code/session_01W9GF8Cy7T6V2rnVcoNd1Nc
