Three issues broke the OAuth callback server on macOS:
1. echo -e doesn't work in bash 3.x — \r\n appears as literal text
in the HTTP response, browser gets malformed headers.
Fix: pre-write response with printf to a file before the subshell.
2. local variables inside ( ... ) & subshell — undefined behavior in
bash 3.x since subshells aren't function scope.
Fix: use plain variables in subshells.
3. ((elapsed++)) when elapsed=0 evaluates to falsy — set -e kills
the script on the first iteration of the timeout loop.
Fix: use elapsed=$((elapsed + 1)) instead.
Also simplified nc_listen detection to only check for BusyBox
(the -p flag check could misfire on macOS nc).
Applied to all 10 lib/common.sh files.
Co-authored-by: Sprite <noreply@sprite.dev>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
