- notify-mail.sh: bash 3.2 (stock macOS) treats expanding an empty array
  under set -u as unbound variable — drop the MSMTP_ARGS array for direct
  branch invocation (works identically on Linux bash 5)
- daily-digest.sh: empty result .json files (run killed / watchdog timeout,
  claude never wrote output) pass 'jq empty' but emit nothing on extraction,
  corrupting the summary array with consecutive commas; treat non-empty-size
  files as parse errors so killed runs show up honestly as interrupted