Bypass Execute() preprocessing for __complete/__completeNoDesc so Cobra's
built-in completion handles shell TAB without creating tasks. Add root
ValidArgsFunction for flexible syntax (e.g. "opal 1 de<TAB>" → delete),
attribute value completions (status:pending, priority:H, date synonyms),
and NoSpace directive on key: completions to avoid trailing space.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Add completion command for bash/zsh/fish/powershell generation. Organize
help text using Cobra command groups (Task Commands, Reports, Other).
Register dynamic ValidArgsFunction on filter-accepting commands to
suggest +tag and project:name completions from the database.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>