By default Twill implements immediately. But it never guesses silently: ambiguous tasks get clarifying questions, and for larger work you can require a reviewable plan before any code is written.
Clarifying questions
When a request is ambiguous — unclear scope, multiple valid interpretations, missing context — Twill asks before proceeding. Questions are posted to the thread where the task started (Slack thread, GitHub issue, Linear comment, or the web app), and your reply continues the task.
Plan mode
In plan mode, Twill researches your codebase first — reading relevant files, checking existing patterns, consulting library docs — and posts an implementation plan instead of code.
You then approve, edit, or reject the plan. Implementation starts only after approval, and the approved plan is what the agent follows.
Ways to get a plan:
- Web app: select Plan in the composer’s mode dropdown.
- GitHub / Slack / Notion / Asana: include a plan-mode
/trigger (for example /plan) in the message, per your routing configs. On GitHub issues, a matching label also works.
- Linear: add a label matching a plan-mode routing trigger.
Use plan mode when the change is large, risky, or when you want to align on
approach before spending agent time on implementation.
Ask mode
Ask mode answers questions about your codebase without changing anything — no branch, no PR, read-only.
/ask How does session refresh work, and where are tokens stored?
- Web app: select Ask in the mode dropdown.
- Slack / GitHub / Notion: start the message with an ask-mode trigger like
/ask.
- CLI:
twill task create --mode ask --command "...".
Answers include file references so you can jump straight to the code. 
