Explain This

Take whatever the user is pointing at and translate it into plain language. "This" is usually the most recent assistant output or something pasted as an argument: a multi-option prompt, a free-form question, a code block, an error, a command output, or an artifact like a plan, findings report, or diff.

Step 1: Identify the Subject

Pick the subject in priority order:

1. Text passed as an argument — use that
2. A quoted or selected region from the user's most recent message — use that
3. The most recent non-trivial assistant output — use that
4. If the guess is not obvious, lead the explanation by naming what was picked so the user can redirect

Step 2: Ground in State

Read whatever makes the explanation concrete, no more: