Function build_next_prompt_prompt 

pub fn build_next_prompt_prompt(digest: &str) -> String

The prompt for session:next_prompt_suggestion. A pure function so its shape is unit-testable. Asked to “output nothing”, the model wrote sentences about doing so, and one reached the composer; SKIP is the only way to decline.

When the assistant’s last message plainly waits for the user (a question in its last paragraph, a tool that asks them), no call is made at all (digest::TurnEnding). The SKIP case for waiting stays as the fallback for a wait the gate can’t see, such as “Tell me which one and I’ll start.”