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Guide

Reference

Concepts

Ask the user a question from inside a phase

Goal: Pause a phase, ask the user something, and resume the same phase with the answer merged into the input.

When to use

  • The phase has all-but-one piece of information and the missing piece can't be inferred.
  • The cost of guessing wrong is higher than the cost of one extra prompt.

Pattern

In phase instructions, describe when to ask. The LLM emits an ask_user Control IR op:

If `relevant_memories` does not specify the user's preferred output
language, ask the user before continuing.

The LLM's emitted op:

{
  "kind": "ask_user",
  "question": "Which language should I write the post in?",
  "suggestions": ["English", "Japanese"]
}

What the OS does

  1. Prints the question (and suggestions, if given).
  2. Reads stdin until a response.
  3. Merges the original input + Q&A into a user_message artifact.
  4. Re-runs the same phase with the merged artifact. Visit count does not increment.

Two events are emitted: user_intervention_requested and user_intervention_received.

Phase instructions: do say / don't say

Do say:

  • WHEN to ask (the trigger condition).
  • WHAT to ask (a domain-specific question).

Don't say:

  • The op's JSON shape ({kind: ask_user, question: ...}). The OS injects this into available_control_ops (P8).

Caveats

  • reyn eval is non-interactive. A skill that asks the user mid-phase will hang in eval mode. Either gate the question on a condition that's never true under eval, or pre-supply the missing field in the eval spec.
  • Don't ask multiple questions in one op. Use one ask_user op at a time; if you need more, ask one, get the answer (which re-enters the same phase), then decide whether to ask another.

See also

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