feat(batch-grill-me): granular fact-finding, don't block the round

Fire fact-finding to a sub-agent and treat a running exploration as an
unsettled prerequisite, so only the downstream questions wait — the rest
of the frontier is asked now, instead of the whole next round blocking
behind one lookup. Phrase throughout in terms of the user.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

skills/in-progress/README.md

@@ -10,3 +10,4 @@ Skills that are still being developed. They're not ready to ship — expect roug
 - **[claude-handoff](./claude-handoff/SKILL.md)** — Hand the current conversation off to a fresh background agent that picks up the work immediately, seeded with a handoff summary via `claude --bg`. User-invoked.
 - **[setup-ts-deep-modules](./setup-ts-deep-modules/SKILL.md)** — Wire dependency-cruiser into a TypeScript repo so each package is a deep module — implementation hidden in subfolders, reachable only through its entry-point files, tests exercising it through those. User-invoked.
 - **[to-questionnaire](./to-questionnaire/SKILL.md)** — Turn a decision you can't fully answer into a Markdown questionnaire for someone else to fill in async, or over a meeting. It grills you about the send (who it's for, what you need back), not the subject. User-invoked.
+- **[batch-grill-me](./batch-grill-me/SKILL.md)** — Relentless interview that walks the design tree in rounds instead of one question at a time — each round asks the whole frontier of decisions whose prerequisites are already settled, then recomputes from your answers. User-invoked.

skills/in-progress/batch-grill-me/SKILL.md

@@ -0,0 +1,15 @@
+---
+name: batch-grill-me
+description: A relentless interview that asks every frontier question at once, round by round.
+disable-model-invocation: true
+---
+
+Interview the user relentlessly until you reach a shared understanding. Map this as a **design tree**: every decision branches into the decisions that hang off it.
+
+Work the tree in **rounds**. The **frontier** is every decision whose prerequisites are already settled — the questions you can ask *now* without guessing at answers you haven't heard yet. Ask the whole frontier in one round: number each question and give your recommended answer. Then wait for the user's answers before the next round.
+
+Each round the user answers reshapes the tree — settled decisions push the frontier outward and unblock questions that depended on them. Recompute the frontier and ask the next round. A question whose answer depends on another question still open in this round belongs to a *later* round, not this one.
+
+Finding *facts* is your job, never the user's. When a frontier question needs a fact from the environment (filesystem, tools, etc.), dispatch a sub-agent to find it — don't ask the user for anything you could look up yourself. Don't block on it: a running exploration is an unsettled prerequisite, so only the questions downstream of it wait for the sub-agent to report — ask the rest of the frontier now. The *decisions* are the user's — put each to them and wait.
+
+The session is done when the frontier is empty: every branch of the design tree visited, nothing left silently assumed. Do not act on it until the user confirms you have reached a shared understanding.

skills/in-progress/batch-grill-me/agents/openai.yaml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "Batch Grill Me"
+  short_description: "Sharpen a plan a round of questions at a time"
+policy:
+  allow_implicit_invocation: false