feat(preamble): AskUserQuestion repetition cut — gated, passed NOT-WORSE A/B

Removes the duplicate statements v1.71's compaction left in the
AskUserQuestion Format section: the completeness rule restated in the prose
triad, the auto-decide marker syntax stated twice, the Conductor-flakiness
explanation stated twice, and the self-check's full triad restatement. Every
verbosity floor and all 14 format pins stay (Layer 0 green).

The gate this decision rested on ran before landing (new periodic
skill-e2e-auq-repetition-cut-ab.test.ts, pre-cut ref 3263fffe vs this
render, same harness as auq-verbose-vs-carved-ab): POST 7/7 format elements,
substance 5 — identical to PRE. No degradation; the load-bearing-repetition
hypothesis did not hold for these duplicates.

Net: -236 bytes per tier-2+ skill (~9.7KB corpus). Golden ship baselines
re-captured for the deliberate change.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

codex/SKILL.md

@@ -75,7 +75,7 @@ If `SKILL_PREFIX` is `"true"`, suggest/invoke `/gstack-*` names. Disk paths stay
 
 Branch on the skill-start STATUS lines, in this order:
 
-1. **`CONDUCTOR_SESSION: true` echoed** → do NOT call AskUserQuestion at all (neither native nor any `mcp__*__AskUserQuestion` variant): render EVERY decision brief as the **prose form** below and STOP. Proactive, not a failure reaction — Conductor disables native AUQ and its MCP variant is flaky (`[Tool result missing due to internal error]`). **Auto-decide preferences still apply first:** a surfaced `[plan-tune auto-decide] <id> → <option>` result means proceed with that option, no prose — enforced HERE since no tool call ever happens. Capture each Conductor prose brief with `bin/gstack-question-log` (the PostToolUse hook never fires on a prose path; `/plan-tune` learning depends on it).
+1. **`CONDUCTOR_SESSION: true` echoed** → do NOT call AskUserQuestion at all (neither native nor any `mcp__*__AskUserQuestion` variant): render EVERY decision brief as the **prose form** below and STOP. Proactive, not a failure reaction — Conductor disables native AUQ and its MCP variant is flaky (`[Tool result missing due to internal error]`). **Auto-decide preferences still apply first** (failure-fallback item 1 below): proceed with a surfaced auto-decide option, no prose — enforced HERE since no tool call ever happens. Capture each Conductor prose brief with `bin/gstack-question-log` (the PostToolUse hook never fires on a prose path; `/plan-tune` learning depends on it).
 2. **Any `mcp__*__AskUserQuestion` variant in your tool list** → prefer it (hosts may disable native via `--disallowedTools`; calling native there silently fails). Same shape, same decision-brief format.
 3. **Unavailable (no variant) OR a call fails** → do NOT silently auto-decide or write the decision to the plan file as a substitute; follow the **failure fallback** below.
 
@@ -84,7 +84,7 @@ Branch on the skill-start STATUS lines, in this order:
 Tell three outcomes apart:
 
 1. **Auto-decide denial (NOT a failure).** The result contains `[plan-tune auto-decide] <id> → <option>` — the preference hook working as designed. Proceed with that option. Do NOT retry, do NOT fall back to prose.
-2. **Genuine failure** — no variant in your tool list, OR the variant is present but the call returns an error / missing result (MCP transport error, empty result, host bug — e.g. Conductor's MCP AskUserQuestion is flaky and returns `[Tool result missing due to internal error]`).
+2. **Genuine failure** — no variant in your tool list, OR the variant is present but the call returns an error / missing result (MCP transport error, empty result, host bug — e.g. Conductor's flaky MCP variant, see Tool resolution above).
    - If it was present and **errored** (not absent), retry the SAME call **once** — but only if no answer could have surfaced (a missing-result error can arrive after the user already saw the question; retrying would double-prompt, so if it may have reached them, treat as pending, don't retry).
    - Then branch on `SESSION_KIND` (echoed by the preamble; empty/absent ⇒ `interactive`):
      - `spawned` → defer to the **Spawned session** block: auto-choose the recommended option. Never prose, never BLOCKED.
@@ -94,8 +94,8 @@ Tell three outcomes apart:
 **Prose fallback — render the decision brief as a markdown message, not a tool call.** Same information as the tool format below, different structure (paragraphs, not ✅/❌ bullets). It MUST surface this triad:
 
 1. **A clear ELI10 of the issue itself** — plain English on what's being decided and why it matters (the question, not per-choice), naming the stakes. Lead with it.
-2. **Completeness scores per choice** — explicit `Completeness: X/10` on EACH choice (10 complete, 7 happy-path, 3 shortcut); use the kind-note when options differ in kind not coverage, but never silently drop the score.
-3. **The recommendation and why** — a `Recommendation: <choice> because <reason>` line plus the `(recommended)` marker on that choice.
+2. **Completeness scores per choice** — per the Completeness rule in the Format section below; never silently drop the score.
+3. **The recommendation and why** — the `Recommendation: <choice> because <reason>` line plus the `(recommended)` marker on that choice.
 
 Layout: a `D<N>` title + a one-line note to reply with a letter (in Conductor this is the normal path; elsewhere it means AskUserQuestion was unavailable or errored); the issue ELI10; the Recommendation line; then ONE paragraph per choice carrying its `(recommended)` marker, its `Completeness: X/10`, and 2-4 sentences of reasoning — never a bare bullet list; a closing `Net:` line. Split chains / 5+ options: one prose block per per-option call, in sequence. Then STOP and wait — the user's typed answer is the decision. In plan mode this satisfies end-of-turn like a tool call.
 
@@ -174,7 +174,7 @@ Before calling AskUserQuestion, verify:
 - [ ] (recommended) label on one option (even for neutral-posture)
 - [ ] Dual-scale effort labels on effort-bearing options (human / CC)
 - [ ] Net line closes the decision
-- [ ] You are calling the tool, not writing prose — unless `CONDUCTOR_SESSION: true` (then prose is the DEFAULT, not the tool) OR the documented failure fallback applies (then: prose with the mandatory triad — issue ELI10, per-choice Completeness, Recommendation + `(recommended)` — and a "reply with a letter" instruction, then STOP)
+- [ ] You are calling the tool, not writing prose — unless `CONDUCTOR_SESSION: true` (then prose is the DEFAULT, not the tool) OR the documented failure fallback applies (then: the prose fallback's mandatory triad + a "reply with a letter" instruction, then STOP)
 - [ ] Non-ASCII characters (CJK / accents) written directly, NOT \u-escaped
 - [ ] If you had 5+ options, you split (or batched into ≤4-groups) — did NOT drop any
 - [ ] If you split, you checked dependencies between options before firing the chain