## Summary
PR 11B in the Brief 11 sequence. Closes the missing-operator inference gap
left by 11A (#343) and ships the per-case audit artifact that Brief 11 §Gate 2
identifies as "the main Brief 11 artifact."
## Why this PR does NOT touch the reader runtime
The naive closure fix for `pre_frame_filler_sentence` (drain
`statement_terminator` at pre-frame) lifts 2 cases from refused → admitted
but creates a `wrong > 0` hazard on `gsm8k-train-sample-v1-0050`:
```
Mark does a gig every other day for 2 weeks. For each gig, he plays 3 songs.
... How many minutes did he play?
```
With the drain enabled, the reader admits `Operation(mark, add, 3, songs)`
with unknown unit `minute` and would project to a wrong answer. The stricter
variant (`pending_entity_ref is None` + no quantities) fires on 0 of the 11
candidate cases. Per Brief 11 §"Failure modes to avoid §1 — Correct-count
greed," this PR rejects both variants and routes the closure fix to a
follow-up that adds the required verb vocabulary or sentence-intent
classifier.
## Deliverables
- `generate/comprehension/audit.py` — three new missing-operator labels:
- `pre_frame_filler_sentence` (8 cases)
- `descriptive_frame_question` (2 cases)
- `question_frame_slot` (1 case)
Closes the 11-case `None`-operator gap left by 11A.
- `evals/gsm8k_math/train_sample/v1/audit_brief_11.json` — per-case audit
artifact pinned by tests.
- `evals/gsm8k_math/train_sample/v1/audit_brief_11.md` — narrative summary
including the rejected-fix design tension and ranked Brief 11B-step-2
backlog.
- `tests/test_brief_11b_audit_artifact.py` — 12 tests pinning the new labels,
the per-case artifact, the wrong=0 invariant, and the refusal taxonomy.
## Bottleneck taxonomy (after Brief 11B labelling)
| missing_operator | count | category |
|-------------------------------|------:|------------------------|
| quantity_extraction | 9 | incomplete_operation |
| lexicon_entry | 9 | unknown_word |
| multi_quantity_composition | 8 | incomplete_operation |
| pre_frame_filler_sentence | 8 | unexpected_category |
| pronoun_resolution | 3 | unresolved_pronoun |
| fraction_percentage_literal | 3 | unexpected_category |
| unit_binding | 3 | unattached_quantity |
| descriptive_frame_question | 2 | unexpected_category |
| (others, 1 each) | 5 | various |
## Test plan
- 12 new tests in `tests/test_brief_11b_audit_artifact.py` pass
- 23 existing 11A tests in `tests/test_brief_11_audit.py` pass
- No runtime changes; reader byte-identical to main
## Hard invariants preserved
- `wrong == 0` — no runtime change, no new admissions
- ADR-0166 — no new canonical eval lanes added; existing
`evals/gsm8k_math/train_sample/v1/` artifact set extended
- No teaching store / pack mutation
## Follow-up
- **11B-step-2** — verb-vocabulary expansion or sentence-intent classifier
for `pre_frame_filler_sentence` (8 cases). See audit_brief_11.md §"design
tension" for the rejected one-line variants and why they fail wrong=0.
- **11C** — existing-lane capability snapshot (still gated on 11B-step-2 or
another closure pass).
