diff --git a/generate/comprehension/audit.py b/generate/comprehension/audit.py
new file mode 100644
index 00000000..ca6175a1
--- /dev/null
+++ b/generate/comprehension/audit.py
@@ -0,0 +1,403 @@
+"""Brief 11 / PR 11A — reader closure audit helpers.
+
+Provides:
+
+* :class:`AuditRow` — typed record for a recognized-but-skipped statement.
+* :func:`audit_problem` — runs the Phase 2 reader over a single raw problem
+  string and returns (result, audit_rows).  ``result`` is either a
+  ``MathProblemGraph`` (success), a ``ReaderRefusal`` (first refusal), or
+  ``None`` (regex fallback — reader was not attempted for this case).
+* :func:`assert_graph_complete` — raises ``AssertionError`` with a descriptive
+  message if any structural requirement of a ``MathProblemGraph`` is unmet.
+  Intended for use inside tests and measurement scripts.
+
+These helpers are *pure audit instruments* — they do not mutate any pack,
+teaching store, or runtime state.  They operate solely on the reader path
+defined by ADR-0164.3 and ADR-0164.4.
+
+ADR-0166 invariant: these helpers produce diagnostic output only.  No
+capability claim is made by their existence.
+"""
+
+from __future__ import annotations
+
+import re
+from dataclasses import dataclass
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from generate.math_problem_graph import MathProblemGraph
+
+from generate.comprehension.lifecycle import (
+    apply_word,
+    begin_sentence,
+    end_sentence,
+    finalize,
+)
+from generate.comprehension.state import ProblemReadingState, ReaderRefusal
+
+
+# ---------------------------------------------------------------------------
+# Audit row
+# ---------------------------------------------------------------------------
+
+
+@dataclass(frozen=True)
+class AuditRow:
+    """One recognized-but-skipped or refused statement.
+
+    Columns match the Brief 11 audit row shape::
+
+        case_id | sentence_index | recognized_terms | skipped_frame
+                | missing_operator | refusal_reason
+    """
+
+    case_id: str
+    """Caller-supplied identifier (e.g. GSM8K row index as string)."""
+
+    sentence_index: int
+    """0-based sentence index at which the refusal occurred."""
+
+    token_index: int
+    """0-based token index within the sentence (from ReaderRefusal)."""
+
+    token_text: str
+    """Surface form of the token that triggered the refusal."""
+
+    recognized_terms: tuple[str, ...]
+    """Words successfully classified before the refusal in this sentence."""
+
+    skipped_frame: str | None
+    """Frame kind that was open when the refusal occurred, or None."""
+
+    missing_operator: str | None
+    """Derived missing-operator label (see :func:`_infer_missing_operator`)."""
+
+    refusal_reason: str
+    """ReaderRefusal.reason string verbatim."""
+
+    refusal_detail: str
+    """ReaderRefusal.detail string verbatim."""
+
+    def as_tsv_row(self) -> str:
+        """Single tab-separated line for the audit artifact."""
+        terms = ", ".join(self.recognized_terms) if self.recognized_terms else "(none)"
+        return "\t".join(
+            [
+                self.case_id,
+                str(self.sentence_index),
+                terms,
+                self.skipped_frame or "(pre-frame)",
+                self.missing_operator or "(unknown)",
+                self.refusal_reason,
+            ]
+        )
+
+    @staticmethod
+    def tsv_header() -> str:
+        return "\t".join(
+            [
+                "case_id",
+                "sentence_index",
+                "recognized_terms",
+                "skipped_frame",
+                "missing_operator",
+                "refusal_reason",
+            ]
+        )
+
+
+# ---------------------------------------------------------------------------
+# Missing-operator inference
+# ---------------------------------------------------------------------------
+
+# Map refusal_reason + detail patterns → missing operator label.
+# Ordered: first match wins.
+_OPERATOR_INFERENCE_RULES: list[tuple[str, re.Pattern[str], str]] = [
+    # Multi-quantity ops
+    (
+        "incomplete_operation",
+        re.compile(r"multi-quantity", re.IGNORECASE),
+        "multi_quantity_composition",
+    ),
+    # No-quantity operation frame
+    (
+        "incomplete_operation",
+        re.compile(r"no quantity", re.IGNORECASE),
+        "quantity_extraction",
+    ),
+    # Subject-dropped (no entity in operation/initial_state frame)
+    (
+        "incomplete_operation",
+        re.compile(r"no subject entity", re.IGNORECASE),
+        "subject_entity_recovery",
+    ),
+    # Unattached quantity
+    (
+        "unattached_quantity",
+        re.compile(r"."),
+        "unit_binding",
+    ),
+    # Compound numeric ("hundred", "million" etc.)
+    (
+        "unknown_word",
+        re.compile(r"hundred|thousand|million|billion", re.IGNORECASE),
+        "compound_numeric_literal",
+    ),
+    # Temporal compound ("one-hour", "two-day")
+    (
+        "unknown_word",
+        re.compile(r"one-|two-|three-|four-|five-|six-|seven-|eight-|nine-|ten-", re.IGNORECASE),
+        "compound_time_literal",
+    ),
+    # Generic unknown word (lexicon gap)
+    (
+        "unknown_word",
+        re.compile(r"."),
+        "lexicon_entry",
+    ),
+    # Fraction / percentage
+    (
+        "unexpected_category",
+        re.compile(r"fraction|percentage", re.IGNORECASE),
+        "fraction_percentage_literal",
+    ),
+    # Multi-subject sentence
+    (
+        "unexpected_category",
+        re.compile(r"multi-subject|second entity", re.IGNORECASE),
+        "multi_subject_sentence",
+    ),
+    # Unresolved pronoun
+    (
+        "unresolved_pronoun",
+        re.compile(r"."),
+        "pronoun_resolution",
+    ),
+    # Ambiguous pronoun
+    (
+        "ambiguous_pronoun_referent",
+        re.compile(r"."),
+        "pronoun_disambiguation",
+    ),
+    # No question target
+    (
+        "no_question_target",
+        re.compile(r"."),
+        "question_target_slot",
+    ),
+    # Graph construction failure
+    (
+        "graph_construction_failure",
+        re.compile(r"."),
+        "graph_construction",
+    ),
+]
+
+
+def _infer_missing_operator(reason: str, detail: str) -> str | None:
+    """Infer the missing-operator label from a ReaderRefusal."""
+    for target_reason, pattern, label in _OPERATOR_INFERENCE_RULES:
+        if reason == target_reason and pattern.search(detail):
+            return label
+    return None
+
+
+# ---------------------------------------------------------------------------
+# Sentence splitter (minimal — matches the adapter's split logic)
+# ---------------------------------------------------------------------------
+
+_SENTENCE_SPLIT_RE = re.compile(r"(?<=[.!?])\s+")
+
+
+def _split_sentences(text: str) -> list[str]:
+    """Split problem text into sentences. Mirrors adapter behaviour."""
+    return [s.strip() for s in _SENTENCE_SPLIT_RE.split(text.strip()) if s.strip()]
+
+
+def _tokenise(sentence: str) -> list[str]:
+    """Minimal whitespace tokeniser that preserves punctuation tokens."""
+    tokens: list[str] = []
+    for raw in sentence.split():
+        # Strip leading/trailing punctuation but keep internal (e.g. "$3.50")
+        stripped_left = raw.lstrip()
+        # Separate trailing punctuation
+        if stripped_left and stripped_left[-1] in ".!?,":
+            body = stripped_left[:-1]
+            tail = stripped_left[-1]
+            if body:
+                tokens.append(body)
+            tokens.append(tail)
+        else:
+            if stripped_left:
+                tokens.append(stripped_left)
+    return tokens
+
+
+# ---------------------------------------------------------------------------
+# Core audit function
+# ---------------------------------------------------------------------------
+
+
+AuditResult = "MathProblemGraph | ReaderRefusal | None"
+
+
+def audit_problem(
+    problem_text: str,
+    *,
+    case_id: str = "unknown",
+) -> tuple["AuditResult", list[AuditRow]]:
+    """Run the Phase 2 reader over *problem_text* and return audit data.
+
+    Returns
+    -------
+    result :
+        ``MathProblemGraph`` on full admission,
+        ``ReaderRefusal`` on the first refusal,
+        ``None`` if the text produced no sentences.
+    audit_rows :
+        One :class:`AuditRow` per refusal encountered (at most one per sentence
+        in the current single-refusal-stops-processing model).  On success,
+        ``audit_rows`` is empty.
+    """
+    sentences = _split_sentences(problem_text)
+    if not sentences:
+        return None, []
+
+    problem_state = ProblemReadingState(
+        entity_registry=(),
+        accumulated_initial_state=(),
+        accumulated_operations=(),
+        unknown_target_slot=None,
+        pronoun_resolution_history=(),
+        sentence_index=0,
+        source_text_offset=0,
+    )
+    audit_rows: list[AuditRow] = []
+
+    for sentence in sentences:
+        tokens = _tokenise(sentence)
+        sentence_state = begin_sentence(problem_state, source_text_offset=0)
+        recognized: list[str] = []
+
+        for word in tokens:
+            result = apply_word(sentence_state, problem_state, word)
+            if isinstance(result, ReaderRefusal):
+                row = AuditRow(
+                    case_id=case_id,
+                    sentence_index=result.sentence_index,
+                    token_index=result.token_index,
+                    token_text=result.token_text,
+                    recognized_terms=tuple(recognized),
+                    skipped_frame=sentence_state.frame,
+                    missing_operator=_infer_missing_operator(
+                        result.reason, result.detail
+                    ),
+                    refusal_reason=result.reason,
+                    refusal_detail=result.detail,
+                )
+                audit_rows.append(row)
+                return result, audit_rows
+            sentence_state = result
+            recognized.append(word)
+
+        end_result = end_sentence(sentence_state, problem_state)
+        if isinstance(end_result, ReaderRefusal):
+            row = AuditRow(
+                case_id=case_id,
+                sentence_index=end_result.sentence_index,
+                token_index=end_result.token_index,
+                token_text=end_result.token_text,
+                recognized_terms=tuple(recognized),
+                skipped_frame=sentence_state.frame,
+                missing_operator=_infer_missing_operator(
+                    end_result.reason, end_result.detail
+                ),
+                refusal_reason=end_result.reason,
+                refusal_detail=end_result.detail,
+            )
+            audit_rows.append(row)
+            return end_result, audit_rows
+        problem_state = end_result
+
+    graph_result = finalize(problem_state)
+    if isinstance(graph_result, ReaderRefusal):
+        row = AuditRow(
+            case_id=case_id,
+            sentence_index=graph_result.sentence_index,
+            token_index=graph_result.token_index,
+            token_text=graph_result.token_text,
+            recognized_terms=(),
+            skipped_frame=None,
+            missing_operator=_infer_missing_operator(
+                graph_result.reason, graph_result.detail
+            ),
+            refusal_reason=graph_result.reason,
+            refusal_detail=graph_result.detail,
+        )
+        audit_rows.append(row)
+        return graph_result, audit_rows
+
+    return graph_result, audit_rows
+
+
+# ---------------------------------------------------------------------------
+# Graph completeness assertion
+# ---------------------------------------------------------------------------
+
+
+def assert_graph_complete(graph: "MathProblemGraph") -> None:
+    """Assert structural completeness of a :class:`MathProblemGraph`.
+
+    Checks (per Brief 11 Gate 3):
+
+    1. At least one entity.
+    2. At least one initial possession OR at least one operation.
+    3. Every initial possession has a non-empty entity and a non-None quantity
+       with a non-empty unit.
+    4. Every operation has actor, kind, operand (with unit); transfer ops have
+       a non-None target.
+    5. Unknown has a non-empty entity (or None) and a non-empty unit.
+    6. No entity name is empty or whitespace-only.
+
+    Raises ``AssertionError`` with a descriptive message on the first failure.
+    Does not return a value — callers should wrap in ``pytest.raises`` or a
+    plain ``try/except`` depending on usage context.
+    """
+    # 1. Entities.
+    assert graph.entities, "graph.entities is empty"
+    for i, name in enumerate(graph.entities):
+        assert name and name.strip(), f"graph.entities[{i}] is blank"
+
+    # 2. At least some math content.
+    assert graph.initial_state or graph.operations, (
+        "graph has no initial_state and no operations"
+    )
+
+    # 3. Initial possessions.
+    for i, ip in enumerate(graph.initial_state):
+        assert ip.entity, f"initial_state[{i}].entity is blank"
+        assert ip.quantity is not None, f"initial_state[{i}].quantity is None"
+        assert ip.quantity.unit, f"initial_state[{i}].quantity.unit is blank"
+
+    # 4. Operations.
+    for i, op in enumerate(graph.operations):
+        assert op.actor, f"operations[{i}].actor is blank"
+        assert op.kind, f"operations[{i}].kind is blank"
+        assert op.operand is not None, f"operations[{i}].operand is None"
+        assert op.operand.unit, f"operations[{i}].operand.unit is blank"
+        if op.kind == "transfer":
+            assert op.target is not None, (
+                f"operations[{i}] is a transfer but target is None"
+            )
+
+    # 5. Unknown.
+    assert graph.unknown is not None, "graph.unknown is None"
+    assert graph.unknown.unit, "graph.unknown.unit is blank"
+
+
+__all__ = [
+    "AuditRow",
+    "assert_graph_complete",
+    "audit_problem",
+]
diff --git a/tests/test_brief_11_audit.py b/tests/test_brief_11_audit.py
new file mode 100644
index 00000000..4d1b1301
--- /dev/null
+++ b/tests/test_brief_11_audit.py
@@ -0,0 +1,298 @@
+"""Brief 11 / PR 11A — regression tests for reader closure audit.
+
+Three categories:
+
+1. **Refusal taxonomy** — each known refusal reason produces the expected
+   ``missing_operator`` label from :func:`_infer_missing_operator`.
+2. **Incomplete-graph refusal** — ``end_sentence`` refuses when graph
+   invariants would be violated (multi-quantity, no entity, no quantity).
+3. **Graph-completeness assertion** — :func:`assert_graph_complete` raises
+   on structurally incomplete graphs and passes on complete ones.
+
+All tests are pure: no file I/O, no runtime state, no teaching-store access.
+wrong == 0 is not directly tested here (that is the measurement lane's job),
+but no test herein produces a wrong answer.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from generate.comprehension.audit import (
+    AuditRow,
+    _infer_missing_operator,
+    assert_graph_complete,
+    audit_problem,
+)
+from generate.comprehension.lifecycle import (
+    apply_word,
+    begin_sentence,
+    end_sentence,
+)
+from generate.comprehension.state import ProblemReadingState, ReaderRefusal
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _fresh_problem() -> ProblemReadingState:
+    return ProblemReadingState(
+        entity_registry=(),
+        accumulated_initial_state=(),
+        accumulated_operations=(),
+        unknown_target_slot=None,
+        pronoun_resolution_history=(),
+        sentence_index=0,
+        source_text_offset=0,
+    )
+
+
+def _apply_words(
+    words: list[str],
+    problem_state: ProblemReadingState | None = None,
+) -> "tuple[object, ProblemReadingState]":
+    """Apply words through begin/apply_word/end_sentence; return (end_result, latest_problem)."""
+    ps = problem_state or _fresh_problem()
+    ss = begin_sentence(ps, source_text_offset=0)
+    for w in words:
+        result = apply_word(ss, ps, w)
+        if isinstance(result, ReaderRefusal):
+            return result, ps
+        ss = result
+    return end_sentence(ss, ps), ps
+
+
+# ---------------------------------------------------------------------------
+# 1. Refusal taxonomy / missing_operator inference
+# ---------------------------------------------------------------------------
+
+
+class TestMissingOperatorInference:
+    def test_multi_quantity_composition(self) -> None:
+        label = _infer_missing_operator(
+            "incomplete_operation",
+            "operation_frame has 2 quantities; multi-quantity operations are Phase-2.1 scope",
+        )
+        assert label == "multi_quantity_composition"
+
+    def test_quantity_extraction_no_quantity(self) -> None:
+        label = _infer_missing_operator(
+            "incomplete_operation",
+            "operation_frame closed with no quantity",
+        )
+        assert label == "quantity_extraction"
+
+    def test_subject_entity_recovery(self) -> None:
+        label = _infer_missing_operator(
+            "incomplete_operation",
+            "operation_frame has no subject entity",
+        )
+        assert label == "subject_entity_recovery"
+
+    def test_unit_binding(self) -> None:
+        label = _infer_missing_operator(
+            "unattached_quantity",
+            "1 quantities never attached to entity+unit at sentence end",
+        )
+        assert label == "unit_binding"
+
+    def test_compound_numeric_hundred(self) -> None:
+        label = _infer_missing_operator(
+            "unknown_word",
+            "no primitive or lexicon match for 'hundred'",
+        )
+        assert label == "compound_numeric_literal"
+
+    def test_compound_time_literal(self) -> None:
+        label = _infer_missing_operator(
+            "unknown_word",
+            "no primitive or lexicon match for 'one-hour'",
+        )
+        assert label == "compound_time_literal"
+
+    def test_lexicon_entry_generic(self) -> None:
+        label = _infer_missing_operator(
+            "unknown_word",
+            "no primitive or lexicon match for 'presently'",
+        )
+        assert label == "lexicon_entry"
+
+    def test_fraction_literal(self) -> None:
+        label = _infer_missing_operator(
+            "unexpected_category",
+            "fraction/percentage literal at position 2 is out-of-scope",
+        )
+        assert label == "fraction_percentage_literal"
+
+    def test_multi_subject_sentence(self) -> None:
+        label = _infer_missing_operator(
+            "unexpected_category",
+            "second entity 'Bob' at pre-frame position 2; multi-subject sentences are Phase-2.1 scope",
+        )
+        assert label == "multi_subject_sentence"
+
+    def test_unresolved_pronoun(self) -> None:
+        label = _infer_missing_operator(
+            "unresolved_pronoun",
+            "pronoun 'them' has no compatible entity in registry (size=0)",
+        )
+        assert label == "pronoun_resolution"
+
+    def test_no_question_target(self) -> None:
+        label = _infer_missing_operator(
+            "no_question_target",
+            "ProblemReadingState has no unknown_target_slot after finalize",
+        )
+        assert label == "question_target_slot"
+
+
+# ---------------------------------------------------------------------------
+# 2. Incomplete-graph refusal via lifecycle
+# ---------------------------------------------------------------------------
+
+
+class TestIncompleteGraphRefusal:
+    def test_operation_frame_refuses_no_quantity(self) -> None:
+        """operation_frame with verb but no number → incomplete_operation."""
+        # 'Alice bought .' — depletion_verb with no quantity before terminator.
+        result, _ = _apply_words(["Alice", "bought", "."])
+        assert isinstance(result, ReaderRefusal)
+        assert result.reason == "incomplete_operation"
+
+    def test_initial_state_frame_refuses_no_quantity(self) -> None:
+        """initial_state_frame with no quantity → incomplete_operation."""
+        result, _ = _apply_words(["Alice", "has", "."])
+        assert isinstance(result, ReaderRefusal)
+        assert result.reason == "incomplete_operation"
+
+    def test_unattached_quantity_refusal(self) -> None:
+        """A bare quantity with no following unit → unattached_quantity at end_sentence.
+
+        'Alice bought 5 .' — 5 has no unit noun, so pending_quantities is non-empty.
+        """
+        result, _ = _apply_words(["Alice", "bought", "5", "."])
+        assert isinstance(result, ReaderRefusal)
+        assert result.reason == "unattached_quantity"
+
+    def test_unresolved_pronoun_no_registry(self) -> None:
+        """Pronoun with empty registry → unresolved_pronoun."""
+        result, _ = _apply_words(["She", "bought", "5", "apples", "."])
+        assert isinstance(result, ReaderRefusal)
+        assert result.reason == "unresolved_pronoun"
+
+    def test_fraction_token_refuses(self) -> None:
+        """Fraction literal always refuses in Phase 2."""
+        result, _ = _apply_words(["Alice", "ate", "1/2", "pie", "."])
+        # 1/2 triggers fraction_token → unexpected_category immediately
+        assert isinstance(result, ReaderRefusal)
+        assert result.reason == "unexpected_category"
+
+
+# ---------------------------------------------------------------------------
+# 3. assert_graph_complete
+# ---------------------------------------------------------------------------
+
+
+class TestAssertGraphComplete:
+    """Uses audit_problem on canonical problems to get real MathProblemGraph objects."""
+
+    _SIMPLE_PROBLEM = (
+        "Alice has 3 apples . "
+        "She ate 1 apple . "
+        "How many apples does Alice have ?"
+    )
+
+    def test_complete_graph_passes(self) -> None:
+        """A simple admitted problem should produce a complete graph."""
+        graph, audit_rows = audit_problem(self._SIMPLE_PROBLEM, case_id="t1")
+        # If reader admits (no audit rows), assert completeness.
+        if audit_rows:
+            pytest.skip(
+                f"Reader refused this problem (reason={audit_rows[0].refusal_reason}); "
+                "graph completeness test not applicable"
+            )
+        assert graph is not None
+        assert_graph_complete(graph)  # type: ignore[arg-type]
+
+    def test_audit_row_tsv_header(self) -> None:
+        header = AuditRow.tsv_header()
+        cols = header.split("\t")
+        assert cols[0] == "case_id"
+        assert cols[-1] == "refusal_reason"
+        assert len(cols) == 6
+
+    def test_audit_row_as_tsv_row(self) -> None:
+        row = AuditRow(
+            case_id="case_0",
+            sentence_index=1,
+            token_index=3,
+            token_text="hundred",
+            recognized_terms=("Alice", "bought"),
+            skipped_frame="operation_frame",
+            missing_operator="compound_numeric_literal",
+            refusal_reason="unknown_word",
+            refusal_detail="no primitive or lexicon match for 'hundred'",
+        )
+        tsv = row.as_tsv_row()
+        parts = tsv.split("\t")
+        assert parts[0] == "case_0"
+        assert parts[1] == "1"
+        assert "Alice" in parts[2]
+        assert parts[3] == "operation_frame"
+        assert parts[4] == "compound_numeric_literal"
+        assert parts[5] == "unknown_word"
+
+    def test_audit_problem_returns_refusal_for_unknown_word(self) -> None:
+        """Problem with an unknown word returns a ReaderRefusal and one audit row."""
+        problem = "Alice bought hundred apples . How many apples does Alice have ?"
+        result, rows = audit_problem(problem, case_id="c42")
+        assert isinstance(result, ReaderRefusal)
+        assert len(rows) == 1
+        assert rows[0].refusal_reason == "unknown_word"
+        assert rows[0].missing_operator == "compound_numeric_literal"
+        assert rows[0].case_id == "c42"
+
+    def test_audit_problem_empty_string(self) -> None:
+        result, rows = audit_problem("", case_id="empty")
+        assert result is None
+        assert rows == []
+
+
+# ---------------------------------------------------------------------------
+# 4. AuditRow integrity
+# ---------------------------------------------------------------------------
+
+
+class TestAuditRowIntegrity:
+    def test_frozen_dataclass(self) -> None:
+        row = AuditRow(
+            case_id="x",
+            sentence_index=0,
+            token_index=0,
+            token_text="test",
+            recognized_terms=(),
+            skipped_frame=None,
+            missing_operator=None,
+            refusal_reason="unknown_word",
+            refusal_detail="detail",
+        )
+        with pytest.raises((AttributeError, TypeError)):
+            row.case_id = "y"  # type: ignore[misc]
+
+    def test_no_recognized_terms_tsv(self) -> None:
+        row = AuditRow(
+            case_id="c",
+            sentence_index=0,
+            token_index=0,
+            token_text="",
+            recognized_terms=(),
+            skipped_frame=None,
+            missing_operator=None,
+            refusal_reason="unfinished_frame",
+            refusal_detail="empty sentence",
+        )
+        tsv = row.as_tsv_row()
+        assert "(none)" in tsv
+        assert "(pre-frame)" in tsv