app/engine/lexical.py

"""Conservative, context-aware vocabulary refinement (no hard-coded word lists)."""

from __future__ import annotations

import logging
import re
from dataclasses import dataclass, field
from functools import lru_cache
from typing import Any

from lemminflect import getInflection
from wordfreq import zipf_frequency

from app.config import (
    ENGINE_LEXICAL_MAX_FREQUENCY_GAP,
    ENGINE_LEXICAL_MAX_HARDER_GAP,
    ENGINE_LEXICAL_MAX_CHANGES,
    ENGINE_LEXICAL_MAX_SIMPLER_GAP,
    ENGINE_LEXICAL_MIN_ZIPF,
    ENGINE_LEXICAL_PREFER_SIMPLER,
    ENGINE_WORDNET_LEXICON,
)
from app.engine.models import LexicalChange
from app.engine.quality import substitution_pos_stable
from app.pipeline.nlp import get_nlp

_POS_MAP = {"NOUN": "n", "VERB": "v", "ADJ": "a", "ADV": "r"}
_PROTECTED_MARKER = re.compile(r"ZZPROTECTED(?:URL|EMAIL|PATH)\d+ZZ", re.I)
_WORD = re.compile(r"[A-Za-z][A-Za-z'-]*")
_CITATION = re.compile(
    r"(?:\[[0-9,\s-]+\]|\([A-Z][^()]{0,60},\s*(?:19|20)\d{2}\))"
)
_QUOTES = frozenset({'"', "“", "”", "‘", "’"})
_CLEFT_PREFIX = re.compile(r"^it is\b", re.I)
logger = logging.getLogger("plainrewrite.lexical")


@dataclass
class LexicalResult:
    text: str
    changes: list[LexicalChange] = field(default_factory=list)
    confidence: float = 0.0
    reason: str = ""


@lru_cache(maxsize=1)
def _get_wordnet() -> Any | None:
    try:
        import wn

        wn.config.allow_multithreading = True
        return wn.Wordnet(ENGINE_WORDNET_LEXICON)
    except Exception as exc:
        logger.warning("Open English WordNet unavailable: %s", exc)
        return None


def lexical_resource_available() -> bool:
    return _get_wordnet() is not None


def _context_terms(doc, target) -> set[str]:
    terms: set[str] = set()
    for token in doc:
        if token.i == target.i or token.is_stop or not token.is_alpha:
            continue
        if token.pos_ not in _POS_MAP and token.pos_ != "PROPN":
            continue
        for value in (token.text.lower(), token.lemma_.lower()):
            if len(value) >= 3:
                terms.add(value)
    return terms


def _terms_from_text(text: str, stop_words: set[str]) -> set[str]:
    terms = {match.group(0).lower() for match in _WORD.finditer(text or "")}
    return {term for term in terms if len(term) >= 3 and term not in stop_words}


def _gloss_terms(synset, stop_words: set[str]) -> tuple[set[str], set[str]]:
    definition = _terms_from_text(synset.definition(), stop_words)
    examples: set[str] = set()
    try:
        for example in synset.examples():
            examples.update(_terms_from_text(example, stop_words))
    except Exception:
        pass
    return definition, examples


def _sense_score(synset, context: set[str], stop_words: set[str]) -> float:
    if not context:
        return 0.0
    definition, examples = _gloss_terms(synset, stop_words)
    definition_overlap = context & definition
    if not definition_overlap:
        return 0.0
    example_overlap = context & examples
    weighted = len(definition_overlap) + (0.25 * len(example_overlap))
    return min(1.0, weighted / max(1, min(5, len(context))))


def _eligible(token, doc) -> bool:
    if token.pos_ not in _POS_MAP:
        return False
    lemma = token.lemma_.lower()
    if (
        token.pos_ == "PROPN"
        or token.ent_type_
        or token.is_stop
        or not token.is_alpha
        or len(lemma) < 3
        or token.dep_ in {"aux", "auxpass", "neg", "mark"}
        or _PROTECTED_MARKER.search(token.text)
    ):
        return False
    if token.tag_ == "VBG" and token.dep_ in {"ROOT", "csubj", "nsubj", "attr"}:
        return False
    if token.tag_ == "VBG" and token.i <= 2 and _CLEFT_PREFIX.search(doc.text):
        return False
    if lemma in {"be", "have", "do"}:
        return False
    if _CLEFT_PREFIX.search(doc.text) and token.text.lower() in {"it"}:
        return False
    # Freeze "* to …" constructions (equipped to, bring to, get to, …).
    if token.i + 1 < len(doc) and doc[token.i + 1].lower_ == "to":
        return False
    # Freeze passive verbal heads ("are brought by …").
    if token.pos_ == "VERB" and (
        token.dep_ in {"auxpass"}
        or any(child.dep_ == "auxpass" for child in token.children)
    ):
        return False
    return True


def _impact_rank(token) -> int:
    if token.pos_ == "ADV":
        return 0
    if token.pos_ == "ADJ":
        return 1
    if token.pos_ == "VERB" and token.dep_ != "ROOT":
        return 2
    if token.pos_ == "VERB":
        return 3
    if token.pos_ == "NOUN" and token.dep_ in {
        "attr",
        "acomp",
        "oprd",
        "pobj",
        "dobj",
        "appos",
    }:
        return 4
    if token.pos_ == "NOUN":
        return 5
    return 6


def _inflect(lemma: str, token) -> str | None:
    forms = getInflection(lemma, tag=token.tag_)
    value = forms[0] if forms else lemma
    if not value or not _WORD.fullmatch(value) or " " in value or "_" in value:
        return None
    if token.text.isupper():
        return value.upper()
    if token.text[:1].isupper():
        return value[:1].upper() + value[1:]
    return value.lower()


def _neighbor_words(doc, token) -> tuple[str, str]:
    left = ""
    right = ""
    if token.i > 0:
        prev = doc[token.i - 1]
        if prev.is_alpha:
            left = prev.text.lower()
    if token.i + 1 < len(doc):
        nxt = doc[token.i + 1]
        if nxt.is_alpha:
            right = nxt.text.lower()
    return left, right


def _object_lemma(token) -> str:
    for child in token.children:
        if child.dep_ in {"dobj", "obj"}:
            return child.lemma_.lower()
    return ""


def _phrase_zipf(word: str, left: str, right: str) -> float:
    scores = [zipf_frequency(word, "en")]
    if left:
        scores.append(zipf_frequency(f"{left} {word}", "en"))
    if right:
        scores.append(zipf_frequency(f"{word} {right}", "en"))
    return max(scores)


def _disaster_vo_blocked(
    source_lemma: str,
    candidate_lemma: str,
    token,
    *,
    left: str,
    right: str,
) -> bool:
    """Hard meaning-break blockers used even in aggressive classical mode."""
    if source_lemma == candidate_lemma:
        return False
    obj = _object_lemma(token)
    src_v = zipf_frequency(source_lemma, "en")
    cand_v = zipf_frequency(candidate_lemma, "en")
    if token.pos_ == "VERB" and obj:
        src_vo = zipf_frequency(f"{source_lemma} {obj}", "en")
        cand_vo = zipf_frequency(f"{candidate_lemma} {obj}", "en")
        src_spec = src_vo - src_v
        cand_spec = cand_vo - cand_v
        # resolve→decide / establish→launch: commoner verb inflates VO, sense drifts.
        if src_vo >= 3.8 and cand_v - src_v >= 0.35 and cand_spec <= src_spec + 0.08:
            return True
        if src_vo >= 3.8 and cand_vo >= src_vo and cand_spec + 0.08 < src_spec:
            return True
        # Crowded VO neighborhood: block only when specificity gets worse
        # (decide/determine/influence issues), allow near-parity (resolve→settle).
        if src_vo >= 4.0 and cand_vo >= 4.0 and cand_spec + 0.05 < src_spec:
            return True
        # Absolute floor: weak-specificity VO targets are almost always sense drift.
        if obj and cand_spec < -0.08 and src_vo >= 4.0:
            return True
        # deliver→function/serve style on service objects.
        if cand_spec < -0.30 and src_spec < -0.15 and cand_spec < src_spec + 0.40:
            return True
    if token.pos_ == "VERB" and right:
        src_bi = zipf_frequency(f"{source_lemma} {right}", "en")
        cand_bi = zipf_frequency(f"{candidate_lemma} {right}", "en")
        # respond promptly → answer promptly (ungrammatical with following "to").
        if (
            right == "promptly"
            and cand_v >= 5.0
            and cand_v - src_v >= 0.40
            and cand_bi + 0.10 >= src_bi
        ):
            return True
    return False


def _collocation_ok(
    source_lemma: str,
    candidate_lemma: str,
    token,
    *,
    left: str,
    right: str,
    classical_strict: bool = False,
    headword_upgrade: bool = False,
    classical_aggressive: bool = False,
) -> bool:
    """Reject swaps that collapse local collocations (algorithmic, no denylist)."""
    # Aggressive mode: restore synonym throughput, keep only disaster VO brakes.
    if classical_aggressive and classical_strict and not headword_upgrade:
        if _disaster_vo_blocked(
            source_lemma, candidate_lemma, token, left=left, right=right
        ):
            return False
        classical_strict = False
    obj = _object_lemma(token)
    src_v = zipf_frequency(source_lemma, "en")
    cand_v = zipf_frequency(candidate_lemma, "en")
    checks: list[tuple[float, float]] = []
    if obj:
        checks.append(
            (
                zipf_frequency(f"{source_lemma} {obj}", "en"),
                zipf_frequency(f"{candidate_lemma} {obj}", "en"),
            )
        )
    if right:
        checks.append(
            (
                zipf_frequency(f"{source_lemma} {right}", "en"),
                zipf_frequency(f"{candidate_lemma} {right}", "en"),
            )
        )
    if left:
        checks.append(
            (
                zipf_frequency(f"{left} {source_lemma}", "en"),
                zipf_frequency(f"{left} {candidate_lemma}", "en"),
            )
        )
    for source_score, candidate_score in checks:
        slack = 0.35 if classical_strict else 0.55
        if source_score >= 2.2 and candidate_score + slack < source_score:
            return False
        if source_score >= 3.0 and candidate_score < (2.4 if classical_strict else 2.0):
            return False
        if source_score >= 3.5 and candidate_score + (
            0.45 if classical_strict else 0.85
        ) < source_score:
            return False
        if source_score >= 4.0 and candidate_score < 2.0:
            return False
        if classical_strict and source_score >= 2.5:
            # Specificity = bigram − bare verb. Blocks resolve→decide / respond→answer
            # where a more common verb inflates raw zipf but weakens the pair.
            src_spec = source_score - src_v
            cand_spec = candidate_score - cand_v
            if headword_upgrade:
                # maintain→keep: allow a specificity drop only with a clear everyday leap.
                if cand_spec + 0.05 < src_spec and cand_v - src_v < 0.90:
                    return False
            else:
                if cand_spec + 0.02 < src_spec:
                    return False
                if candidate_score > source_score and cand_spec < src_spec:
                    return False
                if cand_v >= 5.15 and cand_v - src_v >= 0.45:
                    return False
    # Verb + object: prefer attested collocations; block free WordNet drift.
    if token.pos_ == "VERB" and obj:
        source_obj = zipf_frequency(f"{source_lemma} {obj}", "en")
        candidate_obj = zipf_frequency(f"{candidate_lemma} {obj}", "en")
        src_spec = source_obj - src_v
        cand_spec = candidate_obj - cand_v
        if classical_strict:
            if headword_upgrade:
                if candidate_obj + 0.05 < source_obj or candidate_obj < 2.0:
                    return False
                if cand_spec + 0.05 < src_spec and cand_v - src_v < 0.90:
                    return False
                return True
            if cand_spec + 0.02 < src_spec:
                return False
            if candidate_obj > source_obj and cand_spec < src_spec:
                return False
            if cand_v >= 5.15 and cand_v - src_v >= 0.45:
                return False
            if cand_spec < -0.30 and src_spec < -0.20 and cand_spec < src_spec + 0.55:
                return False
            # Both rare with this object → synonym roulette (decide/define issues).
            if source_obj < 2.2 and candidate_obj < 2.2:
                return False
            if source_obj >= 2.0 and candidate_obj + 0.20 < source_obj:
                return False
            if candidate_obj < 2.0:
                return False
            if abs(cand_v - src_v) < 0.40 and cand_spec <= src_spec + 0.05:
                return False
            return True
        if source_obj >= 1.8 and candidate_obj + 0.35 < source_obj:
            return False
        if source_obj < 1.5 and candidate_obj < 1.5:
            # Both rare with this object — require the candidate verb itself to be
            # clearly more everyday, handled elsewhere; still block near-ties.
            return candidate_obj + 0.1 >= source_obj
    elif classical_strict and token.pos_ == "VERB":
        # No object: block leaps into ultra-common verbs unless a true headword leap.
        if cand_v >= 5.15 and cand_v - src_v >= 0.45:
            if not headword_upgrade or cand_v - src_v < 0.90:
                return False
    return True


def _peer_cycle_blocked(
    source_lemma: str,
    candidate_lemma: str,
    source_frequency: float,
    candidate_frequency: float,
    *,
    classical_strict: bool,
    classical_aggressive: bool = False,
    allow_headword_upgrade: bool = False,
) -> bool:
    """Block synonym oscillation.

    Strict mode blocks near-peer swaps. Aggressive mode only blocks clear
    demotions (rarer candidate) so each pass can still diverge.
    """
    if not classical_strict or allow_headword_upgrade:
        return False
    if classical_aggressive:
        # Allow near-peer motion across passes (keep↔maintain); only block
        # severe demotions into rare wording.
        return candidate_frequency + 0.85 < source_frequency
    if candidate_frequency + 0.20 < source_frequency:
        return True
    if (
        abs(candidate_frequency - source_frequency) < 0.40
        and candidate_frequency < source_frequency + 0.45
    ):
        return True
    return False


def _frequency_ok(
    source_frequency: float,
    candidate_frequency: float,
    *,
    classical_aggressive: bool = False,
) -> bool:
    if classical_aggressive:
        # Allow broader everyday band so multi-pass wording can keep moving.
        if candidate_frequency < max(3.2, ENGINE_LEXICAL_MIN_ZIPF - 0.8):
            return False
        return abs(candidate_frequency - source_frequency) <= 1.8
    if candidate_frequency < ENGINE_LEXICAL_MIN_ZIPF:
        return False
    if ENGINE_LEXICAL_PREFER_SIMPLER:
        if candidate_frequency > source_frequency:
            return (
                candidate_frequency - source_frequency
                <= ENGINE_LEXICAL_MAX_SIMPLER_GAP
            )
        return source_frequency - candidate_frequency <= ENGINE_LEXICAL_MAX_HARDER_GAP
    return (
        abs(candidate_frequency - source_frequency)
        <= ENGINE_LEXICAL_MAX_FREQUENCY_GAP
    )


def _candidate_for_synset(
    synset,
    token,
    doc,
    *,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> tuple[str, float] | None:
    source = token.lemma_.lower()
    source_surface = token.text.lower()
    source_frequency = max(
        zipf_frequency(source, "en"),
        zipf_frequency(source_surface, "en"),
    )
    left, right = _neighbor_words(doc, token)
    source_phrase = _phrase_zipf(source_surface, left, right)
    try:
        words = synset.words()
    except Exception:
        return None

    ranked: list[tuple[float, float, float, str]] = []
    for word in words:
        lemma = (word.lemma() or "").replace("_", " ").strip().lower()
        if (
            not lemma
            or lemma == source
            or " " in lemma
            or not _WORD.fullmatch(lemma)
        ):
            continue
        if not _collocation_ok(
            source,
            lemma,
            token,
            left=left,
            right=right,
            classical_strict=classical_strict,
            headword_upgrade=False,
            classical_aggressive=classical_aggressive,
        ):
            continue
        replacement = _inflect(lemma, token)
        if not replacement or replacement.lower() == token.text.lower():
            continue
        candidate_frequency = zipf_frequency(lemma, "en")
        rank_frequency = zipf_frequency(replacement.lower(), "en")
        if not _frequency_ok(
            source_frequency,
            max(candidate_frequency, rank_frequency),
            classical_aggressive=classical_aggressive,
        ):
            continue
        if _peer_cycle_blocked(
            source,
            lemma,
            source_frequency,
            max(candidate_frequency, rank_frequency),
            classical_strict=classical_strict,
            classical_aggressive=classical_aggressive,
        ):
            continue

        # Avoid noun swaps into ultra-common generic words (goal→end).
        if (
            token.pos_ == "NOUN"
            and max(candidate_frequency, rank_frequency) >= 5.5
            and max(candidate_frequency, rank_frequency) - source_frequency >= 0.5
        ):
            continue
        phrase = _phrase_zipf(replacement.lower(), left, right)
        phrase_slack = (
            0.55
            if classical_aggressive
            else (0.25 if classical_strict else 0.55)
        )
        if phrase + phrase_slack < source_phrase:
            continue
        if left and token.pos_ == "NOUN":
            source_bigram = zipf_frequency(f"{left} {source_surface}", "en")
            candidate_bigram = zipf_frequency(
                f"{left} {replacement.lower()}", "en"
            )
            if source_bigram >= 3.0 and candidate_bigram + 0.45 < source_bigram:
                continue
        if (
            token.pos_ == "NOUN"
            and left
            and token.i > 0
            and doc[token.i - 1].pos_ == "ADJ"
            and phrase > source_phrase + 0.25
        ):
            continue
        if not substitution_pos_stable(doc.text, token.i, replacement):
            continue
        ranked.append(
            (
                max(candidate_frequency, rank_frequency) - source_frequency,
                -abs(
                    max(candidate_frequency, rank_frequency)
                    - (
                        source_frequency
                        + (0.55 if ENGINE_LEXICAL_PREFER_SIMPLER else 0.0)
                    )
                ),
                phrase,
                -float(len(replacement)),
                replacement,
            )
        )

    if not ranked:
        return None
    # Prefer a clear everyday upgrade when available (assist→help), otherwise
    # the nearest modest step that still passes frequency checks.
    clear = [item for item in ranked if item[0] >= 0.45]
    pool = clear if clear else [item for item in ranked if item[0] >= 0.0]
    if not pool:
        pool = ranked
    if classical_aggressive:
        # Prefer surface-different wording so multi-pass rewrites keep moving.
        pool.sort(
            key=lambda item: (
                abs(len(item[4]) - len(source_surface))
                + sum(1 for a, b in zip(item[4].lower(), source_surface) if a != b),
                item[0],
                item[2],
            ),
            reverse=True,
        )
    else:
        pool.sort(key=lambda item: (item[1], item[0], item[2], item[3]), reverse=True)
    best = pool[0][4]
    return best, pool[0][0]


def _article_for(word: str) -> str:
    return "an" if word[:1].lower() in {"a", "e", "i", "o", "u"} else "a"


def _synset_single_word_lemmas(synset) -> list[str]:
    lemmas: list[str] = []
    try:
        words = synset.words()
    except Exception:
        return lemmas
    for word in words:
        lemma = (word.lemma() or "").replace("_", " ").strip().lower()
        if lemma and " " not in lemma and _WORD.fullmatch(lemma):
            lemmas.append(lemma)
    return lemmas


def _source_lemma_rank(synset, source_lemma: str) -> int:
    """Lower rank = source is a more canonical member of this synset."""
    lemmas = _synset_single_word_lemmas(synset)
    try:
        return lemmas.index(source_lemma)
    except ValueError:
        return 99


def _candidate_lemma_for_replacement(synset, token, replacement: str) -> str:
    """Map an inflected replacement back to a synset lemma when possible."""
    surface = replacement.lower()
    for lemma in _synset_single_word_lemmas(synset):
        form = _inflect(lemma, token)
        if form and form.lower() == surface:
            return lemma
        if lemma == surface:
            return lemma
    return surface


def _unglossed_verb_allowed(
    synset,
    *,
    source_lemma: str,
    cand_lemma: str,
    stop_words: set[str],
    classical_strict: bool = False,
) -> bool:
    """Allow unglossed verb swaps only with strong sense evidence.

    Blocks preserve→continue while keeping purchase→buy, assist→help,
    construct→build, and require→need on canonical senses.
    """
    defn_terms = _terms_from_text(synset.definition(), stop_words)
    lemmas = _synset_single_word_lemmas(synset)
    others = [lemma for lemma in lemmas if lemma != source_lemma]
    source_rank = _source_lemma_rank(synset, source_lemma)
    # Never demote a headword to a secondary lemma (keep→maintain).
    if classical_strict and source_rank == 0 and cand_lemma in lemmas[1:]:
        return False
    # Definition names the candidate in a sense where source is near-canonical.
    if (
        cand_lemma in defn_terms
        and source_rank <= 2
        and len(lemmas) >= 3
    ):
        return True
    # Two-word everyday headword pair (buy/purchase, end/terminate).
    if (
        len(others) == 1
        and others[0] == cand_lemma
        and lemmas
        and lemmas[0] == cand_lemma
        and source_rank == 1
    ):
        defn_l = (synset.definition() or "").lower()
        if cand_lemma in defn_terms:
            return True
        # "obtain by purchase" style definitions name the source as the method.
        if f"by {source_lemma}" in defn_l or f"of {source_lemma}" in defn_l:
            return True
    # Headword in a multi-lemma sense (construct/build/make).
    if (
        source_rank == 0
        and len(lemmas) >= 3
        and cand_lemma in lemmas[:3]
        and not classical_strict
    ):
        return True
    return False


def _polish_headword_upgrade(synset, source_lemma: str, cand_lemma: str) -> bool:
    """Polish-only: allow source→headword upgrades in small verb synsets.

    Example: maintain→keep on keep/maintain/hold. Blocks identify→place where
    the source is already the headword.
    """
    lemmas = _synset_single_word_lemmas(synset)
    if not lemmas or lemmas[0] != cand_lemma:
        return False
    source_rank = _source_lemma_rank(synset, source_lemma)
    return 1 <= source_rank <= 4 and 2 <= len(lemmas) <= 5


def _headword_candidate_for_synset(
    synset,
    token,
    doc,
    *,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> tuple[str, float] | None:
    """Try the synset headword directly for polish-only verb upgrades."""
    lemmas = _synset_single_word_lemmas(synset)
    if not lemmas:
        return None
    head = lemmas[0]
    replacement = _inflect(head, token)
    if not replacement or replacement.lower() == token.text.lower():
        return None
    source = token.lemma_.lower()
    source_surface = token.text.lower()
    source_frequency = max(
        zipf_frequency(source, "en"),
        zipf_frequency(source_surface, "en"),
    )
    left, right = _neighbor_words(doc, token)
    source_phrase = _phrase_zipf(source_surface, left, right)
    if not _collocation_ok(
        source,
        head,
        token,
        left=left,
        right=right,
        classical_strict=classical_strict,
        headword_upgrade=True,
        classical_aggressive=classical_aggressive,
    ):
        return None
    candidate_frequency = zipf_frequency(head, "en")
    rank_frequency = zipf_frequency(replacement.lower(), "en")
    if not _frequency_ok(
        source_frequency,
        max(candidate_frequency, rank_frequency),
        classical_aggressive=classical_aggressive,
    ):
        return None
    phrase = _phrase_zipf(replacement.lower(), left, right)
    phrase_slack = 0.55 if classical_aggressive else (0.25 if classical_strict else 0.55)
    if phrase + phrase_slack < source_phrase:
        return None
    if not substitution_pos_stable(doc.text, token.i, replacement):
        return None
    return replacement, max(candidate_frequency, rank_frequency) - source_frequency


def _pick_verb_candidate(
    token,
    doc,
    synsets: list[Any],
    context: set[str],
    stop_words: set[str],
    *,
    effective_min: float,
    gain_floor: float,
    polish: bool = False,
    aggressive: bool = False,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> tuple[float, str, float, Any] | None:
    """Choose a verb synonym from a few top senses with collocational safety."""
    obj = _object_lemma(token)
    src_lemma = token.lemma_.lower()
    weak_gloss = max(float(effective_min), 0.25)
    # Prenominal/predicative participles often act like adjectives
    # ("satisfying customer experience") — never trust unglossed verb senses.
    adjectival_participle = token.tag_ == "VBG" and token.dep_ in {
        "amod",
        "acomp",
        "oprd",
    }
    options: list[tuple[float, int, float, float, str, Any]] = []
    # WordNet orders senses by frequency. Without a meaning gate, a wide window
    # lets marginal senses supply peers (settle "reside" → locate), so classical
    # mode only considers the dominant readings.
    sense_window = 3 if classical_strict else 6
    ordered = sorted(
        synsets[:sense_window],
        key=lambda synset: (
            _source_lemma_rank(synset, src_lemma),
            -_sense_score(synset, context, stop_words),
        ),
    )
    for synset in ordered:
        score = _sense_score(synset, context, stop_words)
        picked = _candidate_for_synset(
            synset,
            token,
            doc,
            classical_strict=classical_strict,
            classical_aggressive=classical_aggressive,
        )
        headword_polish = False
        if (
            polish
            and not aggressive
            and score < weak_gloss
            and _source_lemma_rank(synset, src_lemma) >= 1
        ):
            headword_pick = _headword_candidate_for_synset(
                synset,
                token,
                doc,
                classical_strict=classical_strict,
                classical_aggressive=classical_aggressive,
            )
            if headword_pick is not None:
                picked = headword_pick
                headword_polish = True
        if not picked:
            continue
        replacement, simplicity_gain = picked
        if (
            score < effective_min
            and simplicity_gain < gain_floor
            and not headword_polish
        ):
            continue
        cand_lemma = _candidate_lemma_for_replacement(synset, token, replacement)
        high_gain_ok = False
        if score < weak_gloss:
            if adjectival_participle:
                continue
            unglossed_ok = _unglossed_verb_allowed(
                synset,
                source_lemma=src_lemma,
                cand_lemma=cand_lemma,
                stop_words=stop_words,
                classical_strict=classical_strict and not classical_aggressive,
            )
            # Polish may upgrade to the synset headword (maintain→keep) when
            # the source is a secondary lemma. Aggressive/ensure stay stricter.
            high_gain_ok = (
                polish
                and simplicity_gain >= 0.08
                and _polish_headword_upgrade(synset, src_lemma, cand_lemma)
            )
            if classical_strict and high_gain_ok:
                # Headword upgrades still need object attestation when present.
                if obj:
                    src_c = zipf_frequency(f"{src_lemma} {obj}", "en")
                    cand_c = zipf_frequency(f"{cand_lemma} {obj}", "en")
                    if cand_c + 0.05 < src_c or cand_c < 2.0:
                        high_gain_ok = False
            if not unglossed_ok and not high_gain_ok:
                continue
            multiword_parent = False
            try:
                for word in synset.words():
                    multi = (word.lemma() or "").replace("_", " ").strip().lower()
                    if multi.startswith(cand_lemma + " "):
                        multiword_parent = True
                        break
            except Exception:
                pass
            if multiword_parent:
                continue
        src_colloc = zipf_frequency(f"{src_lemma} {obj}", "en") if obj else 0.0
        cand_colloc = zipf_frequency(f"{cand_lemma} {obj}", "en") if obj else 0.0
        # Strong verb+object phrases need real context gloss, not synonymy alone
        # (blocks create→make results while allowing purchase→buy).
        if obj and src_colloc >= 4.7 and score < weak_gloss and score < effective_min:
            continue
        if (
            score < weak_gloss
            and polish
            and high_gain_ok
            and obj
            and (
                cand_colloc + 0.05 < src_colloc
                # Large collocation jumps often mark a different sense
                # (identify areas → name areas), while modest ones are OK
                # (maintain attitude → keep attitude).
                or (src_colloc >= 4.2 and cand_colloc - src_colloc >= 0.45)
            )
        ):
            continue
        if classical_strict and obj and cand_colloc < 2.0:
            continue
        options.append(
            (
                score,
                _source_lemma_rank(synset, src_lemma),
                simplicity_gain,
                cand_colloc,
                replacement,
                synset,
            )
        )
    if not options:
        return None
    options.sort(key=lambda item: (-item[0], item[1], -item[2], -item[3]))
    score, _rank, gain, _colloc, replacement, synset = options[0]
    return (max(score, effective_min), replacement, gain, synset)


def dynamic_lexical_budget(text: str, *, polish: bool = False) -> int:
    """Choose how many synonym swaps a sentence may take from its length.

    Longer sentences get a larger budget so wording density scales with size
    instead of a fixed environment cap.
    """
    words = len(_WORD.findall(text or ""))
    if words < 3:
        return 0
    # Normal: about one safe swap per 8 words; polish: denser (~per 4 words).
    stride = 4 if polish else 8
    budget = max(1, (words + stride - 1) // stride)
    if polish and words >= 5:
        budget = max(budget, 2)
    # Soft ceiling grows with length; polish allows a bit more.
    ceiling = (6 + words // 6) if polish else (4 + words // 10)
    budget = min(budget, max(1, min(ceiling, 15)))
    if ENGINE_LEXICAL_MAX_CHANGES > 0:
        budget = min(budget, ENGINE_LEXICAL_MAX_CHANGES)
    return budget


def _related_modifier_synsets(synset) -> list[Any]:
    """WordNet-linked adjective/adverb senses (no hardcoded synonym lists)."""
    related: list[Any] = []
    seen: set[str] = set()
    for relation in ("also", "similar"):
        try:
            linked = list(synset.get_related(relation) or [])
        except Exception:
            linked = []
        for item in linked:
            syn_id = str(getattr(item, "id", item))
            if syn_id in seen:
                continue
            seen.add(syn_id)
            related.append(item)
            if len(related) >= 12:
                return related
    return related


def _pick_related_modifier_candidate(
    token,
    doc,
    synsets: list[Any],
    *,
    gain_floor: float,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> tuple[float, str, float, Any] | None:
    """Polish helper: try WordNet related senses when same-synset synonyms are thin."""
    if classical_strict and not classical_aggressive:
        return None
    source_freq = max(
        zipf_frequency(token.lemma_.lower(), "en"),
        zipf_frequency(token.text.lower(), "en"),
    )
    options: list[tuple[float, float, str, Any]] = []
    for synset in synsets[:2]:
        for related in _related_modifier_synsets(synset):
            picked = _candidate_for_synset(
                related,
                token,
                doc,
                classical_strict=classical_strict,
                classical_aggressive=classical_aggressive,
            )
            if not picked:
                continue
            replacement, simplicity_gain = picked
            if simplicity_gain < gain_floor or simplicity_gain > 0.95:
                continue
            cand_freq = zipf_frequency(replacement.lower(), "en")
            if cand_freq < ENGINE_LEXICAL_MIN_ZIPF:
                continue
            # Related senses are broader than true synonyms; keep them everyday
            # but avoid ultra-generic leaps (effective→strong, important→big).
            if cand_freq >= 5.2:
                continue
            if cand_freq - source_freq >= 0.85:
                continue
            options.append((simplicity_gain, cand_freq, replacement, related))
    if not options:
        return None
    options.sort(key=lambda item: (item[0], item[1]), reverse=True)
    gain, _freq, replacement, synset = options[0]
    return (max(0.12, gain_floor), replacement, gain, synset)


def refine_sentence(
    text: str,
    *,
    min_wsd: float,
    max_changes: int | None = None,
    wordnet: Any | None = None,
    aggressive: bool = False,
    polish: bool = False,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> LexicalResult:
    """Replace low-impact words with simpler everyday synonyms when safe."""
    source = (text or "").strip()
    if not source:
        return LexicalResult(text=text, reason="empty")
    if any(quote in source for quote in _QUOTES):
        return LexicalResult(text=source, reason="quoted")
    if _CITATION.search(source):
        return LexicalResult(text=source, reason="citation")
    if _PROTECTED_MARKER.search(source):
        return LexicalResult(text=source, reason="protected")

    nlp = get_nlp()
    resource = wordnet if wordnet is not None else _get_wordnet()
    if nlp is None or resource is None:
        return LexicalResult(text=source, reason="resource_unavailable")
    try:
        doc = nlp(source)
    except Exception:
        return LexicalResult(text=source, reason="parse_failed")

    tight = classical_strict and not classical_aggressive
    if aggressive:
        if tight:
            # No forced aggressive synonym roulette without a meaning gate.
            return LexicalResult(text=source, reason="classical_strict_no_aggressive")
        effective_min = max(0.05, min_wsd * 0.5)
        verb_gain_floor = 0.08 if classical_aggressive else 0.40
        adj_adv_gain_floor = 0.0 if classical_aggressive else 0.15
    elif polish:
        # Polish mode should feel stronger on any sentence, not only because the
        # sentence earned a larger budget. Keep the same safety rails, but allow
        # slightly weaker-yet-still-supported everyday substitutions.
        effective_min = max(0.05, min_wsd * 0.6) if classical_aggressive else max(0.10, min_wsd * 0.85)
        verb_gain_floor = 0.08 if classical_aggressive else (0.45 if tight else 0.30)
        adj_adv_gain_floor = 0.0 if classical_aggressive else (0.20 if tight else 0.10)
    else:
        effective_min = max(0.08, min_wsd * 0.7) if classical_aggressive else (min_wsd if not tight else max(min_wsd, 0.18))
        verb_gain_floor = 0.15 if classical_aggressive else (0.45 if not tight else 0.55)
        adj_adv_gain_floor = 0.0 if not tight else 0.15
    stop_words = set(nlp.Defaults.stop_words)
    proposals: list[tuple[float, int, float, int, int, str, Any]] = []
    for token in doc:
        if not _eligible(token, doc):
            continue
        # Prefer low-impact slots: modifiers first; nouns/verbs need stronger sense support.
        context = _context_terms(doc, token)
        try:
            synsets = list(
                resource.synsets(
                    token.lemma_.lower(),
                    pos=_POS_MAP[token.pos_],
                )
            )
        except Exception:
            continue
        if not synsets:
            continue

        # Nouns stay on the primary sense. Verbs search canonical senses first.
        if token.pos_ in {"NOUN", "VERB"}:
            if token.pos_ == "VERB":
                picked_verb = _pick_verb_candidate(
                    token,
                    doc,
                    synsets,
                    context,
                    stop_words,
                    effective_min=effective_min,
                    gain_floor=verb_gain_floor,
                    polish=polish,
                    aggressive=aggressive,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if not picked_verb:
                    continue
                best_score, replacement, simplicity_gain, chosen = picked_verb
            else:
                chosen = synsets[0]
                best_score = _sense_score(chosen, context, stop_words)
                picked = _candidate_for_synset(
                    chosen,
                    token,
                    doc,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if not picked:
                    continue
                replacement, simplicity_gain = picked
                noun_min = (
                    effective_min if not aggressive else max(0.08, effective_min)
                )
                if (
                    best_score < noun_min
                    or simplicity_gain
                    < (
                        (-0.15 if classical_aggressive else 0.25)
                        if polish and not aggressive
                        else (-0.05 if classical_aggressive else 0.35)
                    )
                    or simplicity_gain
                    > (1.8 if classical_aggressive else (1.45 if polish and not aggressive else 1.25))
                ):
                    continue
                cand_freq = zipf_frequency(replacement.lower(), "en")
                if cand_freq >= 5.5 and simplicity_gain >= (
                    0.7 if polish and not aggressive else 0.5
                ):
                    continue
                if best_score < effective_min:
                    best_score = effective_min
            proposals.append(
                (
                    best_score,
                    _impact_rank(token),
                    -simplicity_gain,
                    token.idx,
                    token.i,
                    replacement,
                    chosen,
                )
            )
            continue
        else:
            scored: list[tuple[float, Any]] = []
            for synset in synsets:
                scored.append((_sense_score(synset, context, stop_words), synset))
            scored.sort(key=lambda item: item[0], reverse=True)
            best_score, best_synset = scored[0]
            chosen = None
            if best_score >= effective_min:
                chosen = best_synset
            elif len(synsets) == 1:
                chosen = best_synset
                best_score = effective_min
            elif polish and not aggressive and best_score >= effective_min * 0.75:
                trial = _candidate_for_synset(
                    best_synset,
                    token,
                    doc,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if trial is not None and trial[1] >= adj_adv_gain_floor:
                    chosen = best_synset
                    best_score = max(best_score, effective_min)
            elif ENGINE_LEXICAL_PREFER_SIMPLER and best_score == 0.0:
                trial = _candidate_for_synset(
                    synsets[0],
                    token,
                    doc,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                gain_need = 0.25 if aggressive else 0.45
                if trial is not None and trial[1] >= gain_need:
                    chosen = synsets[0]
                    best_score = effective_min
            elif aggressive and best_score >= effective_min * 0.5:
                trial = _candidate_for_synset(
                    best_synset,
                    token,
                    doc,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if trial is not None and trial[1] >= adj_adv_gain_floor:
                    chosen = best_synset
                    best_score = max(best_score, effective_min)

            picked = (
                _candidate_for_synset(
                    chosen,
                    token,
                    doc,
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if chosen is not None
                else None
            )
            if not picked and polish and not aggressive:
                # Same-synset lemmas are often empty (essential→?). Use WordNet
                # related senses so polish can still densify wording safely.
                related = _pick_related_modifier_candidate(
                    token,
                    doc,
                    synsets,
                    gain_floor=max(adj_adv_gain_floor, 0.25),
                    classical_strict=classical_strict,
                    classical_aggressive=classical_aggressive,
                )
                if related:
                    best_score, replacement, simplicity_gain, chosen = related
                    picked = (replacement, simplicity_gain)
            if not picked:
                continue
            replacement, simplicity_gain = picked
            if aggressive and simplicity_gain < adj_adv_gain_floor and best_score < min_wsd:
                continue
            if polish and not aggressive and simplicity_gain < adj_adv_gain_floor:
                continue
            proposals.append(
                (
                    best_score,
                    _impact_rank(token),
                    -simplicity_gain,
                    token.idx,
                    token.i,
                    replacement,
                    chosen,
                )
            )

    if not proposals:
        return LexicalResult(text=source, reason="no_confident_candidate")

    if max_changes is None:
        limit = dynamic_lexical_budget(source, polish=polish)
    else:
        limit = max(1, min(int(max_changes), 15))
    if classical_strict and not classical_aggressive:
        limit = min(limit, 2 if polish else 1)
    elif classical_aggressive:
        # Aggressive multi-pass: denser wording each hop.
        limit = max(limit, 5 if polish else 3)
        limit = min(limit, 10 if polish else 6)
    if limit <= 0:
        return LexicalResult(text=source, reason="budget_zero")
    proposals.sort(key=lambda item: (-item[0], item[1], item[2], item[4]))
    selected = proposals[:limit]
    output = source
    changes: list[LexicalChange] = []
    for confidence, _impact, _gain, offset, token_index, replacement, synset in sorted(
        selected,
        key=lambda item: item[3],
        reverse=True,
    ):
        token = doc[token_index]
        output = output[:offset] + replacement + output[offset + len(token.text) :]
        if token_index > 0 and doc[token_index - 1].lower_ in {"a", "an"}:
            prev = doc[token_index - 1]
            needed = _article_for(replacement)
            if prev.lower_ != needed:
                article = needed.capitalize() if prev.text[:1].isupper() else needed
                output = (
                    output[: prev.idx]
                    + article
                    + output[prev.idx + len(prev.text) :]
                )
        changes.append(
            LexicalChange(
                original=token.text,
                replacement=replacement,
                token_index=token_index,
                lemma=token.lemma_,
                synset_id=str(getattr(synset, "id", synset)),
                confidence=round(confidence, 4),
            )
        )
    if polish and not aggressive and (classical_aggressive or not classical_strict) and len(changes) < limit:
        # Fill remaining polish budget with same-synset aggressive swaps only.
        # Related-sense expansion stays single-pass to avoid chains like
        # effective→strong→hard.
        extra = refine_sentence(
            output,
            min_wsd=max(0.08, min_wsd * 0.8),
            max_changes=limit - len(changes),
            wordnet=resource,
            aggressive=True,
            polish=False,
            classical_strict=classical_strict,
            classical_aggressive=classical_aggressive,
        )
        if extra.changes and extra.text != output:
            seen = {
                (change.original.lower(), change.replacement.lower())
                for change in changes
            }
            appended = False
            for change in extra.changes:
                pair = (change.original.lower(), change.replacement.lower())
                if pair not in seen:
                    changes.append(change)
                    seen.add(pair)
                    appended = True
            if appended:
                output = extra.text
    changes.sort(key=lambda change: change.token_index)
    confidence = min(change.confidence for change in changes)
    return LexicalResult(text=output, changes=changes, confidence=confidence)


def ensure_wording_change(
    text: str,
    *,
    min_wsd: float = 0.08,
    max_changes: int | None = None,
    wordnet: Any | None = None,
    polish: bool = False,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> LexicalResult:
    """Last-resort meaning-safe wording change for still-unchanged sentences."""
    source = (text or "").strip()
    if not source:
        return LexicalResult(text=text, reason="empty")

    if classical_strict and not classical_aggressive:
        # Without MiniLM, do not force synonym swaps just to look different.
        return LexicalResult(text=source, reason="classical_strict_no_ensure")

    aggressive = refine_sentence(
        source,
        min_wsd=min_wsd,
        max_changes=max_changes,
        wordnet=wordnet,
        aggressive=True,
        polish=polish,
        classical_strict=classical_strict,
        classical_aggressive=classical_aggressive,
    )
    if aggressive.changes and aggressive.text.strip() != source:
        aggressive.reason = aggressive.reason or "ensure_aggressive"
        return aggressive

    forced = _force_one_safe_swap(
        source,
        wordnet=wordnet,
        classical_strict=classical_strict,
        classical_aggressive=classical_aggressive,
    )
    if forced.changes and forced.text.strip() != source:
        return forced
    return LexicalResult(text=source, reason="ensure_unavailable")

def _force_one_safe_swap(
    text: str,
    *,
    wordnet: Any | None = None,
    classical_strict: bool = False,
    classical_aggressive: bool = False,
) -> LexicalResult:
    """Pick one low-impact ADV/ADJ/VERB swap from the primary sense when possible."""
    source = (text or "").strip()
    nlp = get_nlp()
    resource = wordnet if wordnet is not None else _get_wordnet()
    if nlp is None or resource is None:
        return LexicalResult(text=source, reason="resource_unavailable")
    try:
        doc = nlp(source)
    except Exception:
        return LexicalResult(text=source, reason="parse_failed")

    stop_words = set(nlp.Defaults.stop_words)
    ranked: list[tuple[int, float, float, int, str, Any]] = []
    for token in doc:
        if not _eligible(token, doc):
            continue
        if token.pos_ not in {"ADV", "ADJ", "VERB"}:
            continue
        try:
            synsets = list(
                resource.synsets(token.lemma_.lower(), pos=_POS_MAP[token.pos_])
            )
        except Exception:
            continue
        if not synsets:
            continue
        context = _context_terms(doc, token)
        if token.pos_ == "VERB":
            picked_verb = _pick_verb_candidate(
                token,
                doc,
                synsets,
                context,
                stop_words,
                effective_min=0.08,
                gain_floor=0.30,
                aggressive=True,
                classical_strict=classical_strict,
                classical_aggressive=classical_aggressive,
            )
            if not picked_verb:
                continue
            sense, replacement, simplicity_gain, synset = picked_verb
            ranked.append(
                (
                    _impact_rank(token),
                    -simplicity_gain,
                    -sense,
                    token.i,
                    replacement,
                    synset,
                )
            )
            continue

        # Prefer primary sense; for modifiers also try the best-scored sense.
        candidates = [synsets[0]]
        if len(synsets) > 1:
            scored = sorted(
                (
                    (_sense_score(s, context, stop_words), idx, s)
                    for idx, s in enumerate(synsets)
                ),
                reverse=True,
            )
            if scored[0][2] not in candidates:
                candidates.append(scored[0][2])
        for synset in candidates:
            picked = _candidate_for_synset(
                synset,
                token,
                doc,
                classical_strict=classical_strict,
                classical_aggressive=classical_aggressive,
            )
            if not picked:
                continue
            replacement, simplicity_gain = picked
            sense = _sense_score(synset, context, stop_words)
            if simplicity_gain < 0.08 and sense < 0.05:
                continue
            ranked.append(
                (
                    _impact_rank(token),
                    -simplicity_gain,
                    -sense,
                    token.i,
                    replacement,
                    synset,
                )
            )
            break

    if not ranked:
        return LexicalResult(text=source, reason="no_force_candidate")
    ranked.sort()
    impact, _gain, _sense, token_index, replacement, synset = ranked[0]
    token = doc[token_index]
    output = source[: token.idx] + replacement + source[token.idx + len(token.text) :]
    if token_index > 0 and doc[token_index - 1].lower_ in {"a", "an"}:
        prev = doc[token_index - 1]
        needed = _article_for(replacement)
        if prev.lower_ != needed:
            article = needed.capitalize() if prev.text[:1].isupper() else needed
            output = (
                output[: prev.idx] + article + output[prev.idx + len(prev.text) :]
            )
    change = LexicalChange(
        original=token.text,
        replacement=replacement,
        token_index=token_index,
        lemma=token.lemma_,
        synset_id=str(getattr(synset, "id", synset)),
        confidence=0.55,
    )
    return LexicalResult(
        text=output,
        changes=[change],
        confidence=0.55,
        reason="ensure_force_swap",
    )