// ChatIPC := Chat Incremental Pattern Constructor

#include <algorithm>
#include <atomic>
#include <cctype>
#include <cinttypes>
#include <cstring>
#include <fstream>
#include <iostream>
#include <iterator>
#include <map>
#include <mutex>
#include <optional>
#include <sstream>
#include <stdexcept>
#include <string>
#include <thread>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#ifdef _OPENMP
#include <omp.h>
#else
inline int omp_get_max_threads(){ return 1; }
inline int omp_get_thread_num(){ return 0; }
#endif

extern unsigned char dictionary_json[];      // provide dictionary.cpp to embed dictionary JSON bytes
extern unsigned int dictionary_json_len;

// --------------------------- Short utility functions ----------------------

static inline bool is_space(char c){ return std::isspace(static_cast<unsigned char>(c)) != 0; }
static inline char to_low(char c){ return static_cast<char>(std::tolower(static_cast<unsigned char>(c))); }
static inline void safe_flush(std::ostream &os){ os.flush(); }

// NEW: dictionary model, normalization, and English-rule helpers.
struct DictionaryEntry {
    std::string pos;
    std::string word;
    std::vector<std::string> definitions;
};

static std::vector<DictionaryEntry> global_dictionary_entries;
static std::unordered_map<std::string, std::vector<std::string>> global_def_tokens_cache;
static std::unordered_map<std::string, std::vector<std::string>> global_pos_cache;

static inline bool is_word_char_for_key(char c){
    unsigned char uc = static_cast<unsigned char>(c);
    return std::isalnum(uc) != 0 || c == '\'' || c == '-';
}

static std::string normalize_dictionary_key(const std::string &s){
    size_t b = 0, e = s.size();
    while (b < e && !is_word_char_for_key(s[b])) ++b;
    while (e > b && !is_word_char_for_key(s[e - 1])) --e;

    std::string out;
    out.reserve(e - b);
    for (size_t i = b; i < e; ++i) out.push_back(to_low(s[i]));
    return out;
}

static std::string normalize_pos_tag(const std::string &s){
    std::string out;
    out.reserve(s.size());
    for (char c : s){
        unsigned char uc = static_cast<unsigned char>(c);
        if (std::isalpha(uc) != 0) out.push_back(to_low(c));
    }
    return out;
}

enum class PosClass {
    Unknown,
    Noun,
    Verb,
    Adj,
    Adv,
    Pron,
    Prep,
    Conj,
    Det,
    Num,
    Interj
};

static PosClass pos_class_from_tag(const std::string &tag){
    if (tag == "n" || tag == "noun") return PosClass::Noun;
    if (tag == "v" || tag == "verb" || tag == "part" || tag == "participle" || tag == "p") return PosClass::Verb;
    if (tag == "a" || tag == "adj" || tag == "adjective") return PosClass::Adj;
    if (tag == "adv" || tag == "adverb") return PosClass::Adv;
    if (tag == "pron" || tag == "pronoun") return PosClass::Pron;
    if (tag == "prep" || tag == "preposition") return PosClass::Prep;
    if (tag == "conj" || tag == "conjunction") return PosClass::Conj;
    if (tag == "art" || tag == "article" || tag == "det" || tag == "determiner") return PosClass::Det;
    if (tag == "num" || tag == "number") return PosClass::Num;
    if (tag == "interj" || tag == "interjection") return PosClass::Interj;
    return PosClass::Unknown;
}

static bool has_pos_class(const std::vector<std::string> &tags, PosClass cls){
    for (const auto &t : tags){
        if (pos_class_from_tag(t) == cls) return true;
    }
    return false;
}

static const std::vector<std::string> &dictionary_pos_for_token(const std::string &surface){
    static const std::vector<std::string> empty;
    auto key = normalize_dictionary_key(surface);
    if (key.empty()) return empty;

    auto it = global_pos_cache.find(key);
    return (it == global_pos_cache.end()) ? empty : it->second;
}

static bool first_alpha_is_upper(const std::string &s){
    for (char c : s){
        unsigned char uc = static_cast<unsigned char>(c);
        if (std::isalpha(uc) != 0) return std::isupper(uc) != 0;
    }
    return false;
}

static bool first_alpha_is_lower(const std::string &s){
    for (char c : s){
        unsigned char uc = static_cast<unsigned char>(c);
        if (std::isalpha(uc) != 0) return std::islower(uc) != 0;
    }
    return false;
}

static bool is_sentence_boundary_token(const std::string &s){
    if (s.empty()) return false;
    char c = s.back();
    return c == '.' || c == '!' || c == '?';
}

static bool is_open_punct_token(const std::string &s){
    return s == "(" || s == "[" || s == "{" || s == "\"" || s == "'";
}

static bool is_punctuation_only_token(const std::string &s){
    if (s.empty()) return false;
    for (char c : s){
        unsigned char uc = static_cast<unsigned char>(c);
        if (std::isalnum(uc) != 0) return false;
    }
    return true;
}

static bool is_common_determiner(const std::string &s){
    return s == "a" || s == "an" || s == "the" || s == "this" || s == "that" ||
           s == "these" || s == "those" || s == "my" || s == "your" || s == "his" ||
           s == "her" || s == "its" || s == "our" || s == "their";
}

static bool is_common_preposition(const std::string &s){
    return s == "of" || s == "in" || s == "on" || s == "at" || s == "by" ||
           s == "for" || s == "from" || s == "with" || s == "into" || s == "onto" ||
           s == "about" || s == "over" || s == "under" || s == "after" || s == "before" ||
           s == "between" || s == "through" || s == "during" || s == "without" || s == "within" ||
           s == "under" || s == "across" || s == "against" || s == "among" || s == "around";
}

static bool is_common_aux_or_modal(const std::string &s){
    return s == "to" || s == "be" || s == "am" || s == "is" || s == "are" || s == "was" ||
           s == "were" || s == "been" || s == "being" || s == "have" || s == "has" ||
           s == "had" || s == "do" || s == "does" || s == "did" || s == "can" ||
           s == "could" || s == "may" || s == "might" || s == "must" || s == "shall" ||
           s == "should" || s == "will" || s == "would";
}

static bool begins_with_vowel_sound(const std::string &s){
    if (s.empty()) return false;

    if (s.rfind("hour", 0) == 0 || s.rfind("honest", 0) == 0 || s.rfind("honor", 0) == 0 ||
        s.rfind("heir", 0) == 0 || s.rfind("herb", 0) == 0) {
        return true;
    }

    if (s.rfind("uni", 0) == 0 || s.rfind("use", 0) == 0 || s.rfind("user", 0) == 0 ||
        s.rfind("one", 0) == 0 || s.rfind("once", 0) == 0 || s.rfind("euro", 0) == 0) {
        return false;
    }

    char c = s[0];
    return c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u';
}

static double english_rule_bonus(const std::string &context_tok, const std::string &cand){
    const std::string ctx_key = normalize_dictionary_key(context_tok);
    const std::string cand_key = normalize_dictionary_key(cand);

    const auto &ctx_tags = dictionary_pos_for_token(context_tok);
    const auto &cand_tags = dictionary_pos_for_token(cand);

    const bool sentence_start = context_tok.empty() || is_sentence_boundary_token(context_tok) || is_open_punct_token(context_tok);

    const bool cand_nounish = has_pos_class(cand_tags, PosClass::Noun) ||
                               has_pos_class(cand_tags, PosClass::Adj) ||
                               has_pos_class(cand_tags, PosClass::Pron) ||
                               has_pos_class(cand_tags, PosClass::Num);

    const bool cand_verbish = has_pos_class(cand_tags, PosClass::Verb);
    const bool cand_advish  = has_pos_class(cand_tags, PosClass::Adv);
    const bool cand_prepish = has_pos_class(cand_tags, PosClass::Prep);
    const bool cand_detish  = has_pos_class(cand_tags, PosClass::Det);

    double bonus = 0.0;

    if (!cand_key.empty()){
        if (sentence_start){
            bonus += first_alpha_is_upper(cand) ? 0.22 : -0.08;
        } else if (first_alpha_is_upper(cand)){
            bonus -= 0.03;
        }
    }

    if (ctx_key == "a" || ctx_key == "an"){
        const bool vowel = begins_with_vowel_sound(cand_key.empty() ? cand : cand_key);
        bonus += ((ctx_key == "an") == vowel) ? 0.28 : -0.18;
    }

    const bool ctx_det = has_pos_class(ctx_tags, PosClass::Det) || is_common_determiner(ctx_key);
    const bool ctx_prep = has_pos_class(ctx_tags, PosClass::Prep) || is_common_preposition(ctx_key);
    const bool ctx_aux = is_common_aux_or_modal(ctx_key);

    if (ctx_det){
        if (cand_nounish) bonus += 0.20;
        if (cand_verbish || cand_advish || cand_prepish) bonus -= 0.08;
    }

    if (ctx_prep){
        if (cand_nounish) bonus += 0.16;
        if (cand_verbish) bonus -= 0.06;
    }

    if (ctx_aux){
        if (cand_verbish) bonus += 0.18;
        if (cand_detish) bonus -= 0.04;
    }

    if (has_pos_class(ctx_tags, PosClass::Pron) || has_pos_class(ctx_tags, PosClass::Noun)){
        if (cand_verbish) bonus += 0.05;
    }

    if (!context_tok.empty() && (context_tok.back() == ',' || context_tok.back() == ';' || context_tok.back() == ':')){
        if (!cand.empty() && first_alpha_is_lower(cand)) bonus += 0.04;
    }

    if (is_punctuation_only_token(cand)){
        if (sentence_start) bonus -= 0.05;
        else if (!context_tok.empty() && std::isalnum(static_cast<unsigned char>(context_tok.back())) != 0) bonus += 0.03;
    }

    if (is_sentence_boundary_token(cand)) bonus += 0.06;

    return bonus;
}

// Tokenize by whitespace
static std::vector<std::string> tokenize_whitespace(const std::string &s){
    std::istringstream iss(s);
    std::vector<std::string> out;
    std::string t;
    while (iss >> t) out.push_back(t);
    return out;
}

// Tokenize by non-alphanumeric characters (for definitions)
static std::vector<std::string> tokenize_non_alnum(const std::string &s){
    std::vector<std::string> out; std::string cur;
    for (char ch : s){
        if (std::isalnum(static_cast<unsigned char>(ch)) || ch=='-' || ch=='\''){
            cur.push_back(to_low(ch));
        } else {
            if (!cur.empty()){ out.push_back(cur); cur.clear(); }
        }
    }
    if (!cur.empty()) out.push_back(cur);
    return out;
}

// --------------------------- String interning (short methods) --------------

struct StringInterner {
    std::unordered_set<std::string> pool;
    std::mutex m;
    const std::string* intern(const std::string &s){
        std::lock_guard<std::mutex> lk(m);
        auto [it, inserted] = pool.emplace(s);
        return &*it;
    }
};

// ---------- Global parsed dictionary (populated once in main) ----------
static void build_def_tokens_cache(){
    global_def_tokens_cache.clear();
    global_pos_cache.clear();

    global_def_tokens_cache.reserve(global_dictionary_entries.size());
    global_pos_cache.reserve(global_dictionary_entries.size());

    for (const auto &entry : global_dictionary_entries){
        const std::string key = normalize_dictionary_key(entry.word);
        if (key.empty()) continue;

        std::string pos = normalize_pos_tag(entry.pos);
        if (!pos.empty()) global_pos_cache[key].push_back(std::move(pos));

        auto &defs = global_def_tokens_cache[key];
        for (const auto &def : entry.definitions){
            auto toks = tokenize_non_alnum(def);
            defs.insert(defs.end(), toks.begin(), toks.end());
        }
    }

    for (auto &pr : global_def_tokens_cache){
        auto &v = pr.second;
        std::sort(v.begin(), v.end());
        v.erase(std::unique(v.begin(), v.end()), v.end());
    }

    for (auto &pr : global_pos_cache){
        auto &v = pr.second;
        std::sort(v.begin(), v.end());
        v.erase(std::unique(v.begin(), v.end()), v.end());
    }
}

// --------------------------- Knowledge base (short methods) --------------
using StrPtr = const std::string*;
struct PtrHash { size_t operator()(StrPtr p) const noexcept { return std::hash<StrPtr>()(p); } };
struct PtrEq   { bool operator()(StrPtr a, StrPtr b) const noexcept { return a == b; } };

using NextSet = std::vector<StrPtr>;

struct KnowledgeBase {
    StringInterner interner;
    std::unordered_map<StrPtr, NextSet, PtrHash, PtrEq> next;
    std::unordered_map<std::string, StrPtr> next_key_index;
    mutable std::mutex m;

    // def-index: for each interned word pointer -> list of interned tokens (definition expansion)
    std::unordered_map<StrPtr, std::vector<StrPtr>, PtrHash, PtrEq> def_index;
    mutable std::mutex def_m;
    int def_depth = 0;

    void add_pair_interned(StrPtr k, StrPtr v){
        std::lock_guard<std::mutex> lk(m);
        next_key_index.emplace(*k, k);
        auto &vec = next[k];
        for (auto p : vec) if (p == v) return;
        vec.push_back(v);
    }

    // set def depth; if changed, drop previously computed def expansions
    void set_def_depth(int D){
        std::lock_guard<std::mutex> lk(def_m);
        if (D != def_depth){
            def_index.clear();
            def_depth = D;
        }
    }

    void ensure_def_for_interned(StrPtr wp){
        if (wp == nullptr) return;
        if (def_depth <= 0) return;

        {
            std::lock_guard<std::mutex> lk(def_m);
            if (def_index.find(wp) != def_index.end()) return;
        }

        std::unordered_set<StrPtr, PtrHash, PtrEq> acc;
        std::vector<StrPtr> frontier;

        const std::string start_key = normalize_dictionary_key(*wp);
        if (!start_key.empty()){
            auto it_def = global_def_tokens_cache.find(start_key);
            if (it_def != global_def_tokens_cache.end()){
                for (const auto &tok : it_def->second){
                    StrPtr tp = interner.intern(tok);
                    if (acc.insert(tp).second) frontier.push_back(tp);
                }
            }
        }

        for (int depth = 1; depth < def_depth && !frontier.empty(); ++depth){
            std::vector<StrPtr> next_frontier;

            for (StrPtr w : frontier){
                const std::string key = normalize_dictionary_key(*w);
                if (key.empty()) continue;

                auto it2 = global_def_tokens_cache.find(key);
                if (it2 == global_def_tokens_cache.end()) continue;

                for (const auto &tok : it2->second){
                    StrPtr tp = interner.intern(tok);
                    if (acc.insert(tp).second) next_frontier.push_back(tp);
                }
            }

            frontier.swap(next_frontier);
        }

        std::vector<StrPtr> out;
        out.reserve(acc.size());
        for (StrPtr p : acc) out.push_back(p);

        {
            std::lock_guard<std::mutex> lk(def_m);
            def_index.emplace(wp, std::move(out));
        }
    }
    // existing public add_pair but now ensure def-expansion is built immediately
    void add_pair(const std::string &k, const std::string &v){
        StrPtr kp = interner.intern(k);
        StrPtr vp = interner.intern(v);
        // ensure definition expansion for both words as soon as they are seen
        ensure_def_for_interned(kp);
        ensure_def_for_interned(vp);
        add_pair_interned(kp, vp);
    }

    std::optional<NextSet> lookup_by_string(const std::string &k) const {
        std::lock_guard<std::mutex> lk(m);
        auto kit = next_key_index.find(k);
        if (kit == next_key_index.end()) return std::nullopt;
        auto it = next.find(kit->second);
        if (it == next.end()) return std::nullopt;
        return it->second;
    }

    std::optional<NextSet> lookup_by_ptr(StrPtr k) const {
        std::lock_guard<std::mutex> lk(m);
        auto it = next.find(k);
        if (it == next.end()) return std::nullopt;
        return it->second;
    }
};

static std::vector<StrPtr>
intern_tokens(KnowledgeBase &kb, const std::vector<std::string> &tokens)
{
    std::vector<StrPtr> out;
    out.reserve(tokens.size());
    for (const auto &t : tokens) out.push_back(kb.interner.intern(t));
    return out;
}

static std::unordered_set<std::string>
aggregate_sets(const std::vector<StrPtr> &tokens,
               const std::unordered_map<StrPtr, std::vector<StrPtr>, PtrHash, PtrEq> &def_index)
{
    std::unordered_set<std::string> agg;

    for (StrPtr t : tokens){
        const std::string tk = normalize_dictionary_key(*t);
        if (!tk.empty()) agg.insert(tk);

        auto it = def_index.find(t);
        if (it != def_index.end()){
            for (StrPtr d : it->second){
                const std::string dk = normalize_dictionary_key(*d);
                if (!dk.empty()) agg.insert(dk);
            }
        }
    }

    return agg;
}

// --------------------------- Small JSON parse helpers ----------------------

static inline bool json_valid_index(size_t i, size_t n){ return i < n; }

static std::string parse_quoted_string(const std::string &text, size_t &i){
    std::string out;
    if (!json_valid_index(i, text.size()) || text[i] != '"') throw std::runtime_error("expected '\"'");
    ++i;
    while (json_valid_index(i, text.size())){
        char c = text[i++];
        if (c == '"') break;
        if (c == '\\'){
            if (!json_valid_index(i, text.size())) break;
            char e = text[i++];
            if (e=='n') out.push_back('\n');
            else if (e=='t') out.push_back('\t');
            else out.push_back(e);
        } else out.push_back(c);
    }
    return out;
}

static void skip_spaces(const std::string &s, size_t &i){
    while (json_valid_index(i, s.size()) && is_space(s[i])) ++i;
}

// Very small JSON-like parser tailored to dictionary_json structure
static void skip_json_value(const std::string &s, size_t &i);

static std::vector<std::string> parse_json_string_array(const std::string &text, size_t &i){
    std::vector<std::string> out;
    if (!json_valid_index(i, text.size()) || text[i] != '[') return out;

    ++i;
    while (true){
        skip_spaces(text, i);
        if (!json_valid_index(i, text.size())) break;
        if (text[i] == ']'){ ++i; break; }

        if (text[i] == '"') out.push_back(parse_quoted_string(text, i));
        else skip_json_value(text, i);

        skip_spaces(text, i);
        if (json_valid_index(i, text.size()) && text[i] == ','){ ++i; continue; }
        if (json_valid_index(i, text.size()) && text[i] == ']'){ ++i; break; }
    }

    return out;
}

static void skip_json_value(const std::string &s, size_t &i){
    skip_spaces(s, i);
    if (!json_valid_index(i, s.size())) return;

    if (s[i] == '"'){
        (void)parse_quoted_string(s, i);
        return;
    }

    if (s[i] == '['){
        ++i;
        while (json_valid_index(i, s.size())){
            skip_spaces(s, i);
            if (!json_valid_index(i, s.size())) break;
            if (s[i] == ']'){ ++i; break; }
            skip_json_value(s, i);
            skip_spaces(s, i);
            if (json_valid_index(i, s.size()) && s[i] == ','){ ++i; continue; }
            if (json_valid_index(i, s.size()) && s[i] == ']'){ ++i; break; }
        }
        return;
    }

    if (s[i] == '{'){
        ++i;
        while (json_valid_index(i, s.size())){
            skip_spaces(s, i);
            if (!json_valid_index(i, s.size())) break;
            if (s[i] == '}'){ ++i; break; }
            if (s[i] == '"'){
                (void)parse_quoted_string(s, i);
                skip_spaces(s, i);
                if (json_valid_index(i, s.size()) && s[i] == ':') ++i;
                skip_json_value(s, i);
                skip_spaces(s, i);
                if (json_valid_index(i, s.size()) && s[i] == ','){ ++i; continue; }
                if (json_valid_index(i, s.size()) && s[i] == '}'){ ++i; break; }
            } else {
                ++i;
            }
        }
        return;
    }

    while (json_valid_index(i, s.size())){
        char c = s[i];
        if (c == ',' || c == ']' || c == '}' || is_space(c)) break;
        ++i;
    }
}

static std::vector<DictionaryEntry> parse_dictionary_json(){
    std::vector<DictionaryEntry> dict;
    if (dictionary_json_len == 0) return dict;

    std::string text;
    text.reserve(dictionary_json_len);
    for (unsigned int b = 0; b < dictionary_json_len; ++b){
        text.push_back(static_cast<char>(dictionary_json[b]));
    }

    size_t i = 0;
    skip_spaces(text, i);
    if (!json_valid_index(i, text.size()) || text[i] != '[') return dict;
    ++i;

    while (true){
        skip_spaces(text, i);
        if (!json_valid_index(i, text.size())) break;
        if (text[i] == ']'){ ++i; break; }
        if (text[i] != '{'){
            skip_json_value(text, i);
            skip_spaces(text, i);
            if (json_valid_index(i, text.size()) && text[i] == ','){ ++i; continue; }
            if (json_valid_index(i, text.size()) && text[i] == ']'){ ++i; break; }
            continue;
        }

        ++i;
        DictionaryEntry entry;

        while (true){
            skip_spaces(text, i);
            if (!json_valid_index(i, text.size())) break;
            if (text[i] == '}'){ ++i; break; }

            std::string field = parse_quoted_string(text, i);
            skip_spaces(text, i);
            if (!json_valid_index(i, text.size()) || text[i] != ':') break;
            ++i;
            skip_spaces(text, i);

            if (field == "word"){
                entry.word = parse_quoted_string(text, i);
            } else if (field == "pos"){
                entry.pos = parse_quoted_string(text, i);
            } else if (field == "definitions"){
                entry.definitions = parse_json_string_array(text, i);
            } else {
                skip_json_value(text, i);
            }

            skip_spaces(text, i);
            if (json_valid_index(i, text.size()) && text[i] == ','){ ++i; continue; }
            if (json_valid_index(i, text.size()) && text[i] == '}'){ ++i; break; }
        }

        if (!entry.word.empty()) dict.push_back(std::move(entry));

        skip_spaces(text, i);
        if (json_valid_index(i, text.size()) && text[i] == ','){ ++i; continue; }
        if (json_valid_index(i, text.size()) && text[i] == ']'){ ++i; break; }
    }

    return dict;
}

static std::string best_candidate_by_similarity(
    const NextSet &cands,
    const std::vector<StrPtr> &prompt_ptrs,
    const std::vector<StrPtr> &resp_ptrs,
    const std::unordered_map<StrPtr, std::vector<StrPtr>, PtrHash, PtrEq> &def_index,
    const std::unordered_map<std::string,int> &recent_counts,
    double repeat_penalty,
    const std::string &context_tok)
{
    if (cands.empty()) return std::string();
    if (cands.size() == 1) return *cands[0];

    auto agg = aggregate_sets(prompt_ptrs, def_index);
    for (StrPtr r : resp_ptrs){
        auto it = def_index.find(r);
        if (it != def_index.end()){
            for (StrPtr d : it->second){
                const std::string dk = normalize_dictionary_key(*d);
                if (!dk.empty()) agg.insert(dk);
            }
        }
    }

    double best = -1e9;
    std::string best_tok;
    size_t M = cands.size();
    std::vector<double> scores(M, 0.0);

    #pragma omp parallel for schedule(static)
    for (ptrdiff_t i = 0; i < static_cast<ptrdiff_t>(M); ++i){
        const StrPtr cand = cands[(size_t)i];
        const std::string cand_key = normalize_dictionary_key(*cand);

        size_t inter = (!cand_key.empty() && agg.count(cand_key)) ? 1 : 0;
        size_t cand_size = 1;

        auto it = def_index.find(cand);
        if (it != def_index.end()){
            cand_size += it->second.size();
            for (StrPtr d : it->second){
                const std::string dk = normalize_dictionary_key(*d);
                if (!dk.empty() && agg.count(dk)) ++inter;
            }
            if (std::find(it->second.begin(), it->second.end(), cand) != it->second.end()){
                --cand_size;
            }
        }

        size_t uni = agg.size() + cand_size - inter;
        double s = uni ? static_cast<double>(inter) / static_cast<double>(uni) : 0.0;
        scores[(size_t)i] = s;
    }

    for (size_t i = 0; i < M; ++i){
        const std::string &tok = *cands[i];
        const std::string tok_key = normalize_dictionary_key(tok);
        const std::string count_key = tok_key.empty() ? tok : tok;

        double s = scores[i];
        auto rc_it = recent_counts.find(count_key);
        int cnt = (rc_it == recent_counts.end() ? 0 : rc_it->second);

        double adjusted = s
                        + english_rule_bonus(context_tok, tok)
                        - repeat_penalty * static_cast<double>(cnt);

        if (adjusted > best || (adjusted == best && tok < best_tok)){
            best = adjusted;
            best_tok = tok;
        }
    }

    return best_tok;
}

static std::vector<std::string> construct_response(KnowledgeBase &kb,
                                                   const std::vector<std::string> &prompt_toks,
                                                   size_t maxlen,
                                                   double repeat_penalty)
{
    std::vector<std::string> resp;
    if (prompt_toks.empty() || maxlen == 0) return resp;

    auto prompt_ptrs = intern_tokens(kb, prompt_toks);
    std::vector<StrPtr> resp_ptrs;
    std::unordered_map<std::string,int> recent_counts;

    auto would_create_2_cycle = [&](const std::string &cand) -> bool {
        if (resp.size() < 3) return false;
        return normalize_dictionary_key(cand) == normalize_dictionary_key(resp[resp.size() - 2]) &&
               normalize_dictionary_key(resp.back()) == normalize_dictionary_key(resp[resp.size() - 3]);
    };

    std::string last_printed;

    for (size_t step = 0; step < maxlen; ++step){
        NextSet candidates;
        bool found = false;
        std::string context_tok;

        if (step == 0){
            for (ssize_t p = static_cast<ssize_t>(prompt_toks.size()) - 1; p >= 0; --p){
                auto opt = kb.lookup_by_string(prompt_toks[(size_t)p]);
                if (opt){
                    candidates = *opt;
                    found = true;
                    context_tok = prompt_toks[(size_t)p];
                    break;
                }
            }
        } else {
            auto opt = kb.lookup_by_string(last_printed);
            if (opt){
                candidates = *opt;
                found = true;
                context_tok = last_printed;
            } else {
                for (ssize_t p = static_cast<ssize_t>(prompt_toks.size()) - 1; p >= 0; --p){
                    auto opt2 = kb.lookup_by_string(prompt_toks[(size_t)p]);
                    if (opt2){
                        candidates = *opt2;
                        found = true;
                        context_tok = prompt_toks[(size_t)p];
                        break;
                    }
                }
            }
        }

        if (!found || candidates.empty()) break;

        if (candidates.size() == 1){
            std::string only = *candidates[0];
            std::string only_key = normalize_dictionary_key(only);
            if (recent_counts[only_key.empty() ? only : only_key] > 0) break;

            resp.push_back(only);
            resp_ptrs.push_back(kb.interner.intern(only));
            recent_counts[only_key.empty() ? only : only_key] += 1;
            last_printed = only;
            std::cout << only << ' ' << std::flush;
            continue;
        }

        std::string chosen = best_candidate_by_similarity(
            candidates, prompt_ptrs, resp_ptrs, kb.def_index, recent_counts, repeat_penalty, context_tok
        );

        if (chosen.empty()) break;
        if (would_create_2_cycle(chosen)) break;

        resp.push_back(chosen);
        resp_ptrs.push_back(kb.interner.intern(chosen));

        std::string chosen_key = normalize_dictionary_key(chosen);
        recent_counts[chosen_key.empty() ? chosen : chosen_key] += 1;

        last_printed = chosen;
        std::cout << chosen << ' ' << std::flush;
    }

    return resp;
}

// --------------------------- Learning from files (short) -------------------

static void learn_from_file(KnowledgeBase &kb, const std::string &fname){
    std::ifstream ifs(fname);
    if (!ifs) return;
    std::string tok;
    std::string prev;
    bool have_prev = false;
    while (ifs >> tok){
        if (have_prev) kb.add_pair(prev, tok);
        prev = tok; have_prev = true;
    }
}

static void learn_files_parallel(KnowledgeBase &kb, const std::vector<std::string> &files){
    #pragma omp parallel for schedule(dynamic)
    for (ptrdiff_t i=0;i<static_cast<ptrdiff_t>(files.size());++i) learn_from_file(kb, files[(size_t)i]);
}

// --------------------------- Serialization (binary, versioned) --------------
static constexpr std::uint64_t KB_MAGIC   = 0x434850434B535641ULL; // "CHPCKSVA"
static constexpr std::uint64_t KB_VERSION = 1ULL;

static void write_u64(std::ostream &os, std::uint64_t v){
    os.write(reinterpret_cast<const char*>(&v), sizeof(v));
    if(!os) throw std::runtime_error("write_u64 failed");
}

static std::uint64_t read_u64(std::istream &is){
    std::uint64_t v = 0;
    is.read(reinterpret_cast<char*>(&v), sizeof(v));
    if(!is) throw std::runtime_error("read_u64 failed");
    return v;
}

static void write_string(std::ostream &os, const std::string &s){
    write_u64(os, static_cast<std::uint64_t>(s.size()));
    if (!s.empty()){
        os.write(s.data(), static_cast<std::streamsize>(s.size()));
        if(!os) throw std::runtime_error("write_string failed");
    }
}

static std::string read_string(std::istream &is){
    std::uint64_t n = read_u64(is);
    if (n > (1ULL << 30)) throw std::runtime_error("corrupt save file: string too large");

    std::string s;
    s.resize(static_cast<size_t>(n));

    if (n != 0){
        is.read(&s[0], static_cast<std::streamsize>(n));
        if(!is) throw std::runtime_error("read_string failed");
    }
    return s;
}

static void save_kb_binary(const KnowledgeBase &kb, const std::string &fname){
    const std::string temp = fname + ".tmp";

    {
        std::ofstream ofs(temp.c_str(), std::ios::binary | std::ios::trunc);
        if (!ofs) throw std::runtime_error("cannot open temp save file");

        std::vector<std::string> pool;
        pool.reserve(kb.interner.pool.size());
        for (const auto &s : kb.interner.pool) pool.push_back(s);

        std::sort(pool.begin(), pool.end());

        std::unordered_map<std::string, std::uint64_t> id;
        id.reserve(pool.size());
        for (std::uint64_t i = 0; i < static_cast<std::uint64_t>(pool.size()); ++i){
            id.emplace(pool[(size_t)i], i);
        }

        write_u64(ofs, KB_MAGIC);
        write_u64(ofs, KB_VERSION);
        write_u64(ofs, static_cast<std::uint64_t>(kb.def_depth));

        write_u64(ofs, static_cast<std::uint64_t>(pool.size()));
        for (const auto &s : pool) write_string(ofs, s);

        write_u64(ofs, static_cast<std::uint64_t>(kb.next.size()));
        for (const auto &pr : kb.next){
            write_u64(ofs, id.at(*pr.first));
            write_u64(ofs, static_cast<std::uint64_t>(pr.second.size()));
            for (StrPtr nxt : pr.second){
                write_u64(ofs, id.at(*nxt));
            }
        }

        write_u64(ofs, static_cast<std::uint64_t>(kb.def_index.size()));
        for (const auto &pr : kb.def_index){
            write_u64(ofs, id.at(*pr.first));
            write_u64(ofs, static_cast<std::uint64_t>(pr.second.size()));
            for (StrPtr tok : pr.second){
                write_u64(ofs, id.at(*tok));
            }
        }

        ofs.flush();
        if (!ofs) throw std::runtime_error("failed while writing temp save file");
    }

    std::remove(fname.c_str());
    if (std::rename(temp.c_str(), fname.c_str()) != 0){
        std::remove(temp.c_str());
        throw std::runtime_error("failed to commit save file");
    }
}

static void load_kb_binary(KnowledgeBase &kb, const std::string &fname, int cli_dict_depth){
    std::ifstream ifs(fname, std::ios::binary);
    if (!ifs) throw std::runtime_error("cannot open load file");

    const std::uint64_t magic = read_u64(ifs);
    if (magic != KB_MAGIC) throw std::runtime_error("bad save file magic");

    const std::uint64_t version = read_u64(ifs);
    if (version != KB_VERSION) throw std::runtime_error("unsupported save file version");

    const std::uint64_t file_def_depth = read_u64(ifs);

    const std::uint64_t N = read_u64(ifs);
    if (N > (1ULL << 26)) throw std::runtime_error("corrupt save file: pool too large");

    std::vector<std::string> strings;
    strings.reserve(static_cast<size_t>(N));

    for (std::uint64_t i = 0; i < N; ++i){
        strings.push_back(read_string(ifs));
    }

    kb.interner.pool.clear();
    kb.interner.pool.reserve(static_cast<size_t>(N));

    std::vector<StrPtr> ptrs;
    ptrs.reserve(static_cast<size_t>(N));
    for (const auto &s : strings){
        ptrs.push_back(kb.interner.intern(s));
    }

    // Rebuild next
    const std::uint64_t E = read_u64(ifs);
    if (E > (1ULL << 26)) throw std::runtime_error("corrupt save file: graph too large");

    {
        std::lock_guard<std::mutex> lk(kb.m);
        kb.next.clear();
        kb.next_key_index.clear();
        kb.next.reserve(static_cast<size_t>(E));
        kb.next_key_index.reserve(static_cast<size_t>(E));
    }

    for (std::uint64_t i = 0; i < E; ++i){
        const std::uint64_t key_idx = read_u64(ifs);
        const std::uint64_t M = read_u64(ifs);

        if (key_idx >= ptrs.size()) throw std::runtime_error("corrupt save file: bad graph key");
        if (M > (1ULL << 26)) throw std::runtime_error("corrupt save file: graph degree too large");

        StrPtr key_ptr = ptrs[(size_t)key_idx];
        NextSet vec;
        vec.reserve(static_cast<size_t>(M));

        for (std::uint64_t j = 0; j < M; ++j){
            const std::uint64_t v_idx = read_u64(ifs);
            if (v_idx >= ptrs.size()) throw std::runtime_error("corrupt save file: bad graph value");
            vec.push_back(ptrs[(size_t)v_idx]);
        }

        {
            std::lock_guard<std::mutex> lk(kb.m);
            kb.next.emplace(key_ptr, std::move(vec));
            kb.next_key_index.emplace(*key_ptr, key_ptr);
        }
    }

    // Rebuild def_index from file
    const std::uint64_t K = read_u64(ifs);
    if (K > (1ULL << 26)) throw std::runtime_error("corrupt save file: def_index too large");

    {
        std::lock_guard<std::mutex> lk(kb.def_m);
        kb.def_index.clear();
        kb.def_index.reserve(static_cast<size_t>(K));
        kb.def_depth = static_cast<int>(file_def_depth);
    }

    for (std::uint64_t i = 0; i < K; ++i){
        const std::uint64_t key_idx = read_u64(ifs);
        const std::uint64_t M = read_u64(ifs);

        if (key_idx >= ptrs.size()) throw std::runtime_error("corrupt save file: bad def key");
        if (M > (1ULL << 26)) throw std::runtime_error("corrupt save file: def list too large");

        std::vector<StrPtr> toks;
        toks.reserve(static_cast<size_t>(M));

        for (std::uint64_t j = 0; j < M; ++j){
            const std::uint64_t v_idx = read_u64(ifs);
            if (v_idx >= ptrs.size()) throw std::runtime_error("corrupt save file: bad def value");
            toks.push_back(ptrs[(size_t)v_idx]);
        }

        {
            std::lock_guard<std::mutex> lk(kb.def_m);
            kb.def_index.emplace(ptrs[(size_t)key_idx], std::move(toks));
        }
    }

    // If the caller asks for a different dict depth, recompute with the current embedded dictionary.
    if (cli_dict_depth != static_cast<int>(file_def_depth)){
        kb.set_def_depth(cli_dict_depth);

        std::vector<StrPtr> targets;
        targets.reserve(ptrs.size() + kb.next.size() * 2);

        std::unordered_set<StrPtr, PtrHash, PtrEq> seen;
        seen.reserve(ptrs.size() + kb.next.size() * 2);

        for (StrPtr p : ptrs){
            if (seen.insert(p).second) targets.push_back(p);
        }

        {
            std::lock_guard<std::mutex> lk(kb.m);
            for (const auto &pr : kb.next){
                if (seen.insert(pr.first).second) targets.push_back(pr.first);
                for (StrPtr v : pr.second){
                    if (seen.insert(v).second) targets.push_back(v);
                }
            }
        }

        #pragma omp parallel for schedule(dynamic)
        for (ptrdiff_t i = 0; i < static_cast<ptrdiff_t>(targets.size()); ++i){
            kb.ensure_def_for_interned(targets[(size_t)i]);
        }
    }
}

// --------------------------- CLI + Interactive loop (shorters) -----------

static void print_usage(const char *p){
    std::cout << "Usage: " << p << " [--maxlen N] [--save FILE] [--load-kb FILE] [--dict-depth D] [--learn f1 f2 ...] [--repeat-penalty P] [--help]\n";
    std::cout << "  --maxlen N          Maximum number of tokens constructed in a response.\n";
    std::cout << "  --save FILE         Save the knowledge-base and dictionary expansions to a binary file.\n";
    std::cout << "  --load-kb FILE      Load a previously saved knowledge-base (and dictionary expansions) from a binary file.\n";
    std::cout << "  --dict-depth D      Depth of dictionary-definition expansion used during learning.\n";
    std::cout << "  --learn f1 f2 ...   Learn from one or more text files to update the knowledge base.\n";
    std::cout << "  --repeat-penalty P  Penalize repeated tokens during response generation (higher values discourage repetition).\n";
    std::cout << "  --help              Show command-line interface options for ChatIPC usage.\n";
}

int main(int argc, char **argv){
    size_t maxlen = 100;
    std::string savefile;
    std::string load_txt;
    std::string load_kb;
    int dict_depth = 2;
    double repeat_penalty = 0.7; // default λ
    std::vector<std::string> learn_files;

    for (int i=1;i<argc;++i){
        std::string a = argv[i];
        if (a=="--help"){ print_usage(argv[0]); return 0; }
        if (a=="--maxlen" && i+1<argc){ maxlen = std::stoul(argv[++i]); continue; }
        if (a=="--save" && i+1<argc){ savefile = argv[++i]; continue; }
        if (a=="--load-kb" && i+1<argc){ load_kb = argv[++i]; continue; }
        if (a=="--dict-depth" && i+1<argc){ dict_depth = std::stoi(argv[++i]); continue; }
        if (a=="--repeat-penalty" && i+1<argc){ repeat_penalty = std::stod(argv[++i]); continue; }
        if (a=="--learn"){
            ++i;
            for (; i<argc; ++i){
                if (!argv[i]) break;
                std::string s = argv[i];
                if (!s.empty() && s[0]=='-'){ --i; break; }
                learn_files.push_back(s);
            }
            continue;
        }
        learn_files.push_back(a);
    }

    KnowledgeBase kb;

    // parse the embedded dictionary once for use by per-word expansion
    global_dictionary_entries = parse_dictionary_json();
    build_def_tokens_cache();
    // set KB def depth (clears any previous expansion)
    kb.set_def_depth(dict_depth);


    if (!load_kb.empty()){
        try { load_kb_binary(kb, load_kb, dict_depth); std::cerr << "Loaded KB: " << load_kb << "\n"; }
        catch (const std::exception &e){ std::cerr << "Load KB error: " << e.what() << "\n"; }
    }

    if (!learn_files.empty()){
        std::cerr << "Learning from file/s (" << learn_files.size() << ") using threads=" << omp_get_max_threads() << "\n";
        learn_files_parallel(kb, learn_files);
    }

    std::string line;
    std::cout << "Ready. Enter prompts.\n";
    while (std::cout << "> " , std::getline(std::cin, line)){
        if (line.empty()){ std::cout << "\n"; continue; }
        auto prompt_toks = tokenize_whitespace(line);
        for (size_t i=1;i<prompt_toks.size();++i) kb.add_pair(prompt_toks[i-1], prompt_toks[i]);
        auto resp = construct_response(kb, prompt_toks, maxlen, repeat_penalty);
        std::cout << "\n";
        if (!resp.empty()){
            std::vector<std::string> combined = prompt_toks;
            combined.insert(combined.end(), resp.begin(), resp.end());
            for (size_t i=1;i<combined.size();++i) kb.add_pair(combined[i-1], combined[i]);
        }
        if (!savefile.empty()){
            try { save_kb_binary(kb, savefile); std::cerr << "Saved KB: " << savefile << "\n"; }
            catch (const std::exception &e){ std::cerr << "Save KB error: " << e.what() << "\n"; }
        }
    }

    if (!savefile.empty()){
        try { save_kb_binary(kb, savefile); std::cerr << "Saved KB: " << savefile << "\n"; }
        catch (const std::exception &e){ std::cerr << "Save KB error: " << e.what() << "\n"; }
    }

    return 0;
}