// Drop-in C++ client library for the KI BMS HTTP API.
//
// Save this file alongside your source as `AtsClient.hpp` and use
// the AtsClient class:
//
//     #include "AtsClient.hpp"
//     ats_client::AtsClient c("pat_...");
//     auto rows  = c.AccountList({{}});
//     auto fresh = c.AccountCreate({{ {{"name", "Example GmbH"}} }});
//
// Every endpoint exposed by the HTTP API is wrapped as a typed
// `<Model><Op>` method on AtsClient. List endpoints take a
// ListOpts; get/update/delete endpoints take the row id as their
// first argument.
//
// Header-only. Requires libcurl headers + linker flag `-lcurl`. The
// JSON encoder / decoder is bundled inline so no other dependency is
// needed. Targets C++17 + libcurl 7.x.
//
// Provided as-is, with no warranty. Vendor freely; modify as needed.
//
// DO NOT EDIT THIS FILE MANUALLY - re-download from the docs site.
// Local edits will be overwritten by the once-per-day version check.

#ifndef ats_client_CLIENT_HPP_
#define ats_client_CLIENT_HPP_

#include <algorithm>
#include <atomic>
#include <cctype>
#include <chrono>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <filesystem>
#include <fstream>
#include <map>
#include <memory>
#include <mutex>
#include <random>
#include <sstream>
#include <stdexcept>
#include <string>
#include <thread>
#include <unordered_set>
#include <vector>

#include <curl/curl.h>

namespace ats_client {

// ── Identity (substituted at generation time) ────────────────────────
inline constexpr const char* kAppSlug       = "ats";
inline constexpr const char* kAppName       = "KI BMS";
inline constexpr const char* kModuleName    = "ats_client";
inline constexpr const char* kClientVersion = "0.3.13";
inline constexpr const char* kLanguage      = "cpp";
inline constexpr const char* kDefaultBase   = "https://www.ki-bewerber-management.de";

// Per-type metadata baked at generation time. Available at runtime
// when calling code needs to know the legal filters / sort columns /
// max_limit for a model without a second round-trip. Decode with
// AtsClient::ParseJson.
inline const char* TypesJson() {
    static const char* kBlob = R"JSON_BLOB({"application":{"ops":["list","read","create","update","delete"],"create_fields":["job_id","candidate_id","stage","previous_stage","position","applied_at","last_stage_at","source_id","source_label","cover_letter","cv_blob_id","cv_url","answers","fit_score","fit_reasoning","fit_flags","fit_computed_at","rejected_reason","rejected_note","tags"],"update_fields":["stage","previous_stage","position","applied_at","last_stage_at","source_id","source_label","cover_letter","cv_blob_id","cv_url","answers","fit_score","fit_reasoning","fit_flags","fit_computed_at","rejected_reason","rejected_note","tags"],"allowed_filters":["data__job_id","data__candidate_id","data__stage","data__source_id","data__rejected_reason","data__is_archived","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","updated_at","data__applied_at","data__fit_score","data__position","data__last_stage_at"],"default_sort":"data__position","max_limit":500,"fields":[{"name":"tags","type":"tags"},{"name":"stage","type":"enum","values":["new","review","screening","interview","offer","hired","rejected","talent_pool"]},{"name":"cv_url","type":"url","max_len":2048},{"name":"job_id","type":"string","max_len":64,"ref":{"type":"job","owned":false,"optional":false}},{"name":"answers","type":"list"},{"name":"position","type":"number"},{"name":"fit_flags","type":"tags"},{"name":"fit_score","type":"number"},{"name":"source_id","type":"string","max_len":64,"ref":{"type":"source","owned":false,"optional":false}},{"name":"applied_at","type":"string","max_len":32},{"name":"cv_blob_id","type":"string","max_len":64},{"name":"candidate_id","type":"string","max_len":64,"ref":{"type":"candidate","owned":false,"optional":false}},{"name":"cover_letter","type":"string","max_len":16000},{"name":"source_label","type":"string","max_len":200},{"name":"fit_reasoning","type":"string","max_len":4000},{"name":"last_stage_at","type":"string","max_len":32},{"name":"rejected_note","type":"string","max_len":2000},{"name":"previous_stage","type":"string","max_len":32},{"name":"fit_computed_at","type":"string","max_len":32},{"name":"rejected_reason","type":"enum","values":["not_qualified","salary_mismatch","location_mismatch","culture_mismatch","withdrew","ghosted","filled_internally","duplicate","other"]}]},"application_note":{"ops":["list","read","create","update","delete"],"create_fields":["body","pinned","private","parent_kind","parent_id"],"update_fields":["body","pinned","private"],"allowed_filters":["data__parent_id","data__parent_kind","data__pinned","data__private","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","updated_at"],"default_sort":"created_at","max_limit":200,"fields":[{"name":"body","type":"string","max_len":8000},{"name":"pinned","type":"bool"},{"name":"private","type":"bool"},{"name":"parent_id","type":"string","max_len":64},{"name":"parent_kind","type":"enum","values":["candidate","application","job"]}]},"candidate":{"ops":["list","read","create","update","delete"],"create_fields":["name","first_name","last_name","salutation","pronouns","email","phone","city","country","current_company","current_role","years_experience","available_from","salary_expectation","currency","linkedin","github","portfolio","cv_url","cv_blob_id","avatar_blob_id","summary","skills","languages","tags","source_id","source_label","pool_status","gdpr_consent","gdpr_consent_at","gdpr_retention_until","preferred_locale","last_touched_at","color"],"update_fields":["name","first_name","last_name","salutation","pronouns","email","phone","city","country","current_company","current_role","years_experience","available_from","salary_expectation","currency","linkedin","github","portfolio","cv_url","cv_blob_id","avatar_blob_id","summary","skills","languages","tags","source_id","source_label","pool_status","gdpr_consent","gdpr_consent_at","gdpr_retention_until","preferred_locale","last_touched_at","color"],"allowed_filters":["data__email","data__name","data__location","data__country","data__source_id","data__tags","data__skills","data__pool_status","data__gdpr_consent","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","updated_at","data__name","data__last_touched_at"],"default_sort":"created_at","max_limit":200,"fields":[{"name":"city","type":"string","max_len":120},{"name":"name","type":"string","max_len":200},{"name":"tags","type":"tags"},{"name":"color","type":"string","max_len":24},{"name":"email","type":"string","max_len":320},{"name":"phone","type":"string","max_len":64},{"name":"cv_url","type":"url","max_len":2048},{"name":"github","type":"url","max_len":2048},{"name":"skills","type":"tags"},{"name":"country","type":"string","max_len":120},{"name":"summary","type":"string","max_len":4000},{"name":"currency","type":"string","max_len":8},{"name":"linkedin","type":"url","max_len":2048},{"name":"pronouns","type":"string","max_len":32},{"name":"languages","type":"tags"},{"name":"last_name","type":"string","max_len":120},{"name":"portfolio","type":"url","max_len":2048},{"name":"source_id","type":"string","max_len":64,"ref":{"type":"source","owned":false,"optional":false}},{"name":"cv_blob_id","type":"string","max_len":64},{"name":"first_name","type":"string","max_len":120},{"name":"salutation","type":"enum","values":["herr","frau","divers","neutral"]},{"name":"pool_status","type":"enum","values":["active","talent_pool","blocked","withdrawn"]},{"name":"current_role","type":"string","max_len":200},{"name":"gdpr_consent","type":"bool"},{"name":"source_label","type":"string","max_len":200},{"name":"available_from","type":"string","max_len":32},{"name":"avatar_blob_id","type":"string","max_len":64},{"name":"current_company","type":"string","max_len":200},{"name":"gdpr_consent_at","type":"string","max_len":32},{"name":"last_touched_at","type":"string","max_len":32},{"name":"preferred_locale","type":"string","max_len":16},{"name":"years_experience","type":"number"},{"name":"salary_expectation","type":"number"},{"name":"gdpr_retention_until","type":"string","max_len":32}]},"email_template":{"ops":["list","read","create","update","delete"],"create_fields":["name","category","subject","body","language","stage_trigger","auto_send","active","variables_doc"],"update_fields":["name","category","subject","body","language","stage_trigger","auto_send","active","variables_doc"],"allowed_filters":["data__name","data__category","data__stage_trigger","data__active","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","data__name"],"default_sort":"data__name","max_limit":100,"fields":[{"name":"body","type":"string","max_len":16000},{"name":"name","type":"string","max_len":200},{"name":"active","type":"bool"},{"name":"subject","type":"string","max_len":400},{"name":"category","type":"enum","values":["acknowledge","screening_invite","interview_invite","rejection","offer","talent_pool","other"]},{"name":"language","type":"string","max_len":16},{"name":"auto_send","type":"bool"},{"name":"stage_trigger","type":"enum","values":["","new","review","screening","interview","offer","hired","rejected","talent_pool"]},{"name":"variables_doc","type":"string","max_len":2000}]},"evaluation":{"ops":["list","read","create","update","delete"],"create_fields":["application_id","interview_id","interviewer_id","skills_score","culture_score","communication_score","potential_score","overall_score","recommendation","highlights","concerns","summary"],"update_fields":["skills_score","culture_score","communication_score","potential_score","overall_score","recommendation","highlights","concerns","summary"],"allowed_filters":["data__application_id","data__interview_id","data__interviewer_id","data__recommendation","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","data__overall_score"],"default_sort":"created_at","max_limit":200,"fields":[{"name":"summary","type":"string","max_len":4000},{"name":"concerns","type":"string","max_len":4000},{"name":"highlights","type":"string","max_len":4000},{"name":"interview_id","type":"string","max_len":64,"ref":{"type":"interview","owned":false,"optional":false}},{"name":"skills_score","type":"number"},{"name":"culture_score","type":"number"},{"name":"overall_score","type":"number"},{"name":"application_id","type":"string","max_len":64,"ref":{"type":"application","owned":false,"optional":false}},{"name":"interviewer_id","type":"string","max_len":64},{"name":"recommendation","type":"enum","values":["strong_yes","yes","neutral","no","strong_no"]},{"name":"potential_score","type":"number"},{"name":"communication_score","type":"number"}]},"interview":{"ops":["list","read","create","update","delete"],"create_fields":["application_id","candidate_id","job_id","kind","status","title","scheduled_at","duration_minutes","location","meeting_url","interviewer_id","interviewer_ids","agenda","notes","send_invite"],"update_fields":["kind","status","title","scheduled_at","duration_minutes","location","meeting_url","interviewer_id","interviewer_ids","agenda","notes","send_invite"],"allowed_filters":["data__application_id","data__candidate_id","data__job_id","data__kind","data__status","data__interviewer_id","status","is_archived","owned_by","created_by"],"allowed_sorts":["data__scheduled_at","created_at","updated_at"],"default_sort":"data__scheduled_at","max_limit":200,"fields":[{"name":"kind","type":"enum","values":["phone","video","onsite","take_home","panel","trial_day"]},{"name":"notes","type":"string","max_len":8000},{"name":"title","type":"string","max_len":200},{"name":"agenda","type":"string","max_len":4000},{"name":"job_id","type":"string","max_len":64},{"name":"status","type":"enum","values":["scheduled","completed","no_show","cancelled","rescheduled"]},{"name":"location","type":"string","max_len":200},{"name":"meeting_url","type":"url","max_len":2048},{"name":"send_invite","type":"bool"},{"name":"candidate_id","type":"string","max_len":64},{"name":"scheduled_at","type":"string","max_len":32},{"name":"application_id","type":"string","max_len":64,"ref":{"type":"application","owned":false,"optional":false}},{"name":"interviewer_id","type":"string","max_len":64},{"name":"interviewer_ids","type":"list"},{"name":"duration_minutes","type":"number"}]},"job":{"ops":["list","read","create","update","delete"],"create_fields":["title","slug","department","location","country","remote","employment_type","seniority","headcount","salary_min","salary_max","currency","salary_visibility","summary","description","responsibilities","requirements","nice_to_have","benefits","language","status","public","ai_screen_enabled","ai_screen_prompt","knockout_questions","screening_questions","tags","hiring_manager_id","team_ids","opened_at","target_close_date","closed_at","external_apply_url","color"],"update_fields":["title","slug","department","location","country","remote","employment_type","seniority","headcount","salary_min","salary_max","currency","salary_visibility","summary","description","responsibilities","requirements","nice_to_have","benefits","language","status","public","ai_screen_enabled","ai_screen_prompt","knockout_questions","screening_questions","tags","hiring_manager_id","team_ids","opened_at","target_close_date","closed_at","external_apply_url","color"],"allowed_filters":["data__title","data__department","data__location","data__employment_type","data__seniority","data__remote","data__status","data__public","data__hiring_manager_id","data__tags","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","updated_at","data__title","data__opened_at","data__target_close_date"],"default_sort":"created_at","max_limit":200,"fields":[{"name":"slug","type":"string","max_len":120},{"name":"tags","type":"tags"},{"name":"color","type":"string","max_len":24},{"name":"title","type":"string","max_len":200},{"name":"public","type":"bool"},{"name":"remote","type":"enum","values":["onsite","hybrid","remote"]},{"name":"status","type":"enum","values":["draft","open","paused","closed","filled"]},{"name":"country","type":"string","max_len":80},{"name":"summary","type":"string","max_len":600},{"name":"benefits","type":"string","max_len":4000},{"name":"currency","type":"string","max_len":8},{"name":"language","type":"string","max_len":16},{"name":"location","type":"string","max_len":120},{"name":"team_ids","type":"list"},{"name":"closed_at","type":"string","max_len":32},{"name":"headcount","type":"number"},{"name":"opened_at","type":"string","max_len":32},{"name":"seniority","type":"enum","values":["junior","mid","senior","lead","principal"]},{"name":"department","type":"string","max_len":120},{"name":"salary_max","type":"number"},{"name":"salary_min","type":"number"},{"name":"description","type":"string","max_len":16000},{"name":"nice_to_have","type":"string","max_len":4000},{"name":"requirements","type":"string","max_len":8000},{"name":"employment_type","type":"enum","values":["full_time","part_time","internship","working_student","freelance","contract"]},{"name":"ai_screen_prompt","type":"string","max_len":4000},{"name":"responsibilities","type":"string","max_len":8000},{"name":"ai_screen_enabled","type":"bool"},{"name":"hiring_manager_id","type":"string","max_len":64},{"name":"salary_visibility","type":"enum","values":["public","team","private"]},{"name":"target_close_date","type":"string","max_len":32},{"name":"external_apply_url","type":"url","max_len":2048},{"name":"knockout_questions","type":"list"},{"name":"screening_questions","type":"list"}]},"message":{"ops":["list","read","create","update","delete"],"create_fields":["candidate_id","application_id","channel","direction","subject","body","status","sent_at","delivered_at","read_at","template_id","from_address","to_address","cc_addresses","thread_id","error"],"update_fields":["subject","body","status","sent_at","delivered_at","read_at","thread_id","error"],"allowed_filters":["data__candidate_id","data__application_id","data__channel","data__status","data__template_id","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","data__sent_at"],"default_sort":"-data__sent_at","max_limit":200,"fields":[{"name":"body","type":"string","max_len":16000},{"name":"error","type":"string","max_len":600},{"name":"status","type":"enum","values":["draft","queued","sent","delivered","failed","bounced"]},{"name":"channel","type":"enum","values":["email","note"]},{"name":"read_at","type":"string","max_len":32},{"name":"sent_at","type":"string","max_len":32},{"name":"subject","type":"string","max_len":400},{"name":"direction","type":"enum","values":["outbound","inbound"]},{"name":"thread_id","type":"string","max_len":200},{"name":"to_address","type":"string","max_len":320},{"name":"template_id","type":"string","max_len":64,"ref":{"type":"email_template","owned":false,"optional":false}},{"name":"candidate_id","type":"string","max_len":64},{"name":"cc_addresses","type":"list"},{"name":"delivered_at","type":"string","max_len":32},{"name":"from_address","type":"string","max_len":320},{"name":"application_id","type":"string","max_len":64}]},"offer":{"ops":["list","read","create","update","delete"],"create_fields":["application_id","candidate_id","job_id","salary_gross","salary_period","currency","bonus","bonus_note","vacation_days","start_date","expires_at","term","term_until","weekly_hours","remote_policy","status","sent_at","decided_at","letter_body","letter_blob_id","decline_reason"],"update_fields":["salary_gross","salary_period","currency","bonus","bonus_note","vacation_days","start_date","expires_at","term","term_until","weekly_hours","remote_policy","status","sent_at","decided_at","letter_body","letter_blob_id","decline_reason"],"allowed_filters":["data__application_id","data__candidate_id","data__job_id","data__status","data__currency","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","data__start_date","data__sent_at"],"default_sort":"created_at","max_limit":100,"fields":[{"name":"term","type":"enum","values":["permanent","fixed_term","trial","intern","freelance"]},{"name":"bonus","type":"number"},{"name":"job_id","type":"string","max_len":64},{"name":"status","type":"enum","values":["draft","sent","accepted","declined","withdrawn","expired"]},{"name":"sent_at","type":"string","max_len":32},{"name":"currency","type":"string","max_len":8},{"name":"bonus_note","type":"string","max_len":600},{"name":"decided_at","type":"string","max_len":32},{"name":"expires_at","type":"string","max_len":32},{"name":"start_date","type":"string","max_len":32},{"name":"term_until","type":"string","max_len":32},{"name":"letter_body","type":"string","max_len":16000},{"name":"candidate_id","type":"string","max_len":64},{"name":"salary_gross","type":"number"},{"name":"weekly_hours","type":"number"},{"name":"remote_policy","type":"string","max_len":200},{"name":"salary_period","type":"enum","values":["yearly","monthly","daily","hourly"]},{"name":"vacation_days","type":"number"},{"name":"application_id","type":"string","max_len":64,"ref":{"type":"application","owned":false,"optional":false}},{"name":"decline_reason","type":"string","max_len":600},{"name":"letter_blob_id","type":"string","max_len":64}]},"source":{"ops":["list","read","create","update","delete"],"create_fields":["name","kind","url","active","notes"],"update_fields":["name","kind","url","active","notes"],"allowed_filters":["data__name","data__kind","data__active","status","is_archived","owned_by","created_by"],"allowed_sorts":["created_at","data__name"],"default_sort":"data__name","max_limit":100,"fields":[{"name":"url","type":"url","max_len":2048},{"name":"kind","type":"enum","values":["linkedin","indeed","stepstone","xing","honeypot","kununu","careers_page","referral","active_sourcing","agency","event","other"]},{"name":"name","type":"string","max_len":200},{"name":"notes","type":"string","max_len":2000},{"name":"active","type":"bool"}]},"task":{"ops":["list","read","create","update","delete"],"create_fields":["title","description","due_date","completed","completed_at","priority","assigned_to","parent_kind","parent_id"],"update_fields":["title","description","due_date","completed","completed_at","priority","assigned_to"],"allowed_filters":["data__parent_id","data__parent_kind","data__assigned_to","data__completed","data__priority","status","is_archived","owned_by","created_by"],"allowed_sorts":["data__due_date","created_at","data__priority"],"default_sort":"data__due_date","max_limit":200,"fields":[{"name":"title","type":"string","max_len":200},{"name":"due_date","type":"string","max_len":32},{"name":"priority","type":"enum","values":["low","normal","high","urgent"]},{"name":"completed","type":"bool"},{"name":"parent_id","type":"string","max_len":64},{"name":"assigned_to","type":"string","max_len":64},{"name":"description","type":"string","max_len":4000},{"name":"parent_kind","type":"enum","values":["candidate","application","job"]},{"name":"completed_at","type":"string","max_len":32}]}})JSON_BLOB";
    return kBlob;
}

// ── Json: tiny self-contained encoder + decoder ──────────────────────
// Recursive variant. Object keeps insertion order so encoded payloads
// round-trip cleanly with the rest of the toolchain.

class Json {
public:
    enum class Kind { Null, Bool, Number, String, Array, Object };

    Json() = default;
    Json(std::nullptr_t)        : kind_(Kind::Null) {}
    Json(bool v)                : kind_(Kind::Bool), bool_(v) {}
    Json(int v)                 : kind_(Kind::Number), num_(static_cast<double>(v)) {}
    Json(long v)                : kind_(Kind::Number), num_(static_cast<double>(v)) {}
    Json(long long v)           : kind_(Kind::Number), num_(static_cast<double>(v)) {}
    Json(double v)              : kind_(Kind::Number), num_(v) {}
    Json(const char* v)         : kind_(Kind::String), str_(v ? v : "") {}
    Json(const std::string& v)  : kind_(Kind::String), str_(v) {}
    Json(std::string&& v)       : kind_(Kind::String), str_(std::move(v)) {}

    static Json Array()  { Json j; j.kind_ = Kind::Array;  return j; }
    static Json Object() { Json j; j.kind_ = Kind::Object; return j; }
    static Json FromInitializerObject(std::initializer_list<std::pair<std::string, Json>> kvs) {
        Json j = Object();
        for (auto& kv : kvs) j.Set(kv.first, kv.second);
        return j;
    }

    Kind GetKind() const { return kind_; }
    bool IsNull()   const { return kind_ == Kind::Null; }
    bool IsBool()   const { return kind_ == Kind::Bool; }
    bool IsNumber() const { return kind_ == Kind::Number; }
    bool IsString() const { return kind_ == Kind::String; }
    bool IsArray()  const { return kind_ == Kind::Array; }
    bool IsObject() const { return kind_ == Kind::Object; }

    bool        AsBool(bool def = false)             const { return IsBool() ? bool_ : def; }
    double      AsNumber(double def = 0.0)           const { return IsNumber() ? num_ : def; }
    long long   AsInt(long long def = 0)             const { return IsNumber() ? static_cast<long long>(num_) : def; }
    std::string AsString(const std::string& def = "") const { return IsString() ? str_ : def; }
    const std::vector<Json>& AsArray() const { return arr_; }
    std::vector<Json>&       AsArray()       { return arr_; }

    void Push(const Json& v) {
        if (kind_ != Kind::Array) { kind_ = Kind::Array; arr_.clear(); }
        arr_.push_back(v);
    }

    void Set(const std::string& key, const Json& v) {
        if (kind_ != Kind::Object) { kind_ = Kind::Object; obj_keys_.clear(); obj_vals_.clear(); }
        for (size_t i = 0; i < obj_keys_.size(); ++i) {
            if (obj_keys_[i] == key) { obj_vals_[i] = v; return; }
        }
        obj_keys_.push_back(key);
        obj_vals_.push_back(v);
    }

    bool Has(const std::string& key) const {
        if (!IsObject()) return false;
        for (size_t i = 0; i < obj_keys_.size(); ++i) if (obj_keys_[i] == key) return true;
        return false;
    }

    const Json& Get(const std::string& key) const {
        static const Json kNull;
        if (!IsObject()) return kNull;
        for (size_t i = 0; i < obj_keys_.size(); ++i) if (obj_keys_[i] == key) return obj_vals_[i];
        return kNull;
    }

    const std::vector<std::string>& Keys() const { return obj_keys_; }
    const std::vector<Json>&        Values() const { return obj_vals_; }

    std::string Encode() const {
        std::ostringstream os;
        EncodeTo(os);
        return os.str();
    }

    static Json Parse(const std::string& src) {
        size_t i = 0;
        SkipWs(src, i);
        Json out = ParseValue(src, i);
        SkipWs(src, i);
        return out;
    }

private:
    Kind kind_ = Kind::Null;
    bool bool_ = false;
    double num_ = 0.0;
    std::string str_;
    std::vector<Json> arr_;
    std::vector<std::string> obj_keys_;
    std::vector<Json> obj_vals_;

    void EncodeTo(std::ostringstream& os) const {
        switch (kind_) {
            case Kind::Null:   os << "null"; break;
            case Kind::Bool:   os << (bool_ ? "true" : "false"); break;
            case Kind::Number: {
                if (num_ == static_cast<long long>(num_) && std::abs(num_) < 1e15) {
                    os << static_cast<long long>(num_);
                } else {
                    os.precision(15);
                    os << num_;
                }
                break;
            }
            case Kind::String: EncodeString(os, str_); break;
            case Kind::Array: {
                os << "[";
                for (size_t i = 0; i < arr_.size(); ++i) {
                    if (i) os << ",";
                    arr_[i].EncodeTo(os);
                }
                os << "]";
                break;
            }
            case Kind::Object: {
                os << "{";
                for (size_t i = 0; i < obj_keys_.size(); ++i) {
                    if (i) os << ",";
                    EncodeString(os, obj_keys_[i]);
                    os << ":";
                    obj_vals_[i].EncodeTo(os);
                }
                os << "}";
                break;
            }
        }
    }

    static void EncodeString(std::ostringstream& os, const std::string& s) {
        os << "\"";
        for (size_t i = 0; i < s.size(); ++i) {
            unsigned char c = static_cast<unsigned char>(s[i]);
            switch (c) {
                case '"':  os << "\\\""; break;
                case '\\': os << "\\\\"; break;
                case '\b': os << "\\b";  break;
                case '\f': os << "\\f";  break;
                case '\n': os << "\\n";  break;
                case '\r': os << "\\r";  break;
                case '\t': os << "\\t";  break;
                default:
                    if (c < 0x20) {
                        char buf[8];
                        std::snprintf(buf, sizeof(buf), "\\u%04x", c);
                        os << buf;
                    } else {
                        os << static_cast<char>(c);
                    }
            }
        }
        os << "\"";
    }

    static void SkipWs(const std::string& s, size_t& i) {
        while (i < s.size() && (s[i] == ' ' || s[i] == '\t' || s[i] == '\n' || s[i] == '\r')) ++i;
    }

    static Json ParseValue(const std::string& s, size_t& i) {
        SkipWs(s, i);
        if (i >= s.size()) throw std::runtime_error("json: unexpected end");
        char c = s[i];
        if (c == '{') return ParseObject(s, i);
        if (c == '[') return ParseArray(s, i);
        if (c == '"') return Json(ParseString(s, i));
        if (c == 't' || c == 'f') return ParseBool(s, i);
        if (c == 'n') { ExpectLiteral(s, i, "null"); return Json(nullptr); }
        return ParseNumber(s, i);
    }

    static Json ParseObject(const std::string& s, size_t& i) {
        Json out = Object();
        ++i; // '{'
        SkipWs(s, i);
        if (i < s.size() && s[i] == '}') { ++i; return out; }
        while (i < s.size()) {
            SkipWs(s, i);
            if (i >= s.size() || s[i] != '"') throw std::runtime_error("json: expected string key");
            std::string key = ParseString(s, i);
            SkipWs(s, i);
            if (i >= s.size() || s[i] != ':') throw std::runtime_error("json: expected ':'");
            ++i;
            Json v = ParseValue(s, i);
            out.Set(key, v);
            SkipWs(s, i);
            if (i < s.size() && s[i] == ',') { ++i; continue; }
            if (i < s.size() && s[i] == '}') { ++i; return out; }
            throw std::runtime_error("json: expected ',' or '}'");
        }
        throw std::runtime_error("json: unterminated object");
    }

    static Json ParseArray(const std::string& s, size_t& i) {
        Json out = Array();
        ++i; // '['
        SkipWs(s, i);
        if (i < s.size() && s[i] == ']') { ++i; return out; }
        while (i < s.size()) {
            Json v = ParseValue(s, i);
            out.Push(v);
            SkipWs(s, i);
            if (i < s.size() && s[i] == ',') { ++i; continue; }
            if (i < s.size() && s[i] == ']') { ++i; return out; }
            throw std::runtime_error("json: expected ',' or ']'");
        }
        throw std::runtime_error("json: unterminated array");
    }

    static std::string ParseString(const std::string& s, size_t& i) {
        if (i >= s.size() || s[i] != '"') throw std::runtime_error("json: expected '\"'");
        ++i;
        std::string out;
        while (i < s.size()) {
            char c = s[i++];
            if (c == '"') return out;
            if (c == '\\') {
                if (i >= s.size()) throw std::runtime_error("json: bad escape");
                char e = s[i++];
                switch (e) {
                    case '"':  out += '"'; break;
                    case '\\': out += '\\'; break;
                    case '/':  out += '/'; break;
                    case 'b':  out += '\b'; break;
                    case 'f':  out += '\f'; break;
                    case 'n':  out += '\n'; break;
                    case 'r':  out += '\r'; break;
                    case 't':  out += '\t'; break;
                    case 'u': {
                        if (i + 4 > s.size()) throw std::runtime_error("json: bad \\u escape");
                        unsigned int cp = 0;
                        for (int k = 0; k < 4; ++k) {
                            char h = s[i++];
                            cp <<= 4;
                            if (h >= '0' && h <= '9') cp |= (h - '0');
                            else if (h >= 'a' && h <= 'f') cp |= (h - 'a' + 10);
                            else if (h >= 'A' && h <= 'F') cp |= (h - 'A' + 10);
                            else throw std::runtime_error("json: bad hex digit");
                        }
                        // Encode as UTF-8 (surrogate pairs not handled - good
                        // enough for our payloads, which never embed BMP-2).
                        if (cp < 0x80) out += static_cast<char>(cp);
                        else if (cp < 0x800) {
                            out += static_cast<char>(0xC0 | (cp >> 6));
                            out += static_cast<char>(0x80 | (cp & 0x3F));
                        } else {
                            out += static_cast<char>(0xE0 | (cp >> 12));
                            out += static_cast<char>(0x80 | ((cp >> 6) & 0x3F));
                            out += static_cast<char>(0x80 | (cp & 0x3F));
                        }
                        break;
                    }
                    default: throw std::runtime_error("json: unknown escape");
                }
            } else {
                out += c;
            }
        }
        throw std::runtime_error("json: unterminated string");
    }

    static Json ParseBool(const std::string& s, size_t& i) {
        if (s.compare(i, 4, "true") == 0)  { i += 4; return Json(true); }
        if (s.compare(i, 5, "false") == 0) { i += 5; return Json(false); }
        throw std::runtime_error("json: expected bool");
    }

    static Json ParseNumber(const std::string& s, size_t& i) {
        size_t start = i;
        if (i < s.size() && s[i] == '-') ++i;
        while (i < s.size() && ((s[i] >= '0' && s[i] <= '9') || s[i] == '.' || s[i] == 'e' || s[i] == 'E' || s[i] == '+' || s[i] == '-')) ++i;
        if (start == i) throw std::runtime_error("json: expected number");
        try {
            return Json(std::stod(s.substr(start, i - start)));
        } catch (...) {
            throw std::runtime_error("json: bad number");
        }
    }

    static void ExpectLiteral(const std::string& s, size_t& i, const char* lit) {
        size_t n = std::strlen(lit);
        if (s.compare(i, n, lit) != 0) throw std::runtime_error("json: expected literal");
        i += n;
    }
};

// ── Errors + options ─────────────────────────────────────────────────

class ApiError : public std::runtime_error {
public:
    ApiError(int status, const std::string& msg, const Json& body = Json())
        : std::runtime_error("HTTP " + std::to_string(status) + ": " + msg),
          status_(status), body_(body) {}
    int Status() const { return status_; }
    const Json& Body() const { return body_; }
private:
    int status_;
    Json body_;
};

struct ListOpts {
    int limit  = 0;
    int offset = 0;
    std::string sort;
    std::string q;
    std::map<std::string, std::string> filters;
};

// ── Client ───────────────────────────────────────────────────────────

class AtsClient {
public:
    explicit AtsClient(const std::string& token = "")
        : token_(token.empty() ? GetEnv("XCLIENT_TOKEN") : token) {
        std::string base = GetEnv("XCLIENT_BASE_URL");
        base_url_ = base.empty() ? std::string(kDefaultBase) : base;
        while (!base_url_.empty() && base_url_.back() == '/') base_url_.pop_back();
        device_id_  = LoadOrMintDeviceId();
        session_id_ = MintUuid();
        std::call_once(curl_global_init_flag_(), []() { curl_global_init(CURL_GLOBAL_DEFAULT); });
    }

    void SetToken(const std::string& tok)   { token_ = tok; }
    void SetBaseUrl(const std::string& url) {
        base_url_ = url;
        while (!base_url_.empty() && base_url_.back() == '/') base_url_.pop_back();
    }

    /// Decode a JSON blob into a Json value. Throws on malformed input.
    static Json ParseJson(const std::string& src) { return Json::Parse(src); }

    /// List `application` rows.
    Json ApplicationList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/application", opts);
    }

    /// Fetch one `application` row by id.
    Json ApplicationGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/application/" + id, Json{});
    }

    /// Create a new `application` row.
    Json ApplicationCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/application", data);
    }

    /// Patch a `application` row.
    Json ApplicationUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/application/" + id, data);
    }

    /// Delete a `application` row.
    bool ApplicationDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/application/" + id, Json{});
        return true;
    }

    /// List `application_note` rows.
    Json ApplicationNoteList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/application_note", opts);
    }

    /// Fetch one `application_note` row by id.
    Json ApplicationNoteGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/application_note/" + id, Json{});
    }

    /// Create a new `application_note` row.
    Json ApplicationNoteCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/application_note", data);
    }

    /// Patch a `application_note` row.
    Json ApplicationNoteUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/application_note/" + id, data);
    }

    /// Delete a `application_note` row.
    bool ApplicationNoteDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/application_note/" + id, Json{});
        return true;
    }

    /// List `candidate` rows.
    Json CandidateList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/candidate", opts);
    }

    /// Fetch one `candidate` row by id.
    Json CandidateGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/candidate/" + id, Json{});
    }

    /// Create a new `candidate` row.
    Json CandidateCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/candidate", data);
    }

    /// Patch a `candidate` row.
    Json CandidateUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/candidate/" + id, data);
    }

    /// Delete a `candidate` row.
    bool CandidateDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/candidate/" + id, Json{});
        return true;
    }

    /// List `email_template` rows.
    Json EmailTemplateList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/email_template", opts);
    }

    /// Fetch one `email_template` row by id.
    Json EmailTemplateGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/email_template/" + id, Json{});
    }

    /// Create a new `email_template` row.
    Json EmailTemplateCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/email_template", data);
    }

    /// Patch a `email_template` row.
    Json EmailTemplateUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/email_template/" + id, data);
    }

    /// Delete a `email_template` row.
    bool EmailTemplateDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/email_template/" + id, Json{});
        return true;
    }

    /// List `evaluation` rows.
    Json EvaluationList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/evaluation", opts);
    }

    /// Fetch one `evaluation` row by id.
    Json EvaluationGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/evaluation/" + id, Json{});
    }

    /// Create a new `evaluation` row.
    Json EvaluationCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/evaluation", data);
    }

    /// Patch a `evaluation` row.
    Json EvaluationUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/evaluation/" + id, data);
    }

    /// Delete a `evaluation` row.
    bool EvaluationDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/evaluation/" + id, Json{});
        return true;
    }

    /// List `interview` rows.
    Json InterviewList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/interview", opts);
    }

    /// Fetch one `interview` row by id.
    Json InterviewGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/interview/" + id, Json{});
    }

    /// Create a new `interview` row.
    Json InterviewCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/interview", data);
    }

    /// Patch a `interview` row.
    Json InterviewUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/interview/" + id, data);
    }

    /// Delete a `interview` row.
    bool InterviewDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/interview/" + id, Json{});
        return true;
    }

    /// List `job` rows.
    Json JobList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/job", opts);
    }

    /// Fetch one `job` row by id.
    Json JobGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/job/" + id, Json{});
    }

    /// Create a new `job` row.
    Json JobCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/job", data);
    }

    /// Patch a `job` row.
    Json JobUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/job/" + id, data);
    }

    /// Delete a `job` row.
    bool JobDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/job/" + id, Json{});
        return true;
    }

    /// List `message` rows.
    Json MessageList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/message", opts);
    }

    /// Fetch one `message` row by id.
    Json MessageGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/message/" + id, Json{});
    }

    /// Create a new `message` row.
    Json MessageCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/message", data);
    }

    /// Patch a `message` row.
    Json MessageUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/message/" + id, data);
    }

    /// Delete a `message` row.
    bool MessageDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/message/" + id, Json{});
        return true;
    }

    /// List `offer` rows.
    Json OfferList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/offer", opts);
    }

    /// Fetch one `offer` row by id.
    Json OfferGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/offer/" + id, Json{});
    }

    /// Create a new `offer` row.
    Json OfferCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/offer", data);
    }

    /// Patch a `offer` row.
    Json OfferUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/offer/" + id, data);
    }

    /// Delete a `offer` row.
    bool OfferDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/offer/" + id, Json{});
        return true;
    }

    /// List `source` rows.
    Json SourceList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/source", opts);
    }

    /// Fetch one `source` row by id.
    Json SourceGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/source/" + id, Json{});
    }

    /// Create a new `source` row.
    Json SourceCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/source", data);
    }

    /// Patch a `source` row.
    Json SourceUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/source/" + id, data);
    }

    /// Delete a `source` row.
    bool SourceDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/source/" + id, Json{});
        return true;
    }

    /// List `task` rows.
    Json TaskList(const ListOpts& opts = {}) {
        return RequestList("/xapi2/data/task", opts);
    }

    /// Fetch one `task` row by id.
    Json TaskGet(const std::string& id) {
        return RequestJson("GET", "/xapi2/data/task/" + id, Json{});
    }

    /// Create a new `task` row.
    Json TaskCreate(const Json& data) {
        return RequestJson("POST", "/xapi2/data/task", data);
    }

    /// Patch a `task` row.
    Json TaskUpdate(const std::string& id, const Json& data) {
        return RequestJson("PATCH", "/xapi2/data/task/" + id, data);
    }

    /// Delete a `task` row.
    bool TaskDelete(const std::string& id) {
        RequestJson("DELETE", "/xapi2/data/task/" + id, Json{});
        return true;
    }


private:
    std::string base_url_;
    std::string token_;
    std::string device_id_;
    std::string session_id_;
    std::atomic<bool> autoupdate_attempted_{false};
    std::atomic<bool> meta_sent_once_{false};
    std::mutex token_mtx_;

    static std::once_flag& curl_global_init_flag_() {
        static std::once_flag f;
        return f;
    }

    static std::string GetEnv(const char* key) {
        const char* v = std::getenv(key);
        return v ? std::string(v) : std::string();
    }

    static bool AutoupdateEnabled() {
        std::string v = GetEnv("XCLIENT_NO_AUTOUPDATE");
        for (auto& c : v) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
        return v != "1" && v != "true" && v != "yes";
    }

    static std::string StateDir() {
        std::string home = GetEnv("HOME");
        if (home.empty()) home = GetEnv("USERPROFILE");
        if (home.empty()) return "";
        std::string d = home + "/." + std::string(kModuleName);
        std::error_code ec;
        std::filesystem::create_directories(d, ec);
        return d;
    }

    static std::string MintUuid() {
        std::random_device rd;
        std::mt19937_64 g(static_cast<std::uint64_t>(rd()) ^
                          static_cast<std::uint64_t>(std::chrono::high_resolution_clock::now().time_since_epoch().count()));
        std::uniform_int_distribution<int> dist(0, 255);
        unsigned char b[16];
        for (int i = 0; i < 16; ++i) b[i] = static_cast<unsigned char>(dist(g));
        b[6] = (b[6] & 0x0f) | 0x40;
        b[8] = (b[8] & 0x3f) | 0x80;
        char out[37];
        std::snprintf(out, sizeof(out),
                      "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
                      b[0], b[1], b[2], b[3], b[4], b[5], b[6], b[7],
                      b[8], b[9], b[10], b[11], b[12], b[13], b[14], b[15]);
        return std::string(out);
    }

    static std::string LoadOrMintDeviceId() {
        std::string d = StateDir();
        if (d.empty()) return MintUuid();
        std::string f = d + "/device.json";
        std::ifstream in(f);
        if (in) {
            std::stringstream buf; buf << in.rdbuf();
            try {
                Json j = Json::Parse(buf.str());
                if (j.IsObject() && j.Get("device_id").IsString()) {
                    std::string did = j.Get("device_id").AsString();
                    if (did.size() >= 32) return did;
                }
            } catch (...) {}
        }
        std::string fresh = MintUuid();
        std::ofstream out(f);
        if (out) {
            Json j = Json::Object();
            j.Set("device_id", Json(fresh));
            out << j.Encode();
        }
        return fresh;
    }

    static Json Fingerprint() {
        Json j = Json::Object();
        std::string tp = GetEnv("TERM_PROGRAM");
        std::string lower = tp;
        for (auto& c : lower) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
        j.Set("term_program", tp.empty() ? Json(nullptr) : Json(tp));
        j.Set("editor_env",   GetEnv("EDITOR").empty() ? Json(nullptr) : Json(GetEnv("EDITOR")));
        j.Set("ci",           Json(!GetEnv("CI").empty() || !GetEnv("GITHUB_ACTIONS").empty()));
        j.Set("claude_code",  Json(!GetEnv("CLAUDECODE").empty() || !GetEnv("CLAUDE_CODE_ENTRYPOINT").empty()));
        j.Set("codex",        Json(!GetEnv("CODEX_HOME").empty()));
        j.Set("vscode",       Json(lower == "vscode" && GetEnv("CURSOR_TRACE_ID").empty()));
        j.Set("cursor",       Json(!GetEnv("CURSOR_TRACE_ID").empty()));
        j.Set("antigravity",  Json(!GetEnv("ANTIGRAVITY_TRACE_ID").empty()));
        j.Set("jetbrains",    Json(lower.find("jetbrains") != std::string::npos));
        return j;
    }

    static const std::unordered_set<int>& Retryable() {
        static const std::unordered_set<int> s = {408, 425, 429, 500, 502, 503, 504};
        return s;
    }

    static double Backoff(int attempt, double retry_after) {
        if (retry_after >= 0) return std::min(retry_after, 60.0);
        double d = static_cast<double>(1ll << attempt);
        return std::min(d, 60.0);
    }

    std::string UserAgent() const {
        return std::string(kModuleName) + "/" + kClientVersion + " (lib/" + kLanguage + "; cpp)";
    }

    static size_t WriteCallback(char* ptr, size_t size, size_t nmemb, void* ud) {
        std::string* out = static_cast<std::string*>(ud);
        out->append(ptr, size * nmemb);
        return size * nmemb;
    }

    static size_t HeaderCallback(char* ptr, size_t size, size_t nmemb, void* ud) {
        auto* hmap = static_cast<std::map<std::string, std::string>*>(ud);
        size_t n = size * nmemb;
        std::string line(ptr, n);
        auto colon = line.find(':');
        if (colon != std::string::npos) {
            std::string k = line.substr(0, colon);
            std::string v = line.substr(colon + 1);
            // Trim
            while (!v.empty() && (v.back() == '\r' || v.back() == '\n' || v.back() == ' ')) v.pop_back();
            while (!v.empty() && v.front() == ' ') v.erase(0, 1);
            for (auto& c : k) c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
            (*hmap)[k] = v;
        }
        return n;
    }

    /// Generic transport. Per-type wrappers forward through here. JSON
    /// in / JSON out; pass an empty Json for read-only verbs. Retries
    /// on 408/425/429/5xx + transport errors with exponential backoff.
    Json RequestJson(const std::string& method, const std::string& path, const Json& body) {
        MaybeAutoupdate();
        std::string url = base_url_ + path;
        std::string body_str;
        bool has_body = !body.IsNull();
        if (has_body) body_str = body.Encode();

        const int max_retries = 3;
        std::string last_err;
        for (int attempt = 0; attempt < max_retries; ++attempt) {
            CURL* h = curl_easy_init();
            if (!h) {
                EmitCallEvent(method, path, 0, false);
                throw ApiError(0, "curl_easy_init failed");
            }
            std::string resp_body;
            std::map<std::string, std::string> resp_headers;
            curl_slist* slist = nullptr;
            slist = curl_slist_append(slist, "Accept: application/json");
            std::string ua = "User-Agent: " + UserAgent();
            slist = curl_slist_append(slist, ua.c_str());
            std::string ch = "X-Client-Channel: client_" + std::string(kLanguage);
            slist = curl_slist_append(slist, ch.c_str());
            std::string cv = "X-Client-Version: " + std::string(kClientVersion);
            slist = curl_slist_append(slist, cv.c_str());
            std::string did = "X-Analytics-Device-Id: " + device_id_;
            slist = curl_slist_append(slist, did.c_str());
            std::string sid = "X-Analytics-Session-Id: " + session_id_;
            slist = curl_slist_append(slist, sid.c_str());
            std::string auth_h;
            {
                std::lock_guard<std::mutex> lk(token_mtx_);
                if (!token_.empty()) {
                    auth_h = "Authorization: Bearer " + token_;
                    slist = curl_slist_append(slist, auth_h.c_str());
                }
            }
            if (has_body) slist = curl_slist_append(slist, "Content-Type: application/json");

            curl_easy_setopt(h, CURLOPT_URL, url.c_str());
            curl_easy_setopt(h, CURLOPT_HTTPHEADER, slist);
            curl_easy_setopt(h, CURLOPT_CUSTOMREQUEST, method.c_str());
            // We follow redirects manually so Authorization can be
            // dropped on cross-origin hops. libcurl preserves headers
            // by default - a misconfigured proxy bouncing requests to
            // an internal host would otherwise leak the PAT.
            curl_easy_setopt(h, CURLOPT_FOLLOWLOCATION, 0L);
            curl_easy_setopt(h, CURLOPT_WRITEFUNCTION, WriteCallback);
            curl_easy_setopt(h, CURLOPT_WRITEDATA, &resp_body);
            curl_easy_setopt(h, CURLOPT_HEADERFUNCTION, HeaderCallback);
            curl_easy_setopt(h, CURLOPT_HEADERDATA, &resp_headers);
            curl_easy_setopt(h, CURLOPT_TIMEOUT, 30L);
            curl_easy_setopt(h, CURLOPT_NOSIGNAL, 1L);
            if (has_body) {
                curl_easy_setopt(h, CURLOPT_POSTFIELDS, body_str.c_str());
                curl_easy_setopt(h, CURLOPT_POSTFIELDSIZE, static_cast<long>(body_str.size()));
            }

            std::string current_method = method;
            CURLcode rc = PerformWithRedirects(h, url, current_method, has_body, body_str, slist, resp_body, resp_headers);
            long status = 0;
            if (rc == CURLE_OK) curl_easy_getinfo(h, CURLINFO_RESPONSE_CODE, &status);
            curl_slist_free_all(slist);
            curl_easy_cleanup(h);

            if (rc != CURLE_OK) {
                last_err = curl_easy_strerror(rc);
                if (attempt + 1 < max_retries) {
                    std::this_thread::sleep_for(std::chrono::milliseconds(static_cast<long>(Backoff(attempt, -1.0) * 1000)));
                    continue;
                }
                EmitCallEvent(method, path, 0, false);
                throw ApiError(0, last_err);
            }

            auto fresh = resp_headers.find("x-auth-refresh-token");
            if (fresh != resp_headers.end() && !fresh->second.empty()) {
                std::lock_guard<std::mutex> lk(token_mtx_);
                token_ = fresh->second;
            }

            if (Retryable().count(static_cast<int>(status)) && attempt + 1 < max_retries) {
                double ra = -1.0;
                auto raIt = resp_headers.find("retry-after");
                if (raIt != resp_headers.end()) {
                    try { ra = std::stod(raIt->second); } catch (...) { ra = -1.0; }
                }
                std::this_thread::sleep_for(std::chrono::milliseconds(static_cast<long>(Backoff(attempt, ra) * 1000)));
                continue;
            }

            Json parsed;
            if (!resp_body.empty()) {
                try { parsed = Json::Parse(resp_body); } catch (...) { parsed = Json(); }
            }
            if (status >= 400) {
                std::string msg = "request failed";
                if (parsed.IsObject()) {
                    if (parsed.Get("detail").IsString())  msg = parsed.Get("detail").AsString();
                    else if (parsed.Get("message").IsString()) msg = parsed.Get("message").AsString();
                }
                EmitCallEvent(method, path, static_cast<int>(status), false);
                throw ApiError(static_cast<int>(status), msg, parsed);
            }
            EmitCallEvent(method, path, static_cast<int>(status), true);
            return parsed;
        }
        EmitCallEvent(method, path, 0, false);
        throw ApiError(0, last_err.empty() ? "request failed" : last_err);
    }

    /// Drive the redirect chain manually. Caps at 5 hops; mirrors the
    /// RFC 7231 method-rewrite semantics of every other client in the
    /// suite. Strips Authorization on cross-origin hops.
    static CURLcode PerformWithRedirects(CURL* h, std::string& url, std::string& method,
                                         bool& has_body, std::string& body_str,
                                         curl_slist*& slist,
                                         std::string& resp_body,
                                         std::map<std::string, std::string>& resp_headers) {
        const int max_hops = 5;
        for (int hop = 0; hop < max_hops; ++hop) {
            resp_body.clear();
            resp_headers.clear();
            CURLcode rc = curl_easy_perform(h);
            if (rc != CURLE_OK) return rc;
            long status = 0;
            curl_easy_getinfo(h, CURLINFO_RESPONSE_CODE, &status);
            if (status < 300 || status >= 400 || status == 304) return CURLE_OK;
            auto loc = resp_headers.find("location");
            if (loc == resp_headers.end()) return CURLE_OK;
            std::string next_url = loc->second;
            // libcurl can resolve relative URLs via curl_url, but we
            // keep dependencies minimal: assume server emits absolute.
            if (next_url.empty()) return CURLE_OK;
            std::string old_origin = OriginOf(url);
            std::string new_origin = OriginOf(next_url);
            if (old_origin != new_origin) {
                // Rebuild header list without Authorization.
                curl_slist* fresh = nullptr;
                for (curl_slist* it = slist; it; it = it->next) {
                    std::string h_line = it->data ? it->data : "";
                    if (StartsWithCaseInsensitive(h_line, "authorization:")) continue;
                    fresh = curl_slist_append(fresh, h_line.c_str());
                }
                curl_slist_free_all(slist);
                slist = fresh;
                curl_easy_setopt(h, CURLOPT_HTTPHEADER, slist);
            }
            if (status == 303 || ((status == 301 || status == 302) && method != "GET" && method != "HEAD")) {
                method   = "GET";
                has_body = false;
                body_str.clear();
                curl_easy_setopt(h, CURLOPT_CUSTOMREQUEST, "GET");
                curl_easy_setopt(h, CURLOPT_POSTFIELDS, "");
                curl_easy_setopt(h, CURLOPT_POSTFIELDSIZE, 0L);
            }
            url = next_url;
            curl_easy_setopt(h, CURLOPT_URL, url.c_str());
        }
        // Too many hops: surface the last response.
        return CURLE_OK;
    }

    static bool StartsWithCaseInsensitive(const std::string& s, const char* prefix) {
        size_t n = std::strlen(prefix);
        if (s.size() < n) return false;
        for (size_t i = 0; i < n; ++i) {
            char a = static_cast<char>(std::tolower(static_cast<unsigned char>(s[i])));
            char b = static_cast<char>(std::tolower(static_cast<unsigned char>(prefix[i])));
            if (a != b) return false;
        }
        return true;
    }

    static std::string OriginOf(const std::string& url) {
        auto scheme_end = url.find("://");
        if (scheme_end == std::string::npos) return "";
        auto host_start = scheme_end + 3;
        auto host_end = url.find('/', host_start);
        if (host_end == std::string::npos) host_end = url.size();
        return url.substr(0, host_end);
    }

    Json RequestList(const std::string& path, const ListOpts& opts) {
        std::ostringstream qs;
        bool first = true;
        auto add = [&](const std::string& k, const std::string& v) {
            if (v.empty()) return;
            qs << (first ? '?' : '&'); first = false;
            qs << UrlEncode(k) << "=" << UrlEncode(v);
        };
        if (opts.limit  > 0) add("limit",  std::to_string(opts.limit));
        if (opts.offset > 0) add("offset", std::to_string(opts.offset));
        add("sort", opts.sort);
        add("q",    opts.q);
        for (auto& kv : opts.filters) add(kv.first, kv.second);
        return RequestJson("GET", path + qs.str(), Json());
    }

    static std::string UrlEncode(const std::string& s) {
        std::ostringstream os;
        os << std::hex;
        for (unsigned char c : s) {
            if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') ||
                c == '-' || c == '_' || c == '.' || c == '~') {
                os << static_cast<char>(c);
            } else {
                os << '%';
                if (c < 16) os << '0';
                os << static_cast<int>(c);
            }
        }
        return os.str();
    }

    void EmitCallEvent(const std::string& method, const std::string& path, int status, bool ok) {
        bool include_env = !meta_sent_once_.exchange(true);
        std::string base = base_url_;
        std::string did  = device_id_;
        std::string sid  = session_id_;
        std::string ua   = UserAgent();
        std::thread([base, did, sid, ua, method, path, status, ok, include_env]() {
            try {
                Json meta = Json::Object();
                meta.Set("channel",        Json(std::string("client_") + kLanguage));
                meta.Set("client_version", Json(std::string(kClientVersion)));
                meta.Set("module_name",    Json(std::string(kModuleName)));
                meta.Set("language",       Json(std::string(kLanguage)));
                meta.Set("os",             Json(std::string("cpp")));
                if (include_env) meta.Set("env", Fingerprint());
                Json evt = Json::Object();
                evt.Set("type", Json(std::string("client.call")));
                evt.Set("ts_client", Json(static_cast<long long>(std::time(nullptr))));
                Json evt_meta = Json::Object();
                evt_meta.Set("method", Json(method));
                std::string p = path; auto q = p.find('?'); if (q != std::string::npos) p = p.substr(0, q);
                if (p.size() > 128) p = p.substr(0, 128);
                evt_meta.Set("path",   Json(p));
                evt_meta.Set("status", Json(status));
                evt_meta.Set("ok",     Json(ok));
                evt.Set("meta", evt_meta);
                Json events = Json::Array();
                events.Push(evt);
                Json body = Json::Object();
                body.Set("device_id",  Json(did));
                body.Set("session_id", Json(sid));
                body.Set("events",     events);
                body.Set("meta",       meta);
                std::string url = base + "/xapi2/analytics/challenge";
                std::string raw = body.Encode();
                CURL* h = curl_easy_init();
                if (!h) return;
                curl_slist* sl = nullptr;
                sl = curl_slist_append(sl, "Content-Type: application/json");
                std::string ua_h = "User-Agent: " + ua;
                sl = curl_slist_append(sl, ua_h.c_str());
                curl_easy_setopt(h, CURLOPT_URL, url.c_str());
                curl_easy_setopt(h, CURLOPT_HTTPHEADER, sl);
                curl_easy_setopt(h, CURLOPT_POSTFIELDS, raw.c_str());
                curl_easy_setopt(h, CURLOPT_POSTFIELDSIZE, static_cast<long>(raw.size()));
                curl_easy_setopt(h, CURLOPT_TIMEOUT, 4L);
                curl_easy_setopt(h, CURLOPT_NOSIGNAL, 1L);
                curl_easy_perform(h);
                curl_slist_free_all(sl);
                curl_easy_cleanup(h);
            } catch (...) { /* fire-and-forget */ }
        }).detach();
    }

    void MaybeAutoupdate() {
        if (autoupdate_attempted_.exchange(true)) return;
        if (!AutoupdateEnabled()) return;
        std::string base = base_url_;
        std::thread([base]() {
            try {
                std::string d = StateDir();
                if (d.empty()) return;
                std::string stamp = d + "/update_check.json";
                std::ifstream in(stamp);
                if (in) {
                    std::stringstream buf; buf << in.rdbuf();
                    try {
                        Json j = Json::Parse(buf.str());
                        if (j.IsObject() && j.Get("checked_at").IsNumber()) {
                            long long last = j.Get("checked_at").AsInt();
                            if (std::time(nullptr) - last < 86400) return;
                        }
                    } catch (...) {}
                }
                Json stamp_body = Json::Object();
                stamp_body.Set("checked_at", Json(static_cast<long long>(std::time(nullptr))));
                std::ofstream out(stamp);
                if (out) out << stamp_body.Encode();
                // Source replacement is intentionally a no-op in C++ -
                // users ship pre-compiled binaries; the .hpp file on
                // disk is just a record of the version they vendored.
                // Surface the new version through the next build.
            } catch (...) { /* best-effort */ }
        }).detach();
    }
};

}  // namespace ats_client

#endif  // ats_client_CLIENT_HPP_