/**
 * TopstepX (ProjectX Gateway) client — the TopstepX twin of TradovateClient.
 *
 * REST: https://api.topstepx.com (auth via API key at POST /api/Auth/loginKey,
 * 24h session token, refreshed through POST /api/Auth/validate).
 * Realtime: SignalR user hub at https://rtc.topstepx.com/hubs/user, which
 * pushes account balances, orders, positions and trades — the analogue of
 * Tradovate's user-sync WebSocket.
 *
 * Differences from Tradovate that shape this file:
 * - There is no cash-history / fund-transaction report. Daily P&L comes from
 *   POST /api/Trade/search (each half-turn carries fees; closing halves carry
 *   profitAndLoss), grouped into Central-time trade dates with the same 5 PM
 *   roll Tradovate uses. Deposits/withdrawals are invisible to the API, so
 *   fund transactions only ever come from whatever the local DB already holds.
 * - There is no OCO order. placeOcoExit places the limit and stop separately
 *   and cancels the sibling the moment one fills (order events, plus a safety
 *   poll) — see the `ocoPairs` machinery.
 * - There is no auto-liquidation profile to read, so autoLiqThresholds stays
 *   all zeros; a blown account shows up as canTrade=false → active=false.
 */

import axios from 'axios';
import * as signalR from '@microsoft/signalr';
import { currentTradeDateCT } from './trading-logic';
import { getCachedContract } from './contract-resolver';
import { signalrWebSocket } from './outbound-proxy';
import { saveDailyPnL, loadDailyPnL, loadAccountMeta, saveAccountMeta, loadFundTransactions, saveFundTransactions, saveEndedCycleStart } from './db';
import { getAccountConfig } from './account-type-resolver';
import type { PlatformClient, PlatformAccount, PlatformContract, ClientHealth } from './platform-client';
import { OrderNotPlacedError, isOrderNotPlaced, errorMessage } from './platform-client';

const API_BASE = 'https://api.topstepx.com';
const USER_HUB = 'https://rtc.topstepx.com/hubs/user';

/**
 * Self-healing timings. The weekend failure was a chain of awaits with no
 * deadline (hub.start, hub.invoke, a re-login) plus a re-login that tore down
 * the sync loop first — one wedged await left the firm "waiting for sync"
 * until PM2 restarted the process. Every hub await now has a deadline, sync
 * and hub setup detect their own wedges, and a watchdog keeps the client from
 * ever sitting with no session and nothing scheduled to get one.
 */
const HUB_START_TIMEOUT_MS = 30_000;
const HUB_INVOKE_TIMEOUT_MS = 15_000;
/** Automatic reconnect gives up by itself within ~45s (0/2/10/30s retries);
 *  a hub still Connecting/Reconnecting after this is stuck, not retrying. */
const HUB_STALL_MS = 2 * 60_000;
/** A hub setup or REST sync still running after this is wedged — start over. */
const HUB_SETUP_WEDGED_MS = 3 * 60_000;
const SYNC_WEDGED_MS = 3 * 60_000;
/** Failed logins back off 60s, 120s, … up to 10 min, ±20% so a fleet of
 *  boxes coming back from the same outage doesn't log in in lockstep. */
const LOGIN_RETRY_BASE_MS = 60_000;
const LOGIN_RETRY_MAX_MS = 10 * 60_000;
const WATCHDOG_INTERVAL_MS = 60_000;
/** Logged in longer than this with no good sync for as long → the session is
 *  presumed dead in a way validate didn't catch; log in again. */
const SESSION_STALE_MS = 10 * 60_000;
/** Auth calls get their own short deadlines: a login that never answers
 *  would hold loginInFlight — and with it every retry — forever. */
const LOGIN_TIMEOUT_MS = 30_000;
const VALIDATE_TIMEOUT_MS = 15_000;
const TOKEN_LIFETIME_MS = 24 * 60 * 60 * 1000;
/** Hard cap on every other REST call. axios's own timeout is a socket-idle
 *  timer that only starts once the socket has connected, so a proxy CONNECT
 *  that never answers hangs the call — and any single-flight flag it holds,
 *  like the daily P&L fetch's — for good. Aborting (rather than racing) also
 *  destroys a request that hasn't been written yet, so an order can't go out
 *  minutes after its caller gave up on it. Longer than the idle timeout, so
 *  it only bites where that one can't. */
const REST_DEADLINE_MS = 90_000;

/** Rejects if `promise` hasn't settled within `ms`. The underlying operation
 *  keeps running (callers discard whatever it belonged to); Promise.race
 *  subscribes to it, so a late rejection never surfaces as unhandled. */
function withTimeout<T>(promise: Promise<T>, ms: number, label: string): Promise<T> {
    let timer: ReturnType<typeof setTimeout> | undefined;
    const deadline = new Promise<never>((_, reject) => {
        timer = setTimeout(() => reject(new Error(`${label} timed out after ${Math.round(ms / 1000)}s`)), ms);
    });
    return Promise.race([promise, deadline]).finally(() => clearTimeout(timer));
}

/**
 * The gateway answered and said no (`success: false`) — as opposed to a
 * transport failure, where the request may or may not have been acted on.
 * placeOrder turns only this (and pre-handler HTTP refusals) into
 * OrderNotPlacedError.
 */
class GatewayRefusedError extends Error {
    readonly errorCode: number | undefined;
    /** Set when a refusal still names an order — that order exists. */
    readonly orderId: number | undefined;
    constructor(message: string, errorCode: number | undefined, orderId: number | undefined) {
        super(message);
        this.name = 'GatewayRefusedError';
        this.errorCode = errorCode;
        this.orderId = orderId;
    }
}

/** PlaceOrderErrorCode 6 (OrderPending) and 7 (UnknownError) don't say the
 *  order wasn't created, so a refusal carrying them stays ambiguous. */
const AMBIGUOUS_PLACE_ERRORS = new Set([6, 7]);

/** HTTP answers given before any order handler runs (by the gateway's
 *  middleware or the Cloudflare edge in front of it): malformed request,
 *  missing/expired token, forbidden, rate-limited. Nothing was placed. */
const REFUSED_BEFORE_HANDLER = new Set([400, 401, 403, 429]);

interface TsxContract {
    id: string;
    name: string;
    description: string;
    tickSize: number;
    tickValue: number;
    activeContract: boolean;
    symbolId: string;
}

interface TsxTrade {
    id: number;
    accountId: number;
    contractId: string;
    creationTimestamp: string;
    price: number;
    profitAndLoss: number | null; // null = half-turn (entry only)
    fees: number;
    side: number; // 0 = Bid/Buy, 1 = Ask/Sell
    size: number;
    voided: boolean;
    orderId: number;
}

/** OrderStatus: 1 Open, 2 Filled, 3 Cancelled, 4 Expired, 5 Rejected, 6 Pending */
const ORDER_FILLED = 2;
const ORDER_GONE = new Set([3, 4, 5]);

/** An order's first fill price (by trade id), or null when it has none —
 *  the price the hub's first trade event carries, so a whole tick. */
function firstFillPrice(trades: TsxTrade[]): number | null {
    let first: TsxTrade | null = null;
    for (const t of trades) {
        if (t.voided || typeof t.price !== 'number') continue;
        if (!first || t.id < first.id) first = t;
    }
    return first ? first.price : null;
}

const SIDE_BUY = 0;
const SIDE_SELL = 1;
const TYPE_LIMIT = 1;
const TYPE_MARKET = 2;
const TYPE_STOP = 4;

export class TopstepXClient implements PlatformClient {
    private name: string;
    private apiKey: string;
    private token: string | null = null;

    public accountList: PlatformAccount[] = [];
    public accountCashBalances: { [accountId: number]: { amount: number; realizedPnL: number } } = {};
    public positions: {
        [accountId: number]: { contractId: string; netPos: number; netPrice: number; timestamp: Date };
    } = {};

    public daysTraded: { [accountId: number]: number } = {};
    public dailyPnL: { [accountId: number]: { date: string; pnl: number }[] } = {};
    public fullDailyPnL: { [accountId: number]: { date: string; pnl: number }[] } = {};
    public lastFundDates: { [accountId: number]: string | null } = {};
    public fundTransactions: { [accountId: number]: { date: string; amount: number }[] } = {};
    public priorProfit: { [accountId: number]: number } = {};
    public autoLiqThresholds: { [accountId: number]: number } = {};

    public fetchDaysComplete = false;
    public syncComplete = false;
    /** Epoch ms of the last sync that came back good (0 = never). */
    public lastSyncAt = 0;
    public lastFetchErrors: Record<string, string> = {};
    public lastFetchRaw: Record<string, string> = {};
    public recentEntityEvents: { entityType: string; eventType: string; entity: unknown; ts: number }[] = [];
    /** Tradovate-only concept; empty keeps fee lookups a clean no-op. */
    public products: { id: number; name: string }[] = [];

    private callbackOnSyncRequest: () => Promise<void>;
    private hub: signalR.HubConnection | null = null;
    private subscribedAccountIds = new Set<number>();
    /** SubscribeAccounts done on the current hub connection. */
    private accountsFeedSubscribed = false;

    /** ensureHub is single-flight; the generation lets a flight declared
     *  wedged be superseded without its late finally clearing the new flag. */
    private hubSetupInFlight = false;
    private hubSetupSince = 0;
    private hubSetupGeneration = 0;
    /** ensureHub was asked for while a flight ran (e.g. the first sync's
     *  accounts landed mid-start) — run once more if the hub came up. */
    private hubRecheckWanted = false;
    /** When the hub was first seen Connecting/Reconnecting/Disconnecting (0 = it wasn't). */
    private hubStalledSince = 0;
    /** Last frame from the hub (event, invoke answer, handshake). */
    private lastInboundAt = 0;

    private syncInterval: ReturnType<typeof setInterval> | null = null;
    private tokenRenewalInterval: ReturnType<typeof setInterval> | null = null;
    private ocoPollInterval: ReturnType<typeof setInterval> | null = null;
    private loginRetryTimer: ReturnType<typeof setTimeout> | null = null;
    private watchdogInterval: ReturnType<typeof setInterval> | null = null;
    private intentionalDisconnect = false;

    /** requestSync is single-flight too, with the same generation trick. */
    private syncInFlight = false;
    private syncInFlightSince = 0;
    private syncGeneration = 0;

    private loginInFlight = false;
    private lastLoginAt = 0;
    private lastLoginError: string | null = null;
    private consecutiveLoginFailures = 0;
    private nextReconnectAt = 0;
    /** When the current token was issued or last renewed (24h lifetime). */
    private tokenRefreshedAt = 0;

    /** Same hourly-with-retry throttle the Tradovate client uses for reports. */
    private daysFetchInFlight = false;
    private daysFetchInFlightSince = 0;
    private lastDaysFetchStartedAt = 0;
    private lastDaysFetchSucceededAt = 0;
    private nextDaysFetchRetryAt = 0;
    /** The first full daily P&L pass has landed (cache fallbacks included).
     *  No sync counts as good before it — see requestSync. */
    private historyLoaded = false;
    /** Accounts whose history this client has loaded (a trade search came
     *  back, or failed with a DB cache to fall back on). historyLoaded above
     *  is the firm's first pass; this is per account, so one that appears
     *  later, or is wiped, stays out of trading until its own fetch lands. */
    private historyLoadedIds = new Set<number>();
    /** Fetched, but not yet past a sync that reconciled its funds. TopstepX
     *  has no funds API: reconcileFunds, inside requestSync, is what books a
     *  withdrawal from the balance the trades don't explain, so a history
     *  fetched without it (after a wipe took the fund rows) would plan the
     *  account as stage 1 until the next sync. */
    private reconcilePendingIds = new Set<number>();
    /** Settles when the sync in flight ends (requestSync hands it to a caller
     *  that arrives mid-pass). */
    private syncRunning: Promise<void> = Promise.resolve();
    /** Accounts a fetchDaysTraded call is working through right now, so the
     *  targeted pass doesn't fetch them again (a wipe fetches outside it). */
    private fetchingIds = new Set<number>();

    /** Trades seen for the current CT trade date, per account — realizedPnL is
     *  recomputed from these on every REST sync and every live trade event. */
    private todayTrades: { [accountId: number]: Map<number, TsxTrade> } = {};

    /** Reported fees per trade date, per account — weights for spreading the
     *  off-book fee drift when reconstructing the MLL floor. */
    private dailyFees: { [accountId: number]: Map<string, number> } = {};

    /** Front-month contract per product symbol, plus name→contract for order
     *  placement (sendOrder receives the contract NAME, e.g. "NQZ5"). */
    private contractByProduct = new Map<string, { contract: TsxContract; resolvedAt: number }>();
    private contractByName = new Map<string, TsxContract>();
    private static CONTRACT_TTL_MS = 30 * 60 * 1000;

    /** Fill waiters keyed by orderId — resolved by GatewayUserTrade events. */
    private fillWaiters: { orderId: number; callback: (trade: TsxTrade) => void }[] = [];

    /** Emulated OCO exit pairs: when one leg fills, cancel the other. */
    private ocoPairs: { accountId: number; limitId: number; stopId: number; done: boolean; placedAt: number }[] = [];

    constructor(name: string, apiKey: string, callbackOnSyncRequest: () => Promise<void>) {
        this.name = name;
        this.apiKey = apiKey;
        this.callbackOnSyncRequest = callbackOnSyncRequest;
        this.watchdogInterval = setInterval(() => this.watchdog(), WATCHDOG_INTERVAL_MS);
        void this.connectAndAuth();
    }

    // ── auth ─────────────────────────────────────────────────────────────────

    private authHeaders() {
        return { Authorization: `Bearer ${this.token}` };
    }

    private async post<T>(path: string, body: unknown): Promise<T> {
        const res = await axios.post(`${API_BASE}${path}`, body, {
            headers: this.authHeaders(),
            signal: AbortSignal.timeout(REST_DEADLINE_MS),
        }).catch((err: unknown) => {
            // The deadline abort surfaces as a bare "canceled" — say what it
            // was. Still a plain Error: for an order it stays ambiguous.
            if (axios.isCancel(err)) throw new Error(`${path} timed out after ${REST_DEADLINE_MS / 1000}s`);
            throw err;
        });
        const data = res.data as T & { success?: boolean; errorMessage?: string | null; errorCode?: number; orderId?: number | null };
        // The gateway answers every call with a JSON object. Anything else —
        // an HTML maintenance or proxy page served with a 200, an empty body —
        // is a failed call, never an empty result: through the callers'
        // `?? []`, a positions answer would read as "flat", a trades answer
        // as "nothing traded today", and the sync would certify both. For an
        // order it stays a plain Error: it may have gone in.
        if (!data || typeof data !== 'object') {
            throw new Error(`${path} returned a non-JSON answer (HTTP ${res.status})`);
        }
        if (data.success === false) {
            throw new GatewayRefusedError(
                `${path} failed: ${data.errorMessage ?? `errorCode=${data.errorCode}`}`,
                typeof data.errorCode === 'number' ? data.errorCode : undefined,
                typeof data.orderId === 'number' && data.orderId > 0 ? data.orderId : undefined,
            );
        }
        return data;
    }

    /**
     * Log in, single-flight. Safe to call from anywhere (constructor, retry
     * timer, token renewal, watchdog) — a second caller while one runs is a
     * no-op, and it never rejects.
     *
     * First login starts the hub, the sync loop and its 60s interval. A
     * RE-login only swaps the token and nudges a sync: it deliberately leaves
     * the sync interval and syncComplete alone. Tearing those down before the
     * new session was proven is what left a firm "waiting for sync" forever
     * when the re-login chain wedged.
     */
    private async connectAndAuth(): Promise<void> {
        if (this.intentionalDisconnect || this.loginInFlight) return;

        if (!this.name) {
            // loginKey requires the platform username the key was generated for.
            // The key alone is storable (per the credential form), but nothing
            // can be traded until the username arrives — say so loudly, once.
            this.lastFetchErrors['login'] =
                'TopstepX username missing — the API key alone cannot log in. Add the username on the dashboard.';
            this.lastLoginError = this.lastFetchErrors['login'];
            console.error(`[topstepx] ${this.lastFetchErrors['login']}`);
            return;
        }

        if (this.loginRetryTimer) { clearTimeout(this.loginRetryTimer); this.loginRetryTimer = null; }
        this.nextReconnectAt = 0;
        this.loginInFlight = true;
        try {
            // A hard deadline on top of axios's own: that one is a socket
            // inactivity timer, which never starts while a proxy CONNECT
            // hangs — and a login that never settles holds loginInFlight.
            const token = await withTimeout(this.login(), LOGIN_TIMEOUT_MS, 'loginKey');
            if (this.intentionalDisconnect) return;

            this.token = token;
            this.lastLoginAt = this.tokenRefreshedAt = Date.now();
            this.consecutiveLoginFailures = 0;
            this.lastLoginError = null;
            console.log(`[topstepx] logged in as ${this.name}`);
            delete this.lastFetchErrors['login'];

            // Session tokens live 24h; re-validate every hour to stay fresh.
            if (this.tokenRenewalInterval) clearInterval(this.tokenRenewalInterval);
            this.tokenRenewalInterval = setInterval(() => void this.renewToken(), 60 * 60 * 1000);

            if (!this.syncInterval) {
                // First login. The hub is never a hard dependency: REST polling
                // carries every feature (slower), and each sync tick calls
                // ensureHub again, so a hub that won't come up now gets retried.
                void this.ensureHub();
                this.syncInterval = setInterval(() => void this.requestSync(), 60_000);
                void this.requestSync();
            } else {
                // Re-login: the loop keeps running; just use the new session now.
                void this.requestSync();
                void this.ensureHub();
            }
        } catch (err) {
            if (this.intentionalDisconnect) return;
            this.consecutiveLoginFailures++;
            const msg = errorMessage(err);
            this.lastLoginError = msg;
            this.lastFetchErrors['login'] = msg;
            const backoff = Math.min(
                LOGIN_RETRY_BASE_MS * 2 ** Math.min(this.consecutiveLoginFailures - 1, 10),
                LOGIN_RETRY_MAX_MS,
            );
            const delay = Math.round(backoff * (0.8 + Math.random() * 0.4));
            this.nextReconnectAt = Date.now() + delay;
            console.error(`[topstepx] login failed for ${this.name}: ${msg} — attempt ${this.consecutiveLoginFailures}, retrying in ${Math.round(delay / 1000)}s`);
            this.loginRetryTimer = setTimeout(() => {
                this.loginRetryTimer = null;
                this.nextReconnectAt = 0;
                void this.connectAndAuth();
            }, delay);
        } finally {
            this.loginInFlight = false;
        }
    }

    /**
     * Never-dead invariant, checked every minute. Every failure path above is
     * supposed to leave a retry scheduled; this catches the ones that don't
     * (and sessions that died without anything failing loudly):
     * - no token, no login running, no retry pending → log in now;
     * - logged in >10 min ago with no good sync for >10 min → the token may
     *   have died in a way validate didn't catch → log in again.
     */
    private watchdog(): void {
        if (!this.name || this.intentionalDisconnect) return;
        if (this.loginInFlight || this.loginRetryTimer) return;
        const now = Date.now();
        if (!this.token) {
            console.warn(`[topstepx] watchdog: ${this.name} has no session and no login pending — logging in`);
            void this.connectAndAuth();
            return;
        }
        if (now - this.lastLoginAt > SESSION_STALE_MS && now - this.lastSyncAt > SESSION_STALE_MS) {
            const since = this.lastSyncAt > 0 ? `in ${Math.round((now - this.lastSyncAt) / 60_000)} min` : 'since login';
            console.warn(`[topstepx] watchdog: no good sync for ${this.name} ${since} — re-logging in`);
            void this.connectAndAuth();
        }
    }

    /** LoginErrorCode names from the gateway swagger — the API itself sends
     *  only the number with a null message. */
    private static LOGIN_ERRORS: Record<number, string> = {
        1: 'UserNotFound',
        2: 'PasswordVerificationFailed',
        3: 'InvalidCredentials — check that the username is the TopstepX platform username the API key was generated for (not an email)',
        4: 'AppNotFound',
        5: 'AppVerificationFailed',
        6: 'InvalidDevice',
        7: 'AgreementsNotSigned — sign the API agreements in the TopstepX platform',
        8: 'UnknownError',
        9: 'ApiSubscriptionNotFound — the account has no API subscription',
        10: 'ApiKeyAuthenticationDisabled',
    };

    private async login(): Promise<string> {
        const res = await axios.post(`${API_BASE}/api/Auth/loginKey`, {
            userName: this.name,
            apiKey: this.apiKey,
        }, {
            timeout: LOGIN_TIMEOUT_MS,
            // Just after connectAndAuth's own deadline: that one gives the
            // clean error; this one kills the request, so a stalled CONNECT
            // can't still log in minutes later.
            signal: AbortSignal.timeout(LOGIN_TIMEOUT_MS + 5_000),
        });
        const data = res.data as { token?: string; success: boolean; errorCode: number; errorMessage: string | null };
        if (!data.success || !data.token) {
            const detail = TopstepXClient.LOGIN_ERRORS[data.errorCode] ?? `errorCode=${data.errorCode}`;
            throw new Error(data.errorMessage ?? `loginKey failed: ${detail}`);
        }
        return data.token;
    }

    private async renewToken(): Promise<void> {
        if (this.intentionalDisconnect || this.loginInFlight) return;
        if (!this.token) { void this.connectAndAuth(); return; }
        const sent = this.token;
        try {
            const res = await withTimeout(axios.post(`${API_BASE}/api/Auth/validate`, {}, {
                headers: this.authHeaders(),
                timeout: VALIDATE_TIMEOUT_MS,
                signal: AbortSignal.timeout(VALIDATE_TIMEOUT_MS + 5_000),
            }), VALIDATE_TIMEOUT_MS, 'token validate');
            if (this.intentionalDisconnect) return;
            const data = res.data as { success: boolean; newToken?: string };
            if (data.success && data.newToken) {
                // A login that landed meanwhile holds a newer session — keep it.
                if (this.token !== sent) return;
                this.token = data.newToken;
                this.tokenRefreshedAt = Date.now();
                console.log('[topstepx] session token renewed');
            } else if (!data.success) {
                console.warn('[topstepx] token validate failed — re-authenticating');
                void this.connectAndAuth();
            }
        } catch (err) {
            if (this.intentionalDisconnect) return;
            // Never the error object: its request config carries the Bearer token.
            console.error(`[topstepx] token renewal error — re-authenticating: ${errorMessage(err)}`);
            void this.connectAndAuth();
        }
    }

    // ── realtime hub ─────────────────────────────────────────────────────────

    /**
     * Bring the user hub to connected-and-subscribed, as far as one pass can.
     * Called on login and every sync tick, and never awaited by anything that
     * matters: REST polling carries every feature on its own (slower), so a
     * wedged hub must never hold up a sync.
     *
     * - no hub → build a fresh one and start it; a failed start discards it
     *   (a HubConnection whose first start failed never auto-reconnects), so
     *   the next pass builds another;
     * - Disconnected (automatic reconnect gave up) → start it again, discard
     *   on failure;
     * - Connecting/Reconnecting/Disconnecting for > 2 min → stuck; discard it
     *   and build a fresh one;
     * - Connected → subscribe whatever isn't subscribed yet.
     *
     * Single-flight; a flight running past HUB_SETUP_WEDGED_MS is superseded
     * (every await in it has a deadline, so that is belt and braces).
     */
    private async ensureHub(): Promise<void> {
        if (this.intentionalDisconnect || !this.token) return;
        if (this.hubSetupInFlight) {
            const runningMs = Date.now() - this.hubSetupSince;
            if (runningMs < HUB_SETUP_WEDGED_MS) {
                this.hubRecheckWanted = true;
                return;
            }
            console.warn(`[topstepx] hub setup running for ${Math.round(runningMs / 1000)}s — looks wedged, starting over`);
        }
        const gen = ++this.hubSetupGeneration;
        this.hubSetupInFlight = true;
        this.hubSetupSince = Date.now();
        this.hubRecheckWanted = false;
        let clean = false;
        try {
            clean = await this.ensureHubPass(gen);
        } catch (err) {
            console.error(`[topstepx] hub setup failed — running on REST polling only: ${errorMessage(err)}`);
        } finally {
            // A superseded flight must not clear its successor's flag.
            if (gen === this.hubSetupGeneration) {
                this.hubSetupInFlight = false;
                this.hubSetupSince = 0;
                // Asked for again mid-flight (typically: the first sync's
                // accounts landed while the hub was starting). Only worth a
                // rerun after a clean pass on a live hub — a failed start or
                // subscribe waits for the next tick rather than retrying hot.
                if (clean && this.hubRecheckWanted && !this.intentionalDisconnect
                    && this.hub?.state === signalR.HubConnectionState.Connected) {
                    this.hubRecheckWanted = false;
                    void this.ensureHub();
                }
            }
        }
    }

    /** One ensureHub pass. True when it ended connected with everything
     *  subscribed; false when it stopped short (the next call carries on). */
    private async ensureHubPass(gen: number): Promise<boolean> {
        const State = signalR.HubConnectionState;
        let hub = this.hub;

        if (hub && (hub.state === State.Connecting || hub.state === State.Reconnecting || hub.state === State.Disconnecting)) {
            const now = Date.now();
            if (!this.hubStalledSince) this.hubStalledSince = now;
            // Automatic reconnect is still working on it — let it.
            if (now - this.hubStalledSince < HUB_STALL_MS) return false;
            console.warn(`[topstepx] hub stuck ${hub.state} for ${Math.round((now - this.hubStalledSince) / 1000)}s — discarding it`);
            this.discardHub();
            hub = null;
        }

        if (!hub) {
            hub = this.buildHub();
            this.hub = hub;
            this.subscribedAccountIds.clear();
            this.accountsFeedSubscribed = false;
            if (!(await this.startHub(hub, gen))) return false;
            console.log('[topstepx] user hub connected');
        } else if (hub.state === State.Disconnected) {
            // Subscriptions died with the old connection.
            this.subscribedAccountIds.clear();
            this.accountsFeedSubscribed = false;
            if (!(await this.startHub(hub, gen))) return false;
            console.log('[topstepx] user hub restarted');
        }

        if (hub.state !== State.Connected) return false;
        this.hubStalledSince = 0;
        return this.subscribeAll(hub, gen);
    }

    /** Start `hub` against a deadline. False when it didn't come up (the hub
     *  is discarded) or was discarded / superseded while starting. */
    private async startHub(hub: signalR.HubConnection, gen: number): Promise<boolean> {
        try {
            await withTimeout(hub.start(), HUB_START_TIMEOUT_MS, 'hub start');
        } catch (err) {
            // REST polling still works without the hub; the next sync tick
            // builds a fresh one.
            console.error(`[topstepx] hub connect failed — falling back to REST polling: ${errorMessage(err)}`);
            if (this.hub === hub) this.discardHub();
            return false;
        }
        if (this.hub !== hub) {
            // Discarded (disconnect, or a stall check) while it was starting.
            void hub.stop().catch(() => { /* discarded */ });
            return false;
        }
        if (gen !== this.hubSetupGeneration) return false;
        this.hubStalledSince = 0;
        this.lastInboundAt = Date.now();
        return true;
    }

    /** Subscribe everything the current connection isn't subscribed to yet.
     *  A failed or timed-out invoke is left for the next pass. True when
     *  nothing was left over. */
    private async subscribeAll(hub: signalR.HubConnection, gen: number): Promise<boolean> {
        const stillCurrent = () =>
            this.hub === hub && gen === this.hubSetupGeneration && hub.state === signalR.HubConnectionState.Connected;
        const invoke = async (method: string, ...args: unknown[]) => {
            await withTimeout(hub.invoke(method, ...args), HUB_INVOKE_TIMEOUT_MS, method);
            this.lastInboundAt = Date.now();
        };
        try {
            if (!this.accountsFeedSubscribed) {
                await invoke('SubscribeAccounts');
                if (!stillCurrent()) return false;
                this.accountsFeedSubscribed = true;
            }
            for (const acc of this.accountList) {
                if (this.subscribedAccountIds.has(acc.id)) continue;
                await invoke('SubscribeOrders', acc.id);
                await invoke('SubscribePositions', acc.id);
                await invoke('SubscribeTrades', acc.id);
                if (!stillCurrent()) return false;
                this.subscribedAccountIds.add(acc.id);
            }
            return true;
        } catch (err) {
            console.error(`[topstepx] hub subscribe failed — retrying on the next sync: ${errorMessage(err)}`);
            return false;
        }
    }

    /** Drop the current hub without waiting on it — stop() can hang as long
     *  as the start it interrupts, so it is fire-and-forget. The hub's
     *  handlers go quiet the moment this.hub stops pointing at it. */
    private discardHub(): void {
        const hub = this.hub;
        this.hub = null;
        this.subscribedAccountIds.clear();
        this.accountsFeedSubscribed = false;
        this.hubStalledSince = 0;
        if (hub) void hub.stop().catch(() => { /* discarded */ });
    }

    /** A fresh HubConnection with every handler wired. Each handler first
     *  checks its hub is still the current one: a discarded connection that
     *  lingers (or reconnects on its own) must never write state. */
    private buildHub(): signalR.HubConnection {
        // signalr's Node path does an unconditional dynamic require('ws') /
        // require('eventsource') when constructing the connection — bundled
        // builds throw "dynamic usage of require is not supported" on it, so
        // the package is listed in next.config serverExternalPackages and any
        // residual failure here is caught by ensureHub (REST polling covers
        // everything the hub does, just slower).
        // With skipNegotiation the hub is a single websocket to a broker
        // endpoint, so it follows the operator's proxy like the REST calls do.
        const proxiedWs = signalrWebSocket();
        const hub = new signalR.HubConnectionBuilder()
            .withUrl(USER_HUB, {
                skipNegotiation: true,
                transport: signalR.HttpTransportType.WebSockets,
                accessTokenFactory: () => this.token ?? '',
                // eslint-disable-next-line @typescript-eslint/no-explicit-any
                ...(proxiedWs ? { WebSocket: proxiedWs as any } : {}),
            })
            .withAutomaticReconnect()
            .configureLogging(signalR.LogLevel.Warning)
            .build();

        // eslint-disable-next-line @typescript-eslint/no-explicit-any
        const unwrap = (raw: unknown): Record<string, any> => {
            // eslint-disable-next-line @typescript-eslint/no-explicit-any
            const r = raw as Record<string, any>;
            return (r && typeof r === 'object' && 'data' in r && typeof r.data === 'object') ? r.data : r;
        };

        hub.on('GatewayUserAccount', (raw: unknown) => {
            if (this.hub !== hub) return;
            this.lastInboundAt = Date.now();
            const acc = unwrap(raw);
            if (typeof acc?.id !== 'number') return;
            this.bufferEvent('account', acc);
            const existing = this.accountCashBalances[acc.id];
            if (typeof acc.balance === 'number') {
                this.accountCashBalances[acc.id] = {
                    amount: acc.balance,
                    realizedPnL: existing?.realizedPnL ?? 0,
                };
            }
            if (typeof acc.canTrade === 'boolean') {
                this.accountList = this.accountList.map((a) =>
                    a.id === acc.id ? { ...a, active: acc.canTrade } : a);
            }
        });

        hub.on('GatewayUserPosition', (raw: unknown) => {
            if (this.hub !== hub) return;
            this.lastInboundAt = Date.now();
            const pos = unwrap(raw);
            if (typeof pos?.accountId !== 'number') return;
            this.bufferEvent('position', pos);
            this.applyPosition(pos as { accountId: number; contractId: string; type: number; size: number; averagePrice: number; creationTimestamp?: string });
        });

        hub.on('GatewayUserTrade', (raw: unknown) => {
            if (this.hub !== hub) return;
            this.lastInboundAt = Date.now();
            const trade = unwrap(raw) as unknown as TsxTrade;
            if (typeof trade?.accountId !== 'number') return;
            this.bufferEvent('trade', trade);
            this.recordTodayTrade(trade);

            // Wake anything waiting on this order's fill.
            const waiters = this.fillWaiters.filter((w) => w.orderId === trade.orderId);
            this.fillWaiters = this.fillWaiters.filter((w) => w.orderId !== trade.orderId);
            for (const w of waiters) {
                try { w.callback(trade); } catch (err) { console.error(`[topstepx] fill callback error: ${errorMessage(err)}`); }
            }
        });

        hub.on('GatewayUserOrder', (raw: unknown) => {
            if (this.hub !== hub) return;
            this.lastInboundAt = Date.now();
            const order = unwrap(raw);
            if (typeof order?.id !== 'number') return;
            this.bufferEvent('order', order);
            this.handleOcoOrderEvent(order.id, order.status);
        });

        hub.onreconnecting(() => {
            if (this.hub !== hub) return;
            // The stall clock ensureHub judges "stuck Reconnecting" by.
            if (!this.hubStalledSince) this.hubStalledSince = Date.now();
        });

        hub.onreconnected(() => {
            if (this.hub !== hub) return;
            this.lastInboundAt = Date.now();
            this.hubStalledSince = 0;
            console.log('[topstepx] hub reconnected — resubscribing');
            this.subscribedAccountIds.clear();
            this.accountsFeedSubscribed = false;
            void this.ensureHub();
            void this.requestSync();
        });

        hub.onclose((err) => {
            if (this.hub !== hub || this.intentionalDisconnect) return;
            this.hubStalledSince = 0;
            console.warn(`[topstepx] hub closed — the next sync restarts it${err ? `: ${errorMessage(err)}` : ''}`);
        });

        return hub;
    }

    private bufferEvent(entityType: string, entity: unknown): void {
        this.recentEntityEvents.push({ entityType, eventType: 'Updated', entity, ts: Date.now() });
        if (this.recentEntityEvents.length > 50) this.recentEntityEvents.shift();
    }

    private applyPosition(pos: { accountId: number; contractId: string; type: number; size: number; averagePrice: number; creationTimestamp?: string }): void {
        // PositionType: 1 Long, 2 Short. Size 0 (or type 0) means flat.
        if (pos.size > 0 && (pos.type === 1 || pos.type === 2)) {
            this.positions[pos.accountId] = {
                contractId: pos.contractId,
                netPos: pos.type === 1 ? pos.size : -pos.size,
                netPrice: pos.averagePrice,
                timestamp: pos.creationTimestamp ? new Date(pos.creationTimestamp) : new Date(),
            };
        } else {
            delete this.positions[pos.accountId];
            // Flat → any surviving emulated-OCO exit legs must go.
            void this.cancelOcoLegsForAccount(pos.accountId);
        }
    }

    private recordTodayTrade(trade: TsxTrade): void {
        if (trade.voided) return;
        const tradeDate = currentTradeDateCT(new Date(trade.creationTimestamp));
        if (tradeDate !== currentTradeDateCT()) return;
        const map = (this.todayTrades[trade.accountId] ??= new Map());
        map.set(trade.id, trade);
        this.recomputeRealized(trade.accountId);
    }

    private recomputeRealized(accountId: number): void {
        const today = currentTradeDateCT();
        const map = this.todayTrades[accountId];
        let realized = 0;
        if (map) {
            for (const t of map.values()) {
                if (t.voided) continue;
                if (currentTradeDateCT(new Date(t.creationTimestamp)) !== today) continue;
                realized += (t.profitAndLoss ?? 0) - (t.fees ?? 0);
            }
        }
        const existing = this.accountCashBalances[accountId];
        this.accountCashBalances[accountId] = {
            amount: existing?.amount ?? 0,
            realizedPnL: Math.round(realized * 100) / 100,
        };
    }

    // ── sync ─────────────────────────────────────────────────────────────────

    /**
     * One REST sync of accounts, positions and today's trades. Single-flight,
     * but a sync still running after SYNC_WEDGED_MS is presumed wedged and a
     * fresh one starts: nothing may hold syncInFlight forever, because a firm
     * that stops syncing stops trading. The superseded run checks its
     * generation after every await and bows out without touching state, and
     * its finally leaves the new run's flag alone.
     */
    private async requestSync(): Promise<void> {
        if (!this.token || this.intentionalDisconnect) return;
        const startedAt = Date.now();
        if (this.syncInFlight) {
            const runningMs = startedAt - this.syncInFlightSince;
            // A caller that awaits gets the running pass's end.
            if (runningMs < SYNC_WEDGED_MS) return this.syncRunning;
            console.warn(`[topstepx] sync running for ${Math.round(runningMs / 1000)}s — looks wedged, starting a fresh one`);
        }
        const gen = ++this.syncGeneration;
        const superseded = () => gen !== this.syncGeneration || this.intentionalDisconnect;
        this.syncInFlight = true;
        this.syncInFlightSince = startedAt;
        let finished!: () => void;
        this.syncRunning = new Promise<void>((resolve) => { finished = resolve; });
        try {
            const accRes = await this.post<{ accounts: { id: number; name: string; balance: number; canTrade: boolean; isVisible: boolean }[] }>(
                '/api/Account/search', { onlyActiveAccounts: false });
            if (superseded()) return;

            this.accountList = (accRes.accounts ?? [])
                .filter((a) => a.isVisible)
                .map((a) => ({ id: a.id, name: a.name, active: a.canTrade }));

            // Trades since yesterday cover the whole current CT trade date
            // (which opens at 5 PM the prior evening) with margin.
            const start = new Date(Date.now() - 2 * 24 * 60 * 60 * 1000).toISOString();
            const end = new Date(Date.now() + 60 * 60 * 1000).toISOString();
            const today = currentTradeDateCT();
            /** Accounts whose positions or trades didn't come back this pass. */
            const staleAccounts: string[] = [];

            for (const acc of this.accountList) {
                const balance = (accRes.accounts ?? []).find((a) => a.id === acc.id)?.balance ?? 0;
                let accountFresh = true;

                try {
                    const posRes = await this.post<{ positions: { accountId: number; contractId: string; type: number; size: number; averagePrice: number; creationTimestamp: string }[] }>(
                        '/api/Position/searchOpen', { accountId: acc.id });
                    if (superseded()) return;
                    const open = (posRes.positions ?? []).filter((p) => p.size > 0);
                    if (open.length > 0) {
                        this.applyPosition(open[0]);
                    } else {
                        delete this.positions[acc.id];
                    }
                } catch (err) {
                    accountFresh = false;
                    console.error(`[topstepx] position sync failed for ${acc.name}: ${errorMessage(err)}`);
                }
                if (superseded()) return;

                try {
                    const tradeRes = await this.post<{ trades: TsxTrade[] }>(
                        '/api/Trade/search', { accountId: acc.id, startTimestamp: start, endTimestamp: end });
                    if (superseded()) return;
                    const map = new Map<number, TsxTrade>();
                    for (const t of tradeRes.trades ?? []) {
                        if (t.voided) continue;
                        if (currentTradeDateCT(new Date(t.creationTimestamp)) !== today) continue;
                        map.set(t.id, t);
                    }
                    this.todayTrades[acc.id] = map;
                } catch (err) {
                    accountFresh = false;
                    console.error(`[topstepx] trade sync failed for ${acc.name}: ${errorMessage(err)}`);
                }
                if (superseded()) return;
                if (!accountFresh) staleAccounts.push(acc.name);

                this.accountCashBalances[acc.id] = { amount: balance, realizedPnL: 0 };
                this.recomputeRealized(acc.id);
                this.autoLiqThresholds[acc.id] = 0;

                // Withdrawal/deposit detection — the books must explain the balance.
                // Never off a failed fetch: a fresh balance against stale trades
                // would book the unseen P&L as a (permanent) fund event.
                let reconciled = false;
                try {
                    if (accountFresh) reconciled = this.reconcileFunds(acc);
                } catch (err) {
                    console.error(`[topstepx] fund reconcile failed for ${acc.name}: ${errorMessage(err)}`);
                }
                // A freshly fetched history is tradable once a fresh pass has
                // actually checked the funds behind the balance (a skipped
                // check — a position still open — waits for a later pass).
                const ours = Boolean(getAccountConfig(acc.id).accountType);
                if ((reconciled || !ours) && this.reconcilePendingIds.delete(acc.id)) this.historyLoadedIds.add(acc.id);

                try {
                    this.updateMllFloor(acc);
                } catch (err) {
                    console.error(`[topstepx] MLL reconstruction failed for ${acc.name}: ${errorMessage(err)}`);
                }
            }

            console.log(`[topstepx] sync — ${this.accountList.length} account(s), ${Object.keys(this.positions).length} open position(s)`);

            // Fire-and-forget: the hub subscribes new accounts on its own
            // schedule and can never hold this sync up.
            void this.ensureHub();
            this.maybeFetchDaysTraded();

            this.syncComplete = true;
            // lastSyncAt is what the scheduler trades on (isClientReady), so it
            // certifies only a pass where every account's positions and trades
            // came back: a stale-flat position or a stale realized P&L walks
            // straight through the "already in trade" / "already traded today"
            // gates. Nor before the first daily P&L pass has landed — until
            // then the plan would run on no history at all.
            if (staleAccounts.length > 0) {
                console.warn(`[topstepx] sync incomplete — not refreshed: ${staleAccounts.join(', ')}; not counted as a good sync`);
            } else if (this.historyLoaded) {
                this.lastSyncAt = Date.now();
            }
            // The resolver runs off this; its failure is not a sync failure.
            try {
                await this.callbackOnSyncRequest();
            } catch (err) {
                console.error(`[topstepx] post-sync callback failed: ${errorMessage(err)}`);
            }
        } catch (err) {
            console.error(`[topstepx] sync failed: ${errorMessage(err)}`);
        } finally {
            if (gen === this.syncGeneration) {
                this.syncInFlight = false;
                this.syncInFlightSince = 0;
            }
            finished();
        }
    }

    /** Re-slice the active cycle out of the full history using the last fund
     *  transaction. A withdrawal's day belongs to the OLD cycle (its min-days
     *  were booked before the payout) so it is excluded; a deposit's day is
     *  included. */
    private applyCycleSlice(accountId: number): void {
        const merged = this.fullDailyPnL[accountId] ?? [];
        const fundDate = this.lastFundDates[accountId];
        const txns = this.fundTransactions[accountId] ?? [];
        const lastAmt = fundDate ? (txns.find((f) => f.date === fundDate)?.amount ?? null) : null;
        const isWithdrawal = lastAmt !== null && lastAmt < 0;
        const active = fundDate
            ? merged.filter((d) => (isWithdrawal ? d.date > fundDate : d.date >= fundDate))
            : merged;
        const prior = fundDate
            ? merged.filter((d) => (isWithdrawal ? d.date <= fundDate : d.date < fundDate))
            : [];
        this.priorProfit[accountId] = Math.round(prior.reduce((s, d) => s + d.pnl, 0) * 100) / 100;
        this.dailyPnL[accountId] = active;
        this.daysTraded[accountId] = active.filter((d) => d.pnl !== 0).length;
    }

    /**
     * Books invariant: for a $0-start account, balance must equal all trade
     * P&L plus all recorded fund transactions. TopstepX has no funds API, so a
     * divergence IS the fund event — a withdrawal (or deposit) the platform
     * never told us about. Recording it advances the withdrawal-stage counter
     * and starts a new cycle; the very first check also books any historical
     * net withdrawal in one lump (fine — the last stage repeats).
     *
     * $200 keeps fee noise and rounding out; the smallest real withdrawal in
     * the drain flow is well above it. Skipped while a position is open (fills
     * in flight) or while the trade history is known-stale.
     */
    /** Books a withdrawal/deposit the trades can't explain. True once it has
     *  actually checked the books against the balance (false when it had to
     *  skip: a position open, no history or balance yet, no account type). */
    private reconcileFunds(account: PlatformAccount): boolean {
        if (this.positions[account.id]) return false;
        if (this.lastFetchErrors[account.name]) return false;
        const history = this.fullDailyPnL[account.id];
        if (!history) return false; // first daily-P&L fetch hasn't landed yet

        const cash = this.accountCashBalances[account.id];
        if (!cash) return false;
        // The account's starting balance ($0 for Express, the funded size
        // otherwise) is part of the balance the books must explain — without
        // it a funded account books a phantom deposit for its whole size. Until
        // the account type is resolved that number is unknown, so hold off
        // rather than guess $0 and misfire on a funded account.
        const acctType = getAccountConfig(account.id).accountType;
        if (!acctType) return false;
        const startBal = acctType.accountSize;
        const today = currentTradeDateCT();
        const tradePnL = history
            .filter((d) => d.date !== today)
            .reduce((s, d) => s + d.pnl, 0) + cash.realizedPnL;
        const txns = this.fundTransactions[account.id] ?? [];
        const funds = txns.reduce((s, f) => s + f.amount, 0);
        const delta = Math.round((cash.amount - startBal - tradePnL - funds) * 100) / 100;
        // The first check on this instance (or since a wipe) only has the
        // fetch window to explain the balance with: a lump it books is unseen
        // P&L and past payouts, not the end of a cycle this instance watched.
        const firstCheck = loadAccountMeta(account.id, 'funds_reconciled') === null;
        if (firstCheck) saveAccountMeta(account.id, 'funds_reconciled', today);
        if (Math.abs(delta) < 200) return true;

        console.log(`[topstepx] ${account.name}: balance ${cash.amount} vs books ${Math.round((tradePnL + funds) * 100) / 100} — recording ${delta < 0 ? 'withdrawal' : 'deposit'} of ${delta}`);
        // A new cycle starts today: note where the one it ends began, by
        // applyCycleSlice's rule for that date's own row, for the reporter's
        // catch-up. A second event today doesn't start another cycle.
        const prevFundDate = this.lastFundDates[account.id] ?? null;
        if (!firstCheck && prevFundDate !== today) {
            const prevAmt = prevFundDate ? (txns.find((f) => f.date === prevFundDate)?.amount ?? null) : null;
            saveEndedCycleStart(account.id, { fundDate: prevFundDate ?? '', includesDay: !(prevAmt !== null && prevAmt < 0) });
        }
        // Same-day events merge into one row (the table keys on account+date),
        // so add today's delta onto whatever is already booked for today.
        const existingToday = txns.find((f) => f.date === today)?.amount ?? 0;
        saveFundTransactions(account.id, account.name, [
            { date: today, amount: Math.round((existingToday + delta) * 100) / 100 },
        ]);
        saveAccountMeta(account.id, 'last_fund_date', today);
        this.fundTransactions[account.id] = loadFundTransactions(account.id);
        this.lastFundDates[account.id] = today;
        this.applyCycleSlice(account.id);
        return true;
    }

    /**
     * Reverse-engineer the account's MLL floor — TopstepX never reports it.
     *
     * Topstep's Maximum Loss Limit sits `trailingDrawdown` below the END-OF-DAY
     * balance high, ratchets up only, and locks at the starting balance ($0 for
     * Express accounts) once the high has climbed the full drawdown:
     *
     *     floor = min(0, eodBalanceHigh − trailingDrawdown)
     *
     * The EOD balance curve is rebuilt from daily P&L + recorded fund events.
     * Balance the books don't explain (sub-threshold off-book fees) is spread
     * across days proportionally to each day's reported fees — validated
     * against a platform-reported MLL to within $0.11.
     *
     * Stored in autoLiqThresholds (negative, or +$0.01 once locked at
     * breakeven — 0 must keep meaning "no floor"), which lights up the same
     * dead-account handling Tradovate's reported floors use. canTrade=false
     * accounts are skipped: the platform has already retired them.
     */
    private updateMllFloor(account: PlatformAccount): void {
        // Deliberately computed for canTrade=false accounts too: when Topstep
        // liquidates a breach and disables the account, the floor must SURVIVE
        // so the dashboards show it as blown (☠), not merely inactive. Retired
        // accounts without an assigned type fall out below via dd = 0.
        const acctType = getAccountConfig(account.id).accountType;
        const dd = acctType?.trailingDrawdown ?? 0;
        // The account's real starting balance: $0 for Express, the funded size
        // otherwise. Everything below is in ABSOLUTE balance terms so the floor
        // is directly comparable to cash.amount.
        const startBal = acctType?.accountSize ?? 0;
        const history = this.fullDailyPnL[account.id];
        const cash = this.accountCashBalances[account.id];
        if (!(dd > 0) || !history || !cash) { this.autoLiqThresholds[account.id] = 0; return; }

        // Only move the floor on SETTLED books: never mid-trade (the fill
        // hasn't landed — the dead check must not fire off half-processed
        // state), and never while the balance disagrees with the books by
        // more than fee noise (a fill or fund event is still being absorbed;
        // reconcileFunds or the next sync settles it). The previous floor
        // stands until then, so `balance ≤ floor` can only come true off a
        // landed, booked fill.
        if (this.positions[account.id]) return;

        const today = currentTradeDateCT();
        const fees = this.dailyFees[account.id] ?? new Map<string, number>();

        // One event per past date: booked P&L plus any fund transaction.
        const events = new Map<string, number>();
        const add = (date: string, amount: number) => events.set(date, (events.get(date) ?? 0) + amount);
        for (const d of history) if (d.date !== today) add(d.date, d.pnl);
        for (const f of this.fundTransactions[account.id] ?? []) if (f.date !== today) add(f.date, f.amount);
        const dates = [...events.keys()].sort();
        if (dates.length === 0) { this.autoLiqThresholds[account.id] = 0; return; }

        // What the books don't explain (bounded by the reconcile threshold) is
        // off-book fee drift — attribute it in proportion to reported fees.
        // Today is handled live: the balance carries today's realized P&L and
        // any fund event detected today, neither of which is in `events`.
        const booked = dates.reduce((s, d) => s + events.get(d)!, 0);
        const todayFund = (this.fundTransactions[account.id] ?? []).find((f) => f.date === today)?.amount ?? 0;
        // Books invariant: cash.amount = startBal + Σ(booked P&L + funds) +
        // today's realized + today's fund. The residual is off-book fee drift.
        const residual = Math.round((cash.amount - startBal - cash.realizedPnL - todayFund - booked) * 100) / 100;
        // Books not settled (an unabsorbed fill or an unbooked fund event) —
        // keep the previous floor rather than skewing the curve with it.
        if (Math.abs(residual) >= 200) return;
        const totalFees = dates.reduce((s, d) => s + (fees.get(d) ?? 0), 0);

        let bal = startBal;
        let high = startBal; // the MLL trails EOD balance, starting a drawdown below startBal
        for (const d of dates) {
            const drift = totalFees > 0 ? residual * ((fees.get(d) ?? 0) / totalFees) : (d === dates[0] ? residual : 0);
            bal += events.get(d)! + drift;
            if (bal > high) high = bal;
        }

        // Absolute floor: a drawdown below the EOD high, locked at the starting
        // balance once the high has climbed the full drawdown above it.
        let floor = high >= startBal + dd
            ? startBal
            : Math.round((high - dd) * 100) / 100;
        // 0 is the "no floor" sentinel — a real $0 floor (Express, locked at
        // breakeven) takes a cent so it still reads as dead-eligible.
        if (floor === 0) floor = 0.01;
        this.autoLiqThresholds[account.id] = floor;
    }

    private maybeFetchDaysTraded(): void {
        if (this.daysFetchInFlight || this.intentionalDisconnect) return;

        const now = Date.now();
        const initialFetchDue = this.lastDaysFetchStartedAt === 0;
        const retryPending = this.nextDaysFetchRetryAt > 0;
        const retryDue = retryPending && now >= this.nextDaysFetchRetryAt;
        const hourlyRefreshDue =
            !retryPending &&
            this.lastDaysFetchSucceededAt > 0 &&
            now - this.lastDaysFetchSucceededAt >= 60 * 60 * 1_000;
        // Accounts held out of trading for want of history (new since the
        // last pass, or wiped) get their own fetch now rather than wait out
        // the hour. A failure falls back to the 5-minute retry.
        const waiting = !initialFetchDue && !retryPending
            ? this.accountList
                .filter((a) => !this.historyLoadedIds.has(a.id)
                    && !this.reconcilePendingIds.has(a.id)
                    && !this.fetchingIds.has(a.id))
                .map((a) => a.id)
            : [];
        const targeted = !retryDue && !hourlyRefreshDue && !initialFetchDue && waiting.length > 0;

        if (!initialFetchDue && !retryDue && !hourlyRefreshDue && !targeted) return;

        this.daysFetchInFlight = true;
        this.daysFetchInFlightSince = now;
        this.lastDaysFetchStartedAt = now;
        if (retryDue) this.nextDaysFetchRetryAt = 0;

        this.fetchDaysTraded(targeted ? waiting : undefined)
            .then(({ failedAccounts }) => {
                if (!this.historyLoaded && !this.intentionalDisconnect) {
                    // Readiness waited on this; sync again now rather than
                    // leaving the firm unready until the next 60s tick.
                    this.historyLoaded = true;
                    void this.requestSync();
                }
                if (failedAccounts > 0) {
                    this.nextDaysFetchRetryAt = Date.now() + 5 * 60 * 1_000;
                    console.warn(`[topstepx] ${failedAccounts} account(s) failed daily P&L fetch — retrying in 5 minutes`);
                    return;
                }
                // A partial pass doesn't restart the hourly clock.
                if (!targeted) this.lastDaysFetchSucceededAt = Date.now();
            })
            .catch((err) => {
                this.nextDaysFetchRetryAt = Date.now() + 5 * 60 * 1_000;
                console.error(`[topstepx] daily P&L fetch failed — retrying in 5 minutes: ${errorMessage(err)}`);
            })
            .finally(() => {
                this.daysFetchInFlight = false;
                this.daysFetchInFlightSince = 0;
            });
    }

    /** Daily P&L from the trades endpoint: net of fees per CT trade date, like
     *  Tradovate's Cash History. Merged over the DB cache so history older than
     *  the fetch window survives. */
    public async fetchDaysTraded(onlyAccountIds?: number[]): Promise<{ failedAccounts: number }> {
        const ids = this.accountList
            .filter((a) => !onlyAccountIds || onlyAccountIds.includes(a.id))
            .map((a) => a.id);
        for (const id of ids) this.fetchingIds.add(id);
        try {
            return await this.fetchDaysTradedPass(onlyAccountIds);
        } finally {
            for (const id of ids) this.fetchingIds.delete(id);
        }
    }

    private async fetchDaysTradedPass(onlyAccountIds?: number[]): Promise<{ failedAccounts: number }> {
        if (!this.token) return { failedAccounts: 0 };
        this.fetchDaysComplete = false;
        let failedAccounts = 0;

        const start = new Date(Date.now() - 27 * 24 * 60 * 60 * 1000).toISOString();
        const end = new Date(Date.now() + 60 * 60 * 1000).toISOString();

        const mergePnL = (
            cached: { date: string; pnl: number }[],
            fresh: { date: string; pnl: number }[]
        ): { date: string; pnl: number }[] => {
            const map = new Map<string, number>();
            for (const e of cached) map.set(e.date, e.pnl);
            for (const e of fresh) map.set(e.date, e.pnl);
            return Array.from(map.entries())
                .map(([date, pnl]) => ({ date, pnl }))
                .sort((a, b) => a.date.localeCompare(b.date));
        };

        for (const account of this.accountList) {
            if (this.intentionalDisconnect) break; // a discarded client fetches (and writes) nothing more
            if (onlyAccountIds && !onlyAccountIds.includes(account.id)) continue;

            // Fund transactions never come from the TopstepX API — only what the
            // DB already holds (imports, manual rows). Usually empty.
            const storedFundDate = loadAccountMeta(account.id, 'last_fund_date');
            this.lastFundDates[account.id] = storedFundDate;
            this.fundTransactions[account.id] = loadFundTransactions(account.id);

            const cached = loadDailyPnL(account.id);

            try {
                const res = await this.post<{ trades: TsxTrade[] }>(
                    '/api/Trade/search', { accountId: account.id, startTimestamp: start, endTimestamp: end });
                const trades = (res.trades ?? []).filter((t) => !t.voided);
                this.lastFetchRaw[account.name] = trades.length > 0 ? JSON.stringify(trades[0]) : '(no trades)';

                const dailyMap: { [date: string]: { pnl: number; fees: number } } = {};
                for (const t of trades) {
                    const date = currentTradeDateCT(new Date(t.creationTimestamp));
                    const entry = (dailyMap[date] ??= { pnl: 0, fees: 0 });
                    entry.pnl += (t.profitAndLoss ?? 0) - (t.fees ?? 0);
                    entry.fees += t.fees ?? 0;
                }

                const fresh = Object.entries(dailyMap)
                    .map(([date, e]) => ({
                        date,
                        pnl: Math.round(e.pnl * 100) / 100,
                        fees: Math.round(e.fees * 10000) / 10000,
                    }))
                    .sort((a, b) => a.date.localeCompare(b.date));

                const merged = mergePnL(cached, fresh);

                // Reported fees per day — the weights the MLL reconstruction
                // uses to place off-book fee drift. Fresh overwrites cached.
                const fees = new Map<string, number>();
                for (const e of cached) fees.set(e.date, e.fees ?? 0);
                for (const e of fresh) fees.set(e.date, e.fees);
                this.dailyFees[account.id] = fees;

                // The last fund transaction (usually one this client detected
                // itself — see reconcileFunds) splits cycles: withdrawals
                // exclude their day, deposits include it.
                this.fullDailyPnL[account.id] = merged;
                this.applyCycleSlice(account.id);
                saveDailyPnL(account.id, account.name, fresh);
                delete this.lastFetchErrors[account.name];
                // One not loaded before (new, wiped, failed) is tradable after
                // the next sync reconciles its funds (requestSync); a refresh
                // of a loaded one keeps the funds it already has.
                if (!this.historyLoadedIds.has(account.id)) this.reconcilePendingIds.add(account.id);
                this.updateMllFloor(account);
            } catch (err) {
                const msg = errorMessage(err);
                console.error(`[topstepx] trade history failed for ${account.name}: ${msg}`);
                failedAccounts++;
                if (cached.length > 0) {
                    this.fullDailyPnL[account.id] = cached;
                    this.dailyFees[account.id] = new Map(cached.map((e) => [e.date, e.fees ?? 0]));
                    this.applyCycleSlice(account.id);
                    this.lastFetchErrors[account.name] = `${msg} (using ${cached.length} cached entries from database)`;
                    // Not loaded before: no funds check has run on this cache,
                    // and none will while the fetch error stands — so it waits
                    // for a fetch that lands (reconcileFunds, requestSync).
                    if (!this.historyLoadedIds.has(account.id)) this.reconcilePendingIds.add(account.id);
                } else {
                    // No history at all is not an empty one: the account
                    // stays out of trading until a fetch lands, instead of
                    // trading as a fresh stage-1 cycle.
                    this.daysTraded[account.id] ??= 0;
                    this.lastFetchErrors[account.name] = msg;
                }
            }
        }
        this.fetchDaysComplete = true;
        // The accounts just fetched wait on a reconciling sync: run one now
        // rather than leave them out for up to a minute, and before returning,
        // so a wipe route reads the result. (The firm's first pass syncs from
        // maybeFetchDaysTraded once readiness allows.)
        const waiting = () => this.accountList.some((a) => this.reconcilePendingIds.has(a.id)
            && (!onlyAccountIds || onlyAccountIds.includes(a.id)));
        if (waiting() && this.historyLoaded && !this.intentionalDisconnect) {
            await this.requestSync(); // a pass already running may have gone past them
            if (waiting()) await this.requestSync();
        }
        return { failedAccounts };
    }

    /** Whether this account's history can be planned on — see PlatformClient.
     *  (Fund transactions come from reconcileFunds within a sync, so no
     *  balance-drift hold is needed here.) */
    public historyReady(accountId: number): boolean {
        return this.historyLoadedIds.has(accountId)
            && this.dailyPnL[accountId] !== undefined
            && this.fundTransactions[accountId] !== undefined;
    }

    /** Drop the account's history from memory (a wipe): it reads unloaded, and
     *  stays out of trading, until the next fetch rebuilds it. */
    public forgetHistory(accountId: number, accountName: string): void {
        this.historyLoadedIds.delete(accountId);
        this.reconcilePendingIds.delete(accountId);
        delete this.dailyPnL[accountId];
        delete this.fullDailyPnL[accountId];
        delete this.daysTraded[accountId];
        delete this.priorProfit[accountId];
        delete this.lastFundDates[accountId];
        delete this.fundTransactions[accountId];
        delete this.dailyFees[accountId];
        delete this.lastFetchErrors[accountName];
        delete this.lastFetchRaw[accountName];
    }

    // ── contracts ────────────────────────────────────────────────────────────

    public async findFrontMonthContract(productName: string): Promise<PlatformContract | null> {
        if (!this.token) return null;

        const cached = this.contractByProduct.get(productName);
        if (cached && Date.now() - cached.resolvedAt < TopstepXClient.CONTRACT_TTL_MS) {
            const c = cached.contract;
            return { id: c.id, name: c.name, tickSize: c.tickSize };
        }

        try {
            const res = await this.post<{ contracts: TsxContract[] }>(
                '/api/Contract/search', { searchText: productName, live: false });
            const candidates = (res.contracts ?? []).filter((c) =>
                c.name.startsWith(productName) && /^[A-Z]\d/.test(c.name.slice(productName.length)));
            if (candidates.length === 0) {
                console.log(`[topstepx] no contract found for ${productName}`);
                return null;
            }

            // Prefer the volume-resolved front month (shared with the Tradovate
            // path — names match across platforms, e.g. "NQZ5"), then TopstepX's
            // own activeContract flag.
            const resolvedName = getCachedContract(productName)?.name;
            const match =
                (resolvedName ? candidates.find((c) => c.name === resolvedName) : undefined)
                ?? candidates.find((c) => c.activeContract)
                ?? candidates[0];

            this.contractByProduct.set(productName, { contract: match, resolvedAt: Date.now() });
            this.contractByName.set(match.name, match);
            return { id: match.id, name: match.name, tickSize: match.tickSize };
        } catch (err) {
            console.error(`[topstepx] contract search failed for ${productName}: ${errorMessage(err)}`);
            return null;
        }
    }

    /** Resolve a contract NAME (e.g. "NQZ5") to its TopstepX contract id. */
    private async resolveContractId(contractSymbol: string): Promise<TsxContract> {
        const known = this.contractByName.get(contractSymbol);
        if (known) return known;

        const res = await this.post<{ contracts: TsxContract[] }>(
            '/api/Contract/search', { searchText: contractSymbol, live: false });
        const match = (res.contracts ?? []).find((c) => c.name === contractSymbol)
            ?? (res.contracts ?? []).find((c) => contractSymbol.startsWith(c.name));
        if (!match) throw new Error(`TopstepX contract not found for symbol ${contractSymbol}`);
        this.contractByName.set(match.name, match);
        return match;
    }

    public async fetchInstrumentFees(): Promise<{ [symbol: string]: number }> {
        // No fee-parameter endpoint on the gateway; per-trade fees arrive with
        // each fill instead, which is what the commission delta reads.
        return {};
    }

    public async getAccountList(): Promise<PlatformAccount[]> {
        return this.accountList;
    }

    // ── orders ───────────────────────────────────────────────────────────────

    /**
     * Everything an order needs before anything is sent: a session and the
     * contract. Failing here means nothing reached the broker, which is the
     * one case the scheduler may un-count a leg for — hence OrderNotPlacedError.
     */
    private async contractForOrder(contractSymbol: string): Promise<TsxContract> {
        if (!this.token) throw new OrderNotPlacedError('TopstepX not logged in — order not sent');
        try {
            return await this.resolveContractId(contractSymbol);
        } catch (err) {
            throw new OrderNotPlacedError(`TopstepX contract lookup failed for ${contractSymbol} — order not sent: ${errorMessage(err)}`);
        }
    }

    /**
     * POST /api/Order/place. Only a failure that proves nothing was placed
     * becomes OrderNotPlacedError: no session, a gateway `success: false`
     * that names no order and no ambiguous code, or an HTTP refusal given
     * before any handler ran. Everything else (timeouts, resets, 5xx) may
     * have placed the order and stays a plain Error — rewrapped so the
     * AxiosError, whose config carries the Bearer token, never travels on
     * into someone's log.
     */
    private async placeOrder(
        accountId: number,
        contractId: string,
        size: number,
        action: 'Buy' | 'Sell',
        type: number,
        limitPrice?: number,
        stopPrice?: number,
    ): Promise<number> {
        if (!this.token) throw new OrderNotPlacedError('TopstepX not logged in — order not sent');
        try {
            const res = await this.post<{ orderId: number }>('/api/Order/place', {
                accountId,
                contractId,
                type,
                side: action === 'Buy' ? SIDE_BUY : SIDE_SELL,
                size,
                limitPrice: limitPrice ?? null,
                stopPrice: stopPrice ?? null,
                trailPrice: null,
                customTag: null,
            });
            return res.orderId;
        } catch (err) {
            if (err instanceof GatewayRefusedError) {
                const ambiguous = err.orderId !== undefined
                    || (err.errorCode !== undefined && AMBIGUOUS_PLACE_ERRORS.has(err.errorCode));
                if (!ambiguous) throw new OrderNotPlacedError(`TopstepX refused the order: ${err.message}`);
                throw new Error(`TopstepX order outcome unknown: ${err.message}`);
            }
            const response = (err as { response?: { status?: unknown; data?: { orderId?: unknown } } } | null)?.response;
            const status = response?.status;
            // Same rule as a refusal: an answer that names an order means it exists.
            const namesOrder = typeof response?.data?.orderId === 'number' && response.data.orderId > 0;
            if (typeof status === 'number' && REFUSED_BEFORE_HANDLER.has(status) && !namesOrder) {
                throw new OrderNotPlacedError(`TopstepX rejected the order request: ${errorMessage(err)}`);
            }
            throw new Error(`TopstepX order request failed (it may still have been placed): ${errorMessage(err)}`);
        }
    }

    /** Place an order and wait for its fill (trade event, with a REST poll as
     *  backstop). Resolves with an object exposing the fill `price`. */
    public async sendOrder(
        accountId: number,
        contractSymbol: string,
        quantity: number,
        action: 'Buy' | 'Sell',
        orderType: 'Market' | 'Limit',
        price?: number
    ): Promise<Record<string, unknown>> {
        const contract = await this.contractForOrder(contractSymbol);
        const orderId = await this.placeOrder(
            accountId, contract.id, quantity, action,
            orderType === 'Market' ? TYPE_MARKET : TYPE_LIMIT,
            orderType === 'Limit' ? price : undefined,
        );
        console.log(`[topstepx] order ${orderId}: ${action} ${quantity}x${contractSymbol} ${orderType}${price ? ` @ ${price}` : ''}`);

        // A market fill can reach the hub before /api/Order/place answers,
        // when no waiter existed yet to hear it. The handler still recorded
        // it, so look there first. No await between here and the waiter
        // registered below, so nothing can slip in between.
        const early = this.bufferedFillPrice(accountId, orderId);
        if (early !== null) {
            console.log(`[topstepx] order ${orderId} filled @ ${early} (before the place response)`);
            return { orderId, price: early, accountId, contractId: contract.id };
        }
        // Wide on purpose: the window is the local clock's, and a PC clock a
        // few minutes off would otherwise search past the fill.
        const since = new Date(Date.now() - 15 * 60_000).toISOString();

        return new Promise((resolve, reject) => {
            let settled = false;
            const timeout = setTimeout(() => {
                if (settled) return;
                const late = this.bufferedFillPrice(accountId, orderId);
                if (late !== null) {
                    this.fillWaiters = this.fillWaiters.filter((w) => w.orderId !== orderId);
                    settle(late);
                    return;
                }
                settled = true;
                clearInterval(poll);
                this.fillWaiters = this.fillWaiters.filter((w) => w.orderId !== orderId);
                // The caller gives up on this order and places no exits, so a
                // late fill would leave a position nothing manages — and one
                // open position blocks every firm through the open-position
                // gate. Cancel it, best effort. The rejection stays a plain
                // Error: it may have filled after all.
                console.warn(`[topstepx] order ${orderId} not filled within 30s — cancelling it`);
                void this.cancelOrder(accountId, orderId).catch((err) =>
                    console.error(`[topstepx] failed to cancel unfilled order ${orderId}: ${errorMessage(err)}`));
                reject(new Error(`Order ${orderId} placed but no fill within 30s (market may be closed) — cancel requested`));
            }, 30_000);

            const settle = (fillPrice: number) => {
                if (settled) return;
                settled = true;
                clearTimeout(timeout);
                clearInterval(poll);
                console.log(`[topstepx] order ${orderId} filled @ ${fillPrice}`);
                resolve({ orderId, price: fillPrice, accountId, contractId: contract.id });
            };

            this.fillWaiters.push({ orderId, callback: (trade) => settle(trade.price) });

            // REST backstop for when the hub is down or the event is missed:
            // the order's trades (the same Trade/search fetchDaysTraded
            // reads), and every fifth poll whether the order died unfilled.
            // Both are documented Gateway endpoints; Order has no searchById.
            let polls = 0;
            const poll = setInterval(() => {
                polls++;
                void this.searchOrderFillPrice(accountId, orderId, since)
                    .then((fillPrice) => {
                        if (fillPrice === null) return;
                        this.fillWaiters = this.fillWaiters.filter((w) => w.orderId !== orderId);
                        settle(fillPrice);
                    })
                    .catch(() => { /* transient — the next poll tries again */ });
                if (polls % 5 !== 0) return;
                void this.post<{ orders?: { id: number; status: number }[] }>(
                    '/api/Order/search', { accountId, startTimestamp: since })
                    .then(async (res) => {
                        const order = res.orders?.find((o) => o.id === orderId);
                        if (!order || !ORDER_GONE.has(order.status) || settled) return;
                        // Cancelled after a partial fill still left a position.
                        const fillPrice = this.bufferedFillPrice(accountId, orderId)
                            ?? await this.searchOrderFillPrice(accountId, orderId, since);
                        this.fillWaiters = this.fillWaiters.filter((w) => w.orderId !== orderId);
                        if (fillPrice !== null) {
                            settle(fillPrice);
                            return;
                        }
                        if (settled) return;
                        settled = true;
                        clearTimeout(timeout);
                        clearInterval(poll);
                        reject(new Error(`Order ${orderId} ended without fill (status=${order.status})`));
                    })
                    .catch(() => { /* transient — the next poll tries again */ });
            }, 2_000);
        });
    }

    /** The price of an order's first fill already heard over the hub — the
     *  price the fill waiter would have resolved with — or null. */
    private bufferedFillPrice(accountId: number, orderId: number): number | null {
        const fills: TsxTrade[] = [...(this.todayTrades[accountId]?.values() ?? [])];
        for (const event of this.recentEntityEvents) {
            if (event.entityType === 'trade') fills.push(event.entity as TsxTrade);
        }
        return firstFillPrice(fills.filter((t) => t?.accountId === accountId && t.orderId === orderId));
    }

    /** The same, from the Gateway's trade history (REST). */
    private async searchOrderFillPrice(accountId: number, orderId: number, since: string): Promise<number | null> {
        const res = await this.post<{ trades?: TsxTrade[] }>('/api/Trade/search', {
            accountId, startTimestamp: since, endTimestamp: new Date(Date.now() + 15 * 60_000).toISOString(),
        });
        return firstFillPrice((res.trades ?? []).filter((t) => t.orderId === orderId));
    }

    /** Place an order and resolve on placement (does not wait for fill). */
    public async placeOrderNoWait(
        accountId: number,
        contractSymbol: string,
        quantity: number,
        action: 'Buy' | 'Sell',
        orderType: 'Market' | 'Limit',
        price?: number
    ): Promise<{ orderId?: number }> {
        const contract = await this.contractForOrder(contractSymbol);
        const orderId = await this.placeOrder(
            accountId, contract.id, quantity, action,
            orderType === 'Market' ? TYPE_MARKET : TYPE_LIMIT,
            orderType === 'Limit' ? price : undefined,
        );
        return { orderId };
    }

    /**
     * Emulated OCO exit: the gateway has no linked-order type, so place the
     * take-profit limit and the stop separately and cancel the survivor when
     * either fills (order events; a poll and the flat-position hook back it
     * up).
     *
     * If the stop doesn't go in, what the caller may do next depends on what
     * is left at the broker — it falls back to a lone limit only on
     * OrderNotPlacedError, and places nothing more on a plain Error:
     * - stop refused, limit cancel confirmed → nothing of the pair is working:
     *   OrderNotPlacedError, and the fallback starts from a clean book;
     * - stop refused, limit cancel failed → the limit may still be working:
     *   plain Error (a fallback on top could double the exit);
     * - stop outcome unknown → it may be working, so the limit is kept (the
     *   position keeps its take-profit, unpaired, as the fallback would have
     *   left it) and the error is plain.
     */
    public async placeOcoExit(
        accountId: number,
        contractSymbol: string,
        quantity: number,
        exitAction: 'Buy' | 'Sell',
        limitPrice: number,
        stopPrice: number,
    ): Promise<{ orderId?: number }> {
        const contract = await this.contractForOrder(contractSymbol);
        const limitId = await this.placeOrder(accountId, contract.id, quantity, exitAction, TYPE_LIMIT, limitPrice);
        let stopId: number;
        try {
            stopId = await this.placeOrder(accountId, contract.id, quantity, exitAction, TYPE_STOP, undefined, stopPrice);
        } catch (err) {
            if (!isOrderNotPlaced(err)) {
                throw new Error(`OCO stop leg outcome unknown — limit ${limitId} left working, unpaired: ${errorMessage(err)}`);
            }
            const limitCancelled = await this.cancelOrder(accountId, limitId).then(() => true, () => false);
            if (limitCancelled) {
                throw new OrderNotPlacedError(`OCO stop leg refused, limit ${limitId} cancelled — no exit working: ${errorMessage(err)}`);
            }
            throw new Error(`OCO stop leg refused and limit ${limitId} could not be cancelled — it may still be working: ${errorMessage(err)}`);
        }

        this.ocoPairs.push({ accountId, limitId, stopId, done: false, placedAt: Date.now() });
        this.ensureOcoPoll();
        console.log(`[topstepx] OCO exit pair placed — limit ${limitId} @ ${limitPrice}, stop ${stopId} @ ${stopPrice}`);
        return { orderId: limitId };
    }

    private async cancelOrder(accountId: number, orderId: number): Promise<void> {
        await this.post('/api/Order/cancel', { accountId, orderId });
    }

    private handleOcoOrderEvent(orderId: number, status: number): void {
        const pair = this.ocoPairs.find((p) => !p.done && (p.limitId === orderId || p.stopId === orderId));
        if (!pair) return;
        if (status === ORDER_FILLED) {
            pair.done = true;
            const sibling = pair.limitId === orderId ? pair.stopId : pair.limitId;
            console.log(`[topstepx] OCO leg ${orderId} filled — cancelling sibling ${sibling}`);
            void this.cancelOrder(pair.accountId, sibling).catch((err) =>
                console.error(`[topstepx] failed to cancel OCO sibling ${sibling}: ${errorMessage(err)}`));
        }
    }

    private async cancelOcoLegsForAccount(accountId: number): Promise<void> {
        const pairs = this.ocoPairs.filter((p) => !p.done && p.accountId === accountId);
        for (const pair of pairs) {
            pair.done = true;
            for (const orderId of [pair.limitId, pair.stopId]) {
                await this.cancelOrder(accountId, orderId).catch(() => { /* already gone */ });
            }
        }
    }

    /** Safety net under the event-driven OCO: while pairs are live, poll open
     *  orders and reap legs whose sibling is gone or whose position is flat. */
    private ensureOcoPoll(): void {
        if (this.ocoPollInterval) return;
        this.ocoPollInterval = setInterval(() => {
            void (async () => {
                const live = this.ocoPairs.filter((p) => !p.done);
                if (live.length === 0) {
                    if (this.ocoPollInterval) { clearInterval(this.ocoPollInterval); this.ocoPollInterval = null; }
                    this.ocoPairs = [];
                    return;
                }
                for (const pair of live) {
                    try {
                        const res = await this.post<{ orders: { id: number }[] }>(
                            '/api/Order/searchOpen', { accountId: pair.accountId });
                        const openIds = new Set((res.orders ?? []).map((o) => o.id));
                        const limitOpen = openIds.has(pair.limitId);
                        const stopOpen = openIds.has(pair.stopId);
                        if (!limitOpen && !stopOpen) {
                            pair.done = true;
                        } else if (limitOpen !== stopOpen && !this.positions[pair.accountId]) {
                            // One leg gone, position flat — the survivor is stale.
                            pair.done = true;
                            const survivor = limitOpen ? pair.limitId : pair.stopId;
                            console.log(`[topstepx] reaping stale OCO leg ${survivor} (position flat)`);
                            await this.cancelOrder(pair.accountId, survivor).catch(() => { /* already gone */ });
                        }
                    } catch { /* transient — retry next poll */ }
                }
            })();
        }, 15_000);
    }

    public onFill(orderId: number, callback: (fill: Record<string, unknown>) => void): void {
        this.fillWaiters.push({ orderId, callback: (trade) => callback(trade as unknown as Record<string, unknown>) });
    }

    // ── lifecycle ────────────────────────────────────────────────────────────

    public health(): ClientHealth {
        return {
            platform: 'topstepx',
            authenticated: !!this.token,
            transport: this.hub ? String(this.hub.state) : 'none',
            syncComplete: this.syncComplete,
            lastSyncAt: this.lastSyncAt,
            lastLoginAt: this.lastLoginAt,
            lastLoginError: this.lastLoginError,
            consecutiveLoginFailures: this.consecutiveLoginFailures,
            nextReconnectAt: this.nextReconnectAt,
            // Validate hands out fresh 24h tokens; this is the latest one's expiry.
            tokenExpiresAt: this.token && this.tokenRefreshedAt ? this.tokenRefreshedAt + TOKEN_LIFETIME_MS : 0,
            lastInboundAt: this.lastInboundAt,
            pendingRequests: this.fillWaiters.length,
            syncInFlightSince: this.syncInFlight ? this.syncInFlightSince : 0,
            daysFetchInFlightSince: this.daysFetchInFlight ? this.daysFetchInFlightSince : 0,
        };
    }

    /** Final: nothing this client scheduled fires afterwards, and every
     *  in-flight login / sync / hub setup checks intentionalDisconnect (or
     *  that its hub is still current) before touching state again. */
    public disconnect(): void {
        this.intentionalDisconnect = true;
        if (this.syncInterval) { clearInterval(this.syncInterval); this.syncInterval = null; }
        if (this.tokenRenewalInterval) { clearInterval(this.tokenRenewalInterval); this.tokenRenewalInterval = null; }
        if (this.ocoPollInterval) { clearInterval(this.ocoPollInterval); this.ocoPollInterval = null; }
        if (this.loginRetryTimer) { clearTimeout(this.loginRetryTimer); this.loginRetryTimer = null; }
        if (this.watchdogInterval) { clearInterval(this.watchdogInterval); this.watchdogInterval = null; }
        this.nextReconnectAt = 0;
        this.daysFetchInFlight = false;
        this.daysFetchInFlightSince = 0;
        this.nextDaysFetchRetryAt = 0;
        this.discardHub();
    }
}