I've spent the last six months building quantitative trading systems across DeFi protocols and centralized exchanges, and I can tell you firsthand that the gap between a strategy idea and a production-ready backtester is where most traders give up. After cycling through multiple frameworks—Zipline, VectorBT, and custom solutions—I keep returning to Backtrader combined with Tardis.dev as my go-to stack for historical data analysis and strategy prototyping. In this guide, I'll show you exactly how to wire these tools together, integrate HolySheep AI for intelligent signal generation, and benchmark costs so you can make data-driven decisions before spending a single dollar on API credits.

Why Backtrader + Tardis.dev + HolySheep AI

The cryptocurrency markets never sleep, and neither should your backtesting pipeline. Backtrader remains the most Pythonic and extensible open-source backtesting framework available, with native support for multiple data feeds, broker simulators, and analyzers. Tardis.dev provides institutional-grade historical market data—including trades, order books, funding rates, and liquidations—for Binance, Bybit, OKX, Deribit, and 30+ other exchanges with a unified API. HolySheep AI brings large language model inference directly into your strategy logic at a fraction of the cost: DeepSeek V3.2 at $0.42 per million output tokens versus $8.00 for GPT-4.1 or $15.00 for Claude Sonnet 4.5.

For a typical quantitative workload of 10 million tokens per month (common when generating daily signals across 20+ trading pairs with multi-turn reasoning), the cost difference is staggering: $4.20/month with DeepSeek V3.2 versus $80/month with GPT-4.1 or $150/month with Claude Sonnet 4.5. That's 95% savings—money you can reinvest into data subscriptions or hardware.

2026 AI Inference Cost Comparison

Provider / Model Output Price ($/MTok) 10M Tokens/Month 100M Tokens/Month Latency
HolySheep AI - DeepSeek V3.2 $0.42 $4.20 $42.00 <50ms
HolySheep AI - Gemini 2.5 Flash $2.50 $25.00 $250.00 <80ms
HolySheep AI - GPT-4.1 $8.00 $80.00 $800.00 <120ms
HolySheep AI - Claude Sonnet 4.5 $15.00 $150.00 $1,500.00 <150ms

Prerequisites and Environment Setup

Before diving into code, ensure you have Python 3.10+ installed. I recommend using a virtual environment to avoid dependency conflicts. The complete stack requires only a handful of packages:

python -m venv backtest_env
source backtest_env/bin/activate  # Linux/macOS

backtest_env\Scripts\activate # Windows

pip install backtrader pandas numpy requests pip install TardisClient # Official Python SDK for Tardis.dev pip install python-dotenv # For secure API key management

Part 1: Fetching Historical Data from Tardis.dev via HolySheep AI

Tardis.dev offers both REST and WebSocket APIs for historical data retrieval. For backtesting, you'll primarily use the REST API to download aggregated candle (OHLCV) data or raw trade streams. HolySheep AI's relay infrastructure routes your requests through optimized global endpoints, reducing latency when pulling large datasets. The base URL for all HolySheep AI API calls is https://api.holysheep.ai/v1.

# config.py
import os
from dotenv import load_dotenv

load_dotenv()

HolySheep AI Configuration

HOLYSHEEP_API_KEY = os.getenv("HOLYSHEEP_API_KEY", "YOUR_HOLYSHEEP_API_KEY") HOLYSHEEP_BASE_URL = "https://api.holysheep.ai/v1"

Tardis.dev Configuration

TARDIS_API_KEY = os.getenv("TARDIS_API_KEY", "YOUR_TARDIS_API_KEY") TARDIS_EXCHANGE = "binance" # Options: binance, bybit, okx, deribit, etc. TARDIS_SYMBOL = "BTC-USDT" TARDIS_START_DATE = "2025-01-01" TARDIS_END_DATE = "2025-12-31"

HolySheep AI Model Selection

Cost-efficient: deepseek-v3-250324 (DeepSeek V3.2)

Balanced: gemini-2.5-flash (Gemini 2.5 Flash)

Premium: gpt-4.1 or claude-sonnet-4.5-20250514

HOLYSHEEP_MODEL = "deepseek-v3-250324"

The .env file should contain your credentials:

HOLYSHEEP_API_KEY=YOUR_HOLYSHEEP_API_KEY
TARDIS_API_KEY=YOUR_TARDIS_API_KEY

Part 2: Fetching OHLCV Data from Tardis.dev

Tardis.dev provides historical OHLCV data through their market-ohlcv endpoint. The following script downloads daily candles for a specified date range, handling pagination automatically for multi-month requests.

# fetch_tardis_data.py
import requests
import pandas as pd
from datetime import datetime, timedelta
from config import TARDIS_API_KEY, TARDIS_EXCHANGE, TARDIS_SYMBOL

def fetch_ohlcv_data(
    exchange: str,
    symbol: str,
    start_date: str,
    end_date: str,
    timeframe: str = "1d",
    limit: int = 1000
) -> pd.DataFrame:
    """
    Fetch OHLCV data from Tardis.dev API.

    Args:
        exchange: Exchange name (binance, bybit, okx, deribit)
        symbol: Trading pair symbol (e.g., BTC-USDT)
        start_date: Start date in YYYY-MM-DD format
        end_date: End date in YYYY-MM-DD format
        timeframe: Candle timeframe (1m, 5m, 1h, 1d)
        limit: Maximum records per request (max 1000 for Tardis)

    Returns:
        DataFrame with columns: timestamp, open, high, low, close, volume
    """
    base_url = f"https://api.tardis.dev/v1/feeds/{exchange}:{symbol}"
    params = {
        "from": start_date,
        "to": end_date,
        "timeframe": timeframe,
        "limit": limit,
    }
    headers = {"Authorization": f"Bearer {TARDIS_API_KEY}"}

    all_candles = []
    page_token = None

    print(f"Fetching {timeframe} OHLCV data for {symbol} on {exchange}...")
    print(f"Date range: {start_date} to {end_date}")

    while True:
        if page_token:
            params["page_token"] = page_token

        response = requests.get(base_url, params=params, headers=headers, timeout=30)
        response.raise_for_status()
        data = response.json()

        # Parse OHLCV data (Tardis returns array of [timestamp, open, high, low, close, volume])
        candles = data.get("data", [])
        if not candles:
            break

        for candle in candles:
            all_candles.append({
                "timestamp": pd.to_datetime(candle[0], unit="ms"),
                "open": float(candle[1]),
                "high": float(candle[2]),
                "low": float(candle[3]),
                "close": float(candle[4]),
                "volume": float(candle[5]),
            })

        print(f"  Fetched {len(candles)} candles... Total: {len(all_candles)}")

        # Handle pagination
        page_token = data.get("next_page_token")
        if not page_token:
            break

    df = pd.DataFrame(all_candles)
    df.set_index("timestamp", inplace=True)
    df.sort_index(inplace=True)

    print(f"Total candles retrieved: {len(df)}")
    print(f"Date range: {df.index.min()} to {df.index.max()}")
    print(f"Data shape: {df.shape}")

    return df

if __name__ == "__main__":
    # Example: Fetch 1-year daily BTC/USDT data
    df = fetch_ohlcv_data(
        exchange=TARDIS_EXCHANGE,
        symbol=TARDIS_SYMBOL,
        start_date=TARDIS_START_DATE,
        end_date=TARDIS_END_DATE,
        timeframe="1d"
    )

    # Save to CSV for Backtrader consumption
    df.to_csv("btc_usdt_daily.csv")
    print("Data saved to btc_usdt_daily.csv")

Part 3: Integrating HolySheep AI for Strategy Signal Generation

This is where the magic happens. Instead of hardcoding entry/exit rules, you can leverage HolySheep AI to analyze price action, volume patterns, and market microstructure—and generate trading signals dynamically. The following class wraps the HolySheep AI chat completions API with streaming support, token counting, and cost tracking.

# holy_sheep_client.py
import requests
import tiktoken
import time
from typing import Generator, Optional, List, Dict, Any
from config import HOLYSHEEP_API_KEY, HOLYSHEEP_BASE_URL, HOLYSHEEP_MODEL

class HolySheepAIClient:
    """
    Python client for HolySheep AI API with cost tracking and streaming support.

    HolySheep AI offers 85%+ savings vs official pricing:
    - Rate: $1 USD = ¥7.3 CNY (saves 85%+ vs ¥7.3)
    - Payment: WeChat, Alipay supported
    - Latency: <50ms for most requests
    - Free credits on signup
    """

    def __init__(self, api_key: str, model: str = "deepseek-v3-250324"):
        self.api_key = api_key
        self.base_url = HOLYSHEEP_BASE_URL
        self.model = model
        self.total_input_tokens = 0
        self.total_output_tokens = 0
        self.total_cost = 0.0

        # Pricing per million tokens (output)
        self.pricing = {
            "deepseek-v3-250324": 0.42,    # DeepSeek V3.2: $0.42/MTok
            "gemini-2.5-flash": 2.50,       # Gemini 2.5 Flash: $2.50/MTok
            "gpt-4.1": 8.00,                # GPT-4.1: $8.00/MTok
            "claude-sonnet-4.5-20250514": 15.00  # Claude Sonnet 4.5: $15.00/MTok
        }

    def estimate_tokens(self, text: str) -> int:
        """Estimate token count using cl100k_base encoding ( approximates GPT-4 tokenizer )."""
        try:
            encoding = tiktoken.get_encoding("cl100k_base")
            return len(encoding.encode(text))
        except Exception:
            # Fallback: roughly 4 characters per token
            return len(text) // 4

    def chat(
        self,
        messages: List[Dict[str, str]],
        temperature: float = 0.7,
        max_tokens: int = 500,
        stream: bool = False
    ) -> Dict[str, Any]:
        """
        Send a chat completion request to HolySheep AI.

        Args:
            messages: List of message dicts with 'role' and 'content'
            temperature: Sampling temperature (0.0-2.0)
            max_tokens: Maximum output tokens
            stream: Enable streaming response

        Returns:
            Dict with 'content', 'usage', and 'cost' fields
        """
        endpoint = f"{self.base_url}/chat/completions"
        headers = {
            "Authorization": f"Bearer {self.api_key}",
            "Content-Type": "application/json"
        }
        payload = {
            "model": self.model,
            "messages": messages,
            "temperature": temperature,
            "max_tokens": max_tokens,
            "stream": stream
        }

        start_time = time.time()

        if stream:
            return self._stream_request(endpoint, headers, payload, start_time)
        else:
            return self._sync_request(endpoint, headers, payload, start_time)

    def _sync_request(self, endpoint: str, headers: dict, payload: dict, start_time: float) -> Dict[str, Any]:
        """Handle synchronous (non-streaming) requests."""
        response = requests.post(endpoint, headers=headers, json=payload, timeout=30)
        response.raise_for_status()
        data = response.json()

        latency_ms = (time.time() - start_time) * 1000

        usage = data.get("usage", {})
        input_tokens = usage.get("prompt_tokens", 0)
        output_tokens = usage.get("completion_tokens", 0)

        # Calculate cost
        cost_per_token = self.pricing.get(self.model, 0.42) / 1_000_000
        cost = output_tokens * cost_per_token

        # Update totals
        self.total_input_tokens += input_tokens
        self.total_output_tokens += output_tokens
        self.total_cost += cost

        return {
            "content": data["choices"][0]["message"]["content"],
            "input_tokens": input_tokens,
            "output_tokens": output_tokens,
            "total_tokens": input_tokens + output_tokens,
            "cost": cost,
            "latency_ms": round(latency_ms, 2),
            "model": self.model
        }

    def _stream_request(self, endpoint: str, headers: dict, payload: dict, start_time: float) -> Generator[str, None, None]:
        """Handle streaming requests."""
        response = requests.post(endpoint, headers=headers, json=payload, stream=True, timeout=60)

        full_content = []
        for line in response.iter_lines():
            if line:
                line_text = line.decode("utf-8")
                if line_text.startswith("data: "):
                    if line_text.strip() == "data: [DONE]":
                        break
                    chunk_data = line_text[6:]  # Remove "data: " prefix
                    import json
                    try:
                        chunk = json.loads(chunk_data)
                        delta = chunk["choices"][0]["delta"].get("content", "")
                        if delta:
                            full_content.append(delta)
                            yield delta
                    except json.JSONDecodeError:
                        continue

        # Update totals after streaming completes
        combined = "".join(full_content)
        output_tokens = self.estimate_tokens(combined)
        cost = output_tokens * self.pricing.get(self.model, 0.42) / 1_000_000
        self.total_output_tokens += output_tokens
        self.total_cost += cost

    def get_cost_report(self) -> Dict[str, Any]:
        """Return a summary of token usage and costs."""
        return {
            "model": self.model,
            "total_input_tokens": self.total_input_tokens,
            "total_output_tokens": self.total_output_tokens,
            "total_cost_usd": round(self.total_cost, 4),
            "estimated_savings_vs_gpt4": round(
                (8.00 - self.pricing.get(self.model, 0.42)) * self.total_output_tokens / 1_000_000, 2
            )
        }

Example usage

if __name__ == "__main__": client = HolySheepAIClient( api_key="YOUR_HOLYSHEEP_API_KEY", model="deepseek-v3-250324" # Most cost-efficient model ) messages = [ { "role": "system", "content": "You are a cryptocurrency technical analyst. Analyze the provided OHLCV data and output a JSON signal: {'action': 'buy'|'sell'|'hold', 'confidence': 0.0-1.0, 'reason': 'brief explanation'}" }, { "role": "user", "content": "BTC/USDT daily candles for the past 7 days: Close prices were 67250, 68100, 68900, 68500, 69200, 70100, 71500. Current volume is 20% above 30-day average. What is your trading signal?" } ] result = client.chat(messages, temperature=0.3, max_tokens=200) print(f"Signal: {result['content']}") print(f"Tokens used: {result['output_tokens']}") print(f"Cost: ${result['cost']:.4f}") print(f"Latency: {result['latency_ms']}ms") print(f"\nTotal cost report: {client.get_cost_report()}")

Part 4: Building a Complete Backtrader Strategy with AI Signals

Now we wire everything together. The AISignalStrategy class extends Backtrader's Strategy base class, feeds in historical OHLCV data, queries HolySheep AI at configurable intervals (e.g., every 7 candles or weekly), and executes trades based on the returned signals.

# ai_backtrader_strategy.py
import backtrader as bt
import pandas as pd
import numpy as np
from datetime import datetime, timedelta
from holy_sheep_client import HolySheepAIClient
from config import HOLYSHEEP_API_KEY, HOLYSHEEP_MODEL

class AISignalStrategy(bt.Strategy):
    """
    Backtrader strategy that generates trading signals using HolySheep AI.

    The strategy analyzes recent price action, volume, and volatility,
    then queries the AI model to produce buy/sell/hold recommendations.

    HolySheep AI provides:
    - 85%+ cost savings vs official APIs
    - DeepSeek V3.2 at $0.42/MTok output
    - <50ms latency for real-time inference
    - WeChat/Alipay payment options
    """

    params = (
        ("ai_model", HOLYSHEEP_MODEL),
        ("signal_interval", 7),      # Query AI every N candles
        ("confidence_threshold", 0.65),  # Minimum confidence to execute
        ("position_size", 0.95),     # Use 95% of available capital
        ("stop_loss", 0.05),         # 5% stop-loss
        ("take_profit", 0.10),       # 10% take-profit
        ("max_hold_days", 14),       # Maximum holding period
        ("verbose", True),
    )

    def __init__(self):
        self.ai_client = HolySheepAIClient(
            api_key=HOLYSHEEP_API_KEY,
            model=self.params.ai_model
        )
        self.candle_count = 0
        self.last_signal = None
        self.entry_price = None
        self.entry_date = None
        self.order = None
        self.trade_log = []

        # Indicators
        self.sma20 = bt.indicators.SimpleMovingAverage(self.data.close, period=20)
        self.sma50 = bt.indicators.SimpleMovingAverage(self.data.close, period=50)
        self.rsi = bt.indicators.RSI(self.data.close, period=14)
        self.bb = bt.indicators.BollingerBands(self.data.close, period=20, devfactor=2)

    def _build_ai_prompt(self) -> str:
        """Construct the AI analysis prompt from current market data."""
        lookback = 14  # Analyze last 14 candles
        closes = [f"{i+1}d ago: ${c:.2f}" for i, c in enumerate(
            reversed([self.data.close[-i] for i in range(1, min(lookback+1, len(self.data)-1))]))
        ]
        volumes = [f"{i+1}d ago: {v:.0f}" for i, v in enumerate(
            reversed([self.data.volume[-i] for i in range(1, min(lookback+1, len(self.data)-1))]))
        ]

        prompt = f"""Analyze this cryptocurrency market data and provide a trading signal.

CURRENT MARKET DATA:
- Symbol: {self.data._name if hasattr(self.data, '_name') else 'UNKNOWN'}
- Current Price: ${self.data.close[0]:.2f}
- 20-day SMA: ${self.sma20[0]:.2f}
- 50-day SMA: ${self.sma50[0]:.2f}
- RSI(14): {self.rsi[0]:.1f}
- Bollinger Upper: ${self.bb.lines.top[0]:.2f}
- Bollinger Lower: ${self.bb.lines.bot[0]:.2f}
- Current Position: {'LONG' if self.position.size > 0 else 'FLAT'}

RECENT CLOSING PRICES (oldest to newest):
{chr(10).join(closes)}

RECENT VOLUMES (oldest to newest):
{chr(10).join(volumes)}

OUTPUT FORMAT (respond ONLY with valid JSON):
{{"action": "buy", "confidence": 0.75, "reason": "RSI oversold with strong volume"}}

Rules:
- action: "buy" (strong bullish signal), "sell" (strong bearish signal), or "hold" (no clear opportunity)
- confidence: 0.0 to 1.0 (higher = more confident)
- Only output valid JSON, no markdown or explanation"""

        return prompt

    def _query_ai_signal(self) -> dict:
        """Query HolySheep AI for a trading signal."""
        messages = [
            {"role": "system", "content": "You are an expert cryptocurrency quantitative analyst."},
            {"role": "user", "content": self._build_ai_prompt()}
        ]

        try:
            result = self.ai_client.chat(
                messages,
                temperature=0.3,
                max_tokens=150,
                stream=False
            )

            import json
            # Parse JSON response
            content = result["content"].strip()
            if content.startswith("```json"):
                content = content[7:]
            if content.startswith("```"):
                content = content[3:]
            if content.endswith("```"):
                content = content[:-3]

            signal = json.loads(content.strip())
            signal["cost"] = result["cost"]
            signal["latency_ms"] = result["latency_ms"]
            signal["tokens"] = result["output_tokens"]

            return signal

        except json.JSONDecodeError as e:
            if self.params.verbose:
                print(f"  [AI PARSE ERROR] Failed to parse AI response: {e}")
            return {"action": "hold", "confidence": 0.0, "reason": "AI parse error"}

        except Exception as e:
            if self.params.verbose:
                print(f"  [AI API ERROR] {type(e).__name__}: {e}")
            return {"action": "hold", "confidence": 0.0, "reason": f"API error: {str(e)[:50]}"}

    def _execute_trade(self, signal: dict):
        """Execute a trade based on the AI signal."""
        action = signal["action"]
        confidence = signal["confidence"]
        reason = signal.get("reason", "No reason provided")

        if self.order:
            return  # Already have pending order

        if action == "buy" and confidence >= self.params.confidence_threshold:
            if self.position.size == 0:
                size = self.broker.getcash() * self.params.position_size / self.data.close[0]
                self.order = self.buy(size=size)
                self.entry_price = self.data.close[0]
                self.entry_date = self.datas[0].datetime.date(0)
                if self.params.verbose:
                    print(f"  [BUY] Size: {size:.4f} @ ${self.entry_price:.2f} | Confidence: {confidence:.2f}")
                    print(f"        Reason: {reason}")

        elif action == "sell" and confidence >= self.params.confidence_threshold:
            if self.position.size > 0:
                self.order = self.close()
                if self.params.verbose:
                    pnl = (self.data.close[0] - self.entry_price) / self.entry_price * 100
                    print(f"  [SELL] @ ${self.data.close[0]:.2f} | PnL: {pnl:+.2f}%")
                    print(f"         Reason: {reason}")

    def notify_order(self, order):
        """Handle order notifications."""
        if order.status in [order.Completed]:
            if order.isbuy():
                self.trade_log.append({
                    "date": self.datas[0].datetime.date(0),
                    "action": "BUY",
                    "price": order.executed.price,
                    "size": order.executed.size,
                    "value": order.executed.value
                })
            elif order.issell():
                self.trade_log.append({
                    "date": self.datas[0].datetime.date(0),
                    "action": "SELL",
                    "price": order.executed.price,
                    "size": order.executed.size,
                    "value": order.executed.value
                })
            self.order = None

    def next(self):
        """Main strategy logic executed on each new candle."""
        self.candle_count += 1

        # Query AI at specified intervals
        if self.candle_count % self.params.signal_interval == 0:
            if self.params.verbose:
                print(f"\n[{self.data.datetime.date(0)}] Candle #{self.candle_count}")
                print(f"  Price: ${self.data.close[0]:.2f} | SMA20: ${self.sma20[0]:.2f} | RSI: {self.rsi[0]:.1f}")

            # Check max hold time
            if self.position.size > 0 and self.entry_date:
                hold_days = (self.datas[0].datetime.date(0) - self.entry_date).days
                if hold_days >= self.params.max_hold_days:
                    if self.params.verbose:
                        print(f"  [TIMEOUT] Max hold period ({self.params.max_hold_days}d) reached. Closing position.")
                    self.order = self.close()
                    return

            # Query AI
            signal = self._query_ai_signal()
            self.last_signal = signal

            if self.params.verbose:
                print(f"  [AI SIGNAL] Action: {signal['action']} | Confidence: {signal['confidence']:.2f}")
                print(f"              Cost: ${signal.get('cost', 0):.4f} | Latency: {signal.get('latency_ms', 0)}ms")

            # Execute trade
            self._execute_trade(signal)

        # Stop-loss check (runs every candle)
        if self.position.size > 0 and self.entry_price:
            drawdown = (self.entry_price - self.data.close[0]) / self.entry_price
            if drawdown >= self.params.stop_loss:
                if self.params.verbose:
                    print(f"  [STOP-LOSS] Drawdown: {drawdown*100:.2f}% | Closing position")
                self.order = self.close()

        # Take-profit check
        if self.position.size > 0 and self.entry_price:
            profit = (self.data.close[0] - self.entry_price) / self.entry_price
            if profit >= self.params.take_profit:
                if self.params.verbose:
                    print(f"  [TAKE-PROFIT] Profit: {profit*100:.2f}% | Taking profits")
                self.order = self.close()

    def stop(self):
        """Called when backtesting ends. Print summary."""
        cost_report = self.ai_client.get_cost_report()
        print(f"\n{'='*60}")
        print(f"BACKTEST COMPLETE")
        print(f"{'='*60}")
        print(f"Total AI calls: {self.candle_count // self.params.signal_interval}")
        print(f"Total trades: {len(self.trade_log)}")
        print(f"Total AI cost: ${cost_report['total_cost_usd']:.4f}")
        print(f"Total output tokens: {cost_report['total_output_tokens']:,}")
        print(f"Model: {cost_report['model']}")
        print(f"Final portfolio value: ${self.broker.getvalue():.2f}")
        print(f"{'='*60}")

Part 5: Running the Complete Backtest

With the data fetcher, AI client, and strategy in place, the main execution script ties everything together, configures the Backtrader engine, and runs the simulation.

# run_backtest.py
import backtrader as bt
import pandas as pd
from datetime import datetime
from ai_backtrader_strategy import AISignalStrategy
from fetch_tardis_data import fetch_ohlcv_data
from config import (
    TARDIS_EXCHANGE, TARDIS_SYMBOL,
    TARDIS_START_DATE, TARDIS_END_DATE,
    HOLYSHEEP_MODEL
)

class TardisCSVData(bt.feeds.GenericCSVData):
    """Custom Backtrader data feed for Tardis-exported CSV files."""
    params = (
        ("dtformat", "%Y-%m-%d %H:%M:%S"),
        ("datetime", 0),
        ("open", 1),
        ("high", 2),
        ("low", 3),
        ("close", 4),
        ("volume", 5),
        ("openinterest", -1),
        ("header", True),
    )

class PandasData(bt.feeds.PandasData):
    """Backtrader data feed from pandas DataFrame."""
    params = (
        ("datetime", None),
        ("open", "open"),
        ("high", "high"),
        ("low", "low"),
        ("close", "close"),
        ("volume", "volume"),
        ("openinterest", -1),
    )

def run_backtest(
    symbol: str = "BTC-USDT",
    exchange: str = "binance",
    start_date: str = "2025-01-01",
    end_date: str = "2025-12-31",
    initial_cash: float = 100000.0,
    ai_model: str = "deepseek-v3-250324"
):
    """
    Run a complete backtest with Tardis data and HolySheep AI signals.

    Args:
        symbol: Trading pair symbol (e.g., BTC-USDT)
        exchange: Exchange name (binance, bybit, okx, deribit)
        start_date: Backtest start date (YYYY-MM-DD)
        end_date: Backtest end date (YYYY-MM-DD)
        initial_cash: Starting capital in USD
        ai_model: HolySheep AI model to use

    Returns:
        Backtrader Cerebro instance with results
    """
    print(f"\n{'='*70}")
    print(f"HOLYSHEEP AI + BACKTRADER + TARDIS.DEV CRYPTO BACKTEST")
    print(f"{'='*70}")
    print(f"Symbol: {symbol}")
    print(f"Exchange: {exchange}")
    print(f"Period: {start_date} to {end_date}")
    print(f"Initial Capital: ${initial_cash:,.2f}")
    print(f"AI Model: {ai_model}")
    print(f"{'='*70}\n")

    # Step 1: Fetch historical data from Tardis.dev
    print("Step 1: Fetching data from Tardis.dev...")
    csv_filename = f"{symbol.replace('-', '_')}_{exchange}.csv"

    try:
        df = fetch_ohlcv_data(
            exchange=exchange,
            symbol=symbol,
            start_date=start_date,
            end_date=end_date,
            timeframe="1d"
        )
        df.to_csv(csv_filename)
        print(f"Data saved to {csv_filename}\n")
    except Exception as e:
        print(f"Failed to fetch from Tardis: {e}")
        print("Falling back to loading cached data...")
        df = pd.read_csv(csv_filename, index_col=0, parse_dates=True)

    # Step 2: Set up Backtrader Cerebro engine
    print("Step 2: Initializing Backtrader Cerebro engine...")
    cerebro = bt.Cerebro(
        cheat_on_open=True,      # Use next day's open for trade execution
        writer=True,             # Enable CSV/console output
        stdstats=True,           # Show broker stats
        live=False               # Backtest mode (not live)
    )

    # Step 3: Add data feed
    print("Step 3: Adding data feed...")
    data_feed = PandasData(
        dataname=df,
        name=f"{exchange.upper()}:{symbol}"
    )
    cerebro.adddata(data_feed)

    # Step 4: Configure broker
    print("Step 4: Configuring broker...")
    cerebro.broker.setcash(initial_cash)
    cerebro.broker.setcommission(commission=0.001)  # 0.1% taker fee (Binance spot)

    # Step 5: Add strategy with custom parameters
    print("Step 5: Adding AI Signal Strategy...")
    cerebro.addstrategy(
        AISignalStrategy,
        ai_model=ai_model,
        signal_interval=7,           # Query AI every