Implement custom 5-minute candlestick charts via Finnhub + QuickChart

Replace FinViz charts with custom-generated candlestick charts:
- Fetch 5-minute OHLC data from Finnhub API
- Generate candlestick chart images via QuickChart API
- Display last 50 candles with time-based x-axis
- Fallback to FinViz daily chart if intraday data unavailable

New FinnhubAPI methods:
- get_intraday_candles(): Fetch 5-min candle data
- generate_chart_url(): Create QuickChart URL from candle data

Chart specifications: 800x400px, Chart.js v3, candlestick type

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

bot.py

@@ -169,9 +169,20 @@ class StockBot(commands.Bot):
         embed.add_field(name="Change", value=change_str, inline=True)
         embed.add_field(name="Previous Close", value=f"${stock_data['previous_close']}", inline=True)
 
-        # Add FinViz daily chart
-        chart_url = f"https://finviz.com/chart.ashx?t={ticker}&ty=c&ta=1&p=d&s=l"
-        embed.set_image(url=chart_url)
+        # Add 5-minute intraday chart from Finnhub + QuickChart
+        if hasattr(self.stock_api, 'get_intraday_candles'):
+            candles = self.stock_api.get_intraday_candles(ticker, resolution=5, days_back=1)
+            if candles:
+                chart_url = self.stock_api.generate_chart_url(ticker, candles)
+                embed.set_image(url=chart_url)
+            else:
+                # Fallback to FinViz daily chart if intraday data unavailable
+                chart_url = f"https://finviz.com/chart.ashx?t={ticker}&ty=c&ta=1&p=d&s=l"
+                embed.set_image(url=chart_url)
+        else:
+            # Fallback for non-Finnhub APIs
+            chart_url = f"https://finviz.com/chart.ashx?t={ticker}&ty=c&ta=1&p=d&s=l"
+            embed.set_image(url=chart_url)
 
         market_status = "🟢 Market Open" if stock_data['market_open'] else "🔴 Market Closed"
         embed.set_footer(text=f"{market_status}")

stock_api/finnhub_api.py

@@ -1,9 +1,11 @@
 import finnhub
 import logging
-from typing import Optional, Dict, Any
+from typing import Optional, Dict, Any, List
 from .base import StockAPIBase
-from datetime import datetime
+from datetime import datetime, timedelta
 import pytz
+import urllib.parse
+import json
 
 
 logger = logging.getLogger(__name__)
@@ -80,3 +82,94 @@ class FinnhubAPI(StockAPIBase):
         except Exception as e:
             logger.error(f"Finnhub API unavailable: {e}")
             return False
+
+    def get_intraday_candles(self, ticker: str, resolution: int = 5, days_back: int = 1) -> Optional[List[Dict[str, Any]]]:
+        """
+        Retrieve intraday candlestick data from Finnhub.
+
+        Args:
+            ticker: Stock ticker symbol
+            resolution: Candle resolution in minutes (1, 5, 15, 30, 60)
+            days_back: Number of days of historical data to fetch
+
+        Returns:
+            List of candle dictionaries or None if unavailable
+        """
+        try:
+            # Calculate time range (Unix timestamps)
+            now = datetime.now(pytz.timezone('America/New_York'))
+            end_time = int(now.timestamp())
+            start_time = int((now - timedelta(days=days_back)).timestamp())
+
+            # Fetch candle data
+            candles = self.client.stock_candles(ticker, resolution, start_time, end_time)
+
+            if not candles or candles.get('s') != 'ok':
+                logger.warning(f"No candle data available for {ticker}")
+                return None
+
+            # Format candles for chart consumption
+            formatted_candles = []
+            for i in range(len(candles['t'])):
+                formatted_candles.append({
+                    'x': candles['t'][i] * 1000,  # Convert to milliseconds
+                    'o': round(candles['o'][i], 2),
+                    'h': round(candles['h'][i], 2),
+                    'l': round(candles['l'][i], 2),
+                    'c': round(candles['c'][i], 2)
+                })
+
+            return formatted_candles
+
+        except Exception as e:
+            logger.error(f"Error fetching candles for {ticker}: {e}")
+            return None
+
+    def generate_chart_url(self, ticker: str, candles: List[Dict[str, Any]]) -> str:
+        """
+        Generate QuickChart URL for candlestick chart.
+
+        Args:
+            ticker: Stock ticker symbol
+            candles: List of candle dictionaries with x, o, h, l, c keys
+
+        Returns:
+            QuickChart URL string
+        """
+        # Limit to last 50 candles for readability
+        chart_data = candles[-50:] if len(candles) > 50 else candles
+
+        chart_config = {
+            'type': 'candlestick',
+            'data': {
+                'datasets': [{
+                    'label': f'{ticker} 5-Minute',
+                    'data': chart_data
+                }]
+            },
+            'options': {
+                'plugins': {
+                    'title': {
+                        'display': True,
+                        'text': f'{ticker} - 5 Minute Chart'
+                    }
+                },
+                'scales': {
+                    'x': {
+                        'type': 'time',
+                        'time': {
+                            'unit': 'minute',
+                            'displayFormats': {
+                                'minute': 'HH:mm'
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        # Encode config for URL
+        config_json = json.dumps(chart_config)
+        encoded_config = urllib.parse.quote(config_json)
+
+        return f"https://quickchart.io/chart?v=3&c={encoded_config}&width=800&height=400"