chore: add AGENTS.md with build, lint, test commands and style guidelines

js/indicators/atr.js

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+// Self-contained ATR indicator
+// Includes math, metadata, signal calculation, and base class
+
+// Signal constants (defined in each indicator file)
+const SIGNAL_TYPES = {
+    BUY: 'buy',
+    SELL: 'sell',
+    HOLD: 'hold'
+};
+
+const SIGNAL_COLORS = {
+    buy: '#26a69a',
+    hold: '#787b86',
+    sell: '#ef5350'
+};
+
+// Base class (inline replacement for BaseIndicator)
+class BaseIndicator {
+    constructor(config) {
+        this.id = config.id;
+        this.type = config.type;
+        this.name = config.name;
+        this.params = config.params || {};
+        this.timeframe = config.timeframe || '1m';
+        this.series = [];
+        this.visible = config.visible !== false;
+        this.cachedResults = null;
+        this.cachedMeta = null;
+        this.lastSignalTimestamp = null;
+        this.lastSignalType = null;
+    }
+}
+
+// Signal calculation for ATR
+function calculateATRSignal(indicator, lastCandle, prevCandle, values) {
+    const atr = values?.atr;
+    const close = lastCandle.close;
+    const prevClose = prevCandle?.close;
+    
+    if (!atr || atr === null || !prevClose) {
+        return null;
+    }
+    
+    const atrPercent = atr / close * 100;
+    const priceChange = Math.abs(close - prevClose);
+    const atrRatio = priceChange / atr;
+    
+    if (atrRatio > 1.5) {
+        return {
+            type: SIGNAL_TYPES.HOLD,
+            strength: 70,
+            value: atr,
+            reasoning: `High volatility: ATR (${atr.toFixed(2)}, ${atrPercent.toFixed(2)}%)`
+        };
+    }
+    
+    return null;
+}
+
+// ATR Indicator class
+export class ATRIndicator extends BaseIndicator {
+    constructor(config) {
+        super(config);
+        this.lastSignalTimestamp = null;
+        this.lastSignalType = null;
+    }
+
+    calculate(candles) {
+        const period = this.params.period || 14;
+        const results = new Array(candles.length).fill(null);
+        const tr = new Array(candles.length).fill(0);
+        
+        for (let i = 1; i < candles.length; i++) {
+            const h_l = candles[i].high - candles[i].low;
+            const h_pc = Math.abs(candles[i].high - candles[i-1].close);
+            const l_pc = Math.abs(candles[i].low - candles[i-1].close);
+            tr[i] = Math.max(h_l, h_pc, l_pc);
+        }
+        
+        let atr = 0;
+        let sum = 0;
+        for (let i = 1; i <= period; i++) sum += tr[i];
+        atr = sum / period;
+        results[period] = atr;
+        
+        for (let i = period + 1; i < candles.length; i++) {
+            atr = (atr * (period - 1) + tr[i]) / period;
+            results[i] = atr;
+        }
+        
+        return results.map(atr => ({ atr }));
+    }
+    
+    getMetadata() {
+        return {
+            name: 'ATR',
+            description: 'Average True Range - measures market volatility',
+            inputs: [{ 
+                name: 'period', 
+                label: 'Period', 
+                type: 'number', 
+                default: 14, 
+                min: 1, 
+                max: 100,
+                description: 'Period for ATR calculation'
+            }],
+            plots: [{ 
+                id: 'value', 
+                color: '#795548', 
+                title: 'ATR',
+                lineWidth: 1
+            }],
+            displayMode: 'pane'
+        };
+    }
+}
+
+export { calculateATRSignal };