phase-2: extract shared utils

server/market/BenchmarkProvider.js

@@ -0,0 +1,73 @@
+import { YahooClient } from './YahooClient.js';
+import { REGIME } from '../config/constants.js';
+
+const TTL_MS = 60 * 60 * 1000;
+
+const DEFAULTS = {
+  sp500Price: 5000,
+  riskFreeRate: 4.5,
+  vixLevel: 20,
+  rateRegime: REGIME.HIGH,
+  volatilityRegime: REGIME.NORMAL,
+  benchmarks: { marketPE: 22, techPE: 30, reitYield: 3.5, igSpread: 1.0 },
+};
+
+const rateRegime = (rate) => (rate < 2 ? REGIME.LOW : rate <= 5 ? REGIME.NORMAL : REGIME.HIGH);
+const volRegime = (vix) => (vix < 15 ? REGIME.LOW : vix <= 25 ? REGIME.NORMAL : REGIME.HIGH);
+
+const pe = (summary) =>
+  summary.summaryDetail?.trailingPE ?? summary.defaultKeyStatistics?.forwardPE;
+
+export class BenchmarkProvider {
+  // logger: object with .warn() — defaults to console so CLI behaviour is unchanged.
+  constructor({ logger = console } = {}) {
+    this.client = new YahooClient();
+    this.cache = { data: null, expiresAt: 0 };
+    this.logger = logger;
+  }
+
+  async getMarketContext() {
+    if (this.cache.data && Date.now() < this.cache.expiresAt) return this.cache.data;
+
+    try {
+      const [sp500, tn10y, vix, spy, xlk, xlre, lqd] = await Promise.all([
+        this.client.fetchSummary('^GSPC'),
+        this.client.fetchSummary('^TNX'),
+        this.client.fetchSummary('^VIX'),
+        this.client.fetchSummary('SPY'),
+        this.client.fetchSummary('XLK'),
+        this.client.fetchSummary('XLRE'),
+        this.client.fetchSummary('LQD'),
+      ]);
+
+      const riskFreeRate = tn10y.price?.regularMarketPrice ?? 0;
+      const sp500Price = sp500.price?.regularMarketPrice ?? 0;
+      const vixLevel = vix.price?.regularMarketPrice ?? 0;
+
+      if (!sp500Price || !riskFreeRate) throw new Error('Invalid market data (zero values)');
+
+      const lqdYield = (lqd.summaryDetail?.trailingAnnualDividendYield ?? 0) * 100;
+
+      const context = {
+        sp500Price,
+        riskFreeRate,
+        vixLevel,
+        rateRegime: rateRegime(riskFreeRate),
+        volatilityRegime: volRegime(vixLevel),
+        benchmarks: {
+          marketPE: pe(spy) ?? 22,
+          techPE: pe(xlk) ?? 30,
+          reitYield: (xlre.summaryDetail?.trailingAnnualDividendYield ?? 0.035) * 100,
+          igSpread: Math.max(0.1, lqdYield - riskFreeRate),
+        },
+        timestamp: new Date().toISOString(),
+      };
+
+      this.cache = { data: context, expiresAt: Date.now() + TTL_MS };
+      return context;
+    } catch (err) {
+      this.logger.warn('Market data fetch failed, using defaults:', err.message);
+      return this.cache.data ?? DEFAULTS;
+    }
+  }
+}