phase-6: typescript introduction

server/screener/RuleMerger.ts

@@ -0,0 +1,49 @@
+import { ScoringRules } from '../config/ScoringConfig.js';
+import { MarketRegime } from '../market/MarketRegime.js';
+import { SCORE_MODE } from '../config/constants.js';
+import type { AssetType, MarketContext } from '../types.js';
+
+interface RuleSet {
+  gates: Record<string, number>;
+  weights: Record<string, number>;
+  thresholds: Record<string, number>;
+}
+
+export const RuleMerger = {
+  getRulesForAsset(
+    type: AssetType,
+    metrics: { sector?: string },
+    marketContext: Partial<MarketContext> = {},
+    mode: string = SCORE_MODE.FUNDAMENTAL,
+  ): RuleSet {
+    const base = ScoringRules[type as keyof typeof ScoringRules];
+    if (!base) throw new Error(`No rules configured for asset type: ${type}`);
+
+    // Deep clone to avoid mutating the source config
+    const rules: RuleSet & { SECTOR_OVERRIDE?: unknown } = JSON.parse(JSON.stringify(base));
+
+    if (type === 'STOCK' && metrics.sector) {
+      const stockBase = ScoringRules.STOCK;
+      const override =
+        stockBase.SECTOR_OVERRIDE?.[
+          metrics.sector.toUpperCase() as keyof typeof stockBase.SECTOR_OVERRIDE
+        ];
+      if (override) {
+        rules.gates = { ...rules.gates, ...override.gates };
+        rules.weights = { ...rules.weights, ...override.weights };
+        rules.thresholds = { ...rules.thresholds, ...override.thresholds };
+      }
+    }
+    delete rules.SECTOR_OVERRIDE;
+
+    if (mode === SCORE_MODE.INFLATED) {
+      const { gates, thresholds } = new MarketRegime(
+        marketContext as MarketContext,
+      ).getInflatedOverrides(type, metrics.sector);
+      rules.gates = { ...rules.gates, ...gates };
+      rules.thresholds = { ...rules.thresholds, ...thresholds };
+    }
+
+    return rules;
+  },
+};