feat: port quality, escalation, KB version, site-map KB, experiments and metrics

bridge/src/experiments.js

@@ -0,0 +1,38 @@
+'use strict';
+
+const crypto = require('crypto');
+const fs = require('fs');
+const path = require('path');
+
+// A/B 实验：按 conversationId 稳定分桶（旧 bridge config/experiments.js 精简版）。
+function createExperimentManager(cfg = {}) {
+  const file = cfg.experimentsPath || path.resolve(__dirname, '..', 'config', 'experiments.json');
+  let experiments = [];
+  try {
+    const data = JSON.parse(fs.readFileSync(file, 'utf8'));
+    experiments = Array.isArray(data.experiments) ? data.experiments : [];
+  } catch {
+    experiments = [];
+  }
+
+  function getVariant(convId, experimentId) {
+    const exp = experiments.find((e) => e.active && (!experimentId || e.id === experimentId));
+    if (!exp) return { experiment_id: null, variant: null, overriddenParams: null };
+    const hash = crypto.createHash('md5').update(`${convId}:${exp.id}`).digest('hex');
+    const bucket = parseInt(hash.slice(0, 8), 16) % 100;
+    let cumulative = 0;
+    for (const v of exp.variants || []) {
+      cumulative += v.weight || 50;
+      if (bucket < cumulative) return { experiment_id: exp.id, variant: v.name, overriddenParams: v.overriddenParams || null };
+    }
+    return { experiment_id: exp.id, variant: (exp.variants && exp.variants[0] && exp.variants[0].name) || null, overriddenParams: null };
+  }
+
+  function getActiveExperiments() {
+    return experiments.filter((e) => e.active);
+  }
+
+  return { getVariant, getActiveExperiments };
+}
+
+module.exports = { createExperimentManager };