feat(brain): aggregator — node heat, distributions, redirect rate (+4 tests)

docs/observer/dashboard-core.js

@@ -137,6 +137,41 @@ export function filterEpisodes(episodes, filter = {}) {
   });
 }
 
+// Aggregates a list of episodes into dashboard metrics.
+export function aggregate(episodes) {
+  const nodeHeat = {};
+  const pathType = {};
+  const outcome = {};
+  const classification = {};
+  const economy = {};
+  let totalErrors = 0;
+  let totalRetries = 0;
+  let redirects = 0;
+  for (const e of episodes) {
+    for (const id of attributeNodes(e).nodeIds) nodeHeat[id] = (nodeHeat[id] || 0) + 1;
+    if (e.pathType) pathType[e.pathType] = (pathType[e.pathType] || 0) + 1;
+    outcome[e.outcome] = (outcome[e.outcome] || 0) + 1;
+    if (e.taskClassification) classification[e.taskClassification] = (classification[e.taskClassification] || 0) + 1;
+    const lvl = e.environment ? e.environment.economy_level : null;
+    const key = lvl == null ? 'n/a' : String(lvl);
+    economy[key] = (economy[key] || 0) + 1;
+    totalErrors += e.errorCount;
+    totalRetries += e.retryCount;
+    if (e.decisionProvenance && e.decisionProvenance.kind === 'user_directed_method') redirects++;
+  }
+  return {
+    nodeHeat,
+    pathType,
+    outcome,
+    classification,
+    economy,
+    totalErrors,
+    totalRetries,
+    redirectRate: episodes.length ? redirects / episodes.length : 0,
+    count: episodes.length,
+  };
+}
+
 export function parseEpisodes(text) {
   const episodes = [];
   let skipped = 0;