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;

tools/brain-dashboard-core.test.mjs

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest';
-import { parseEpisodes, normalizeEpisode, attributeNodes, filterEpisodes, groupBySession } from '../docs/observer/dashboard-core.js';
+import { parseEpisodes, normalizeEpisode, attributeNodes, filterEpisodes, groupBySession, aggregate } from '../docs/observer/dashboard-core.js';
 
 const v1 = {
   task_id: 'a', timestamps: { started_at: '2026-05-19T05:18:16.342Z', ended_at: '2026-05-19T06:05:55.439Z' },
@@ -138,3 +138,33 @@ describe('groupBySession', () => {
     expect(groups[0].taskRef).toBe('S');
   });
 });
+
+describe('aggregate', () => {
+  const mk = (over) => normalizeEpisode({ ...v2, ...over });
+  it('counts node heat from attributed nodes', () => {
+    const list = [
+      mk({ events: [{ kind: 'skill_invoked', skill: 'superpowers:writing-plans' }] }),
+      mk({ events: [{ kind: 'skill_invoked', skill: 'superpowers:writing-plans' }] }),
+    ];
+    expect(aggregate(list).nodeHeat.sk_wplans).toBe(2);
+  });
+  it('computes redirect rate', () => {
+    const list = [
+      mk({ decision_provenance: { kind: 'user_directed_method', claude_would_have_chosen: 'x' } }),
+      mk({ decision_provenance: { kind: 'autonomous', claude_would_have_chosen: null } }),
+    ];
+    expect(aggregate(list).redirectRate).toBe(0.5);
+  });
+  it('tallies path_type and outcome distributions', () => {
+    const list = [mk({ path_type: 'improvised', outcome: 'unknown' }), mk({ path_type: 'regulated', outcome: 'success' })];
+    const a = aggregate(list);
+    expect(a.pathType).toEqual({ improvised: 1, regulated: 1 });
+    expect(a.outcome).toEqual({ unknown: 1, success: 1 });
+  });
+  it('reports total error and retry counts', () => {
+    const list = [mk({ events: [{ kind: 'error', message: 'e' }, { kind: 'retry' }] })];
+    const a = aggregate(list);
+    expect(a.totalErrors).toBe(1);
+    expect(a.totalRetries).toBe(1);
+  });
+});