feat: eval CLI tools + docs cleanup

Add eval:list, eval:compare, eval:summary CLI scripts for exploring
eval history from ~/.gstack-dev/evals/. eval:compare reuses the shared
comparison functions from eval-store.ts.

- eval:list: sorted table with branch/tier/cost filters
- eval:compare: thin wrapper around compareEvalResults + formatComparison
- eval:summary: aggregate stats, flaky test detection, branch rankings
- Remove unused @anthropic-ai/claude-agent-sdk from devDependencies
- Update CLAUDE.md: streaming docs, eval CLI commands, remove Agent SDK refs
- Add GH Actions eval upload (P2) and web dashboard (P3) to TODOS.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/eval-summary.ts

@@ -0,0 +1,134 @@
+#!/usr/bin/env bun
+/**
+ * Aggregate summary of all eval runs from ~/.gstack-dev/evals/
+ *
+ * Usage: bun run eval:summary
+ */
+
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import type { EvalResult } from '../test/helpers/eval-store';
+
+const EVAL_DIR = path.join(os.homedir(), '.gstack-dev', 'evals');
+
+let files: string[];
+try {
+  files = fs.readdirSync(EVAL_DIR).filter(f => f.endsWith('.json'));
+} catch {
+  console.log('No eval runs yet. Run: EVALS=1 bun run test:evals');
+  process.exit(0);
+}
+
+if (files.length === 0) {
+  console.log('No eval runs yet. Run: EVALS=1 bun run test:evals');
+  process.exit(0);
+}
+
+// Load all results
+const results: EvalResult[] = [];
+for (const file of files) {
+  try {
+    results.push(JSON.parse(fs.readFileSync(path.join(EVAL_DIR, file), 'utf-8')));
+  } catch { continue; }
+}
+
+// Aggregate stats
+const e2eRuns = results.filter(r => r.tier === 'e2e');
+const judgeRuns = results.filter(r => r.tier === 'llm-judge');
+const totalCost = results.reduce((s, r) => s + (r.total_cost_usd || 0), 0);
+const avgE2ECost = e2eRuns.length > 0 ? e2eRuns.reduce((s, r) => s + r.total_cost_usd, 0) / e2eRuns.length : 0;
+const avgJudgeCost = judgeRuns.length > 0 ? judgeRuns.reduce((s, r) => s + r.total_cost_usd, 0) / judgeRuns.length : 0;
+
+// Detection rates from outcome evals
+const detectionRates: number[] = [];
+for (const r of e2eRuns) {
+  for (const t of r.tests) {
+    if (t.detection_rate !== undefined) {
+      detectionRates.push(t.detection_rate);
+    }
+  }
+}
+const avgDetection = detectionRates.length > 0
+  ? detectionRates.reduce((a, b) => a + b, 0) / detectionRates.length
+  : null;
+
+// Flaky tests (passed in some runs, failed in others)
+const testResults = new Map<string, boolean[]>();
+for (const r of results) {
+  for (const t of r.tests) {
+    const key = `${r.tier}:${t.name}`;
+    if (!testResults.has(key)) testResults.set(key, []);
+    testResults.get(key)!.push(t.passed);
+  }
+}
+const flakyTests: string[] = [];
+for (const [name, outcomes] of testResults) {
+  if (outcomes.length >= 2) {
+    const hasPass = outcomes.some(o => o);
+    const hasFail = outcomes.some(o => !o);
+    if (hasPass && hasFail) flakyTests.push(name);
+  }
+}
+
+// Branch stats
+const branchStats = new Map<string, { runs: number; avgDetection: number; detections: number[] }>();
+for (const r of e2eRuns) {
+  if (!branchStats.has(r.branch)) {
+    branchStats.set(r.branch, { runs: 0, avgDetection: 0, detections: [] });
+  }
+  const stats = branchStats.get(r.branch)!;
+  stats.runs++;
+  for (const t of r.tests) {
+    if (t.detection_rate !== undefined) {
+      stats.detections.push(t.detection_rate);
+    }
+  }
+}
+for (const stats of branchStats.values()) {
+  stats.avgDetection = stats.detections.length > 0
+    ? stats.detections.reduce((a, b) => a + b, 0) / stats.detections.length
+    : 0;
+}
+
+// Print summary
+console.log('');
+console.log('Eval Summary');
+console.log('═'.repeat(60));
+console.log(`  Total runs:        ${results.length} (${e2eRuns.length} e2e, ${judgeRuns.length} llm-judge)`);
+console.log(`  Total spend:       $${totalCost.toFixed(2)}`);
+console.log(`  Avg cost/e2e:      $${avgE2ECost.toFixed(2)}`);
+console.log(`  Avg cost/judge:    $${avgJudgeCost.toFixed(2)}`);
+if (avgDetection !== null) {
+  console.log(`  Avg detection:     ${avgDetection.toFixed(1)} bugs`);
+}
+console.log('─'.repeat(60));
+
+if (flakyTests.length > 0) {
+  console.log(`  Flaky tests (${flakyTests.length}):`);
+  for (const name of flakyTests) {
+    console.log(`    - ${name}`);
+  }
+  console.log('─'.repeat(60));
+}
+
+if (branchStats.size > 0) {
+  console.log('  Branches:');
+  const sorted = [...branchStats.entries()].sort((a, b) => b[1].avgDetection - a[1].avgDetection);
+  for (const [branch, stats] of sorted) {
+    const det = stats.detections.length > 0 ? ` avg det: ${stats.avgDetection.toFixed(1)}` : '';
+    console.log(`    ${branch.padEnd(30)} ${stats.runs} runs${det}`);
+  }
+  console.log('─'.repeat(60));
+}
+
+// Date range
+const timestamps = results.map(r => r.timestamp).filter(Boolean).sort();
+if (timestamps.length > 0) {
+  const first = timestamps[0].replace('T', ' ').slice(0, 16);
+  const last = timestamps[timestamps.length - 1].replace('T', ' ').slice(0, 16);
+  console.log(`  Date range: ${first} → ${last}`);
+}
+
+console.log(`  Dir: ${EVAL_DIR}`);
+console.log('');