phase-7: code restructure

scripts/summary-reporter.ts

@@ -1,23 +1,34 @@
 // Minimal test reporter: silent on pass, prints failures in full, ends with one summary line.
-export default async function* summaryReporter(source) {
-  const failures = [];
+import type { TestEvent } from 'node:test/reporters';
+
+interface Failure {
+  name: string;
+  reason: string;
+}
+
+export default async function* summaryReporter(
+  source: AsyncIterable<TestEvent>,
+): AsyncGenerator<string> {
+  const failures: Failure[] = [];
   let passed = 0,
     failed = 0,
     totalMs = 0;
 
   for await (const event of source) {
-    // Skip file-level wrapper events (name ends in .js) — only count individual tests.
-    if (event.data?.name?.endsWith('.js')) continue;
+    // Skip file-level wrapper events (name ends in .ts) — only count individual tests.
+    if ((event.data as { name?: string })?.name?.endsWith('.ts')) continue;
 
     if (event.type === 'test:pass') {
       passed++;
-      totalMs += event.data.details?.duration_ms ?? 0;
+      totalMs += (event.data as { details?: { duration_ms?: number } }).details?.duration_ms ?? 0;
     } else if (event.type === 'test:fail') {
       failed++;
-      totalMs += event.data.details?.duration_ms ?? 0;
-      const err = event.data.details?.error;
+      totalMs += (event.data as { details?: { duration_ms?: number } }).details?.duration_ms ?? 0;
+      const err = (
+        event.data as { details?: { error?: { cause?: { message?: string }; message?: string } } }
+      ).details?.error;
       failures.push({
-        name: event.data.name,
+        name: (event.data as { name?: string }).name ?? 'unknown',
         reason: err?.cause?.message ?? err?.message ?? 'unknown',
       });
     }