test(hls): [PKG-HLS-SDK-01] checkpoint unresolved Firefox diagnostics

test/helpers/worker-observer.js

@@ -0,0 +1,19 @@
+// Browser-only diagnostic observer; messages and termination still use native workers.
+export function observeWorkers() {
+  const NativeWorker = window.Worker
+  window.workerEvidence = []
+  window.Worker = class extends NativeWorker {
+    constructor(url, options) {
+      super(url, options)
+      const record = { url: String(url), messages: [], errors: [], terminated: 0 }
+      window.workerEvidence.push(record)
+      this.addEventListener('message', event => record.messages.push(event.data?.event))
+      this.addEventListener('error', event => record.errors.push(event.message))
+      const terminate = this.terminate.bind(this)
+      this.terminate = () => {
+        record.terminated++
+        return terminate()
+      }
+    }
+  }
+}