fix: improve parallel pack downloads and suppress stale notifications

Download hosted pack files concurrently, recover file transfers from proxy and content-encoding failures, and prevent old installation failures from reappearing in notifications.

apps/app-frontend/src/helpers/install-job-notification-visibility.test.ts

@@ -0,0 +1,35 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import type { InstallJobSnapshot, InstallJobStatus } from './install.ts'
+import { createInstallJobNotificationFilter } from './install-job-notification-visibility.ts'
+
+function job(jobId: string, status: InstallJobStatus): InstallJobSnapshot {
+	return { job_id: jobId, status } as InstallJobSnapshot
+}
+
+test('does not resurrect failures that finished before the notification surface started', () => {
+	const oldFailure = job('old-failure', 'failed')
+	const filter = createInstallJobNotificationFilter([oldFailure, job('old-success', 'succeeded')])
+
+	assert.deepEqual(filter([oldFailure, job('old-success', 'succeeded')]), [])
+	assert.deepEqual(filter([oldFailure, job('current', 'running')]).map((item) => item.job_id), [
+		'current',
+	])
+})
+
+test('keeps an observed task visible when it finishes', () => {
+	const filter = createInstallJobNotificationFilter([job('old-failure', 'failed')])
+
+	assert.deepEqual(filter([job('current', 'running')]).map((item) => item.job_id), ['current'])
+	assert.deepEqual(filter([job('current', 'failed')]).map((item) => item.job_id), ['current'])
+	assert.deepEqual(filter([job('current', 'succeeded')]).map((item) => item.job_id), ['current'])
+})
+
+test('shows a newly received failure even if its active phase completed too quickly to observe', () => {
+	const filter = createInstallJobNotificationFilter([job('old-failure', 'failed')])
+
+	assert.deepEqual(filter([job('new-failure', 'failed')]).map((item) => item.job_id), [
+		'new-failure',
+	])
+})