fix: 修复实时日志与数据库切换可靠性

apps/app-frontend/src/composables/live-log-reconciler.test.ts

@@ -0,0 +1,70 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+
+import {
+	createLiveLogReconciler,
+	type LiveLogSnapshot,
+} from './live-log-reconciler.ts'
+
+test('merges the authoritative snapshot with queued events without gaps or duplicates', async () => {
+	let resolveSnapshot!: (snapshot: LiveLogSnapshot) => void
+	const displayed: number[] = []
+	const reconciler = createLiveLogReconciler(
+		() =>
+			new Promise((resolve) => {
+				resolveSnapshot = resolve
+			}),
+		(snapshot) => {
+			displayed.splice(
+				0,
+				displayed.length,
+				...snapshot.lines.map((line) => line.sequence),
+			)
+		},
+		(event) => displayed.push(event.last_sequence),
+	)
+
+	const syncing = reconciler.sync()
+	reconciler.accept({ first_sequence: 3, last_sequence: 3 })
+	resolveSnapshot({
+		lines: [
+			{ sequence: 1, message: 'one' },
+			{ sequence: 2, message: 'two' },
+		],
+		last_sequence: 2,
+	})
+	await syncing
+	assert.deepEqual(displayed, [1, 2, 3])
+
+	await reconciler.accept({ first_sequence: 3, last_sequence: 3 })
+	assert.deepEqual(displayed, [1, 2, 3])
+})
+
+test('resynchronizes when an event sequence reveals a missed batch', async () => {
+	const displayed: number[] = []
+	let loads = 0
+	const reconciler = createLiveLogReconciler(
+		async () => {
+			loads++
+			return {
+				lines: [1, 2, 3, 4].map((sequence) => ({
+					sequence,
+					message: String(sequence),
+				})),
+				last_sequence: 4,
+			}
+		},
+		(snapshot) => {
+			displayed.splice(
+				0,
+				displayed.length,
+				...snapshot.lines.map((line) => line.sequence),
+			)
+		},
+		(event) => displayed.push(event.last_sequence),
+	)
+
+	await reconciler.accept({ first_sequence: 4, last_sequence: 4 })
+	assert.equal(loads, 1)
+	assert.deepEqual(displayed, [1, 2, 3, 4])
+})