fix: 修复实时日志与数据库切换可靠性

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

@@ -0,0 +1,81 @@
+export interface LiveLogSnapshot {
+	lines: Array<{ sequence: number; message: string }>
+	last_sequence: number
+}
+
+export interface SequencedLogEvent {
+	first_sequence: number
+	last_sequence: number
+}
+
+export function createLiveLogReconciler<T extends SequencedLogEvent>(
+	loadSnapshot: () => Promise<LiveLogSnapshot>,
+	replace: (snapshot: LiveLogSnapshot) => void,
+	append: (event: T) => void,
+) {
+	let lastSequence = 0
+	let queued: T[] = []
+	let syncing: Promise<void> | null = null
+	let disposed = false
+
+	function drainQueued(): boolean {
+		const events = queued
+		queued = []
+		for (let index = 0; index < events.length; index++) {
+			const event = events[index]!
+			if (event.last_sequence <= lastSequence) continue
+			if (event.first_sequence > lastSequence + 1) {
+				queued.push(...events.slice(index))
+				return false
+			}
+			append(event)
+			lastSequence = event.last_sequence
+		}
+		return true
+	}
+
+	function sync(): Promise<void> {
+		if (syncing) return syncing
+		const request = (async () => {
+			do {
+				const snapshot = await loadSnapshot()
+				if (disposed) return
+				replace(snapshot)
+				lastSequence = snapshot.last_sequence
+			} while (!drainQueued())
+		})()
+		const completion = request.finally(() => {
+			if (syncing === completion) syncing = null
+		})
+		syncing = completion
+		return completion
+	}
+
+	function resync(): Promise<void> {
+		return syncing ? syncing.then(sync) : sync()
+	}
+
+	function accept(event: T): Promise<void> | undefined {
+		if (disposed || event.last_sequence <= lastSequence) return
+		if (syncing) {
+			queued.push(event)
+			return syncing
+		}
+		if (event.first_sequence > lastSequence + 1) {
+			queued.push(event)
+			return sync()
+		}
+		append(event)
+		lastSequence = event.last_sequence
+	}
+
+	return {
+		accept,
+		resync,
+		sync,
+		dispose() {
+			disposed = true
+			queued = []
+		},
+	}
+}