feat: align with upstream 1.5.9.9

server/utils/song-duration-policy.ts

@@ -0,0 +1,39 @@
+import { SONG_DURATION_MAX_SECONDS, SONG_DURATION_MIN_SECONDS } from '../config/constants.ts'
+
+/** 时长差异容差（秒），差异不超过此值视为一致 */
+export const DURATION_TOLERANCE_SECONDS = 5
+
+export type SongDurationOutcome = 'keep' | 'clear' | 'fill' | 'nocheck'
+
+export interface SongDurationDecision {
+  outcome: SongDurationOutcome
+  durationSeconds: number | null
+}
+
+/** 归一化已有时长：非法值或越出合法区间视为无时长 */
+export function normalizeStoredDuration(value: unknown): number | null {
+  if (value === null || value === undefined || value === '') return null
+  const parsed = Number(value)
+  if (!Number.isFinite(parsed)) return null
+  const seconds = Math.floor(parsed)
+  if (seconds < SONG_DURATION_MIN_SECONDS || seconds > SONG_DURATION_MAX_SECONDS) return null
+  return seconds
+}
+
+/** 时长决策：库中无值且平台可查则补齐，有值但与平台不符则清空 */
+export function decideDurationOutcome(
+  storedDurationSeconds: number | null,
+  actualDurationSeconds: number | null,
+  toleranceSeconds: number = DURATION_TOLERANCE_SECONDS
+): SongDurationDecision {
+  if (actualDurationSeconds === null) {
+    return { outcome: 'nocheck', durationSeconds: storedDurationSeconds }
+  }
+  if (storedDurationSeconds === null) {
+    return { outcome: 'fill', durationSeconds: actualDurationSeconds }
+  }
+  if (Math.abs(actualDurationSeconds - storedDurationSeconds) > toleranceSeconds) {
+    return { outcome: 'clear', durationSeconds: null }
+  }
+  return { outcome: 'keep', durationSeconds: storedDurationSeconds }
+}