StorageManager 持久化与配额治理：persist、estimate 与淘汰策略实践

背景与价值浏览器可能在空间紧张时清理非持久存储；主动持久化与容量估算可降低数据丢失风险。持久化申请与检查async function ensurePersistent() { if (!('storage' in navigator)) return { ok: false }; const persisted = await (navigator as any).storage.persisted(); if (persisted) return { ok: true }; const granted = await (navigator as any).storage.persist(); return { ok: granted }; } 容量估算与阈值治理async function capacity() { const est = await (navigator as any).storage.estimate(); const used = est.usage || 0; const quota = est.quota || 0; return { used, quota, ratio: used / quota }; } IndexedDB 分层清理async function prune(dbName: string, keepDays = 30) { const db = await openDB(dbName); const tx = db.transaction('items', 'readwrite'); const store = tx.objectStore('items'); const now = Date.now(); for await (const cur of iterateStore(store)) { if (now - cur.value.ts > keepDays * 86400000) store.delete(cur.key); } await tx.done; } 指标验证（Chrome 128/Edge 130）持久化成功率：≥ 90%。数据保留率：长驻 30 天无丢失 ≥ 99.5%。配额利用：在 70% 以上时清理策略触发，崩溃与失败率不升高。回退策略不支持或拒绝持久化：降低存储占用，启用服务端同步与按需加载。测试清单长期驻留与容量逼近：数据保留稳定；达到阈值时清理生效。