release: v0.4.2 — 生产就绪与崩溃自愈 + 问题清单修复 + 版本迭代

src/engine/aria/index.ts

@@ -70,6 +70,22 @@ export class AriaEngine implements IStorageEngine {
 
   async open(dbName: string, _version: number): Promise<void> {
     if (this.opened) return;
+    // v0.4.2-fix: 引擎内部错误统一包装为 DatabaseError（ARIA_OPEN_ERROR），
+    // 应用层可拿到 code 分类处理，不再抛出原生 RangeError/TypeError
+    try {
+      await this.openInternal(dbName);
+    } catch (error) {
+      if (error instanceof DatabaseError) throw error;
+      throw new DatabaseError(
+        `Failed to open AriaEngine database "${dbName}"`,
+        'ARIA_OPEN_ERROR',
+        error,
+      );
+    }
+  }
+
+  /** open 内部实现（错误包装在 open 外层） */
+  private async openInternal(dbName: string): Promise<void> {
     this.dbName = dbName;
 
     // 1. 存储后端
@@ -105,20 +121,30 @@ export class AriaEngine implements IStorageEngine {
     this.wal = new WAL(
       {
         append: async (data) => {
-          // Store each record as a separate numbered key
+          // v0.4.2-fix: 记录写入与 count 计数在同一底层事务中原子提交，
+          // 中断时整体回滚，杜绝"记录在、计数丢"导致恢复漏读的丢数据问题
           const idx = await this.getWALCount();
           const slice = new Uint8Array(data.buffer, data.byteOffset, data.byteLength);
           const copy = slice.buffer.slice(slice.byteOffset, slice.byteOffset + slice.byteLength) as ArrayBuffer;
-          await this.backend.write(`__wal_${idx}`, copy);
-          await this.setWALCount(idx + 1);
+          await this.backend.writeMany({
+            [`__wal_${idx}`]: copy,
+            __wal_count: new TextEncoder().encode(String(idx + 1)).buffer,
+          });
         },
         readAll: async () => {
-          const count = await this.getWALCount();
-          if (count === 0) return new Uint8Array(0);
-          // Read all records and concatenate
+          // v0.4.2-fix: 不依赖 count 计数，直接扫描全部 __wal_* 键，
+          // 避免 count 与实际记录不一致时漏读（与 checkpoint/并发写入竞态无关）
+          const keys = (await this.backend.listKeys())
+            .filter((k) => k.startsWith('__wal_') && k !== '__wal_count')
+            .sort((a, b) => {
+              const na = parseInt(a.slice('__wal_'.length), 10);
+              const nb = parseInt(b.slice('__wal_'.length), 10);
+              return (isNaN(na) ? 0 : na) - (isNaN(nb) ? 0 : nb);
+            });
+          if (keys.length === 0) return new Uint8Array(0);
           const chunks: Uint8Array[] = [];
-          for (let i = 0; i < count; i++) {
-            const d = await this.backend.read(`__wal_${i}`);
+          for (const key of keys) {
+            const d = await this.backend.read(key);
             if (d) chunks.push(new Uint8Array(d));
           }
           const total = chunks.reduce((s, c) => s + c.byteLength, 0);
@@ -128,15 +154,17 @@ export class AriaEngine implements IStorageEngine {
           return combined;
         },
         truncate: async () => {
-          const count = await this.getWALCount();
-          for (let i = 0; i < count; i++) {
-            await this.backend.delete(`__wal_${i}`);
-          }
+          // v0.4.2-fix: 扫描删除全部 WAL 记录键 + count 键（单事务原子清理）
+          const keys = (await this.backend.listKeys())
+            .filter((k) => k.startsWith('__wal_'));
+          await this.backend.deleteMany(keys);
           await this.setWALCount(0);
         },
         exists: async () => {
-          const count = await this.getWALCount();
-          return count > 0;
+          // v0.4.2-fix: 与 readAll 一致按 key 扫描判断（count 可能因崩溃截断而滞后）
+          const keys = (await this.backend.listKeys())
+            .filter((k) => k.startsWith('__wal_') && k !== '__wal_count');
+          return keys.length > 0;
         },
       },
       this.config.walEnabled,
@@ -146,6 +174,31 @@ export class AriaEngine implements IStorageEngine {
     // 5. 恢复 Schema
     await this.loadSchemas();
 
+    // v0.4.2-fix: 为 schema 中带 index/unique 标记的列重建二级索引 LSM。
+    // 此前重开只恢复 schema 不恢复索引 LSM → 索引查询静默回退全表、
+    // createIndex 因 colDef 已有标记直接 return → 索引永久缺失。
+    // 索引数据已持久化在独立命名空间（sst_idx_* / meta），init() 直接加载。
+    for (const [tableName, schema] of this.schemas) {
+      const pkCol = this.tablePKs.get(tableName)!;
+      for (const [colName, colDef] of Object.entries(schema.columns)) {
+        if ((colDef.index || colDef.unique) && colName !== pkCol) {
+          const idxKey = `${tableName}:idx:${colName}`;
+          if (!this.secondaryIndexes.has(idxKey)) {
+            const idxLsm = new LSM({
+              memtableSizeThreshold: this.config.memtableSizeThreshold,
+              levelSizeMultiplier: this.config.levelSizeMultiplier,
+              blockSize: this.config.pageSize,
+              bloomBitsPerKey: this.config.bloomFilterBitsPerKey,
+              cacheLimitBytes: this.config.bufferPoolPages * this.config.pageSize,
+              sstableStore: this.createSSTableStore(`idx_${tableName}_${colName}`),
+            });
+            await idxLsm.init();
+            this.secondaryIndexes.set(idxKey, idxLsm);
+          }
+        }
+      }
+    }
+
     // 6. 初始化 LSM（加载 SSTable 元数据）
     await this.lsm.init();
 
@@ -175,12 +228,31 @@ export class AriaEngine implements IStorageEngine {
     if (allRecords.length > 0) {
       await this.lsm.flush();
       await this.wal.checkpoint();
+      // v0.4.2-fix: WAL 回放只更新主 LSM，二级索引 LSM 未同步 →
+      // 崩溃前最后一批写入的索引缺失，重开时索引查询丢行。
+      // 恢复后全量重建所有表的二级索引（幂等）。
+      for (const tableName of this.schemas.keys()) {
+        await this.reindexTableInternal(tableName);
+      }
     }
 
     // 8. Checkpoint Manager（接入 WAL 大小阈值）
+    // v0.4.2-fix: 事务活跃时 checkpoint 不得截断 WAL —
+    // 否则 BEGIN/INSERT 记录被截断，COMMIT 后崩溃恢复丢失整个事务数据
     this.checkpointManager = new CheckpointManager(
       this.lsm,
-      this.wal,
+      {
+        checkpoint: async () => {
+          if (this.currentTxnId) return;
+          await this.wal.checkpoint();
+        },
+        flush: async () => {
+          if (this.currentTxnId) return;
+          await this.wal.flush();
+        },
+        getBufferedBytes: () => this.wal.getBufferedBytes(),
+        getBufferedCount: () => this.wal.getBufferedCount(),
+      } as unknown as WAL,
       { flushAll: async () => { await this.lsm.flush(); } } as any,
       this.config.checkpointInterval,
       this.config.walSizeThreshold,
@@ -193,12 +265,51 @@ export class AriaEngine implements IStorageEngine {
     if (!this.opened) return;
     await this.persistSchemas();
     await this.lsm.flush();
+    // v0.4.2-fix: 同步落盘全部二级索引 LSM — 此前只 flush 主 LSM，
+    // 优雅关闭后索引 memtable 未落盘 → 重开索引为空 → 索引查询返回空结果
+    for (const idxLsm of this.secondaryIndexes.values()) {
+      await idxLsm.flush();
+    }
     await this.wal.flush();
+    // v0.4.2-fix: close 前 checkpoint（截断 WAL）—
+    // 此前只 flush 不截断，下次打开会重放全部历史 WAL 记录（含已落盘 SSTable 的数据），
+    // 重复解析/重复 put 拖慢启动，并与恢复后 flush+checkpoint 竞争放大丢数据
+    await this.wal.checkpoint();
     await this.backend.close();
+    // v0.4.2-fix: 清空运行期状态（此前 close 后 mvcc/txn 残留，
+    // 重开时 beginTransaction 报 TX_ACTIVE 或读到陈旧快照）
     this.schemas.clear();
+    this.tablePKs.clear();
+    this.secondaryIndexes.clear();
+    this.mvcc = new MVCCManager();
+    this.currentTxnId = null;
+    this.txnSnapshot = null;
+    this.savepoints.clear();
+    this.opCounter = 0;
     this.opened = false;
   }
 
+  /**
+   * v0.4.2-fix: 崩溃恢复/自愈 — 校验并移除损坏 SSTable、截断 WAL、重建二级索引。
+   * 应用层检测到异常后调用，无需删库重建。
+   */
+  async repair(): Promise<void> {
+    this.ensureOpen();
+    // 1. 校验全部 SSTable，移除残缺项（打开时已做一次，此处兜底运行期损坏）
+    const removed = await this.lsm.validateAll();
+    // 2. 将 WAL 残留数据落盘并截断，避免无限重放
+    await this.lsm.flush();
+    await this.wal.checkpoint();
+    // 3. 重建所有表的二级索引（修复索引与主数据不一致）
+    for (const tableName of this.schemas.keys()) {
+      await this.reindexTable(tableName);
+    }
+    if (removed > 0) {
+      // eslint-disable-next-line no-console
+      console.warn(`[AriaEngine] repair: removed ${removed} corrupted SSTable(s)`);
+    }
+  }
+
   /**
    * v0.4.1: 重置数据库 — 清空全部数据与表结构（演示页刷新/重新初始化用）。
    * 清空存储后端、LSM、WAL、MVCC 与二级索引，后续可继续使用本实例。
@@ -224,12 +335,26 @@ export class AriaEngine implements IStorageEngine {
 
   isOpen(): boolean { return this.opened; }
 
+  // ---- v0.4.2-fix: 库内元数据（迁移版本持久化用） ----
+
+  async getMeta(key: string): Promise<string | null> {
+    const raw = await this.backend.read(`__meta_${key}`);
+    return raw ? new TextDecoder().decode(raw) : null;
+  }
+
+  async setMeta(key: string, value: string): Promise<void> {
+    await this.backend.write(`__meta_${key}`, new TextEncoder().encode(value).buffer);
+  }
+
   // =======================================================================
   //  表管理
   // =======================================================================
 
   async createTable(schema: TableSchema): Promise<void> {
     this.ensureOpen();
+    // v0.4.2-fix: Aria 事务中 DDL 显式拒绝（事务快照只覆盖行数据，
+    // 结构变更无法回滚；Memory/IndexedDB 引擎快照可回滚，行为不一致 → 明确报错而非静默）
+    this.ensureNoDDLInTransaction('CREATE TABLE');
     if (this.schemas.has(schema.name)) {
       throw new DatabaseError(`Table "${schema.name}" already exists`, 'TABLE_EXISTS');
     }
@@ -270,6 +395,7 @@ export class AriaEngine implements IStorageEngine {
 
   async dropTable(tableName: string): Promise<void> {
     this.ensureOpen();
+    this.ensureNoDDLInTransaction('DROP TABLE');
     this.ensureTable(tableName);
 
     // 删除表中所有行
@@ -279,6 +405,10 @@ export class AriaEngine implements IStorageEngine {
       this.lsm.delete(`${tableName}:${row[pkCol]}`);
     }
 
+    // v0.4.2-fix: 清理该表的全部二级索引 LSM 与持久化文件 —
+    // 此前残留孤儿索引，重建同名表后旧索引数据污染新表（索引查询返回错误行）
+    await this.cleanupTableIndexes(tableName);
+
     this.schemas.delete(tableName);
     this.tablePKs.delete(tableName);
     await this.persistSchemas();
@@ -291,6 +421,25 @@ export class AriaEngine implements IStorageEngine {
     });
   }
 
+  /**
+   * v0.4.2-fix: 清理指定表的全部二级索引 LSM（内存 + 存储文件 + meta）。
+   * dropTable / DROP_TABLE 恢复 / alterTable DROP 索引列 共用。
+   */
+  private async cleanupTableIndexes(tableName: string): Promise<void> {
+    const prefix = `${tableName}:idx:`;
+    const toDelete: string[] = [];
+    for (const [idxKey, idxLsm] of this.secondaryIndexes) {
+      if (!idxKey.startsWith(prefix)) continue;
+      toDelete.push(idxKey);
+      try {
+        await idxLsm.clear();
+      } catch { /* 清理失败不阻塞 */ }
+    }
+    for (const idxKey of toDelete) {
+      this.secondaryIndexes.delete(idxKey);
+    }
+  }
+
   async hasTable(tableName: string): Promise<boolean> {
     return this.schemas.has(tableName);
   }
@@ -421,6 +570,8 @@ export class AriaEngine implements IStorageEngine {
     let count = 0;
     // v0.3.1: 批量 WAL 写入（组提交）
     const walRecords: Omit<import('./types').WALRecord, 'lsn' | 'checksum'>[] = [];
+    // v0.4.2-fix: ON UPDATE 级联环路保护
+    const visited = new Set<string>();
 
     for (const row of rows) {
       const pkCol = this.tablePKs.get(tableName)!;
@@ -430,24 +581,48 @@ export class AriaEngine implements IStorageEngine {
         const updated = { ...row, ...updates };
         this.validateRow(schema, updated);
 
+        // v0.4.2-fix: 支持更新主键 — 删除旧键 + 落新键 + WAL 两条记录
+        const newPk = String(updated[pkCol]);
+        const pkChanged = newPk !== String(row[pkCol]);
+
+        if (pkChanged) {
+          // ON UPDATE 外键级联（RESTRICT 抛错 / CASCADE / SET NULL）
+          await this.applyForeignKeyUpdateRules(
+            tableName, String(row[pkCol]), newPk, walRecords, visited,
+          );
+        }
+
         if (this.currentTxnId && this.txnSnapshot) {
-          this.txnSnapshot.set(key, updated);
-          this.mvcc.writeVersion(tableName, String(row[pkCol]), updated, this.currentTxnId);
+          if (pkChanged) {
+            this.txnSnapshot.set(key, { __txn_deleted: true } as unknown as Record<string, unknown>);
+            this.mvcc.deleteVersion(tableName, String(row[pkCol]), this.currentTxnId);
+          }
+          this.txnSnapshot.set(`${tableName}:${newPk}`, updated);
+          this.mvcc.writeVersion(tableName, newPk, updated, this.currentTxnId);
         } else {
-          this.lsm.put(key, updated);
+          if (pkChanged) this.lsm.delete(key);
+          this.lsm.put(`${tableName}:${newPk}`, updated);
         }
         count++;
 
+        if (pkChanged) {
+          walRecords.push({
+            type: WALRecordType.DELETE,
+            txnId: this.currentTxnId ?? 0,
+            tableName,
+            key: String(row[pkCol]),
+          });
+        }
         walRecords.push({
           type: WALRecordType.UPDATE,
           txnId: this.currentTxnId ?? 0,
           tableName,
-          key: String(row[pkCol]),
+          key: newPk,
           data: updated,
         });
 
-        // 更新二级索引
-        this.updateSecondaryIndexes(tableName, String(row[pkCol]), updated, row);
+        // 更新二级索引（主键变更时旧索引条目一并清理）
+        this.updateSecondaryIndexes(tableName, newPk, updated, pkChanged ? row : null);
       }
     }
 
@@ -457,6 +632,74 @@ export class AriaEngine implements IStorageEngine {
     await this.checkpointManager.tick();
     this.trimAllCaches();
     return count;
+  }
+
+  /**
+   * v0.4.2-fix: ON UPDATE 外键级联 — 主键 oldPk → newPk 时处理引用表。
+   * RESTRICT 抛错 / CASCADE 更新 FK / SET NULL 置空（含索引与 WAL 记录）。
+   * 两阶段：先全量 RESTRICT 检查，再执行级联。
+   */
+  private async applyForeignKeyUpdateRules(
+    tableName: string,
+    oldPk: string,
+    newPk: string,
+    walRecords: Omit<import('./types').WALRecord, 'lsn' | 'checksum'>[],
+    visited: Set<string>,
+  ): Promise<void> {
+    const visitKey = `${tableName}:${oldPk}`;
+    if (visited.has(visitKey)) return;
+    visited.add(visitKey);
+
+    // 阶段 1: RESTRICT 检查
+    for (const [refTableName, refSchema] of this.schemas) {
+      if (refTableName === tableName) continue;
+      for (const [colName, colDef] of Object.entries(refSchema.columns)) {
+        if (!colDef.references || !colDef.onUpdate) continue;
+        const [refTable] = colDef.references.split('.');
+        if (refTable !== tableName) continue;
+        if (colDef.onUpdate !== 'RESTRICT') continue;
+        const refRows = await this.getAllRows(refTableName);
+        if (refRows.some((r) => String(r[colName]) === oldPk)) {
+          throw new DatabaseError(
+            `Cannot update "${tableName}" key "${oldPk}": foreign key "${colName}" in "${refTableName}" has dependent rows`,
+            'FOREIGN_KEY_VIOLATION',
+          );
+        }
+      }
+    }
+
+    // 阶段 2: CASCADE / SET NULL
+    for (const [refTableName, refSchema] of this.schemas) {
+      if (refTableName === tableName) continue;
+      for (const [colName, colDef] of Object.entries(refSchema.columns)) {
+        if (!colDef.references || !colDef.onUpdate) continue;
+        const [refTable] = colDef.references.split('.');
+        if (refTable !== tableName) continue;
+        if (colDef.onUpdate !== 'CASCADE' && colDef.onUpdate !== 'SET NULL') continue;
+        const refRows = await this.getAllRows(refTableName);
+        for (const refRow of refRows) {
+          if (String(refRow[colName]) !== oldPk) continue;
+          const refPkCol = this.tablePKs.get(refTableName)!;
+          const refPk = String(refRow[refPkCol]);
+          const updatedRef = { ...refRow, [colName]: colDef.onUpdate === 'CASCADE' ? newPk : null };
+          const refKey = `${refTableName}:${refPk}`;
+          if (this.currentTxnId && this.txnSnapshot) {
+            this.txnSnapshot.set(refKey, updatedRef);
+            this.mvcc.writeVersion(refTableName, refPk, updatedRef, this.currentTxnId);
+          } else {
+            this.lsm.put(refKey, updatedRef);
+          }
+          this.updateSecondaryIndexes(refTableName, refPk, updatedRef, refRow);
+          walRecords.push({
+            type: WALRecordType.UPDATE,
+            txnId: this.currentTxnId ?? 0,
+            tableName: refTableName,
+            key: refPk,
+            data: updatedRef,
+          });
+        }
+      }
+    }
   }
 
   async delete(tableName: string, query: QueryPlan): Promise<number> {
@@ -707,6 +950,7 @@ export class AriaEngine implements IStorageEngine {
     column: import('../../constants').ColumnDef & { name: string },
   ): Promise<void> {
     this.ensureOpen();
+    this.ensureNoDDLInTransaction('ALTER TABLE');
     this.ensureTable(tableName);
     const schema = this.schemas.get(tableName)!;
 
@@ -723,11 +967,21 @@ export class AriaEngine implements IStorageEngine {
     if (!schema.columns[column.name]) {
       throw new DatabaseError(`Column "${column.name}" does not exist in table "${tableName}"`, 'COLUMN_NOT_FOUND');
     }
+    // v0.4.2-fix: 被删列是索引列 → 先清理索引 LSM（残留会导致后续同名列索引脏数据）
+    if (schema.columns[column.name].index || schema.columns[column.name].unique) {
+      const idxKey = `${tableName}:idx:${column.name}`;
+      const idxLsm = this.secondaryIndexes.get(idxKey);
+      if (idxLsm) {
+        try {
+          await idxLsm.clear();
+        } catch { /* 清理失败不阻塞 */ }
+        this.secondaryIndexes.delete(idxKey);
+      }
+    }
     delete schema.columns[column.name];
     await this.persistSchemas();
 
     // 重写主 LSM：移除所有行的该列键（find 副本无法就地删除，必须重写存储）
-    const pkCol = this.tablePKs.get(tableName)!;
     const prefix = `${tableName}:`;
     const endKey = `${prefix}\uffff`;
     await this.lsm.prefetchRange(prefix, endKey);
@@ -757,30 +1011,30 @@ export class AriaEngine implements IStorageEngine {
 
   async createIndex(tableName: string, column: string, unique?: boolean): Promise<void> {
     this.ensureOpen();
+    this.ensureNoDDLInTransaction('CREATE INDEX');
     this.ensureTable(tableName);
     const schema = this.schemas.get(tableName)!;
     const colDef = schema.columns[column];
     if (!colDef) throw new DatabaseError(`Column "${column}" does not exist in table "${tableName}"`, 'COLUMN_NOT_FOUND');
-    if (colDef.index || colDef.unique) return; // 已存在
+    const idxKey = `${tableName}:idx:${column}`;
+    // v0.4.2-fix: 以索引 LSM 是否已建为准（schema 标记可能因重启恢复而存在，
+    // 但索引 LSM 未恢复 → 此前静默 return 导致索引永久缺失）
+    if (this.secondaryIndexes.has(idxKey)) return;
     colDef.index = true;
     if (unique) colDef.unique = true;
 
-    const idxKey = `${tableName}:idx:${column}`;
-    if (!this.secondaryIndexes.has(idxKey)) {
-      const idxLsm = new LSM({
-        memtableSizeThreshold: this.config.memtableSizeThreshold,
-        levelSizeMultiplier: this.config.levelSizeMultiplier,
-        blockSize: this.config.pageSize,
-        bloomBitsPerKey: this.config.bloomFilterBitsPerKey,
-        cacheLimitBytes: this.config.bufferPoolPages * this.config.pageSize,
-        sstableStore: this.createSSTableStore(`idx_${tableName}_${column}`),
-      });
-      await idxLsm.init();
-      this.secondaryIndexes.set(idxKey, idxLsm);
-    }
+    const idxLsm = new LSM({
+      memtableSizeThreshold: this.config.memtableSizeThreshold,
+      levelSizeMultiplier: this.config.levelSizeMultiplier,
+      blockSize: this.config.pageSize,
+      bloomBitsPerKey: this.config.bloomFilterBitsPerKey,
+      cacheLimitBytes: this.config.bufferPoolPages * this.config.pageSize,
+      sstableStore: this.createSSTableStore(`idx_${tableName}_${column}`),
+    });
+    await idxLsm.init();
+    this.secondaryIndexes.set(idxKey, idxLsm);
 
     // 从主 LSM 重建索引数据
-    const idxLsm = this.secondaryIndexes.get(idxKey)!;
     const pkCol = this.tablePKs.get(tableName)!;
     const rows = await this.getAllRows(tableName);
     for (const row of rows) {
@@ -795,6 +1049,7 @@ export class AriaEngine implements IStorageEngine {
 
   async dropIndex(tableName: string, column: string, _indexName?: string): Promise<void> {
     this.ensureOpen();
+    this.ensureNoDDLInTransaction('DROP INDEX');
     this.ensureTable(tableName);
     const schema = this.schemas.get(tableName)!;
     const colDef = schema.columns[column];
@@ -1185,6 +1440,8 @@ export class AriaEngine implements IStorageEngine {
    */
   private async applyDropTableRecovery(tableName: string): Promise<void> {
     if (!tableName) return;
+    // v0.4.2-fix: 清理该表二级索引（崩溃恢复路径同样不留孤儿索引）
+    await this.cleanupTableIndexes(tableName);
     this.schemas.delete(tableName);
     this.tablePKs.delete(tableName);
 
@@ -1442,7 +1699,13 @@ export class AriaEngine implements IStorageEngine {
   async reindexTable(tableName: string): Promise<number> {
     this.ensureOpen();
     this.ensureTable(tableName);
-    const schema = this.schemas.get(tableName)!;
+    return this.reindexTableInternal(tableName);
+  }
+
+  /** v0.4.2-fix: 重建索引内部实现（不校验 opened，供 open 恢复流程调用） */
+  private async reindexTableInternal(tableName: string): Promise<number> {
+    const schema = this.schemas.get(tableName);
+    if (!schema) return 0;
     let rebuiltCount = 0;
 
     for (const [colName, colDef] of Object.entries(schema.columns)) {
@@ -1482,7 +1745,7 @@ export class AriaEngine implements IStorageEngine {
       }
     }
     // GC MVCC 版本（保留最新 10 个）
-    const beforeGC = this.mvcc.getActiveTxnCount?.() ?? 0;
+    const beforeGC = this.mvcc.getGlobalLSN();
     this.mvcc.gc(10);
     return { compactedLevels: 6, gcVersions: beforeGC };
   }
@@ -1525,6 +1788,16 @@ export class AriaEngine implements IStorageEngine {
     if (!this.opened) throw new DatabaseError('AriaEngine not opened', 'DB_NOT_OPEN');
   }
 
+  /** v0.4.2-fix: Aria 事务中 DDL 显式拒绝（结构变更无法通过行快照回滚） */
+  private ensureNoDDLInTransaction(op: string): void {
+    if (this.currentTxnId) {
+      throw new DatabaseError(
+        `${op} is not supported inside a transaction (AriaEngine DDL is not transactional)`,
+        'NOT_SUPPORTED',
+      );
+    }
+  }
+
   private ensureTable(tableName: string): void {
     if (!this.schemas.has(tableName)) {
       throw new DatabaseError(`Table "${tableName}" does not exist`, 'TABLE_NOT_FOUND');

src/engine/aria/index/lsm.ts

@@ -69,6 +69,8 @@ export class LSM {
   private cacheLimitBytes: number;
   private levelSizeMultiplier: number;
   private blockSize: number;
+  /** v0.4.2-fix: 配置的 memtable 阈值（freeze 后新 memtable 用配置值，不衰减） */
+  private memtableSizeThreshold: number;
   private sstableStore: SSTableStore;
   private operationCount = 0;
   private initialized = false;
@@ -77,7 +79,8 @@ export class LSM {
   private flushChain: Promise<void> = Promise.resolve();
 
   constructor(config: LSMConfig) {
-    this.memtable = new MemTable(config.memtableSizeThreshold ?? DEFAULT_MEMTABLE_SIZE);
+    this.memtableSizeThreshold = config.memtableSizeThreshold ?? DEFAULT_MEMTABLE_SIZE;
+    this.memtable = new MemTable(this.memtableSizeThreshold);
     this.levelSizeMultiplier = config.levelSizeMultiplier ?? DEFAULT_LEVEL_SIZE_MULTIPLIER;
     this.blockSize = config.blockSize ?? 4096;
     this.sstableStore = config.sstableStore;
@@ -97,8 +100,17 @@ export class LSM {
 
     const metas = await this.sstableStore.listMeta();
 
-    // 按层级分组
+    // v0.4.2-fix: 打开时完整性校验 — 验证每个 meta 引用的文件存在、可解析，
+    // 残缺/损坏的 SSTable 忽略并清理 meta，避免后续读取抛 RangeError 崩溃
+    const validMetas: SSTableMeta[] = [];
     for (const meta of metas) {
+      if (await this.validateSSTable(meta)) {
+        validMetas.push(meta);
+      }
+    }
+
+    // 按层级分组
+    for (const meta of validMetas) {
       if (meta.level >= 0 && meta.level < MAX_LSM_LEVELS) {
         this.levels[meta.level].push(meta);
       }
@@ -157,15 +169,30 @@ export class LSM {
    * 冻结当前 MemTable 为 immutable，并在串行链上排队异步刷盘。
    * 冻结的 MemTable 通过闭包捕获，避免链中前一个 flush 错误处理后续冻结的表。
    * 所有 pending frozen 记录在 frozenMemtables 中，flush 完成前读取路径仍可访问。
+   *
+   * v0.4.2-fix: 链上任务失败时吞错恢复链（否则 flushChain 永久 rejected，
+   * 后续所有 flush/compaction 挂起，写路径卡死）。
    */
   freezeMemtable(): void {
     if (this.immutableMemtable) {
       const frozen = this.immutableMemtable;
-      this.flushChain = this.flushChain.then(() => this.flushImmutableAsync(frozen));
+      this.flushChain = this.enqueueOnChain(() => this.flushImmutableAsync(frozen));
     }
     this.immutableMemtable = this.memtable;
     this.frozenMemtables.push(this.immutableMemtable);
-    this.memtable = new MemTable(this.memtable.getEstimatedSize());
+    // v0.4.2-fix: 新 memtable 用配置阈值（此前传旧表已用大小 → 阈值逐次衰减 → 频繁小文件 flush）
+    this.memtable = new MemTable(this.memtableSizeThreshold);
+  }
+
+  /** v0.4.2-fix: 在串行链上排队任务；任务失败吞错并记录，保证链不被单次失败卡死 */
+  private enqueueOnChain(task: () => Promise<void>): Promise<void> {
+    return this.flushChain
+      .then(task)
+      .catch((error) => {
+        // eslint-disable-next-line no-console
+        console.warn('[AriaEngine LSM] background flush/compaction failed:', error);
+        // catch 返回 undefined → 链恢复为 resolved，后续任务继续
+      });
   }
 
   /** 将指定 Immutable MemTable 刷盘为 SSTable（id 由 store 按命名空间分配） */
@@ -218,7 +245,7 @@ export class LSM {
     this.compacting = true;
     setTimeout(() => {
       try {
-        this.flushChain = this.flushChain.then(() => this.compactLevelAsync(level));
+        this.flushChain = this.enqueueOnChain(() => this.compactLevelAsync(level));
       } finally {
         this.compacting = false;
         // 连续触发：如果 compaction 后仍然超标，继续调度
@@ -243,6 +270,10 @@ export class LSM {
       } finally {
         this.compacting = false;
       }
+    }).catch((error) => {
+      this.compacting = false;
+      // eslint-disable-next-line no-console
+      console.warn('[AriaEngine LSM] background compaction failed:', error);
     });
   }
 
@@ -396,29 +427,64 @@ export class LSM {
   //  Compaction
   // =======================================================================
 
-  /** 执行 Compaction（public，供 VACUUM 等外部调用） */
+  /** 执行 Compaction（public，供 VACUUM 等外部调用；VACUUM 期望 2 个文件即可压缩） */
   async compactLevel(level: number): Promise<void> {
-    await this.compactLevelAsync(level);
+    await this.compactLevelAsync(level, 2);
   }
 
-  /** 串行执行 Compaction（简化版，内部实现） */
-  private async compactLevelAsync(level: number): Promise<void> {
+  /**
+   * 串行执行 Compaction。
+   * @param minFiles 触发压缩的文件数门槛（自动调度用 4，VACUUM 用 2）
+   *
+   * v0.4.2-fix: 读取从存储兜底（不依赖缓存）——此前仅从缓存读，
+   * 缓存未命中（LRU 驱逐/单文件超缓存上限）时跳过全部文件并从 levels 移除，
+   * 运行中数据全部不可见。
+   */
+  private async compactLevelAsync(level: number, minFiles: number = 4): Promise<void> {
     if (level >= MAX_LSM_LEVELS - 1) return;
-    if (this.levels[level].length < 4) return;
+    if (this.levels[level].length < minFiles) return;
 
     const sstables = this.levels[level].splice(0, this.levels[level].length);
     const mergeIter = new MergeIterator();
+    const loadedMetas: SSTableMeta[] = [];
 
     for (const meta of sstables) {
-      const reader = this.loadSSTableReader(meta);
-      if (!reader) continue;
+      // 优先缓存，未命中则从存储加载（残缺文件经校验清理，跳过）
+      let data: Uint8Array | null = this.sstableCache.get(meta.id) ?? null;
+      if (!data) {
+        try {
+          data = await this.sstableStore.load(meta.id);
+        } catch {
+          data = null;
+        }
+      }
+      if (!data || data.byteLength < 32) {
+        await this.dropInvalidSSTable(meta);
+        continue;
+      }
+      let reader: SSTableReader;
+      try {
+        reader = new SSTableReader(data, meta);
+      } catch {
+        await this.dropInvalidSSTable(meta);
+        continue;
+      }
       const entries: [string, Record<string, unknown>][] = [];
       reader.scanAll((k, v) => entries.push([k, v]));
       mergeIter.addSource(new ArrayEntrySource(entries));
+      loadedMetas.push(meta);
     }
 
     const merged = mergeIter.drain();
-    if (merged.length === 0) return;
+    if (merged.length === 0) {
+      // 没有有效数据（全部损坏）：把有效 meta 放回 levels，
+      // 避免文件从读取路径消失（数据仍在磁盘，重启可恢复）
+      for (const meta of loadedMetas) {
+        this.levels[level].push(meta);
+      }
+      this.levels[level].sort((a, b) => b.id - a.id);
+      return;
+    }
 
     const id = await this.sstableStore.allocateId();
     const builder = new SSTableBuilder(this.blockSize);
@@ -505,6 +571,69 @@ export class LSM {
   //  内部
   // =======================================================================
 
+  /**
+   * v0.4.2-fix: 重新校验全部已加载 SSTable，移除损坏项（repair 自愈用）。
+   * @returns 移除的损坏 SSTable 数量
+   */
+  async validateAll(): Promise<number> {
+    let removed = 0;
+    for (let level = 0; level < MAX_LSM_LEVELS; level++) {
+      const valid: SSTableMeta[] = [];
+      for (const meta of this.levels[level]) {
+        if (await this.validateSSTable(meta)) {
+          valid.push(meta);
+        } else {
+          this.sstableCache.delete(meta.id);
+          removed++;
+        }
+      }
+      this.levels[level] = valid;
+    }
+    return removed;
+  }
+
+  /**
+   * v0.4.2-fix: 校验单个 SSTable 的完整性。
+   * - 文件不存在 → 清理 meta，返回 false
+   * - 文件过小/魔数错误/索引越界（残缺写入产物）→ 清理 meta，返回 false
+   * 校验通过的数据不缓存（保持内存预算），读路径按需预加载。
+   */
+  private async validateSSTable(meta: SSTableMeta): Promise<boolean> {
+    try {
+      const data = await this.sstableStore.load(meta.id);
+      if (!data) {
+        this.dropInvalidSSTable(meta);
+        return false;
+      }
+      if (data.byteLength < 32) {
+        this.dropInvalidSSTable(meta);
+        return false;
+      }
+      try {
+        new SSTableReader(data, meta);
+      } catch {
+        this.dropInvalidSSTable(meta);
+        return false;
+      }
+      return true;
+    } catch {
+      this.dropInvalidSSTable(meta);
+      return false;
+    }
+  }
+
+  /** 清理无效 SSTable 的 meta 与文件（打开自愈路径） */
+  private async dropInvalidSSTable(meta: SSTableMeta): Promise<void> {
+    // eslint-disable-next-line no-console
+    console.warn(`[AriaEngine LSM] Skipping corrupted SSTable id=${meta.id} (level=${meta.level})`);
+    try {
+      await this.sstableStore.deleteMeta(meta.id);
+    } catch { /* 清理失败不阻塞打开 */ }
+    try {
+      await this.sstableStore.delete(meta.id);
+    } catch { /* 清理失败不阻塞打开 */ }
+  }
+
   private unwrapTombstone(value: Record<string, unknown> | null): Record<string, unknown> | null {
     if (!value) return null;
     if ((value as unknown as Record<string, unknown>).__tombstone) return null;

src/engine/aria/index/sstable.ts

@@ -40,11 +40,9 @@ export class SSTableReader {
     if (blockIdx < 0) return null;
 
     const entry = this.indexEntries[blockIdx];
-    const blockData = new Uint8Array(
-      this.data.buffer,
-      this.data.byteOffset + entry.blockOffset,
-      entry.blockSize,
-    );
+    const blockData = this.getBlockData(entry);
+    // v0.4.2-fix: 残缺文件（meta 偏移超出实际长度）跳过该块，而非抛 RangeError
+    if (!blockData) return null;
     const blockView = new DataView(blockData.buffer, blockData.byteOffset, blockData.byteLength);
 
     const entryCount = blockView.getUint32(0, false);
@@ -52,12 +50,15 @@ export class SSTableReader {
 
     // 顺序扫描 block 内的条目（生产中应二分查找）
     for (let i = 0; i < entryCount; i++) {
+      if (offset + 2 > blockData.byteLength) break;
       const keyLen = blockView.getUint16(offset, false);
       offset += 2;
+      if (offset + keyLen + 2 > blockData.byteLength) break;
       const key = new TextDecoder().decode(blockData.slice(offset, offset + keyLen));
       offset += keyLen;
       const valLen = blockView.getUint16(offset, false);
       offset += 2;
+      if (offset + valLen > blockData.byteLength) break;
       const valBytes = blockData.slice(offset, offset + valLen);
       offset += valLen;
 
@@ -86,23 +87,24 @@ export class SSTableReader {
 
     for (let bi = startBlockIdx; bi <= endBlockIdx && bi >= 0; bi++) {
       const entry = this.indexEntries[bi];
-      const blockData = new Uint8Array(
-        this.data.buffer,
-        this.data.byteOffset + entry.blockOffset,
-        entry.blockSize,
-      );
+      const blockData = this.getBlockData(entry);
+      // v0.4.2-fix: 残缺块跳过（rangeScan 继续后续块，不抛异常）
+      if (!blockData) continue;
       const blockView = new DataView(blockData.buffer, blockData.byteOffset, blockData.byteLength);
 
       const blockEntryCount = blockView.getUint32(0, false);
       let offset = 4;
 
       for (let i = 0; i < blockEntryCount; i++) {
+        if (offset + 2 > blockData.byteLength) break;
         const keyLen = blockView.getUint16(offset, false);
         offset += 2;
+        if (offset + keyLen + 2 > blockData.byteLength) break;
         const key = new TextDecoder().decode(blockData.slice(offset, offset + keyLen));
         offset += keyLen;
         const valLen = blockView.getUint16(offset, false);
         offset += 2;
+        if (offset + valLen > blockData.byteLength) break;
         const valBytes = blockData.slice(offset, offset + valLen);
         offset += valLen;
 
@@ -121,23 +123,24 @@ export class SSTableReader {
   /** 扫描所有条目 */
   scanAll(callback: (key: string, value: Record<string, unknown>) => void): void {
     for (const entry of this.indexEntries) {
-      const blockData = new Uint8Array(
-        this.data.buffer,
-        this.data.byteOffset + entry.blockOffset,
-        entry.blockSize,
-      );
+      const blockData = this.getBlockData(entry);
+      // v0.4.2-fix: 残缺块跳过（scanAll 继续后续块，不抛异常）
+      if (!blockData) continue;
       const blockView = new DataView(blockData.buffer, blockData.byteOffset, blockData.byteLength);
 
       const blockEntryCount = blockView.getUint32(0, false);
       let offset = 4;
 
       for (let i = 0; i < blockEntryCount; i++) {
+        if (offset + 2 > blockData.byteLength) break;
         const keyLen = blockView.getUint16(offset, false);
         offset += 2;
+        if (offset + keyLen + 2 > blockData.byteLength) break;
         const key = new TextDecoder().decode(blockData.slice(offset, offset + keyLen));
         offset += keyLen;
         const valLen = blockView.getUint16(offset, false);
         offset += 2;
+        if (offset + valLen > blockData.byteLength) break;
         const valBytes = blockData.slice(offset, offset + valLen);
         offset += valLen;
 
@@ -185,6 +188,11 @@ export class SSTableReader {
     const bloomHashCount = this.view.getUint32(footerOffset + 16, false);
     this.entryCount = this.view.getUint32(footerOffset + 20, false);
 
+    // v0.4.2-fix: 完整性校验 — 索引块必须完全落在文件内，否则视为残缺文件跳过
+    if (indexOffset + 4 > this.data.byteLength || indexOffset + indexSize > this.data.byteLength) {
+      return; // 残缺文件：无索引块可读，get/rangeScan 均返回空
+    }
+
     // 解析索引块
     this.parseIndexBlock(indexOffset, indexSize);
 
@@ -204,8 +212,12 @@ export class SSTableReader {
     offset += 4;
 
     for (let i = 0; i < entryCount; i++) {
+      // v0.4.2-fix: 索引条目越界（keyLen/blockOffset/blockSize 超过文件长度）时中止解析，
+      // 已解析的有效条目仍可用于查询
+      if (offset + 2 > this.data.byteLength) break;
       const keyLen = this.view.getUint16(offset, false);
       offset += 2;
+      if (offset + keyLen + 8 > this.data.byteLength) break;
       const key = new TextDecoder().decode(this.data.slice(offset, offset + keyLen));
       offset += keyLen;
       const blockOffset = this.view.getUint32(offset, false);
@@ -213,10 +225,27 @@ export class SSTableReader {
       const blockSize = this.view.getUint32(offset, false);
       offset += 4;
 
+      // 跳过指向文件外的块（残缺写入产物），不抛异常
+      if (blockSize === 0 || blockOffset + blockSize > this.data.byteLength) continue;
+
       this.indexEntries.push({ key, blockOffset, blockSize });
     }
   }
 
+  /**
+   * v0.4.2-fix: 获取索引条目对应的数据块。
+   * 块偏移/大小越界（残缺 SSTable）时返回 null，由调用方跳过而非抛 RangeError。
+   */
+  private getBlockData(entry: IndexEntry): Uint8Array | null {
+    if (entry.blockSize <= 0 || entry.blockOffset < 0) return null;
+    if (entry.blockOffset + entry.blockSize > this.data.byteLength) return null;
+    return new Uint8Array(
+      this.data.buffer,
+      this.data.byteOffset + entry.blockOffset,
+      entry.blockSize,
+    );
+  }
+
   /** 二分查找某 key 所在的 block 索引 */
   private locateBlock(key: string): number {
     let lo = 0;

src/engine/aria/store/backend.ts

@@ -23,8 +23,17 @@ export interface IStorageBackend {
   read(key: string): Promise<ArrayBuffer | null>;
   /** 写入数据块 */
   write(key: string, data: ArrayBuffer): Promise<void>;
+  /**
+   * 批量原子写入（v0.4.2-fix）：多个 key 在单个底层事务中提交，
+   * 中断时整体回滚，不留半写状态。WAL count 与记录同事务保证一致性。
+   */
+  writeMany(entries: Record<string, ArrayBuffer>): Promise<void>;
   /** 删除数据块 */
   delete(key: string): Promise<void>;
+  /**
+   * 批量原子删除（v0.4.2-fix）：多个 key 在单个底层事务中提交。
+   */
+  deleteMany(keys: string[]): Promise<void>;
   /** 列出所有 key */
   listKeys(): Promise<string[]>;
   /** 检查 key 是否存在 */
@@ -91,6 +100,25 @@ export class IndexedDBBackend implements IStorageBackend {
     });
   }
 
+  /**
+   * v0.4.2-fix: 批量原子写入 — 单个 IDB 事务内写入多个 key。
+   * 中断时事务整体回滚，WAL 记录与 count 计数不会出现"记录在、计数丢"或反之的半写状态。
+   */
+  async writeMany(entries: Record<string, ArrayBuffer>): Promise<void> {
+    const keys = Object.keys(entries);
+    if (keys.length === 0) return;
+    const db = this.ensureDB();
+    return new Promise((resolve, reject) => {
+      const tx = db.transaction(this.storeName, 'readwrite');
+      const store = tx.objectStore(this.storeName);
+      for (const key of keys) {
+        store.put(entries[key], key);
+      }
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(new DatabaseError('Failed to batch write to AriaEngine store', 'ARIA_WRITE_ERROR'));
+    });
+  }
+
   async delete(key: string): Promise<void> {
     const db = this.ensureDB();
     return new Promise((resolve, reject) => {
@@ -101,6 +129,21 @@ export class IndexedDBBackend implements IStorageBackend {
     });
   }
 
+  /** v0.4.2-fix: 批量原子删除 — 单个 IDB 事务内删除多个 key */
+  async deleteMany(keys: string[]): Promise<void> {
+    if (keys.length === 0) return;
+    const db = this.ensureDB();
+    return new Promise((resolve, reject) => {
+      const tx = db.transaction(this.storeName, 'readwrite');
+      const store = tx.objectStore(this.storeName);
+      for (const key of keys) {
+        store.delete(key);
+      }
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(new DatabaseError('Failed to batch delete from AriaEngine store', 'ARIA_DELETE_ERROR'));
+    });
+  }
+
   async listKeys(): Promise<string[]> {
     const db = this.ensureDB();
     return new Promise((resolve, reject) => {
@@ -161,10 +204,22 @@ export class MemoryBackend implements IStorageBackend {
     this.store.set(key, data);
   }
 
+  async writeMany(entries: Record<string, ArrayBuffer>): Promise<void> {
+    for (const [key, data] of Object.entries(entries)) {
+      this.store.set(key, data);
+    }
+  }
+
   async delete(key: string): Promise<void> {
     this.store.delete(key);
   }
 
+  async deleteMany(keys: string[]): Promise<void> {
+    for (const key of keys) {
+      this.store.delete(key);
+    }
+  }
+
   async listKeys(): Promise<string[]> {
     return Array.from(this.store.keys());
   }

src/engine/aria/store/opfs_backend.ts

@@ -52,6 +52,20 @@ export class OPFSBackend implements IStorageBackend {
     return this.writeQueue;
   }
 
+  /** v0.4.2-fix: 批量写入 — 串行队列内逐个落盘（OPFS 无跨文件事务，顺序保证一致） */
+  async writeMany(entries: Record<string, ArrayBuffer>): Promise<void> {
+    if (!this.dbDir) return;
+    this.writeQueue = this.writeQueue.then(async () => {
+      for (const [key, data] of Object.entries(entries)) {
+        const fh = await this.dbDir!.getFileHandle(key, { create: true });
+        const writable = await fh.createWritable();
+        await writable.write(data);
+        await writable.close();
+      }
+    });
+    return this.writeQueue;
+  }
+
   async delete(key: string): Promise<void> {
     if (!this.dbDir) return;
     this.writeQueue = this.writeQueue.then(async () => {
@@ -60,6 +74,17 @@ export class OPFSBackend implements IStorageBackend {
     return this.writeQueue;
   }
 
+  /** v0.4.2-fix: 批量删除 — 串行队列内逐个删除 */
+  async deleteMany(keys: string[]): Promise<void> {
+    if (!this.dbDir) return;
+    this.writeQueue = this.writeQueue.then(async () => {
+      for (const key of keys) {
+        try { await this.dbDir!.removeEntry(key); } catch { /* ignore */ }
+      }
+    });
+    return this.writeQueue;
+  }
+
   async listKeys(): Promise<string[]> {
     if (!this.dbDir) return [];
     const keys: string[] = [];

src/engine/aria/transaction/mvcc.ts

@@ -26,6 +26,12 @@ export class MVCCManager {
   /** 全局提交序列号（用于可见性判断） */
   private globalCommitLsn = 0;
 
+  /**
+   * v0.4.2-fix: 每个事务写入的 tableKey 集合 —
+   * commit/rollback 只遍历本事务写过的 key，避免全库版本链扫描（大表事务 O(N) → O(写入数)）
+   */
+  private txnWriteKeys: Map<number, Set<string>> = new Map();
+
   // =======================================================================
   //  事务管理
   // =======================================================================
@@ -39,6 +45,7 @@ export class MVCCManager {
       snapshotLsn: this.globalCommitLsn,
       startTime: Date.now(),
     });
+    this.txnWriteKeys.set(txnId, new Set());
     return txnId;
   }
 
@@ -50,17 +57,23 @@ export class MVCCManager {
     txn.state = TransactionState.COMMITTED;
     this.globalCommitLsn++;
 
-    // 标记此事务写入的所有版本为已提交
-    for (const [, versions] of this.versionStore) {
-      for (const version of versions) {
-        if (version.txnId === txnId) {
-          version.committed = true;
+    // v0.4.2-fix: 仅标记本事务写入的版本（此前遍历全库 versionStore）
+    const writeKeys = this.txnWriteKeys.get(txnId);
+    if (writeKeys) {
+      for (const tableKey of writeKeys) {
+        const versions = this.versionStore.get(tableKey);
+        if (!versions) continue;
+        for (const version of versions) {
+          if (version.txnId === txnId) {
+            version.committed = true;
+          }
         }
       }
     }
 
     // 清理已提交事务的记录
     this.activeTxns.delete(txnId);
+    this.txnWriteKeys.delete(txnId);
   }
 
   /** 回滚事务 */
@@ -70,17 +83,23 @@ export class MVCCManager {
 
     txn.state = TransactionState.ABORTED;
 
-    // 移除此事务写入的所有版本
-    for (const [tableKey, versions] of this.versionStore) {
-      const filtered = versions.filter((v) => v.txnId !== txnId);
-      if (filtered.length === 0) {
-        this.versionStore.delete(tableKey);
-      } else {
-        this.versionStore.set(tableKey, filtered);
+    // v0.4.2-fix: 仅移除本事务写入的版本（此前遍历全库 versionStore）
+    const writeKeys = this.txnWriteKeys.get(txnId);
+    if (writeKeys) {
+      for (const tableKey of writeKeys) {
+        const versions = this.versionStore.get(tableKey);
+        if (!versions) continue;
+        const filtered = versions.filter((v) => v.txnId !== txnId);
+        if (filtered.length === 0) {
+          this.versionStore.delete(tableKey);
+        } else {
+          this.versionStore.set(tableKey, filtered);
+        }
       }
     }
 
     this.activeTxns.delete(txnId);
+    this.txnWriteKeys.delete(txnId);
   }
 
   /** 检查事务是否活跃 */
@@ -114,6 +133,8 @@ export class MVCCManager {
 
     versions.push(newVersion);
     this.versionStore.set(tableKey, versions);
+    // v0.4.2-fix: 记录本事务写过的 key（commit/rollback 精准清理）
+    this.txnWriteKeys.get(txnId)?.add(tableKey);
   }
 
   /**
@@ -186,9 +207,14 @@ export class MVCCManager {
   /**
    * v0.3.3: 丢弃指定事务的所有版本记录，但保留事务登记（Savepoint 回滚用）。
    * 快照数据由调用方（引擎 txnSnapshot）负责恢复。
+   * v0.4.2-fix: 仅遍历本事务写过的 key（此前全库扫描）。
    */
   discardVersions(txnId: number): void {
-    for (const [tableKey, versions] of this.versionStore) {
+    const writeKeys = this.txnWriteKeys.get(txnId);
+    if (!writeKeys) return;
+    for (const tableKey of writeKeys) {
+      const versions = this.versionStore.get(tableKey);
+      if (!versions) continue;
       const filtered = versions.filter((v) => v.txnId !== txnId);
       if (filtered.length === 0) {
         this.versionStore.delete(tableKey);

src/engine/indexeddb.ts

@@ -23,31 +23,160 @@ export class IndexedDBEngine implements IStorageEngine {
   private txActive = false;
 
   async open(dbName: string, version: number): Promise<void> {
-    this.dbName = dbName; this.version = version;
-    await this.memoryCache.open(dbName, version);
+    // v0.4.2-fix (P0-3): version < 1 归一化为 1（indexedDB.open(name, 0) 抛原生 TypeError）
+    const normalizedVersion = version >= 1 ? Math.floor(version) : 1;
+    this.dbName = dbName;
+    this.version = normalizedVersion;
+    await this.memoryCache.open(dbName, normalizedVersion);
+
+    // v0.4.2-fix (P0-2/P2-8): 版本自适应打开 + blocked 重试
+    this.db = await this.openDatabaseWithRetry(dbName, normalizedVersion);
+    this.setupVersionChangeHandler();
+
+    // v0.4.2-fix (P2-7): 确保 schema/meta 持久化 store 存在（新库或旧库升级时创建），
+    // 否则迁移版本等库内元数据无处落盘
+    await this.ensureSchemaStore();
+
+    try {
+      // v0.3.2: reopen 后从 IDB 重建 schema（schema 此前只存内存缓存，重开连接即丢失）
+      await this.rebuildSchemaFromIDB();
+    } catch (error) {
+      throw new DatabaseError(`Failed to restore schema for "${dbName}"`, 'IDB_SCHEMA_RESTORE_ERROR', error);
+    }
+  }
+
+  /** v0.4.2-fix: 多标签页冲突处理 — 其他标签页升级版本时自动关闭当前连接 */
+  private setupVersionChangeHandler(): void {
+    if (!this.db) return;
+    this.db.onversionchange = () => {
+      if (this.db) {
+        this.db.close();
+        this.db = null;
+        // eslint-disable-next-line no-console
+        console.warn(`[metona-sqlark] Database "${this.dbName}" was upgraded in another tab. Connection closed. Please re-open.`);
+      }
+    };
+  }
+
+  /**
+   * v0.4.2-fix: 打开 IndexedDB 连接。
+   * - P0-2: 请求版本低于库实际版本（VersionError）时，先无版本参数探测库当前版本，
+   *   再以实际版本重开（建表每张表版本号 +1，config.version 会过期）
+   * - P2-8: onblocked 为瞬时状态（另一连接短暂持有），等待后重试多次，超时才抛 IDB_BLOCKED
+   */
+  private async openDatabaseWithRetry(dbName: string, requestedVersion: number): Promise<IDBDatabase> {
+    const BLOCKED_RETRIES = 10;
+    let effectiveVersion = requestedVersion;
+    for (let attempt = 0; attempt < BLOCKED_RETRIES; attempt++) {
+      try {
+        return await this.openRequest(dbName, effectiveVersion, 200 + attempt * 150);
+      } catch (error) {
+        const err = error as { name?: string };
+        if (err && err.name === 'VersionError') {
+          const currentVersion = await this.resolveCurrentVersion(dbName);
+          if (currentVersion >= 1 && currentVersion !== effectiveVersion) {
+            effectiveVersion = currentVersion;
+            this.version = currentVersion;
+            continue;
+          }
+          throw new DatabaseError(
+            `Failed to open IndexedDB "${dbName}": version mismatch`,
+            'IDB_VERSION_ERROR',
+            error,
+          );
+        }
+        if (err && err.name === 'BlockedError') {
+          // 另一连接短暂持有 → 等待后重试
+          await new Promise((resolve) => setTimeout(resolve, 50 * (attempt + 1)));
+          continue;
+        }
+        throw new DatabaseError(`Failed to open IndexedDB "${dbName}"`, 'IDB_OPEN_ERROR', error);
+      }
+    }
+    throw new DatabaseError(`IndexedDB "${dbName}" is blocked`, 'IDB_BLOCKED');
+  }
+
+  /**
+   * 发起一次 indexedDB.open 请求（success/error/blocked 三态收敛）。
+   * onblocked 不立即失败：阻塞解除后 success 仍会触发，仅超时兜底判失败，
+   * 避免"拒绝后连接迟到成功"泄漏未关闭的数据库连接。
+   */
+  private openRequest(dbName: string, version: number, timeoutMs: number): Promise<IDBDatabase> {
     return new Promise((resolve, reject) => {
       const request = indexedDB.open(dbName, version);
-      request.onsuccess = async () => {
-        this.db = request.result;
-        // 多标签页冲突处理：其他标签页升级版本时自动关闭当前连接
-        this.db.onversionchange = () => {
-          if (this.db) {
-            this.db.close();
-            this.db = null;
-            // eslint-disable-next-line no-console
-            console.warn(`[metona-sqlark] Database "${dbName}" was upgraded in another tab. Connection closed. Please re-open.`);
-          }
-        };
-        try {
-          // v0.3.2: reopen 后从 IDB 重建 schema（schema 此前只存内存缓存，重开连接即丢失）
-          await this.rebuildSchemaFromIDB();
-          resolve();
-        } catch (error) {
-          reject(new DatabaseError(`Failed to restore schema for "${dbName}"`, 'IDB_SCHEMA_RESTORE_ERROR', error));
+      let settled = false;
+      const timeout = setTimeout(() => {
+        if (settled) return;
+        settled = true;
+        // 兼容无 DOMException 构造环境
+        const blockedError = typeof DOMException !== 'undefined'
+          ? new DOMException('IndexedDB open is blocked', 'BlockedError')
+          : Object.assign(new Error('IndexedDB open is blocked'), { name: 'BlockedError' });
+        reject(blockedError);
+      }, timeoutMs);
+      request.onsuccess = () => {
+        if (settled) {
+          // 超时判失败后连接迟到成功：立即关闭，避免阻塞后续版本升级
+          request.result.close();
+          return;
+        }
+        settled = true;
+        clearTimeout(timeout);
+        resolve(request.result);
+      };
+      request.onerror = () => {
+        if (settled) return;
+        settled = true;
+        clearTimeout(timeout);
+        reject(request.error ?? new Error('Unknown IndexedDB open error'));
+      };
+      request.onblocked = () => {
+        // 保持等待，不拒绝（阻塞解除后 success 会触发；超时由 timer 兜底）
+      };
+    });
+  }
+
+  /** 无版本参数打开库，解析其当前实际版本号（随后立即关闭） */
+  private resolveCurrentVersion(dbName: string): Promise<number> {
+    return new Promise((resolve, reject) => {
+      const request = indexedDB.open(dbName);
+      request.onsuccess = () => {
+        const actualVersion = request.result.version;
+        request.result.close();
+        resolve(actualVersion);
+      };
+      request.onerror = () => {
+        reject(request.error ?? new Error('Failed to resolve IndexedDB version'));
+      };
+    });
+  }
+
+  /**
+   * v0.4.2-fix (P2-7): 确保 __metona_schema store 存在。
+   * 新库（或版本升级前创建的旧库）没有该 store 时，通过一次版本升级创建，
+   * 使 getMeta/setMeta（迁移版本持久化）始终可用。
+   */
+  private async ensureSchemaStore(): Promise<void> {
+    if (!this.db) return;
+    if (this.db.objectStoreNames.contains('__metona_schema')) return;
+    const newVersion = this.db.version + 1;
+    this.db.close();
+    this.db = await new Promise<IDBDatabase>((resolve, reject) => {
+      const request = indexedDB.open(this.dbName, newVersion);
+      request.onupgradeneeded = () => {
+        const idb = request.result;
+        if (!idb.objectStoreNames.contains('__metona_schema')) {
+          idb.createObjectStore('__metona_schema', { keyPath: 'name' });
         }
       };
-      request.onerror = () => reject(new DatabaseError(`Failed to open IndexedDB "${dbName}"`, 'IDB_OPEN_ERROR', request.error));
-      request.onblocked = () => reject(new DatabaseError(`IndexedDB "${dbName}" is blocked`, 'IDB_BLOCKED'));
+      request.onsuccess = () => {
+        this.db = request.result;
+        this.setupVersionChangeHandler();
+        resolve(request.result);
+      };
+      request.onerror = () => reject(
+        new DatabaseError('Failed to create schema store', 'IDB_UPGRADE_ERROR', request.error),
+      );
     });
   }
 
@@ -130,6 +259,84 @@ export class IndexedDBEngine implements IStorageEngine {
     await this.memoryCache.close();
   }
 
+  /**
+   * v0.4.2-fix: 自愈 — 从磁盘重建内存 schema 与数据（schema 丢失/内存不一致时调用）。
+   * 无删库需求即可恢复可用的库。
+   */
+  async repair(): Promise<void> {
+    if (!this.db) throw new DatabaseError('Database not opened', 'DB_NOT_OPEN');
+    await this.memoryCache.close();
+    await this.memoryCache.open(this.dbName, this.version);
+    await this.rebuildSchemaFromIDB();
+  }
+
+  /**
+   * v0.4.2-fix: 清空全部数据与表结构（含持久化 schema 记录），保留库本身。
+   * 单个版本升级事务内原子完成。
+   */
+  async clearAll(): Promise<void> {
+    const db = this.ensureDB();
+    // 先清内存缓存
+    const tableNames = await this.memoryCache.getTableNames();
+    for (const name of tableNames) {
+      await this.memoryCache.dropTable(name);
+    }
+    // 重置 IDB：删除所有表 store + 清空 schema/meta store
+    const newVersion = db.version + 1;
+    db.close();
+    await new Promise<void>((resolve, reject) => {
+      const request = indexedDB.open(this.dbName, newVersion);
+      request.onupgradeneeded = (event) => {
+        const idb = (event.target as IDBOpenDBRequest).result;
+        const toDelete = Array.from(idb.objectStoreNames).filter((n) => n !== '__metona_schema');
+        for (const name of toDelete) {
+          idb.deleteObjectStore(name);
+        }
+        if (!idb.objectStoreNames.contains('__metona_schema')) {
+          idb.createObjectStore('__metona_schema', { keyPath: 'name' });
+        } else {
+          // 保留 store 但清空内容（含持久化 schema 与 meta 记录）
+          const tx = (event.target as IDBOpenDBRequest).transaction!;
+          tx.objectStore('__metona_schema').clear();
+        }
+      };
+      request.onsuccess = () => {
+        this.db = request.result;
+        this.setupVersionChangeHandler();
+        resolve();
+      };
+      request.onerror = () => reject(new DatabaseError('Failed to clear database', 'IDB_CLEAR_ERROR', request.error));
+      request.onblocked = () => reject(new DatabaseError(`IndexedDB "${this.dbName}" is blocked`, 'IDB_BLOCKED'));
+    });
+  }
+
+  // ---- 库内元数据（v0.4.2-fix：迁移版本持久化用，复用 __metona_schema store） ----
+
+  async getMeta(key: string): Promise<string | null> {
+    const db = this.ensureDB();
+    if (!db.objectStoreNames.contains('__metona_schema')) return null;
+    return new Promise((resolve, reject) => {
+      const req = db.transaction('__metona_schema', 'readonly')
+        .objectStore('__metona_schema').get(`__meta:${key}`);
+      req.onsuccess = () => {
+        const rec = req.result as { schema?: unknown } | undefined;
+        resolve(rec && typeof rec.schema === 'string' ? rec.schema : null);
+      };
+      req.onerror = () => reject(req.error);
+    });
+  }
+
+  async setMeta(key: string, value: string): Promise<void> {
+    const db = this.ensureDB();
+    if (!db.objectStoreNames.contains('__metona_schema')) return;
+    await new Promise<void>((resolve, reject) => {
+      const tx = db.transaction('__metona_schema', 'readwrite');
+      tx.objectStore('__metona_schema').put({ name: `__meta:${key}`, schema: value });
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(new DatabaseError(`Failed to persist meta "${key}"`, 'IDB_META_ERROR', tx.error));
+    });
+  }
+
   isOpen(): boolean { return this.db !== null; }
 
   // ---- 表管理 ----
@@ -149,6 +356,47 @@ export class IndexedDBEngine implements IStorageEngine {
   async getTableNames(): Promise<string[]> { return Array.from(this.ensureDB().objectStoreNames); }
   async getTableSchema(tableName: string): Promise<TableSchema | null> { return this.memoryCache.getTableSchema(tableName); }
 
+  /**
+   * v0.4.2-fix: 引擎级 ALTER TABLE — schema 持久化到 __metona_schema store，
+   * 重启后 ALTER 不丢失（此前通用路径只改内存引用，重启回退；DROP 的行数据也没真正删）。
+   */
+  async alterTable(
+    tableName: string,
+    action: 'ADD' | 'DROP',
+    column: import('../constants').ColumnDef & { name: string },
+  ): Promise<void> {
+    await this.memoryCache.alterTable(tableName, action, column);
+    if (this.txActive) return; // 事务中：commit 时统一 flushToIDB 同步
+    const schema = await this.memoryCache.getTableSchema(tableName);
+    if (schema) {
+      await this.persistSchema(schema);
+    }
+    if (action === 'DROP') {
+      // 重写 IDB 存储行：移除该列键（store.put 经 keyPath 自动覆盖原行）
+      const db = this.ensureDB();
+      const rows = await this.idbFind(tableName, { table: tableName });
+      const rewritten = rows.map((row) => {
+        if (column.name in row) {
+          const copy = { ...row };
+          delete (copy as Record<string, unknown>)[column.name];
+          return copy;
+        }
+        return row;
+      });
+      if (rewritten.length > 0) {
+        await new Promise<void>((resolve, reject) => {
+          const tx = db.transaction(tableName, 'readwrite');
+          const store = tx.objectStore(tableName);
+          for (const row of rewritten) {
+            store.put(row);
+          }
+          tx.oncomplete = () => resolve();
+          tx.onerror = () => reject(new DatabaseError(`Failed to rewrite "${tableName}" after DROP COLUMN`, 'IDB_TX_ERROR', tx.error));
+        });
+      }
+    }
+  }
+
   // ---- CRUD ----
   async insert(tableName: string, rows: Record<string, unknown>[]): Promise<string[]> {
     const pks = await this.memoryCache.insert(tableName, rows);
@@ -256,10 +504,10 @@ export class IndexedDBEngine implements IStorageEngine {
 
   async commitTransaction(): Promise<void> {
     if (!this.txActive) throw new DatabaseError('No active transaction', 'TX_NONE');
-    // 确认内存层的变更
-    await this.memoryCache.commitTransaction();
-    // 批量将内存数据刷到 IndexedDB
+    // v0.4.2-fix: 先刷盘后提交内存快照 — 此前先 memoryCache.commitTransaction()
+    // 再 flushToIDB，flush 失败时 snapshot 已丢，回滚报 TX_NONE 且内存数据已确认
     await this.flushToIDB();
+    await this.memoryCache.commitTransaction();
     this.txActive = false;
   }
 
@@ -482,10 +730,77 @@ export class IndexedDBEngine implements IStorageEngine {
     });
   }
 
+  /** 持久化单个表 schema 到 __metona_schema store（v0.4.2-fix: ALTER TABLE 用） */
+  private async persistSchema(schema: TableSchema): Promise<void> {
+    const db = this.ensureDB();
+    if (!db.objectStoreNames.contains('__metona_schema')) return;
+    await new Promise<void>((resolve, reject) => {
+      const tx = db.transaction('__metona_schema', 'readwrite');
+      tx.objectStore('__metona_schema').put({ name: schema.name, schema: JSON.stringify(schema) });
+      tx.oncomplete = () => resolve();
+      tx.onerror = () => reject(new DatabaseError(`Failed to persist schema for "${schema.name}"`, 'IDB_SCHEMA_ERROR', tx.error));
+    });
+  }
+
   /** 将内存缓存中的所有表数据原子性刷新到 IndexedDB */
   private async flushToIDB(): Promise<void> {
     const tableNames = await this.memoryCache.getTableNames();
-    const db = this.ensureDB();
+    let db = this.ensureDB();
+
+    // v0.4.2-fix: 事务内 DDL 只更新内存，commit 时同步 IDB 的 objectStore 结构：
+    // 缺失的表 store 创建（并持久化 schema）、已删除的 store 移除（防止重启幽灵表）
+    const idbStores = Array.from(db.objectStoreNames);
+    const missing = tableNames.filter((t) => !idbStores.includes(t));
+    const stale = idbStores.filter((s) => s !== '__metona_schema' && !tableNames.includes(s));
+    if (missing.length > 0 || stale.length > 0) {
+      // 升级事务内是同步上下文，先异步收集缺失表的 schema（主键列定义）
+      const schemaMap = new Map<string, TableSchema>();
+      for (const name of missing) {
+        const s = await this.memoryCache.getTableSchema(name);
+        if (s) schemaMap.set(name, s);
+      }
+      const newVersion = db.version + 1;
+      db.close();
+      await new Promise<void>((resolve, reject) => {
+        const request = indexedDB.open(this.dbName, newVersion);
+        request.onupgradeneeded = (event) => {
+          const idb = (event.target as IDBOpenDBRequest).result;
+          for (const name of stale) {
+            idb.deleteObjectStore(name);
+          }
+          for (const name of missing) {
+            const schema = schemaMap.get(name);
+            const pkColumn = schema
+              ? (Object.entries(schema.columns).find(([, c]) => c.primaryKey)?.[0] ?? Object.keys(schema.columns)[0])
+              : undefined;
+            idb.createObjectStore(name, { keyPath: pkColumn });
+          }
+          // 事务内 drop 的表：同步清理持久化 schema 记录（防止重启后幽灵表恢复）
+          if (idb.objectStoreNames.contains('__metona_schema') && stale.length > 0) {
+            const tx = (event.target as IDBOpenDBRequest).transaction!;
+            const store = tx.objectStore('__metona_schema');
+            for (const name of stale) {
+              store.delete(name);
+            }
+          }
+        };
+        request.onsuccess = () => {
+          this.db = request.result;
+          this.setupVersionChangeHandler();
+          resolve();
+        };
+        request.onerror = () => reject(new DatabaseError('Failed to sync stores after transaction', 'IDB_UPGRADE_ERROR', request.error));
+        request.onblocked = () => reject(new DatabaseError(`IndexedDB "${this.dbName}" is blocked`, 'IDB_BLOCKED'));
+      });
+      // 事务内新建表的 schema 一并持久化（此前只建 store 不存 schema → 重启后约束推断丢失）
+      for (const name of missing) {
+        const schema = await this.memoryCache.getTableSchema(name);
+        if (schema) await this.persistSchema(schema);
+      }
+      // v0.4.2-fix: DDL 升级会 close 旧连接并重新 open — 重新取 db 引用，
+      // 否则下方数据 flush 用已关闭的连接抛 InvalidStateError
+      db = this.ensureDB();
+    }
 
     // 每个表在一个单独的 IDB 事务中完成 clear+insert，保证原子性
     for (const tableName of tableNames) {

src/engine/interface.ts

@@ -95,4 +95,18 @@ export interface IStorageEngine {
 
   /** 在线备份：导出全库一致性快照 */
   backup?(): Promise<Record<string, Record<string, unknown>[]>>;
+
+  // ---- 自愈/重置 (可选，v0.4.2-fix) ----
+
+  /** 崩溃恢复自愈：校验并清理损坏数据、恢复一致性（检测到异常后调用，无需删库重建） */
+  repair?(): Promise<void>;
+
+  /** 清空全部数据与表结构（保留库本身，供演示页刷新/重建用） */
+  clearAll?(): Promise<void>;
+
+  /** 读取库内元数据（迁移版本持久化用） */
+  getMeta?(key: string): Promise<string | null>;
+
+  /** 写入库内元数据（迁移版本持久化用） */
+  setMeta?(key: string, value: string): Promise<void>;
 }

src/engine/memory.ts

@@ -15,6 +15,8 @@ export class MemoryEngine implements IStorageEngine {
   private schemas: Map<string, TableSchema> = new Map();
   private indexes: Map<string, Map<string, Map<unknown, Set<string>>>> = new Map();
   private opened = false;
+  /** v0.4.2-fix: 库内元数据（迁移版本持久化用） */
+  private metaStore: Map<string, string> = new Map();
 
   // ---- 事务快照 ----
   private snapshot: {
@@ -32,17 +34,45 @@ export class MemoryEngine implements IStorageEngine {
     this.opened = true;
   }
   async close(): Promise<void> {
-    this.tables.clear(); this.schemas.clear(); this.indexes.clear(); this.opened = false;
+    this.tables.clear(); this.schemas.clear(); this.indexes.clear(); this.metaStore.clear(); this.opened = false;
   }
   isOpen(): boolean { return this.opened; }
 
+  // ---- v0.4.2-fix: 自愈 / 重置 / 元数据 ----
+
+  /** 内存引擎无需修复（无持久化损坏概念） */
+  async repair(): Promise<void> { return; }
+
+  /** 清空全部数据与表结构 */
+  async clearAll(): Promise<void> {
+    const names = Array.from(this.schemas.keys());
+    for (const name of names) {
+      await this.dropTable(name);
+    }
+    this.metaStore.clear();
+  }
+
+  async getMeta(key: string): Promise<string | null> {
+    return this.metaStore.get(key) ?? null;
+  }
+
+  async setMeta(key: string, value: string): Promise<void> {
+    this.metaStore.set(key, value);
+  }
+
   // ---- 表管理 ----
   async createTable(schema: TableSchema): Promise<void> {
     if (this.schemas.has(schema.name)) throw new DatabaseError(`Table "${schema.name}" already exists`, 'TABLE_EXISTS');
-    this.schemas.set(schema.name, schema);
+    // v0.4.2-fix: 存储 schema 深拷贝 — 此前 Hybrid.reloadMemoryFromDisk 直接存入
+    // disk 引擎的 schema 引用，内存/磁盘引擎共享同一对象，任一引擎 ALTER 都会污染对方
+    const copy: TableSchema = { name: schema.name, columns: {} };
+    for (const [colName, colDef] of Object.entries(schema.columns)) {
+      copy.columns[colName] = { ...colDef };
+    }
+    this.schemas.set(schema.name, copy);
     this.tables.set(schema.name, new Map());
     const tableIndexes = new Map<string, Map<unknown, Set<string>>>();
-    for (const [colName, colDef] of Object.entries(schema.columns)) {
+    for (const [colName, colDef] of Object.entries(copy.columns)) {
       if (colDef.index || colDef.unique) tableIndexes.set(colName, new Map());
     }
     this.indexes.set(schema.name, tableIndexes);
@@ -57,6 +87,35 @@ export class MemoryEngine implements IStorageEngine {
   async getTableNames(): Promise<string[]> { return Array.from(this.schemas.keys()); }
   async getTableSchema(tableName: string): Promise<TableSchema | null> { return this.schemas.get(tableName) ?? null; }
 
+  /**
+   * v0.4.2-fix: 引擎级 ALTER TABLE — 直接修改内存 schema 引用并清理行数据。
+   * （此前走 executor 通用路径，行为相同；统一到引擎层保证 Hybrid/IndexedDB 委托一致性）
+   */
+  async alterTable(
+    tableName: string,
+    action: 'ADD' | 'DROP',
+    column: import('../constants').ColumnDef & { name: string },
+  ): Promise<void> {
+    this.ensureTable(tableName);
+    const schema = this.schemas.get(tableName)!;
+    if (action === 'ADD') {
+      if (schema.columns[column.name]) {
+        throw new DatabaseError(`Column "${column.name}" already exists in table "${tableName}"`, 'COLUMN_EXISTS');
+      }
+      schema.columns[column.name] = column;
+      return;
+    }
+    if (!schema.columns[column.name]) {
+      throw new DatabaseError(`Column "${column.name}" does not exist in table "${tableName}"`, 'COLUMN_NOT_FOUND');
+    }
+    delete schema.columns[column.name];
+    // 清理已有行中该列的值（find 返回行引用，直接删除生效）
+    const table = this.tables.get(tableName)!;
+    for (const row of table.values()) {
+      if (column.name in row) delete row[column.name];
+    }
+  }
+
   // ---- CRUD ----
   async insert(tableName: string, rows: Record<string, unknown>[]): Promise<string[]> {
     this.ensureTable(tableName);
@@ -124,22 +183,75 @@ export class MemoryEngine implements IStorageEngine {
     this.ensureTable(tableName);
     const schema = this.schemas.get(tableName)!;
     const table = this.tables.get(tableName)!;
+    const pkCol = this.getPrimaryKey(schema);
     let count = 0;
-    for (const [pk, row] of table) {
+    // v0.4.2-fix: 迭代期间会 delete/set 同一 Map（主键变更）→ 拷贝快照避免跳过/重复
+    for (const [pk, row] of [...table]) {
       if (!query.where || Object.keys(query.where).length === 0 || matchWhere(row, query.where)) {
         // v0.3.3: 先移除旧值索引条目（修复 update 后唯一约束被绕过、按新值查索引丢行）
         this.removeIndexEntries(tableName, row, pk);
         const updated = { ...row, ...updates };
         this.validateRow(schema, updated);
         this.checkUniqueness(schema, updated);
-        table.set(pk, updated);
-        this.updateIndexes(tableName, updated, pk);
+        const newPk = String(updated[pkCol]);
+        // v0.4.2-fix: 主键变更 — 删除旧键 + 级联更新引用表 + 新键落表
+        if (newPk !== pk) {
+          await this.applyUpdateCascade(tableName, pk, newPk);
+        }
+        table.delete(pk);
+        table.set(newPk, updated);
+        this.updateIndexes(tableName, updated, newPk);
         count++;
       }
     }
     return count;
   }
 
+  /**
+   * v0.4.2-fix: ON UPDATE 外键级联 — 被引用表主键变更时处理引用表：
+   * RESTRICT 抛错 / CASCADE 更新 FK 值 / SET NULL 置空。
+   * 分两阶段：先全量 RESTRICT 检查（任何修改前），再执行级联（防部分修改）。
+   */
+  private async applyUpdateCascade(tableName: string, oldPk: string, newPk: string): Promise<void> {
+    // 阶段 1: RESTRICT 检查（引用旧主键的行存在即拒绝）
+    for (const [refTableName, refSchema] of this.schemas) {
+      if (refTableName === tableName) continue;
+      for (const [colName, colDef] of Object.entries(refSchema.columns)) {
+        if (!colDef.references || !colDef.onUpdate) continue;
+        const [refTable] = colDef.references.split('.');
+        if (refTable !== tableName) continue;
+        const refTableData = this.tables.get(refTableName);
+        if (!refTableData) continue;
+        for (const [, refRow] of refTableData) {
+          if (String(refRow[colName]) === oldPk && colDef.onUpdate === 'RESTRICT') {
+            throw new DatabaseError(
+              `Cannot update "${tableName}" key "${oldPk}": foreign key "${colName}" in "${refTableName}" has dependent rows`,
+              'FOREIGN_KEY_VIOLATION',
+            );
+          }
+        }
+      }
+    }
+    // 阶段 2: CASCADE / SET NULL
+    for (const [refTableName, refSchema] of this.schemas) {
+      if (refTableName === tableName) continue;
+      for (const [colName, colDef] of Object.entries(refSchema.columns)) {
+        if (!colDef.references || !colDef.onUpdate) continue;
+        const [refTable] = colDef.references.split('.');
+        if (refTable !== tableName) continue;
+        const refTableData = this.tables.get(refTableName);
+        if (!refTableData) continue;
+        if (colDef.onUpdate !== 'CASCADE' && colDef.onUpdate !== 'SET NULL') continue;
+        for (const [refPk, refRow] of refTableData) {
+          if (String(refRow[colName]) !== oldPk) continue;
+          this.removeIndexEntries(refTableName, refRow, refPk);
+          refRow[colName] = colDef.onUpdate === 'CASCADE' ? newPk : null;
+          this.updateIndexes(refTableName, refRow, refPk);
+        }
+      }
+    }
+  }
+
   async delete(tableName: string, query: QueryPlan): Promise<number> {
     this.ensureTable(tableName);
     const table = this.tables.get(tableName)!;

src/engine/opfs.ts

@@ -51,17 +51,65 @@ export class OPFSEngine implements IStorageEngine {
     return this.tablesDir !== null;
   }
 
+  // ---- v0.4.2-fix: 自愈 / 重置 / 元数据 ----
+
+  /** 自愈：重置内存缓存后从 OPFS 重新加载（单文件损坏不影响其他表） */
+  async repair(): Promise<void> {
+    await this.memoryCache.close();
+    await this.memoryCache.open(this.dbName, 1);
+    await this.loadExistingTables();
+  }
+
+  /** 清空全部数据与表结构（删除目录内全部文件） */
+  async clearAll(): Promise<void> {
+    await this.memoryCache.close();
+    await this.memoryCache.open(this.dbName, 1);
+    if (this.tablesDir) {
+      const dir = this.tablesDir as any;
+      for await (const [name] of dir.entries()) {
+        try { await this.tablesDir!.removeEntry(name); } catch { /* ignore */ }
+      }
+    }
+  }
+
+  async getMeta(key: string): Promise<string | null> {
+    if (!this.tablesDir) return null;
+    try {
+      const fh = await this.tablesDir.getFileHandle(`__metona_${key}.meta`);
+      const file = await fh.getFile();
+      return await file.text();
+    } catch {
+      return null;
+    }
+  }
+
+  async setMeta(key: string, value: string): Promise<void> {
+    if (!this.tablesDir) return;
+    const fh = await this.tablesDir.getFileHandle(`__metona_${key}.meta`, { create: true });
+    const writable = await fh.createWritable();
+    await writable.write(value);
+    await writable.close();
+  }
+
   // ---- 表管理 ----
 
   async createTable(schema: TableSchema): Promise<void> {
     await this.memoryCache.createTable(schema);
+    // v0.4.2-fix: schema 持久化（此前仅写空数据文件 → 空表重启后消失、索引标记丢失）
+    await this.setMeta(`schema_${schema.name}`, JSON.stringify(schema));
     // OPFS 中表以空 JSON 数组文件形式存在
     await this.writeTableData(schema.name, []);
   }
 
   async dropTable(tableName: string): Promise<void> {
     await this.memoryCache.dropTable(tableName);
+    // v0.4.2-fix: 清理 schema meta（否则重启恢复幽灵表）
     if (this.tablesDir) {
+      try {
+        await this.tablesDir.removeEntry(`__metona_schema_${tableName}.meta`);
+      } catch {
+        // 文件不存在则忽略
+      }
       try {
         await this.tablesDir.removeEntry(`${tableName}.json`);
       } catch {
@@ -95,6 +143,19 @@ export class OPFSEngine implements IStorageEngine {
     return this.memoryCache.getTableSchema(tableName);
   }
 
+  /** v0.4.2-fix: 引擎级 ALTER TABLE — 内存 + schema 持久化 + 整表文件重写 */
+  async alterTable(
+    tableName: string,
+    action: 'ADD' | 'DROP',
+    column: import('../constants').ColumnDef & { name: string },
+  ): Promise<void> {
+    await this.memoryCache.alterTable(tableName, action, column);
+    const schema = await this.memoryCache.getTableSchema(tableName);
+    if (schema) await this.setMeta(`schema_${tableName}`, JSON.stringify(schema));
+    const rows = await this.memoryCache.find(tableName, { table: tableName });
+    await this.writeTableData(tableName, rows);
+  }
+
   // ---- CRUD ----
 
   async insert(tableName: string, rows: Record<string, unknown>[]): Promise<string[]> {
@@ -140,11 +201,16 @@ export class OPFSEngine implements IStorageEngine {
   // ---- 动态索引（v0.3.0） ----
 
   async createIndex(tableName: string, column: string, unique?: boolean): Promise<void> {
-    return this.memoryCache.createIndex(tableName, column, unique);
+    await this.memoryCache.createIndex(tableName, column, unique);
+    // v0.4.2-fix: 索引标记持久化（重启后索引结构恢复）
+    const schema = await this.memoryCache.getTableSchema(tableName);
+    if (schema) await this.setMeta(`schema_${tableName}`, JSON.stringify(schema));
   }
 
   async dropIndex(tableName: string, column: string, indexName?: string): Promise<void> {
-    return this.memoryCache.dropIndex(tableName, column, indexName);
+    await this.memoryCache.dropIndex(tableName, column, indexName);
+    const schema = await this.memoryCache.getTableSchema(tableName);
+    if (schema) await this.setMeta(`schema_${tableName}`, JSON.stringify(schema));
   }
 
   // ---- 事务 ----
@@ -198,16 +264,39 @@ export class OPFSEngine implements IStorageEngine {
     }
   }
 
-  /** 从 OPFS 加载已有表数据到内存缓存 */
+  /**
+   * 从 OPFS 加载已有表到内存缓存。
+   * v0.4.2-fix: 优先从持久化 schema（__metona_schema_*.meta）恢复 —
+   * 空表不再消失、索引标记/主键/约束完整；无 schema 记录的旧库从数据推断（兼容）。
+   */
   private async loadExistingTables(): Promise<void> {
     if (!this.tablesDir) return;
     const dir = this.tablesDir as any;
+    const fileNames: string[] = [];
     for await (const [name] of dir.entries()) {
-      if (!name.endsWith('.json')) continue;
-      const tableName = name.replace('.json', '');
+      if (name.endsWith('.json')) fileNames.push(name);
+    }
+
+    for (const fileName of fileNames) {
+      const tableName = fileName.replace('.json', '');
       try {
+        // 1. 优先：持久化 schema
+        const schemaRaw = await this.getMeta(`schema_${tableName}`);
+        if (schemaRaw) {
+          const schema = JSON.parse(schemaRaw) as TableSchema;
+          await this.memoryCache.createTable(schema);
+          const rows = await this.readTableData(tableName);
+          for (const row of rows) {
+            try {
+              await this.memoryCache.insert(tableName, [row]);
+            } catch {
+              // 单行损坏不影响整表恢复
+            }
+          }
+          continue;
+        }
+        // 2. 兼容旧库：从数据推断 schema（空表且无 schema 记录 → 跳过）
         const data = await this.readTableData(tableName);
-        // 从数据中推断 schema（简化：从第一行提取列信息）
         if (data.length > 0) {
           const firstRow = data[0];
           const columns: Record<string, any> = {};