fix(P2): v0.6.3 原子性/一致性/资源治理 — 8 项修复 + 12 回归

- KVStore 混合写单记录原子：新增 writeBatch（put+delete 同一条日志记录），
  KVStoreEngine 全部混合写路径统一（兑现真原子宣称，崩溃无新旧行并存）
- WAL full 模式写入失败抛错（此前 console.warn 吞错 → 崩溃即丢且无感知）
- MemoryEngine SET NULL 级联索引残留：复用 removeIndexEntries（消除虚假 UNIQUE_VIOLATION）
- delete 级联两阶段：先全量 RESTRICT 预检（沿 CASCADE 链递归）再执行，无部分级联
  （Memory/Aria 对齐）
- BufferPool 驱逐同步清理 pages Map（EvictionManager onRemove 回调，内存预算真实生效）
- MVCC commit 清理已提交版本（版本链仅作事务内 undo，消除行数据双份常驻）
- LSM.flush 重复入链修复（入链即置空 immutable）+ frozenMemtables 可见性时序
- rollbackToSavepoint 重建受影响表二级索引（消除过期索引条目）

测试 1114 → 1126（71 套件）；行覆盖率 89.7%；版本 0.6.3

tests/engine/aria-mvcc-savepoint.test.ts

@@ -31,12 +31,13 @@ describe('AriaEngine — MVCC 事务 + Savepoint', () => {
     expect(id1).not.toBe(id2);
   });
 
-  it('commit 后版本标记已提交', () => {
+  it('commit 后清理本事务版本（undo 记录不保留，v0.6.3）', () => {
     const txnId = (engine as any).mvcc.beginTransaction();
     (engine as any).mvcc.writeVersion('users', '1', { name: 'Alice' }, txnId);
     (engine as any).mvcc.commitTransaction(txnId);
     const store = (engine as any).mvcc.versionStore;
-    expect(store.get('users.1')[0].committed).toBe(true);
+    // v0.6.3: 已提交版本随 commit 清理（快照读取已移除，版本链仅作事务内 undo）
+    expect(store.has('users.1')).toBe(false);
   });
 
   it('rollback 移除本事务版本', () => {
@@ -62,16 +63,30 @@ describe('AriaEngine — MVCC 事务 + Savepoint', () => {
     expect(await engine.count('users')).toBe(1);
   });
 
-  it('GC 清理过旧版本（保留最新 N 个）', () => {
+  it('GC 清理过旧版本（未提交版本链保留最新 N 个）', () => {
     for (let i = 0; i < 200; i++) {
       const txnId = (engine as any).mvcc.beginTransaction();
       (engine as any).mvcc.writeVersion('users', '1', { ver: i }, txnId);
-      (engine as any).mvcc.commitTransaction(txnId);
+      // 不 commit：未提交版本保留在链上（活跃事务 undo）
     }
     (engine as any).mvcc.gc(50);
     expect((engine as any).mvcc.versionStore.get('users.1').length).toBe(50);
   });
 
+  it('多事务并发未提交 + 部分提交：commit 版本清理、未提交保留', () => {
+    const mvcc = (engine as any).mvcc;
+    const txnA = mvcc.beginTransaction();
+    mvcc.writeVersion('users', '1', { name: 'A1' }, txnA);
+    const txnB = mvcc.beginTransaction();
+    mvcc.writeVersion('users', '1', { name: 'B1' }, txnB);
+    mvcc.commitTransaction(txnA);
+    // txnA 版本已清理；txnB 未提交版本保留
+    const versions = mvcc.versionStore.get('users.1') as { txnId: number }[];
+    expect(versions.map((v) => v.txnId)).toEqual([txnB]);
+    mvcc.rollbackTransaction(txnB);
+    expect(mvcc.versionStore.has('users.1')).toBe(false);
+  });
+
   // ---- Savepoint ----
   it('savepoint 创建成功', async () => {
     await engine.beginTransaction();

tests/engine/aria-wal-mvcc.test.ts

@@ -157,13 +157,13 @@ describe('AriaEngine — MVCC', () => {
     expect(id1).not.toBe(id2);
   });
 
-  it('commit 标记版本为已提交并清理事务登记', () => {
+  it('commit 清理本事务版本并清理事务登记（v0.6.3）', () => {
     const txnId = mvcc.beginTransaction();
     mvcc.writeVersion('users', '1', { name: 'Alice' }, txnId);
     mvcc.commitTransaction(txnId);
-    const versions = (mvcc as unknown as { versionStore: Map<string, { committed: boolean }[]> }).versionStore.get('users.1');
-    expect(versions).toHaveLength(1);
-    expect(versions![0].committed).toBe(true);
+    // v0.6.3: 已提交版本随 commit 清理（快照读取已移除，版本链仅作事务内 undo）
+    const store = (mvcc as unknown as { versionStore: Map<string, unknown> }).versionStore;
+    expect(store.has('users.1')).toBe(false);
   });
 
   it('rollback 移除写入的版本', () => {
@@ -184,14 +184,14 @@ describe('AriaEngine — MVCC', () => {
     expect(versions[1].prevVersion).not.toBeNull(); // 版本链
   });
 
-  it('deleteVersion 写入墓碑版本', () => {
+  it('deleteVersion 写入墓碑版本（未提交可见，commit 清理）', () => {
     const txnId = mvcc.beginTransaction();
     mvcc.deleteVersion('users', '1', txnId);
-    mvcc.commitTransaction(txnId);
-    const store = (mvcc as unknown as { versionStore: Map<string, { data: Record<string, unknown>; committed: boolean }[]> }).versionStore;
+    const store = (mvcc as unknown as { versionStore: Map<string, { data: Record<string, unknown> }[]> }).versionStore;
     const versions = store.get('users.1')!;
-    expect(versions[0].committed).toBe(true);
     expect((versions[0].data as unknown as { __mvcc_tombstone: boolean }).__mvcc_tombstone).toBe(true);
+    mvcc.commitTransaction(txnId);
+    expect(store.has('users.1')).toBe(false);
   });
 
   it('活跃事务可并发登记', () => {
@@ -205,21 +205,19 @@ describe('AriaEngine — MVCC', () => {
     expect(store.has('users.2')).toBe(true);
   });
 
-  it('gc 清理过旧版本', () => {
-    // 创建很多版本后 gc
+  it('gc 清理过旧版本（未提交版本链保留最新 N 个）', () => {
+    // 创建很多未提交版本后 gc（活跃事务 undo 链）
     for (let i = 0; i < 200; i++) {
       const txnId = mvcc.beginTransaction();
       mvcc.writeVersion('users', '1', { ver: i }, txnId);
-      mvcc.commitTransaction(txnId);
     }
     mvcc.gc(100);
     // gc 后版本保留最新 100 个
     const store = (mvcc as unknown as { versionStore: Map<string, unknown[]> }).versionStore;
     expect(store.get('users.1')!.length).toBe(100);
-    // gc 后引擎仍可继续写入
+    // gc 后仍可继续写入
     const txnId = mvcc.beginTransaction();
     mvcc.writeVersion('users', '1', { ver: 999 }, txnId);
-    mvcc.commitTransaction(txnId);
     expect(store.get('users.1')!.length).toBe(101);
   });
 });