fix(P0): SSTable rangeScan 尾块漏读 — 索引块记录块尾 key 但二分按块首语义定位，endKey 落在块尾时下一块被排除导致二级索引查询丢数据（5万行丢106~771条）；endBlockIdx 多扫一块 + 4 个 sstable 边界回归 + 重建二级索引大数据量回归（含崩溃恢复）。附带：checkpoint 同步 flush 二级索引 LSM（P1）、kv 后端页面化 + SharedMemoryBackend chunk 化、生产负载验证测试

tests/engine/aria-sstable.test.ts

@@ -83,6 +83,81 @@ describe('AriaEngine — SSTable Builder + Reader', () => {
     expect(items).toHaveLength(count);
   });
 
+  // v0.6.1-fix(P0): 索引键是"块内最后一个 key"，locateBlockLE 排除尾 key 越界的
+  // 下一块会导致范围扫描漏读尾部数据（二级索引 5 万行查询丢 106~219 条）。
+  it('v0.6.1-fix — 范围扫描跨前缀边界不漏尾部数据', () => {
+    // 小块强制多块；t5 数据分散在多块中，最后一个 t5 块之后紧跟 t6 块（尾 key 越界）
+    const builder = new SSTableBuilder(120);
+    for (let i = 0; i < 30; i++) {
+      builder.add(`t5:k${String(i).padStart(5, '0')}`, { pk: `k${i}` });
+    }
+    for (let i = 0; i < 30; i++) {
+      builder.add(`t6:k${String(i).padStart(5, '0')}`, { pk: `k${i}` });
+    }
+    for (let i = 0; i < 30; i++) {
+      builder.add(`t7:k${String(i).padStart(5, '0')}`, { pk: `k${i}` });
+    }
+    const { sstableData } = builder.build();
+
+    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
+    const t5: [string, Record<string, unknown>][] = [];
+    reader.rangeScan('t5', 't5\uffff', (k, v) => t5.push([k, v]));
+    expect(t5).toHaveLength(30);
+    expect(t5[0][0]).toBe('t5:k00000');
+    expect(t5[t5.length - 1][0]).toBe('t5:k00029');
+  });
+
+  it('v0.6.1-fix — 范围扫描 endKey 恰在块尾（不越界不丢、不多扫错数据）', () => {
+    const builder = new SSTableBuilder(150);
+    for (let i = 0; i < 40; i++) {
+      builder.add(`p-${String(i).padStart(3, '0')}`, { v: i });
+    }
+    for (let i = 0; i < 20; i++) {
+      builder.add(`q-${String(i).padStart(3, '0')}`, { v: i });
+    }
+    const { sstableData } = builder.build();
+
+    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
+    // endKey 恰等于某条存在的 key：结果必须包含它且不含 p 之外的 key
+    const results: [string, Record<string, unknown>][] = [];
+    reader.rangeScan('p-000', 'p-039', (k, v) => results.push([k, v]));
+    expect(results).toHaveLength(40);
+    expect(results[39][0]).toBe('p-039');
+  });
+
+  it('v0.6.1-fix — 范围扫描 endKey 超出全部数据（返回全量）', () => {
+    const builder = new SSTableBuilder(100);
+    for (let i = 0; i < 25; i++) {
+      builder.add(`z-${String(i).padStart(3, '0')}`, { v: i });
+    }
+    const { sstableData } = builder.build();
+
+    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
+    const results: [string, Record<string, unknown>][] = [];
+    reader.rangeScan('z-000', '\uffff\uffff', (k, v) => results.push([k, v]));
+    expect(results).toHaveLength(25);
+  });
+
+  it('v0.6.1-fix — 多前缀数据 rangeScan 与 scanAll 结果一致', () => {
+    // 模拟索引混合写入：t0..t9 交叉 + 尾部跨块（flush 路径先排序再构建）
+    const items: [string, Record<string, unknown>][] = [];
+    for (let i = 0; i < 120; i++) {
+      const tag = `t${i % 10}`;
+      items.push([`${tag}:k${String(i).padStart(5, '0')}`, { pk: `k${i}` }]);
+    }
+    items.sort((a, b) => (a[0] < b[0] ? -1 : 1));
+    const builder = new SSTableBuilder(200);
+    for (const [k, v] of items) builder.add(k, v);
+    const { sstableData } = builder.build();
+
+    const reader = new SSTableReader(sstableData, makeMeta(sstableData));
+    for (let t = 0; t < 10; t++) {
+      const keys: string[] = [];
+      reader.rangeScan(`t${t}`, `t${t}\uffff`, (k) => keys.push(k));
+      expect(keys).toHaveLength(12);
+    }
+  });
+
 
   it('边界 — 空 SSTable 不抛异常', () => {
     const builder = new SSTableBuilder(4096);