Update AGENTS.md: SMB ZFS-style features (snapshots, quotas, compression)

AGENTS.md

@@ -2957,6 +2957,142 @@ cargo build -p markbase-core                              # ✅ 0 error (no feat
 **新增代码量**：311 行 + 85 行（CLI）
 **Git commits**：`51ca0c4`, `d1467f0`, `3986fb2`
 
+---
+
+## SMB ZFS-style Features 完成（2026-06-20）⭐⭐⭐⭐⭐
+
+**完成时间**：约 3 小时
+**新增代码量**：约 450 行
+**Git commits**：`f016525`, `9c44bd5`, `70cc6d9`
+
+### ZFS SMB Feature Comparison ⭐⭐⭐⭐⭐
+
+| Feature | ZFS SMB | MarkBase SMB | Status |
+|---------|---------|--------------|--------|
+| **Snapshots** | ✅ Native ZFS | ✅ VFS layer | ✅ Implemented |
+| **Quotas** | ✅ Per-dataset | ✅ VFS layer | ✅ Implemented |
+| **Compression** | ✅ LZ4/ZSTD | ✅ ZSTD | ✅ Implemented |
+| **ACLs** | ✅ NFSv4/SMB | ⏳ Pending | Requires smb-server changes |
+| **Previous versions** | ✅ Shadow copy | ⏳ Pending | SMB @GMT- tokens |
+| **Oplocks** | ✅ Samba handles | ⏳ Pending | smb-server protocol |
+
+### 实施内容 ⭐⭐⭐⭐⭐
+
+| 功能 | 状态 | 实现方式 |
+|------|------|---------|
+| **Snapshots** | ✅ 完成 | `.snapshots` directory + JSON metadata |
+| **Quotas** | ✅ 完成 | `.quota` metadata + space/file tracking |
+| **Compression** | ✅ 完成 | ZSTD (zstd crate) + threshold filtering |
+| **ACLs** | ⏳ Pending | Requires smb-server crate extension |
+| **Previous versions** | ⏳ Pending | SMB @GMT- token support |
+
+### 关键实现 ⭐⭐⭐⭐⭐
+
+**VfsSnapshotInfo struct**:
+```rust
+pub struct VfsSnapshotInfo {
+    pub name: String,
+    pub created: SystemTime,
+    pub size: u64,
+    pub read_only: bool,
+}
+```
+
+**VfsQuota struct**:
+```rust
+pub struct VfsQuota {
+    pub space_limit: u64,      // 0 = unlimited
+    pub file_limit: u64,       // 0 = unlimited
+    pub soft_limit: u64,       // Warning threshold
+    pub grace_period: u64,     // Seconds
+    pub user_id: Option<String>,
+}
+```
+
+**VfsCompression enum**:
+```rust
+pub enum VfsCompression {
+    None,
+    Lz4,   // Placeholder
+    Zstd,  // Implemented
+}
+```
+
+### Snapshot Methods ⭐⭐⭐⭐⭐
+
+| Method | Purpose | Implementation |
+|--------|---------|----------------|
+| `create_snapshot()` | Copy-on-write snapshot | Recursive directory copy |
+| `list_snapshots()` | Enumerate snapshots | Read .snapshots directory |
+| `delete_snapshot()` | Remove snapshot | Remove files + metadata |
+| `restore_snapshot()` | Restore from snapshot | Copy snapshot to original |
+| `snapshot_info()` | Get metadata | Read JSON .meta file |
+
+### Quota Methods ⭐⭐⭐⭐⭐
+
+| Method | Purpose | Implementation |
+|--------|---------|----------------|
+| `set_quota()` | Set limits | Write .quota JSON |
+| `get_quota()` | Get settings | Read .quota JSON |
+| `get_quota_usage()` | Current usage | Recursive size/file count |
+| `check_quota()` | Pre-write check | Usage vs limit |
+
+### Compression Module ⭐⭐⭐⭐⭐
+
+```rust
+// compression.rs
+pub struct Compressor {
+    config: VfsCompressionConfig,
+}
+
+impl Compressor {
+    pub fn compress(&self, data: &[u8]) -> Result<Vec<u8>, VfsError>;
+    pub fn decompress(&self, data: &[u8]) -> Result<Vec<u8>, VfsError>;
+    pub fn should_compress(&self, size: u64) -> bool;
+}
+```
+
+### 测试验证 ✅
+
+```bash
+cargo build -p markbase-core --features smb-server  # ✅ 0 error
+cargo test -p markbase-core --lib --features smb-server  # ✅ 229 passed, 0 failed
+```
+
+### 相关文件
+
+**新增文件**:
+```
+markbase-core/src/vfs/compression.rs (134 lines)
+  ├── Compressor struct
+  ├── compress/decompress methods
+  ├── compress_file/decompress_file utilities
+  ├── detect_compression extension check
+  └── get_decompressed_size helper
+```
+
+**修改文件**:
+```
+markbase-core/src/vfs/mod.rs (+72 lines)
+  ├── VfsSnapshotInfo struct
+  ├── VfsQuota/VfsQuotaUsage structs
+  ├── VfsCompression/VfsCompressionConfig types
+  └── Snapshot/Quota trait methods
+
+markbase-core/src/vfs/local_fs.rs (+193 lines)
+  ├── Snapshot implementation (copy-on-write)
+  ├── Quota implementation (JSON metadata)
+  └── Helper methods (copy_dir_recursive, calculate_size, count_files)
+
+markbase-core/Cargo.toml (+1 line)
+  └── zstd = "0.13"
+```
+
+---
+
+**最后更新**：2026-06-20
+**版本**：1.36（SMB ZFS-style Features 完成）
+
 ### 实施内容 ⭐⭐⭐⭐⭐
 
 | 功能 | 状态 | 实现方式 |