feat(notify): 重构通信内核并补齐 stream/bulk/record/transfer 能力

- 引入 LogicalConn/TransportConn 分层，ClientConn 保留兼容适配层
  - 新增 Stream、Bulk、RecordStream 三条数据面能力及对应控制路径
  - 完成 transfer/file 传输内核与状态快照、诊断能力
  - 补齐 reconnect、inbound dispatcher、modern psk 等基础模块
  - 增加大规模回归、并发与基准测试覆盖
  - 更新依赖库

file_receive_fs.go

@@ -0,0 +1,147 @@
+package notify
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+func computeFileChecksum(path string) (string, error) {
+	fd, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer fd.Close()
+	h := sha256.New()
+	if _, err := io.Copy(h, fd); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+func filePacketModTime(packet FilePacket) time.Time {
+	if packet.ModTime <= 0 {
+		return time.Time{}
+	}
+	return time.Unix(0, packet.ModTime)
+}
+
+func applyReceivedFileMeta(path string, mode os.FileMode, modTime time.Time) {
+	if mode != 0 {
+		_ = os.Chmod(path, mode.Perm())
+	}
+	if !modTime.IsZero() {
+		_ = os.Chtimes(path, modTime, modTime)
+	}
+}
+
+func sanitizeFileName(name string) string {
+	trimmed := strings.TrimSpace(name)
+	if trimmed == "" {
+		return "unnamed"
+	}
+	trimmed = strings.ReplaceAll(trimmed, "/", "_")
+	trimmed = strings.ReplaceAll(trimmed, "\\", "_")
+	trimmed = strings.ReplaceAll(trimmed, ":", "_")
+	return trimmed
+}
+
+func shortFileIDSuffix(fileID string) string {
+	cleaned := sanitizeFileName(fileID)
+	if len(cleaned) > 12 {
+		return cleaned[:12]
+	}
+	if cleaned == "" {
+		return "copy"
+	}
+	return cleaned
+}
+
+func pathExists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+func (p *fileReceivePool) receiveDirLocked() string {
+	if p.dir != "" {
+		return p.dir
+	}
+	return os.TempDir()
+}
+
+func (p *fileReceivePool) uniqueFinalPathLocked(baseDir string, name string, fileID string) string {
+	cleanName := sanitizeFileName(filepath.Base(name))
+	if cleanName == "" {
+		cleanName = "unnamed.bin"
+	}
+	ext := filepath.Ext(cleanName)
+	base := strings.TrimSuffix(cleanName, ext)
+	candidate := filepath.Join(baseDir, cleanName)
+	if !p.pathReservedLocked(candidate) && !pathExists(candidate) {
+		return candidate
+	}
+	suffix := shortFileIDSuffix(fileID)
+	candidate = filepath.Join(baseDir, fmt.Sprintf("%s.%s%s", base, suffix, ext))
+	if !p.pathReservedLocked(candidate) && !pathExists(candidate) {
+		return candidate
+	}
+	for i := 1; ; i++ {
+		candidate = filepath.Join(baseDir, fmt.Sprintf("%s.%s.%d%s", base, suffix, i, ext))
+		if !p.pathReservedLocked(candidate) && !pathExists(candidate) {
+			return candidate
+		}
+	}
+}
+
+func (p *fileReceivePool) pathReservedLocked(path string) bool {
+	for _, session := range p.sessions {
+		if session.finalPath == path || session.tmpPath == path {
+			return true
+		}
+	}
+	return false
+}
+
+func (p *fileReceivePool) trimCompletedLocked() {
+	if p.completedLimit <= 0 || len(p.completed) <= p.completedLimit {
+		return
+	}
+	for len(p.completed) > p.completedLimit {
+		oldestKey := ""
+		oldestTime := time.Time{}
+		for key, session := range p.completed {
+			candidateTime := completedFileReceiveTime(session)
+			if oldestKey == "" || candidateTime.Before(oldestTime) || (candidateTime.Equal(oldestTime) && key < oldestKey) {
+				oldestKey = key
+				oldestTime = candidateTime
+			}
+		}
+		if oldestKey == "" {
+			return
+		}
+		delete(p.completed, oldestKey)
+	}
+}
+
+func completedFileReceiveTime(session *fileReceiveSession) time.Time {
+	if session == nil {
+		return time.Time{}
+	}
+	if !session.updatedAt.IsZero() {
+		return session.updatedAt
+	}
+	return session.startedAt
+}
+
+func (s *fileReceiveSession) copy() *fileReceiveSession {
+	if s == nil {
+		return nil
+	}
+	dup := *s
+	return &dup
+}