fix(watch): 串行化命令重启流程（by AI）

CHANGELOG.md

@@ -1,5 +1,10 @@
 # CHANGELOG
 
+## Unreleased (2026-08-24)
+- **重启可靠性**:
+  - 文件事件、终端 `rs` 和 `SIGUSR1` 重启请求统一串行处理，防止并行启动多个子进程。
+  - 等待旧进程完整退出后再启动新进程，并输出停止或启动失败信息。
+
 ## v1.5.4 (2026-06-27)
 - **修复 Bug**: 修复了配置 `Types`（文件类型白名单）时，目录本身的创建/删除等事件未能被正确过滤的问题。
 - **CLI 体验大幅升级**:

README.md

@@ -63,6 +63,7 @@ kill -USR1 "$(cat watch.pid)"
 watch -r                         # 读取当前目录 watch.pid
 watch --reload path/to/watch.pid # 指定 PID 文件
 ```
+所有文件事件、`rs` 和信号重启请求均串行执行；旧命令退出完成后才会启动新命令。
 
 **参数说明**：
 

TEST.md

@@ -36,3 +36,4 @@ BenchmarkKeyGenerationWithFmt-16    	 7360394	       167.6 ns/op
 5. **极简接口**: 验证 `EasyStart` 的可用性。
 6. **性能优化验证**: 验证在高频匹配场景下的 $O(1)$ 查找能力。
 7. **类型白名单与目录过滤**: 验证开启 Types 白名单时，正常过滤目录变更事件，不误触发回调 (`TestDirEventWithTypeFilter`)。
+8. **重启并发控制**: 连续发送多个 `SIGUSR1` 时重启串行执行，旧监听端口释放后才启动新进程。

watch/main.go

@@ -328,23 +328,21 @@ func runMonitor(config watch.Config) {
 func runCommand(config watch.Config, command []string, clearScreen bool) {
 	execDir, _ := os.Getwd()
 
-	var proc *shell.Process
 	sigCh := make(chan os.Signal, 1)
 	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM, syscall.SIGHUP, syscall.SIGUSR1)
+	restartCh := make(chan *watch.Event, 1)
+	stopCh := make(chan struct{})
+	doneCh := make(chan struct{})
 
-	restart := func(e *watch.Event) {
+	requestRestart := func(e *watch.Event) {
-		if clearScreen {
+		select {
-			fmt.Print("\033[2J\033[H")
+		case restartCh <- e:
+		default:
+			// A restart is already pending; one restart will include all recent changes.
 		}
-		printEvent(e)
-		printRestart(command)
-		if proc != nil {
-			proc.Kill() // shell.Kill() 已内置完整的进程树(PGID)清理逻辑
-		}
-		proc, _ = shell.Start(command[0], command[1:], &shell.Options{Dir: execDir, CatchSignal: true})
 	}
 
-	w, err := watch.Start(config, restart)
+	w, err := watch.Start(config, requestRestart)
 	if err != nil {
 		logError("failed to start watcher: " + err.Error())
 		os.Exit(1)
@@ -357,28 +355,62 @@ func runCommand(config watch.Config, command []string, clearScreen bool) {
 		for scanner.Scan() {
 			text := strings.TrimSpace(scanner.Text())
 			if text == "rs" {
-				restart(&watch.Event{Path: "manual restart", Type: watch.Change})
+				requestRestart(&watch.Event{Path: "manual restart", Type: watch.Change})
 			}
 		}
 	}()
 
-	// 启动时先执行一次
+	// A single worker owns proc so file events, rs, and signals cannot restart concurrently.
+	go func() {
+		defer close(doneCh)
+		var proc *shell.Process
+		start := func() {
+			printRestart(command)
+			var err error
+			proc, err = shell.Start(command[0], command[1:], &shell.Options{Dir: execDir, CatchSignal: true})
+			if err != nil {
+				proc = nil
+				logError("failed to start command: " + err.Error())
+			}
+		}
 		if clearScreen {
 			fmt.Print("\033[2J\033[H")
 		}
-	printRestart(command)
+		start()
-	proc, _ = shell.Start(command[0], command[1:], &shell.Options{Dir: execDir, CatchSignal: true})
+		for {
+			select {
+			case e := <-restartCh:
+				if clearScreen {
+					fmt.Print("\033[2J\033[H")
+				}
+				printEvent(e)
+				if proc != nil {
+					if err := proc.Kill(); err != nil {
+						logError("failed to stop command: " + err.Error())
+						continue
+					}
+				}
+				start()
+			case <-stopCh:
+				if proc != nil {
+					if err := proc.Kill(); err != nil {
+						logError("failed to stop command: " + err.Error())
+					}
+				}
+				return
+			}
+		}
+	}()
 
 	for sig := range sigCh {
 		if sig == syscall.SIGUSR1 {
-			restart(&watch.Event{Path: "manual reload", Type: watch.Change})
+			requestRestart(&watch.Event{Path: "manual reload", Type: watch.Change})
 			continue
 		}
 		break
 	}
-	if proc != nil {
+	close(stopCh)
-		proc.Kill()
+	<-doneCh
-	}
 	fmt.Printf("\n%s%s Stopped.%s\n", dim, gray, reset)
 }