feat: 通用步骤支持概率触发、循环按时间、预计结束时间上报

- 步骤新增 probability 参数：<100 时按百分比概率决定是否执行（实现"偶尔点赞"）
- loop 支持 loop_mode=rounds/time，按时间循环跑满 loop_duration 秒
- BaseWorker._start_timer 上报 end_time（开始+max_duration），task_manager 透出

tasks/generic/task.py

@@ -21,6 +21,7 @@ worker 按 steps 顺序执行，支持 loop 步骤循环、停止信号、进度
   group       - 动作组（含 children 步骤列表，按序执行一次，可折叠复用）
 """
 import random
+import time
 
 from tasks.base import BaseTask, register_task
 from core.device_worker import BaseWorker, _update_status
@@ -43,7 +44,7 @@ STEP_TYPES = [
     {"type": "wait", "label": "等待", "icon": "⏱",
      "params": {"min": 1.0, "max": 3.0}},
     {"type": "loop", "label": "循环块", "icon": "↻",
-     "params": {"max_iterations": 10, "children": []}},
+     "params": {"loop_mode": "rounds", "max_iterations": 10, "loop_duration": 600, "children": []}},
     {"type": "group", "label": "动作组", "icon": "📦",
      "params": {"children": []}},
 ]
@@ -112,6 +113,11 @@ class GenericStepsWorker(BaseWorker):
         stype = step.get("type", "")
         label = step.get("label", stype)
         params = step.get("params", {})
+        # 概率触发：probability=100 必执行，<100 按百分比概率决定本次是否执行
+        prob = float(params.get("probability", 100))
+        if prob < 100 and random.random() * 100 > prob:
+            _log.info(f"[{self.serial}] 步骤 '{label}' 概率 {prob}% 未触发，跳过")
+            return
         self.set_action(f"执行: {label}")
         _log.info(f"[{self.serial}] 步骤: {label}({stype}) params={params}")
 
@@ -196,16 +202,32 @@ class GenericStepsWorker(BaseWorker):
         random_sleep(min_s, max_s)
 
     def _exec_loop(self, d, params, depth=0):
-        max_iter = int(params.get("max_iterations", 10))
         children = params.get("children", [])
         if not children:
             return
-        for i in range(max_iter):
-            if self.stopped() or self.is_time_up():
+        mode = params.get("loop_mode", "rounds")
+        if mode == "time":
+            # 按时间循环：跑满 loop_duration 秒，同时受全局 stopped/max_duration 约束
+            duration = float(params.get("loop_duration", 0) or 0)
+            if duration <= 0:
+                _log.warning(f"[{self.serial}] 按时间循环未设置时长，跳过")
                 return
-            self.set_action(f"循环第 {i+1}/{max_iter} 轮")
-            _log.info(f"[{self.serial}] loop 第 {i+1}/{max_iter} 轮")
-            self._exec_steps(d, children, depth + 1)
+            start = time.time()
+            i = 0
+            while not self.stopped() and not self.is_time_up() and (time.time() - start) < duration:
+                i += 1
+                self.set_action(f"循环第 {i} 轮(按时间)")
+                _log.info(f"[{self.serial}] loop 第 {i} 轮(按时间, 已{(time.time()-start):.0f}s/{duration:.0f}s)")
+                self._exec_steps(d, children, depth + 1)
+        else:
+            # 按轮次循环
+            max_iter = int(params.get("max_iterations", 10))
+            for i in range(max_iter):
+                if self.stopped() or self.is_time_up():
+                    return
+                self.set_action(f"循环第 {i+1}/{max_iter} 轮")
+                _log.info(f"[{self.serial}] loop 第 {i+1}/{max_iter} 轮")
+                self._exec_steps(d, children, depth + 1)
 
     def _exec_group(self, d, params, depth=0):
         """动作组：按序执行 children 一次（类似 loop 但不循环）。