fix(panel): heartbeat is authoritative for phase; disk signals only as fallback

digitimes updates registry/index incrementally while still fetching, so a
mid-fetch registry write was misread as 推送/收尾 and overrode the agent's
own correct 采集中 heartbeat. Disk inference has now been wrong in both
directions (stale when the agent forgets to flip,超前 on incremental
writers) — trust the agent's heartbeat whenever present; disk evidence
and neutral 运行中 remain fallbacks only.

web/app.py

@@ -592,38 +592,34 @@ def _harvest_phase(source):
     except OSError:
         return None, None
 
-    # 1) 真实阶段文件(进程自己写的)——磁盘证据必须比心跳最后写入时间新才能覆盖它。
-    #    基准锚在心跳而非任务开始:自动重试的 attempt2 会重置心跳为"采集中"重新抓取,
-    #    attempt1 的收尾文件(registry 等)虽比任务开始新,但比新心跳旧,不得污染新阶段。
+    # 1) 心跳 = 采集会话亲述的阶段,绝对优先(实测磁盘信号两个方向都会说谎:
+    #    会话忘翻牌时过旧;digitimes 这类边抓边写 registry 的源又过超前,
+    #    抓取中途的 registry 更新会被误读成"推送/收尾")。
     phase_file = LOG_DIR / f"{source}.phase"
-    hb_txt, hb_mtime = "", None
     if phase_file.exists():
         try:
             hb_txt = phase_file.read_text(encoding="utf-8").strip()
-            hb_mtime = mtime(phase_file)
         except OSError:
-            hb_txt, hb_mtime = "", None
-    baseline = hb_mtime or start
+            hb_txt = ""
+        if hb_txt:
+            return start, hb_txt
 
+    # 2) 无心跳时才用磁盘信号兜底(尽力而为)
     def disk_phase_and_mtime():
         if not (day_dir and day_dir.is_dir()):
             return None, None
         reg = mtime(day_dir / "registry.json")
-        if reg and reg > baseline:
-            return "推送/收尾", reg
+        if reg and reg > start:
+            return "推送/收尾"
         summ = mtime(day_dir / ".summaries.json")
-        if summ and summ > baseline:
-            return "摘要生成", summ
+        if summ and summ > start:
+            return "摘要生成"
         mani = mtime(day_dir / ".manifest.json")
-        if mani and mani > baseline:
-            return "摘要生成", mani
-        return None, None
+        if mani and mani > start:
+            return "摘要生成"
+        return None
 
-    dp, dp_mtime = disk_phase_and_mtime()
-    if hb_txt and hb_mtime:
-        if not dp or hb_mtime >= dp_mtime:
-            return start, hb_txt
-        return start, dp  # 磁盘证据比心跳新:信磁盘(会话忘翻牌的场景)
+    dp = disk_phase_and_mtime()
     if dp:
         return start, dp
     # 3) 无信号:中性显示,不猜