fix(agents): compare a claude process's lstart in UTC (Issue #31, Mac review)

time.mktime read ps's local lstart, which is ambiguous in the hour a DST
change repeats: the start could come out an hour off and a live holder be
taken for a reused pid (or the reverse). ps now runs with TZ=UTC0, which BSD
ps and procps both honour, and calendar.timegm reads it. No /proc.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.agents/skills/lib_py/agents/adapters/claude.py

@@ -1,4 +1,4 @@
-import os, re, json, glob, math, stat, time, shutil, subprocess
+import os, re, json, glob, math, stat, time, shutil, calendar, subprocess
 from typing import Optional, Any
 from lib_py.agents.base import BaseAgentAdapter, DiscoveryContext, conversation_in_use, scan_names, _plausible_id
 from lib_py.verify_session import workspace_key
@@ -84,10 +84,11 @@ def _session_file_live(data: dict, pid) -> bool:
             or not math.isfinite(started) or started <= 0:
         return True
     started = started / 1000.0
+    # lstart in UTC: a local time is ambiguous in the hour a DST change repeats.
     try:
         out = subprocess.run(["ps", "-p", str(pid), "-o", "lstart="], capture_output=True, text=True,
-                             timeout=5, env=dict(os.environ, LC_ALL="C")).stdout
-        lstart = time.mktime(time.strptime(" ".join(out.split()), "%a %b %d %H:%M:%S %Y"))
+                             timeout=5, env=dict(os.environ, LC_ALL="C", TZ="UTC0")).stdout
+        lstart = calendar.timegm(time.strptime(" ".join(out.split()), "%a %b %d %H:%M:%S %Y"))
     except Exception:
         return True
     # startedAt is written 1.7-3.2 s after the process starts; 2 s covers