chore: round-2 review nits (re-review #9)

- tests/agent/test_session_activity.py asserts against
  ACTIVITY_DESCRIPTION_MAX instead of the literal 120.
- The session-stall WARNING log line names its config knob
  (agent.session_stall_timeout) so operators can find the setting.
- hermes_state.py: collapse the triple blank line near line 191.
- hermes_cli/status.py no longer imports the private
  hermes_cli.main._relative_time: the helper moved to a public home
  (hermes_cli.timefmt.relative_time); main._relative_time stays as a
  thin back-compat wrapper (sessions_cmd and external patchers keep
  working).

hermes_cli/main.py

@@ -944,21 +944,15 @@ def _termux_should_prefetch_update_check() -> bool:
 
 
 def _relative_time(ts) -> str:
-    """Format a timestamp as relative time (e.g., '2h ago', 'yesterday')."""
-    if not ts:
-        return "?"
-    delta = _time.time() - ts
-    if delta < 60:
-        return "just now"
-    if delta < 3600:
-        return f"{int(delta / 60)}m ago"
-    if delta < 86400:
-        return f"{int(delta / 3600)}h ago"
-    if delta < 172800:
-        return "yesterday"
-    if delta < 604800:
-        return f"{int(delta / 86400)}d ago"
-    return datetime.fromtimestamp(ts).strftime("%Y-%m-%d")
+    """Format a timestamp as relative time (e.g., '2h ago', 'yesterday').
+
+    Thin wrapper kept for backward compatibility; the implementation lives
+    in :mod:`hermes_cli.timefmt` so lightweight consumers don't have to
+    import the whole CLI surface.
+    """
+    from hermes_cli.timefmt import relative_time
+
+    return relative_time(ts)
 
 
 def _has_any_provider_configured() -> bool:

hermes_cli/status.py

@@ -65,9 +65,9 @@ def _format_iso_timestamp(value) -> str:
 
 def _format_relative_ts(ts: float) -> str:
     """Format an epoch timestamp as a short relative age for status output."""
-    from hermes_cli.main import _relative_time
+    from hermes_cli.timefmt import relative_time
 
-    return _relative_time(ts)
+    return relative_time(ts)
 
 
 def _configured_model_label(config: dict) -> str:

hermes_cli/timefmt.py

@@ -0,0 +1,30 @@
+"""Small shared time-formatting helpers for CLI output.
+
+Public home for helpers that used to live as private functions on
+``hermes_cli.main`` — importing that module drags in the whole CLI
+surface, which lightweight consumers (``hermes status``, dump tooling)
+should not pay for.
+"""
+
+from __future__ import annotations
+
+import time as _time
+from datetime import datetime
+
+
+def relative_time(ts) -> str:
+    """Format a timestamp as relative time (e.g., '2h ago', 'yesterday')."""
+    if not ts:
+        return "?"
+    delta = _time.time() - ts
+    if delta < 60:
+        return "just now"
+    if delta < 3600:
+        return f"{int(delta / 60)}m ago"
+    if delta < 86400:
+        return f"{int(delta / 3600)}h ago"
+    if delta < 172800:
+        return "yesterday"
+    if delta < 604800:
+        return f"{int(delta / 86400)}d ago"
+    return datetime.fromtimestamp(ts).strftime("%Y-%m-%d")