fix: normalize imported session timestamps

OpenClaw session imports can leave ISO-8601 timestamps in SessionDB rows.
Normalize legacy string timestamps before rendering or comparing session
activity so session listing and resume surfaces do not crash on imported
history.

hermes_cli/main.py

@@ -198,8 +198,30 @@ from hermes_constants import AI_GATEWAY_BASE_URL, OPENROUTER_BASE_URL
 logger = logging.getLogger(__name__)
 
 
+def _coerce_timestamp(ts):
+    """Best-effort parse for epoch or ISO-8601 timestamps."""
+    if ts is None or ts == "":
+        return None
+    if isinstance(ts, (int, float)):
+        return float(ts)
+    if isinstance(ts, str):
+        raw = ts.strip()
+        if not raw:
+            return None
+        try:
+            return float(raw)
+        except ValueError:
+            pass
+        try:
+            return datetime.fromisoformat(raw.replace("Z", "+00:00")).timestamp()
+        except ValueError:
+            return None
+    return None
+
+
 def _relative_time(ts) -> str:
     """Format a timestamp as relative time (e.g., '2h ago', 'yesterday')."""
+    ts = _coerce_timestamp(ts)
     if not ts:
         return "?"
     delta = _time.time() - ts

hermes_state.py

@@ -21,6 +21,7 @@ import re
 import sqlite3
 import threading
 import time
+from datetime import datetime
 from pathlib import Path
 from hermes_constants import get_hermes_home
 from typing import Any, Callable, Dict, List, Optional, TypeVar
@@ -29,6 +30,32 @@ logger = logging.getLogger(__name__)
 
 T = TypeVar("T")
 
+
+def _normalize_timestamp(value: Any) -> Any:
+    """Best-effort normalization for legacy/imported timestamp values.
+
+    Session rows are supposed to store REAL epoch seconds, but imported data may
+    contain ISO-8601 strings. Normalize those on read so downstream callers can
+    safely compare/subtract timestamps without exploding.
+    """
+    if value is None or value == "":
+        return value
+    if isinstance(value, (int, float)):
+        return float(value)
+    if isinstance(value, str):
+        raw = value.strip()
+        if not raw:
+            return value
+        try:
+            return float(raw)
+        except ValueError:
+            pass
+        try:
+            return datetime.fromisoformat(raw.replace("Z", "+00:00")).timestamp()
+        except ValueError:
+            return value
+    return value
+
 DEFAULT_DB_PATH = get_hermes_home() / "state.db"
 
 SCHEMA_VERSION = 8
@@ -858,6 +885,9 @@ class SessionDB:
         sessions = []
         for row in rows:
             s = dict(row)
+            for key in ("started_at", "ended_at", "last_active"):
+                if key in s:
+                    s[key] = _normalize_timestamp(s.get(key))
             # Build the preview from the raw substring
             raw = s.pop("_preview_raw", "").strip()
             if raw:
@@ -930,6 +960,9 @@ class SessionDB:
         if not row:
             return None
         s = dict(row)
+        for key in ("started_at", "ended_at", "last_active"):
+            if key in s:
+                s[key] = _normalize_timestamp(s.get(key))
         raw = s.pop("_preview_raw", "").strip()
         if raw:
             text = raw[:60]

tests/hermes_cli/test_relative_time.py

@@ -0,0 +1,10 @@
+import time
+
+from hermes_cli.main import _relative_time
+
+
+def test_relative_time_accepts_iso_timestamps():
+    ts = time.time() - 7200
+    iso = time.strftime("%Y-%m-%dT%H:%M:%S", time.localtime(ts))
+
+    assert _relative_time(iso) == "2h ago"

tests/test_hermes_state.py

@@ -1438,6 +1438,22 @@ class TestListSessionsRich:
         # No messages, so last_active falls back to started_at
         assert sessions[0]["last_active"] == sessions[0]["started_at"]
 
+    def test_last_active_normalizes_legacy_iso_started_at(self, db):
+        db.create_session("legacy", "cli")
+        db._conn.execute(
+            "UPDATE sessions SET started_at=?, ended_at=? WHERE id=?",
+            ("2026-04-09T12:00:00", "2026-04-09T13:00:00", "legacy"),
+        )
+        db._conn.commit()
+
+        sessions = db.list_sessions_rich()
+        legacy = next(s for s in sessions if s["id"] == "legacy")
+
+        assert isinstance(legacy["started_at"], float)
+        assert isinstance(legacy["ended_at"], float)
+        assert isinstance(legacy["last_active"], float)
+        assert legacy["last_active"] == legacy["started_at"]
+
     def test_rich_list_includes_title(self, db):
         db.create_session("s1", "cli")
         db.set_session_title("s1", "refactoring auth")