fix(timezone): add timezone-aware clock across agent, cron, and execute_code

hermes_time.py

@@ -0,0 +1,119 @@
+"""
+Timezone-aware clock for Hermes.
+
+Provides a single ``now()`` helper that returns a timezone-aware datetime
+based on the user's configured IANA timezone (e.g. ``Asia/Kolkata``).
+
+Resolution order:
+  1. ``HERMES_TIMEZONE`` environment variable
+  2. ``timezone`` key in ``~/.hermes/config.yaml``
+  3. Falls back to the server's local time (``datetime.now().astimezone()``)
+
+Invalid timezone values log a warning and fall back safely — Hermes never
+crashes due to a bad timezone string.
+"""
+
+import logging
+import os
+from datetime import datetime, timezone as _tz
+from pathlib import Path
+from typing import Optional
+
+logger = logging.getLogger(__name__)
+
+try:
+    from zoneinfo import ZoneInfo
+except ImportError:
+    # Python 3.8 fallback (shouldn't be needed — Hermes requires 3.9+)
+    from backports.zoneinfo import ZoneInfo  # type: ignore[no-redef]
+
+# Cached state — resolved once, reused on every call.
+# Call reset_cache() to force re-resolution (e.g. after config changes).
+_cached_tz: Optional[ZoneInfo] = None
+_cached_tz_name: Optional[str] = None
+_cache_resolved: bool = False
+
+
+def _resolve_timezone_name() -> str:
+    """Read the configured IANA timezone string (or empty string).
+
+    This does file I/O when falling through to config.yaml, so callers
+    should cache the result rather than calling on every ``now()``.
+    """
+    # 1. Environment variable (highest priority — set by Supervisor, etc.)
+    tz_env = os.getenv("HERMES_TIMEZONE", "").strip()
+    if tz_env:
+        return tz_env
+
+    # 2. config.yaml ``timezone`` key
+    try:
+        import yaml
+        hermes_home = Path(os.getenv("HERMES_HOME", Path.home() / ".hermes"))
+        config_path = hermes_home / "config.yaml"
+        if config_path.exists():
+            with open(config_path) as f:
+                cfg = yaml.safe_load(f) or {}
+            tz_cfg = cfg.get("timezone", "")
+            if isinstance(tz_cfg, str) and tz_cfg.strip():
+                return tz_cfg.strip()
+    except Exception:
+        pass
+
+    return ""
+
+
+def _get_zoneinfo(name: str) -> Optional[ZoneInfo]:
+    """Validate and return a ZoneInfo, or None if invalid."""
+    if not name:
+        return None
+    try:
+        return ZoneInfo(name)
+    except (KeyError, Exception) as exc:
+        logger.warning(
+            "Invalid timezone '%s': %s. Falling back to server local time.",
+            name, exc,
+        )
+        return None
+
+
+def get_timezone() -> Optional[ZoneInfo]:
+    """Return the user's configured ZoneInfo, or None (meaning server-local).
+
+    Resolved once and cached. Call ``reset_cache()`` after config changes.
+    """
+    global _cached_tz, _cached_tz_name, _cache_resolved
+    if not _cache_resolved:
+        _cached_tz_name = _resolve_timezone_name()
+        _cached_tz = _get_zoneinfo(_cached_tz_name)
+        _cache_resolved = True
+    return _cached_tz
+
+
+def get_timezone_name() -> str:
+    """Return the IANA name of the configured timezone, or empty string."""
+    global _cached_tz_name, _cache_resolved
+    if not _cache_resolved:
+        get_timezone()  # populates cache
+    return _cached_tz_name or ""
+
+
+def now() -> datetime:
+    """
+    Return the current time as a timezone-aware datetime.
+
+    If a valid timezone is configured, returns wall-clock time in that zone.
+    Otherwise returns the server's local time (via ``astimezone()``).
+    """
+    tz = get_timezone()
+    if tz is not None:
+        return datetime.now(tz)
+    # No timezone configured — use server-local (still tz-aware)
+    return datetime.now().astimezone()
+
+
+def reset_cache() -> None:
+    """Clear the cached timezone. Used by tests and after config changes."""
+    global _cached_tz, _cached_tz_name, _cache_resolved
+    _cached_tz = None
+    _cached_tz_name = None
+    _cache_resolved = False