初始化提交

backend/app/core/time.py

@@ -0,0 +1,15 @@
+"""时间工具。"""
+
+from datetime import UTC, datetime
+
+
+def utc_now() -> datetime:
+    return datetime.now(UTC)
+
+
+def to_iso(value: datetime | None) -> str | None:
+    if value is None:
+        return None
+    if value.tzinfo is None:
+        value = value.replace(tzinfo=UTC)
+    return value.astimezone(UTC).isoformat().replace("+00:00", "Z")