diff --git a/agentserver/message_bus/message_state.py b/agentserver/message_bus/message_state.py
new file mode 100644
index 0000000..15a96bb
--- /dev/null
+++ b/agentserver/message_bus/message_state.py
@@ -0,0 +1,29 @@
+from dataclasses import dataclass, field
+from lxml.etree import Element
+from typing import Any
+
+@dataclass
+class HandlerMetadata:
+    """Trustworthy context passed to every handler."""
+    thread_id: str
+    from_id: str
+    own_name: str | None = None          # Only for agent: true listeners
+    is_self_call: bool = False           # Convenience flag
+
+
+@dataclass
+class MessageState:
+    """Universal intermediate representation flowing through all pipelines."""
+    raw_bytes: bytes | None = None
+    envelope_tree: Element | None = None
+    payload_tree: Element | None = None
+    payload: Any | None = None           # Deserialized @xmlify instance
+
+    thread_id: str | None = None
+    from_id: str | None = None
+
+    target_listeners: list['Listener'] | None = None   # Forward reference
+
+    error: str | None = None
+
+    metadata: dict[str, Any] = field(default_factory=dict)  # Extension point
\ No newline at end of file
diff --git a/agentserver/message_bus/steps/__init__.py b/agentserver/message_bus/steps/__init__.py
new file mode 100644
index 0000000..e69de29