refactor: remove legacy assistant compatibility

backend/routes/assistants.py

@@ -20,7 +20,7 @@ from schemas import (
 )
 from services.auth import require_admin
 from services.masking import mask, resolve_incoming_key
-from services.node_specs import graph_references, normalize_graph, validate_graph
+from services.node_specs import copy_graph, graph_references, validate_graph
 from services.state_expressions import StateExpressionError, validate_update_rules
 from services.system_tools import RESERVED_TOOL_NAMES
 from services.tool_policy import policy_for_tool
@@ -98,9 +98,9 @@ def _validate_workflow(body: AssistantUpsert) -> None:
     if body.graph and str(body.graph.get("specVersion") or "") != "4":
         raise HTTPException(
             400,
-            "Workflow API 仅接受 specVersion=4；旧图请先执行数据库迁移",
+            "Workflow API 仅接受当前 specVersion=4 图结构",
         )
-    body.graph = normalize_graph(body.graph or {})
+    body.graph = copy_graph(body.graph or {})
     errors = validate_graph(body.graph)
     settings = body.graph.get("settings") or {}
     graph_runtime_mode = str(settings.get("runtimeMode") or "pipeline")
@@ -636,7 +636,7 @@ async def _to_out(session: AsyncSession, assistant: Assistant) -> AssistantOut:
         api_key=mask(assistant.api_key),
         app_id=assistant.app_id,
         graph=(
-            normalize_graph(assistant.graph or {})
+            copy_graph(assistant.graph or {})
             if assistant.type == "workflow"
             else {}
         ),

backend/routes/voice_webrtc.py

@@ -63,24 +63,23 @@ async def _wait_for_pipeline_close(
 
 
 async def shutdown_active_sessions() -> None:
-    """Compatibility proxy; now drains RTVI and OpenAI Realtime sessions."""
+    """Drain RTVI and OpenAI Realtime sessions."""
     _http_peers.clear()
     await realtime_lifecycle.shutdown_active_sessions(
         timeout=PIPELINE_CLOSE_GRACE_SECONDS,
     )
 
 
-def _decode_client_tool_names(encoded: str | None) -> list[str] | None:
+def _decode_client_tool_names(encoded: str | None) -> list[str]:
     """Decode client capabilities carried outside the WebRTC SDP body.
 
     Pipecat's browser transport replaces the body of a ``Request`` endpoint
     with its SDP offer and drops ``APIRequest.requestData``. Request headers are
-    preserved, so they are the authoritative metadata channel for this path.
-    ``None`` means the header was absent and callers should use the legacy body.
+    preserved, so they are the single metadata channel for this path.
     """
 
     if encoded is None:
-        return None
+        return []
     try:
         padding = "=" * (-len(encoded) % 4)
         value = json.loads(
@@ -134,21 +133,16 @@ async def http_offer(request: Request, payload: dict = Body(...)):
         header_variables = json.loads(
             base64.urlsafe_b64decode(encoded_variables + padding).decode("utf-8")
         )
-    header_client_tools = _decode_client_tool_names(
+    client_tool_names = _decode_client_tool_names(
         request.headers.get("x-pipecat-client-tools")
     )
-    client_tool_names = (
-        header_client_tools
-        if header_client_tools is not None
-        else request_data.get("client_tool_names") or []
-    )
     logger.debug(f"WebRTC 客户端工具上报: {client_tool_names or '<none>'}")
     offer_payload = {
         **payload,
         "assistant_id": request.headers.get("x-pipecat-assistant-id"),
         "dynamic_variables": header_variables,
         **request_data,
-        # Keep header metadata authoritative when both paths are present.
+        # Client capabilities have one canonical transport: the request header.
         "client_tool_names": client_tool_names,
     }
     answer = await _handle_offer_payload(offer_payload, _http_peers)