feat: Implement Dify LLM provider and update related configurations and tests
This commit is contained in:
Xin Wang
226
engine/providers/llm/dify.py
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226
engine/providers/llm/dify.py
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"""Dify-backed LLM provider."""
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from __future__ import annotations
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import asyncio
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import json
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import uuid
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from typing import Any, AsyncIterator, Dict, List, Optional
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import aiohttp
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from loguru import logger
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from providers.common.base import BaseLLMService, LLMMessage, LLMStreamEvent, ServiceState
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class DifyLLMService(BaseLLMService):
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"""LLM provider that delegates chat orchestration to Dify Service API."""
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def __init__(
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self,
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*,
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api_key: str,
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base_url: str,
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model: str = "dify",
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system_prompt: Optional[str] = None,
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):
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super().__init__(model=model or "dify")
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self.api_key = api_key
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self.base_url = str(base_url or "").rstrip("/")
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self.system_prompt = system_prompt or ""
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self._session: Optional[aiohttp.ClientSession] = None
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self._cancel_event = asyncio.Event()
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self._conversation_id: Optional[str] = None
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self._user_id = f"engine_{uuid.uuid4().hex}"
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self._knowledge_config: Dict[str, Any] = {}
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self._tool_schemas: List[Dict[str, Any]] = []
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async def connect(self) -> None:
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if not self.api_key:
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raise ValueError("Dify API key not provided")
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if not self.base_url:
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raise ValueError("Dify base URL not provided")
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headers = {
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"Authorization": f"Bearer {self.api_key}",
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"Content-Type": "application/json",
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}
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self._session = aiohttp.ClientSession(headers=headers)
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self.state = ServiceState.CONNECTED
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logger.info("Dify LLM service connected: base_url={}", self.base_url)
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async def disconnect(self) -> None:
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if self._session is not None:
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await self._session.close()
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self._session = None
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self.state = ServiceState.DISCONNECTED
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logger.info("Dify LLM service disconnected")
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def cancel(self) -> None:
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self._cancel_event.set()
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def set_knowledge_config(self, config: Optional[Dict[str, Any]]) -> None:
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# Dify owns retriever orchestration in this provider mode.
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self._knowledge_config = dict(config or {})
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def set_tool_schemas(self, schemas: Optional[List[Dict[str, Any]]]) -> None:
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# Dify owns tool/workflow orchestration in this provider mode.
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self._tool_schemas = list(schemas or [])
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async def get_initial_greeting(self) -> Optional[str]:
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if self._session is None:
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return None
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url = f"{self.base_url}/parameters"
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async with self._session.get(url, params={"user": self._user_id}) as response:
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await self._raise_for_status(response, "Dify parameters request failed")
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payload = await response.json()
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opening_statement = str(payload.get("opening_statement") or "").strip()
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return opening_statement or None
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async def generate(
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self,
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messages: List[LLMMessage],
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temperature: float = 0.7,
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max_tokens: Optional[int] = None,
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) -> str:
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parts: List[str] = []
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async for event in self.generate_stream(messages, temperature=temperature, max_tokens=max_tokens):
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if event.type == "text_delta" and event.text:
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parts.append(event.text)
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return "".join(parts)
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async def generate_stream(
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self,
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messages: List[LLMMessage],
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temperature: float = 0.7,
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max_tokens: Optional[int] = None,
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) -> AsyncIterator[LLMStreamEvent]:
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del temperature, max_tokens
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if self._session is None:
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raise RuntimeError("LLM service not connected")
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query = self._extract_query(messages)
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if not query:
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yield LLMStreamEvent(type="done")
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return
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if self.system_prompt:
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logger.debug("Ignoring local system prompt for Dify-managed assistant config")
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payload: Dict[str, Any] = {
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"inputs": {},
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"query": query,
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"user": self._user_id,
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"response_mode": "streaming",
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}
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if self._conversation_id:
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payload["conversation_id"] = self._conversation_id
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self._cancel_event.clear()
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url = f"{self.base_url}/chat-messages"
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response = await self._session.post(url, json=payload)
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try:
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await self._raise_for_status(response, "Dify chat request failed")
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async for event in self._iter_sse_events(response):
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if self._cancel_event.is_set():
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logger.info("Dify stream cancelled")
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break
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event_name = str(event.get("event") or "").strip().lower()
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if event.get("conversation_id"):
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self._conversation_id = str(event.get("conversation_id"))
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if event_name in {"message", "agent_message"}:
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text = self._extract_text_delta(event)
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if text:
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yield LLMStreamEvent(type="text_delta", text=text)
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elif event_name == "error":
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raise RuntimeError(str(event.get("message") or event.get("error") or "Dify stream error"))
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elif event_name in {"message_end", "agent_message_end"}:
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continue
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finally:
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response.close()
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yield LLMStreamEvent(type="done")
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@staticmethod
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def _extract_query(messages: List[LLMMessage]) -> str:
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for message in reversed(messages):
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if str(message.role or "").strip().lower() == "user":
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return str(message.content or "").strip()
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for message in reversed(messages):
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content = str(message.content or "").strip()
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if content:
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return content
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return ""
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@staticmethod
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def _extract_text_delta(event: Dict[str, Any]) -> str:
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for key in ("answer", "text", "content"):
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value = event.get(key)
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if value is not None:
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text = str(value)
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if text:
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return text
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return ""
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async def _raise_for_status(self, response: aiohttp.ClientResponse, context: str) -> None:
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if int(response.status) < 400:
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return
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try:
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payload = await response.json()
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except Exception:
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payload = await response.text()
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raise RuntimeError(f"{context}: HTTP {response.status} {payload}")
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async def _iter_sse_events(self, response: aiohttp.ClientResponse) -> AsyncIterator[Dict[str, Any]]:
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event_name = ""
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data_lines: List[str] = []
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async for raw_line in response.content:
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line = raw_line.decode("utf-8", errors="ignore").rstrip("\r\n")
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if not line:
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payload = self._decode_sse_payload(event_name, data_lines)
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event_name = ""
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data_lines = []
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if payload is not None:
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yield payload
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continue
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if line.startswith(":"):
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continue
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if line.startswith("event:"):
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event_name = line.split(":", 1)[1].strip()
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continue
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if line.startswith("data:"):
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data_lines.append(line.split(":", 1)[1].lstrip())
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payload = self._decode_sse_payload(event_name, data_lines)
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if payload is not None:
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yield payload
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@staticmethod
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def _decode_sse_payload(event_name: str, data_lines: List[str]) -> Optional[Dict[str, Any]]:
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if not data_lines:
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return None
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raw = "\n".join(data_lines).strip()
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if not raw:
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return None
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if raw == "[DONE]":
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return {"event": "message_end"}
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try:
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payload = json.loads(raw)
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except json.JSONDecodeError:
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logger.debug("Skipping non-JSON Dify SSE payload: {}", raw)
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return None
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if not isinstance(payload, dict):
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return None
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if event_name and not payload.get("event"):
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payload["event"] = event_name
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return payload
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