feat: RAG Integration (#238)

* feat: add rag provider and retriever

* feat: retriever tool

* feat: add retriever tool to the researcher node

* feat: add rag http apis

* feat: new message input supports resource mentions

* feat: new message input component support resource mentions

* refactor: need_web_search to need_search

* chore: RAG integration docs

* chore: change example api host

* fix: user message color in dark mode

* fix: mentions style

* feat: add local_search_tool to researcher prompt

* chore: research prompt

* fix: ragflow page size and reporter with

* docs: ragflow integration and add acknowledgment projects

* chore: format

src/rag/retriever.py

@@ -0,0 +1,77 @@
+import abc
+from pydantic import BaseModel, Field
+
+
+class Chunk:
+    content: str
+    similarity: float
+
+    def __init__(self, content: str, similarity: float):
+        self.content = content
+        self.similarity = similarity
+
+
+class Document:
+    """
+    Document is a class that represents a document.
+    """
+
+    id: str
+    url: str | None = None
+    title: str | None = None
+    chunks: list[Chunk] = []
+
+    def __init__(
+        self,
+        id: str,
+        url: str | None = None,
+        title: str | None = None,
+        chunks: list[Chunk] = [],
+    ):
+        self.id = id
+        self.url = url
+        self.title = title
+        self.chunks = chunks
+
+    def to_dict(self) -> dict:
+        d = {
+            "id": self.id,
+            "content": "\n\n".join([chunk.content for chunk in self.chunks]),
+        }
+        if self.url:
+            d["url"] = self.url
+        if self.title:
+            d["title"] = self.title
+        return d
+
+
+class Resource(BaseModel):
+    """
+    Resource is a class that represents a resource.
+    """
+
+    uri: str = Field(..., description="The URI of the resource")
+    title: str = Field(..., description="The title of the resource")
+    description: str | None = Field("", description="The description of the resource")
+
+
+class Retriever(abc.ABC):
+    """
+    Define a RAG provider, which can be used to query documents and resources.
+    """
+
+    @abc.abstractmethod
+    def list_resources(self, query: str | None = None) -> list[Resource]:
+        """
+        List resources from the rag provider.
+        """
+        pass
+
+    @abc.abstractmethod
+    def query_relevant_documents(
+        self, query: str, resources: list[Resource] = []
+    ) -> list[Document]:
+        """
+        Query relevant documents from the resources.
+        """
+        pass