revert: "chore(cleanup)!: remove tool_runtime.rag_tool" (#3877)

Reverts llamastack/llama-stack#3871

This PR broke RAG (even from Responses -- there _is_ a dependency)

llama_stack/core/routers/tool_runtime.py

@@ -8,8 +8,16 @@ from typing import Any
 
 from llama_stack.apis.common.content_types import (
     URL,
+    InterleavedContent,
+)
+from llama_stack.apis.tools import (
+    ListToolDefsResponse,
+    RAGDocument,
+    RAGQueryConfig,
+    RAGQueryResult,
+    RAGToolRuntime,
+    ToolRuntime,
 )
-from llama_stack.apis.tools import ListToolDefsResponse, ToolRuntime
 from llama_stack.log import get_logger
 
 from ..routing_tables.toolgroups import ToolGroupsRoutingTable
@@ -18,6 +26,36 @@ logger = get_logger(name=__name__, category="core::routers")
 
 
 class ToolRuntimeRouter(ToolRuntime):
+    class RagToolImpl(RAGToolRuntime):
+        def __init__(
+            self,
+            routing_table: ToolGroupsRoutingTable,
+        ) -> None:
+            logger.debug("Initializing ToolRuntimeRouter.RagToolImpl")
+            self.routing_table = routing_table
+
+        async def query(
+            self,
+            content: InterleavedContent,
+            vector_store_ids: list[str],
+            query_config: RAGQueryConfig | None = None,
+        ) -> RAGQueryResult:
+            logger.debug(f"ToolRuntimeRouter.RagToolImpl.query: {vector_store_ids}")
+            provider = await self.routing_table.get_provider_impl("knowledge_search")
+            return await provider.query(content, vector_store_ids, query_config)
+
+        async def insert(
+            self,
+            documents: list[RAGDocument],
+            vector_store_id: str,
+            chunk_size_in_tokens: int = 512,
+        ) -> None:
+            logger.debug(
+                f"ToolRuntimeRouter.RagToolImpl.insert: {vector_store_id}, {len(documents)} documents, chunk_size={chunk_size_in_tokens}"
+            )
+            provider = await self.routing_table.get_provider_impl("insert_into_memory")
+            return await provider.insert(documents, vector_store_id, chunk_size_in_tokens)
+
     def __init__(
         self,
         routing_table: ToolGroupsRoutingTable,
@@ -25,6 +63,11 @@ class ToolRuntimeRouter(ToolRuntime):
         logger.debug("Initializing ToolRuntimeRouter")
         self.routing_table = routing_table
 
+        # HACK ALERT this should be in sync with "get_all_api_endpoints()"
+        self.rag_tool = self.RagToolImpl(routing_table)
+        for method in ("query", "insert"):
+            setattr(self, f"rag_tool.{method}", getattr(self.rag_tool, method))
+
     async def initialize(self) -> None:
         logger.debug("ToolRuntimeRouter.initialize")
         pass