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)

tests/unit/rag/test_vector_store.py

@@ -4,6 +4,10 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
+import base64
+import mimetypes
+import os
+from pathlib import Path
 from unittest.mock import AsyncMock, MagicMock
 
 import numpy as np
@@ -13,13 +17,37 @@ from llama_stack.apis.inference.inference import (
     OpenAIEmbeddingData,
     OpenAIEmbeddingsRequestWithExtraBody,
 )
+from llama_stack.apis.tools import RAGDocument
 from llama_stack.apis.vector_io import Chunk
 from llama_stack.providers.utils.memory.vector_store import (
+    URL,
     VectorStoreWithIndex,
     _validate_embedding,
+    content_from_doc,
     make_overlapped_chunks,
 )
 
+DUMMY_PDF_PATH = Path(os.path.abspath(__file__)).parent / "fixtures" / "dummy.pdf"
+# Depending on the machine, this can get parsed a couple of ways
+DUMMY_PDF_TEXT_CHOICES = ["Dummy PDF file", "Dumm y PDF file"]
+
+
+def read_file(file_path: str) -> bytes:
+    with open(file_path, "rb") as file:
+        return file.read()
+
+
+def data_url_from_file(file_path: str) -> str:
+    with open(file_path, "rb") as file:
+        file_content = file.read()
+
+    base64_content = base64.b64encode(file_content).decode("utf-8")
+    mime_type, _ = mimetypes.guess_type(file_path)
+
+    data_url = f"data:{mime_type};base64,{base64_content}"
+
+    return data_url
+
 
 class TestChunk:
     def test_chunk(self):
@@ -88,6 +116,45 @@ class TestValidateEmbedding:
 
 
 class TestVectorStore:
+    async def test_returns_content_from_pdf_data_uri(self):
+        data_uri = data_url_from_file(DUMMY_PDF_PATH)
+        doc = RAGDocument(
+            document_id="dummy",
+            content=data_uri,
+            mime_type="application/pdf",
+            metadata={},
+        )
+        content = await content_from_doc(doc)
+        assert content in DUMMY_PDF_TEXT_CHOICES
+
+    @pytest.mark.allow_network
+    async def test_downloads_pdf_and_returns_content(self):
+        # Using GitHub to host the PDF file
+        url = "https://raw.githubusercontent.com/meta-llama/llama-stack/da035d69cfca915318eaf485770a467ca3c2a238/llama_stack/providers/tests/memory/fixtures/dummy.pdf"
+        doc = RAGDocument(
+            document_id="dummy",
+            content=url,
+            mime_type="application/pdf",
+            metadata={},
+        )
+        content = await content_from_doc(doc)
+        assert content in DUMMY_PDF_TEXT_CHOICES
+
+    @pytest.mark.allow_network
+    async def test_downloads_pdf_and_returns_content_with_url_object(self):
+        # Using GitHub to host the PDF file
+        url = "https://raw.githubusercontent.com/meta-llama/llama-stack/da035d69cfca915318eaf485770a467ca3c2a238/llama_stack/providers/tests/memory/fixtures/dummy.pdf"
+        doc = RAGDocument(
+            document_id="dummy",
+            content=URL(
+                uri=url,
+            ),
+            mime_type="application/pdf",
+            metadata={},
+        )
+        content = await content_from_doc(doc)
+        assert content in DUMMY_PDF_TEXT_CHOICES
+
     @pytest.mark.parametrize(
         "window_len, overlap_len, expected_chunks",
         [