chore: mark diskann as optional

README.md

@@ -49,13 +49,23 @@ git submodule update --init --recursive
 brew install llvm libomp boost protobuf
 export CC=$(brew --prefix llvm)/bin/clang
 export CXX=$(brew --prefix llvm)/bin/clang++
+
+# Install with HNSW backend (default, recommended for most users)
 uv sync
+
+# Or add DiskANN backend if you want to test more options
+uv sync --extra diskann
 ```
 
 **Linux (Ubuntu/Debian):**
 ```bash
 sudo apt-get install libomp-dev libboost-all-dev protobuf-compiler libabsl-dev libmkl-full-dev libaio-dev
+
+# Install with HNSW backend (default, recommended for most users)
 uv sync
+
+# Or add DiskANN backend if you want to test more options
+uv sync --extra diskann
 ```
 
 **Ollama Setup (Optional for Local LLM):**

pyproject.toml

@@ -9,7 +9,6 @@ requires-python = ">=3.10"
 
 dependencies = [
     "leann-core",
-    "leann-backend-diskann",
     "leann-backend-hnsw",
     "numpy>=1.26.0",
     "torch",
@@ -48,6 +47,10 @@ dev = [
     "huggingface-hub>=0.20.0",
 ]
 
+diskann = [
+    "leann-backend-diskann",
+]
+
 [tool.setuptools]
 py-modules = []