> ## Documentation Index > Fetch the complete documentation index at: https://vecgrep.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Architecture > How VecGrep works under the hood ## Vector pipeline ``` Source files │ ▼ [Chunker] ── tree-sitter AST → semantic chunks (functions, classes) │ fallback: sliding-window for unsupported file types │ ▼ [Embedder] ── fastembed ONNX (default) or sentence-transformers (torch) │ all-MiniLM-L6-v2-code-search-512 (384-dim) │ ▼ [Store] ── LanceDB vector store (~/.vecgrep//lancedb/) │ IVF-PQ ANN index for sub-linear search │ merkle.json for O(files) change detection │ ▼ [Server] ── MCP server exposing index_codebase, search_code, get_index_status, hybrid_search ``` ## Graph pipeline ``` Source files │ ▼ [AST parser] ── tree-sitter → nodes (file, function, class, method) │ edges (contains, calls, imports, inherits) │ no LLM — pure static analysis │ ▼ [Store] ── networkx graph → ~/.vecgrep//graph.json │ ▼ [Server] ── MCP server exposing index_graph, search_graph, graph_neighbors ``` ## Hybrid search `hybrid_search` blends both pipelines at query time: ``` score = alpha * vector_score + (1 - alpha) * graph_score ``` Default `alpha=0.6` weights semantic relevance slightly higher than structural connectivity. Degrades to pure vector search when `graph.json` is absent. ## Index location Each project gets its own isolated directory: ``` ~/.vecgrep// lancedb/ # vector store merkle.json # change-detection fingerprints graph.json # knowledge graph (optional, created by index_graph) ``` ## Change detection VecGrep tracks mtime and file size in `merkle.json`. On re-index, only files whose mtime or size has changed are re-embedded — unchanged files are skipped in O(1) per file.