gist-retriever

Fuse BM25 and GIST seeds with RRF and ColBERT reranking for GraphRAG retrieval.

Updated Apr 20, 2026
One-click install
npx skills add https://github.com/thistleknot/skills --skill gist-retriever
Or copy as Structured Prompt for Agent
Please help me install this Agent Skill.
Skill: gist-retriever
Source: https://github.com/thistleknot/skills/tree/main/gist-retriever
Command: npx skills add https://github.com/thistleknot/skills --skill gist-retriever

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill solves the problem of reliably retrieving relevant evidence from a large knowledge corpus by combining lexical, dense, and graph-adjacent neighborhood expansion into a single candidate pipeline.

Core Features & Use Cases

  • Multi-tier Retrieval Cascade (L1-first): Routes queries through a tiered fallback approach that escalates from wiki/markdown to local memory retrieval and finally to deep-research.
  • Hybrid Seed Retrieval and Fusion: Builds an initial candidate pool using BM25 and dense GIST/semantic retrieval, then fuses results with RRF to preserve ranking diversity.
  • L2 Neighborhood Expansion + Late Reranking: Expands seeds into a local semantic neighborhood (BM25 triplet expansion + dense centroid expansion) and applies ColBERT late interaction for higher-precision final ranking.
  • Reconstruction and Final Selection: Reconstructs candidates into coherent units (subclass-specific) and selects the final set according to a defined stopping rule.

Quick Start

Use gist-retriever to retrieve a high-quality evidence candidate set for a query before running syllogistic reasoning or answer synthesis.

Frequently Asked Questions about gist-retriever

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I combine BM25 lexical search with dense semantic retrieval for RAG?

Hybrid BM25 and dense retrieval combines lexical and semantic results using Reciprocal Rank Fusion (RRF). This preserves ranking diversity while building a single candidate pool for downstream neighborhood expansion and reranking.

What is GraphRAG neighborhood expansion and when do I need it for evidence retrieval?

GraphRAG neighborhood expansion takes fused BM25 and dense seeds and maps them into a local L2 semantic space using triplet expansion and dense centroids. It is needed when flat vector search misses conceptually adjacent context.

How does ColBERT late interaction reranking improve RAG precision?

ColBERT late interaction reranking improves RAG precision by applying token-level scoring to expanded neighborhood candidates. It refines the fused pool after L2 expansion, ensuring higher-precision final ranking before candidate reconstruction.

Can I use gist-retriever with Chroma vector search for agentic coding memory?

Yes, gist-retriever executes locally over a compact semantic triplet space using Chroma-based vector search. It routes queries through a tiered cascade from wiki and markdown to local memory, making it suitable for agentic coding.

What's the best way to fuse lexical and dense search results without losing ranking diversity?

The best way to fuse lexical and dense search results is Reciprocal Rank Fusion (RRF). It merges BM25 lexical seeds with dense GIST semantic seeds into a unified candidate pool, preserving ranking diversity before L2 neighborhood expansion.

What are the limitations of relying solely on BM25 for knowledge corpus retrieval?

Relying solely on BM25 for corpus retrieval misses semantic context and fails to capture conceptually adjacent evidence. Expanding fused seeds into an L2 neighborhood with dense centroids and ColBERT reranking overcomes these lexical matching limitations.