Architecture
Technical approach: a self-built thin retrieval layer
We do not wrap an external RAG platform. The chunking pipeline, embedding calls, hybrid retrieval, reranking, and source assembly are all built in-house — about six core modules in total.
Chunking
Structure-aware chunking. Clause numbers, section headings, and table rows all inform boundary decisions — no cutting by character count.
Embedding
An embedding endpoint on the intranet, with 1024-dimensional normalized vectors. The query side gets an Instruct prefix; the document side doesn't.
Hybrid Retrieval
Dual-path retrieval: dense vectors + a full-text inverted index (Chinese bigram, English word-level, a BM25 variant).
Fusion
RRF fusion, k=60. It looks only at rank, not score scale, so it adapts to heterogeneous retrieval sources.
Rerank
A reranker refines candidate chunks; on failure it degrades to pure hybrid retrieval, marking the state without blocking search.
Provenance
When generating an answer it concatenates sources, labels source numbers and relevance scores, and lets you click back to the original text.