RAG450 Wikipedia articles19,391 passagesruns on CPU

Ask a question. Get the exact sentence it came from.

Type or say your question. The assistant searches its knowledge base with keyword and embedding search, re-ranks the results with a trained model, and quotes the answer word for word with its source. If the answer isn't there, it tells you instead of guessing.

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In the stacks

Measured on 10,570 questions it never saw

SQuAD v1.1 dev questions, none used for training. Each has a known source passage, so every number below is checked against the truth.

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answered
when the answer is in the knowledge base
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of answers are right
the quoted sentence contains SQuAD's answer
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declined correctly
when the article isn't in the knowledge base

Finding the right passage

by retriever

RetrieverRecall@1@5@10MRR@10p95

Recall@k is the share of questions whose source passage is in the top k results. Latency is per query on a 2-vCPU machine.

Right passage ranked first

Recall@1

How it finds the answer

Everything runs on CPU inside one serverless function. The highlighted steps are models trained for this project.

Question BM25 keyword67K-term index Dense embeddingsWordLlama 256-d Learned re-ranker16 features, listwise Answer selectorbest of top 3 Quote + citationor decline if unsure top 50 from each, merged

Two searches, one ranking. Keyword search (BM25) and embedding search each pull their top 50 passages. A small neural ranker, trained on 15,000 separate questions, orders the merged list using 16 signals: both scores, how many of the question's rare words a passage contains, how tightly they cluster in one or two sentences, and title overlap.

Quotes, not paraphrases. A second model picks the sentence most likely to hold the answer from the top three passages, so every answer is a verbatim quote with a citation. A confidence model, trained on questions about articles left out of the index, decides when to decline. Voice input uses your browser's own speech recognition, and read-aloud uses its built-in voices.