# RAG that cannot quote a wrong price

> A retrieval pipeline that cites stale prices and invented SKUs is worse than none at all. Grounding is a pipeline problem, not a prompt problem.

The demo works because the demo's data is clean. Production fails on the boring parts: chunking that splits a price from its product, retrieval that returns last year's catalogue, and a prompt that lets the model fill gaps from memory.

## Chunk around the fact, not the token count

If a product's name, price and stock land in different chunks, retrieval can hand the model the price of a different product and nothing in the prompt will notice. Chunk by document structure — one item, one chunk — and let the size vary.

## Freshness is a field, not a hope

Every chunk carries the timestamp of the source it came from, and retrieval prefers recent sources when facts conflict. A catalogue update that does not trigger a re-index is a hallucination scheduled for next week.

## The prompt's job is refusal, not eloquence

Instruct the model to answer only from retrieved context and to say so when the context does not cover the question. A visible 'I don't have that in the current catalogue' is a feature; a confidently wrong price is a liability.

## What to take away

- Chunk by document structure, not by token count.
- Timestamp every chunk; re-index on every source update.
- Prompt for refusal when context is missing, not for fluency.
- Cite the chunk in the answer so wrong answers are debuggable.

## Tags

RAG, LLM, Embeddings, Data

## We build this for clients

https://dfieldsolutions.com/en/services/ai-automation

## More from the lab

- https://dfieldsolutions.com/en/lab/prompt-evals.md — Prompts are code: eval them like code
- https://dfieldsolutions.com/en/lab/n8n-self-hosted-vs-zapier.md — Self-hosted n8n or Zapier — where the bill actually differs
- https://dfieldsolutions.com/en/lab/mcp-servers-production.md — MCP servers in production, not in the demo
- https://dfieldsolutions.com/en/lab/invoice-pipeline-automation.md — The invoice pipeline that ended the Friday admin block

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Source: https://dfieldsolutions.com/en/lab/rag-grounding
DField Solutions — Dunakeszi, Hungary — dezso@dfieldsolutions.com
Booking: see https://dfieldsolutions.com/en/contact