A case study in source-grounded fine-tuning: I trained an 8B model on a public-domain 19th-century corpus to force it to cite chapter/verse — here’s where it works and where it fails
A case study in source-grounded fine-tuning: I trained an 8B model on a public-domain 19th-century corpus to force it to cite chapter/verse — here’s where it works and where it fails

A case study in source-grounded fine-tuning: I trained an 8B model on a public-domain 19th-century corpus to force it to cite chapter/verse — here’s where it works and where it fails

Solo project, sharing it here for the AI angle rather than the subject matter.

I fine-tuned Llama 3.1 8B (QLoRA, single T4) on the complete works of a 19th-century author whose corpus is fully public domain. The interesting problem wasn't the domain — it was trying to get a small model to cite its source (book, chapter, item) on every answer instead of just asserting things confidently.

What I learned, which might be useful to others doing domain fine-tunes:

- Teaching the *format* of citation is easy. Teaching *correct* citation is hard. The model reliably produces "Source: [Book], chapter X, item Y" — and the concept is usually right, but the exact number is often wrong. It learned the shape of grounding without the precision.

- That gap is exactly why I run the production version as RAG over the same corpus instead of trusting the fine-tune's recall. The fine-tune sets tone and structure; retrieval handles the facts.

- For a low-resource target (Brazilian Portuguese, archaic register), ~4.9k well-structured Q&A pairs was enough to shift tone meaningfully but not enough to make it authoritative on its own.

Model + dataset are open (Apache-2.0) if anyone wants to poke at the data structure: huggingface.co/ia-espirita

Question for the sub: for those who've done domain fine-tunes — have you found any reliable way to get a small model to ground specific citations correctly, or is RAG just the honest answer and fine-tuning should never be trusted for exact references?

https://iaespirita.com/noticias/modelos-riv-ai-1260-downloads-hugging-face

submitted by /u/SideSuspicious8083
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