User Story

As Maya, in order to demonstrate that a small fine-tuned model can match or beat prompted larger models on a narrow domain task, I want an extraction variant powered by a LoRA fine-tune of a small open model, served from our own inference endpoint.

Preconditions

• #58 (Story 10 variant picker) merged to main
• Training data pipeline exists (can be bootstrapped in this story)

Acceptance Criteria

• Training dataset committed under data/fine-tuning/extraction/ — at least 50 (PDF description → spec) pairs, either hand-curated from fixtures or Opus-generated and reviewed
• LoRA fine-tuning script under scripts/fine-tune-extraction.ts (or language appropriate to the trainer)
• Trained adapter checkpoint committed or clearly documented with retrieval instructions
• FastAPI inference endpoint deployed to existing EC2, reachable via the app’s Caddy routing — separate NixOS service, managed alongside the main app
• New variant extraction/lora-v1 in the extraction registry that calls the inference endpoint via HTTP
• Extraction tab in Settings → Variants lists the LoRA variant
• Evaluation run comparing the LoRA variant against Sonnet/Haiku baselines
• New catalog page catalog/experiments/pdf-field-extraction/lora-v1.md including: base model, training data size, LoRA rank/alpha, training hyperparameters, deployment architecture, and metric deltas vs baselines
• catalog/experiments/_roadmap.md updated with shipped status and one-line finding
• If scope becomes unachievable (time/cost), catalog page clearly marks scope-deferred with reasoning — “attempted” is an honest outcome

Success Metrics

• Either: the LoRA variant ships and hits a reasonable recall number (>50%), OR the catalog honestly documents what was attempted and what blocked shipping
• If shipped, cost-per-extraction documented vs API variants

Notes

• Class topic: fine-tuning (Ch 5), MLOps (Ch 4), production deployment (Ch 6) — the headline rubric item
• Base model choice: smallest viable — Llama 3.2 3B or Mistral 7B
• Cost gate: explicit user approval before GPU training spend
• This is the most ambitious story; acceptable to scope-defer with a written explanation

Definition of Done

• Acceptance criteria met (or clearly documented scope-deferral)
• Tests pass
• Type checking passes
• Threat model updated (new service, new external training process)
• CI pipeline green
• Deployed and demoable