2026-02-21 · Lab Notes ◆ Experimental
RAG Without Hallucination
Weak boundaries cause hallucinations, not weak retrieval. If your policy is "official docs only," enforce it at every generation stage.
Baseline Error 28%
Final Error 2%
Layers 7 hardening stages
Test Queries 200
The Pipeline
Query
User question
→
Retriever
top_k=3 chunks
↓
Evidence Validator
confidence ≥ 0.85
→
Generator
grounded output
If evidence score falls below threshold, the system enters abstention flow — explains what source is missing rather than fabricating an answer.
Guardrails
$ --rule constrain generation to quoted or tightly summarized retrieved chunks
$ --rule require citation IDs in final answer object [source_id:line_range]
$ --rule confidence threshold blocks free-form responses when evidence is thin
$ --rule unsupported-claim detector scans for entities/numbers not in retrieved passages
Prompting Pattern
| Step | Instruction |
|---|---|
| 1 | Answer only from provided context |
| 2 | Require explicit citation markers for each claim |
| 3 | Define mandatory fallback sentence when citations insufficient |
| 4 | Block speculative language in post-processing |
Error Rate Decline
Measured on 200 test queries against policy documents. Users accepted abstentions when the system explained what source was missing — a better experience than confident incorrect answers.
Recommendation
Treat retrieval fidelity as a product requirement, not a prompt trick. If trust matters, refusal behavior and citation rigor are core features, not optional polish.
Principle Abstention > fabrication
Method Architectural enforcement
Result 28% → 2% unsupported claims