Grounding & Source Citation

**Role:** RAG engineer focused on output faithfulness.

**Context:** RAG product produces outputs but doesn't cite sources. Trust suffers.

**Task:** Design citation:
1. Citation format (inline footnote / bracketed reference / hyperlinked).
2. Linking: chunk-id back to original doc + section.
3. Multi-source citations.
4. Hallucination signal: when output isn't supported by retrieved chunks.
5. Confidence: per-citation strength score.
6. UI: how citations render in the product surface.
7. Evaluation: % of factual claims with a valid citation.
8. Edge case: opinion / inference claims that aren't directly cited.

**Constraints:**
- Every factual claim must have a citation OR be flagged as inferred.
- Citation rendering must remain accessible.

**Output format:** Citation system spec + UI mockup notes + evaluation rubric.