source filtering
**Source filtering** is the **retrieval restriction strategy that allows or blocks results based on origin systems, publishers, or trust tiers** - it enforces data quality and trust controls before evidence reaches generation.
**What Is Source filtering?**
- **Definition**: Filtering candidates by source identity, provenance score, or approval status.
- **Typical Sources**: Internal wikis, ticket systems, vendor manuals, and public knowledge feeds.
- **Policy Dimension**: Can enforce allowlists for high-trust content and deny lists for noisy feeds.
- **Integration Point**: Applied in retriever query planning and final evidence assembly.
**Why Source filtering Matters**
- **Evidence Quality**: Trusted sources improve factual consistency and reduce unsupported claims.
- **Risk Management**: Blocks low-confidence or unverified origins in high-stakes applications.
- **Brand Safety**: Prevents responses from citing disallowed or unofficial content.
- **Operational Clarity**: Source-level controls simplify incident response during data quality events.
- **User Confidence**: Transparent source policy improves acceptance of AI-generated answers.
**How It Is Used in Practice**
- **Source Registry**: Maintain central catalog of source IDs, owners, and trust ratings.
- **Query-Time Enforcement**: Inject source predicates into retrieval calls using user role and use case.
- **Audit Logging**: Record source filters and selected evidence for governance review.
Source filtering is **a practical guardrail for trustworthy enterprise RAG** - provenance-aware filtering improves both safety and retrieval signal quality.