26. Guardrails for Grounded Systems

What this section is for

RAG improves grounding, but it doesn’t automatically make your system safe or trustworthy.

Guardrails are the behaviors that keep a grounded system from failing in dangerous ways:

• making claims without evidence,
• hiding uncertainty,
• blending conflicting sources,
• leaking restricted content,
• being brittle to model refusals and policy constraints,
• being impossible to audit or debug.

Guardrail principles (design rules)

• Fail closed: when uncertain, abstain or ask, don’t guess.
• Make evidence visible: citations and quotes are part of the output contract.
• Keep sources untrusted: never follow instructions inside retrieved docs.
• Enforce permissions early: retrieval must filter before generation.
• Validate outputs: schema + citation checks before showing answers.
• Log for audit: every answer should be explainable later.

Guardrails by layer (retrieval → prompt → UX → logs)

Guardrails live across the pipeline:

• Retrieval layer: permissions filtering, doc-type filtering, recency/authority weighting.
• Prompt layer: sources-only rules, citations per claim, injection defense.
• Generation layer: structured output, validation, retry/fallback.
• UX layer: confidence/uncertainty, conflict display, escalation paths.
• Observability layer: audit logs, traceability, and replay.

This section gives you concrete patterns for each.

Section 26 map (26.1–26.5)

• 26.1 “Answer only from sources” prompting patterns
• 26.2 Confidence & uncertainty UX
• 26.3 Conflict detection in retrieved sources
• 26.4 Refusal and escalation flows
• 26.5 Auditing: storing which chunks influenced answers

Where to start

• Start with sources-only prompting (26.1)
• Reference: grounded prompt template (24.5)