# Out-of-scope requests are refused gracefully

- **Pattern:** `ab-000209` (`ai-response-quality.hallucination-prevention.out-of-scope-refusal`)
- **Severity:** medium
- **Lifecycle:** active
- **Last modified:** 2026-04-18
- **Canonical URL:** https://auditbuffet.com/patterns/ab-000209
- **License:** CC-BY-4.0 — attribute to AuditBuffet Pattern Catalog (https://auditbuffet.com/patterns/ab-000209)

## Why it matters

A domain-scoped assistant without a scope boundary becomes a general-purpose chatbot the moment a user asks anything off-topic. Customer-support bots start giving medical advice, code assistants opine on tax law, and the company inherits liability for confabulated answers outside its expertise. This violates the inference-contract taxon — you shipped a support product and delivered an unconstrained LLM. Worse, out-of-scope answers are where hallucination rates spike, because the model has no grounding.

## Severity rationale

Medium because scope leakage expands liability and hallucination surface beyond the product's tested domain.

## Remediation

Write an explicit scope statement in the system prompt naming the domain, and define a graceful refusal template that redirects users rather than terse-rejecting them. Update `lib/ai/prompts.ts` with:

```ts
const systemPrompt = `You are a support assistant for [Product]. You answer installation, configuration, billing, and usage questions. For anything else, reply: "That's outside what I can help with here. For [topic], try [resource]."`
```

## Detection

- **ID:** `out-of-scope-refusal`
- **Severity:** `medium`
- **What to look for:** Enumerate all relevant files and For applications with a defined scope (domain-specific assistants, customer support bots, code assistants, etc.), check whether the system prompt defines the scope boundary and instructs the AI to decline out-of-scope requests gracefully. Look for scope definition language in the system prompt — "You are a customer support agent for [Company] and answer only questions about [Product]", "Do not answer questions unrelated to [domain]". Check for a graceful refusal pattern ("That's outside what I can help with here — for that, you might try...") rather than a terse rejection.
- **Pass criteria:** At least 1 conforming pattern must exist. System prompt defines the application's scope and includes a graceful out-of-scope refusal pattern that redirects the user rather than abruptly refusing.
- **Fail criteria:** Application has a narrow-scope use case (customer support, domain-specific assistant) but the system prompt has no scope boundary or refusal instruction — AI will answer any question regardless of domain.
- **Skip (N/A) when:** Application is explicitly a general-purpose assistant with no scope restrictions.
- **Detail on fail:** `"Customer support chatbot system prompt has no scope boundary — AI will answer unrelated questions and potentially confabulate"` (max 500 chars)
- **Remediation:** Define scope and a graceful refusal in your system prompt:

  ```ts
  const systemPrompt = `
  You are a support assistant for [Product]. You answer questions about installation,
  configuration, billing, and usage. If a user asks about something outside this scope,
  respond politely: "That's outside what I can help with here. For [topic], I'd suggest
  [relevant resource or next step]."
  `
  ```

## External references

- owasp-llm LLM09

Taxons: inference-contract

HTML version: https://auditbuffet.com/patterns/ab-000209