Restrict to Topic Guardrail

The Restrict to Topic guardrail (restrict_to_topic) is a non-deterministic guardrail that uses an AI provider (LLM) to classify whether the user's message matches configured lists of allowed or disallowed topics. It implements both NonDeterministicGuardrailInterface and NonStreamableGuardrailInterface.

When to Use

Use this guardrail to: - Confine a chatbot to specific subject areas (e.g., support for a particular product only). - Proactively block off-topic queries or attempts to distract the model (prompt injection, roleplay, etc.). - Blocklist specific sensitive or forbidden subjects.

Configurable Fields

Field	Key	Type	Default	Description
Valid Topics	valid_topics	Textarea	None	List of allowed topics (one per line). If any are configured, the message must relate to at least one of these topics to pass.
Invalid Topics	invalid_topics	Textarea	None	List of disallowed topics (one per line). If any match, the message is blocked.
Message to send if invalid topics are present	invalid_topics_present_message	Textarea	The text contains invalid topics	The violation message displayed when the input matches one of the disallowed topics.
Message to send if no valid topics are found	valid_topics_missing_message	Textarea	The text does not contain any of the valid topics	The violation message displayed when the input does not match any of the allowed topics (only evaluated if Valid Topics is not empty).
AI Provider	llm_provider	Select	None	The AI provider (e.g., OpenAI, Anthropic) used to classify the text's topics.
AI Model	llm_model	Select	None	The specific model used for the topic classification query.

[!NOTE] Under the hood, this guardrail issues a classification prompt to the selected LLM. If no provider is configured, it falls back to the site's default chat provider configured in the AI module settings.

Example Configuration

Below is an example configuration restricting a chatbot to customer support topics while disallowing financial advice:

id: restrict_to_topic
valid_topics: |
  shipping questions
  product returns
  billing issues
  general inquiries
invalid_topics: |
  financial advice
  investment strategies
  stock market tips
invalid_topics_present_message: "We cannot discuss financial advice or investments here."
valid_topics_missing_message: "Please ask a question related to shipping, returns, billing, or general store support."
llm_provider: openai
llm_model: gpt-4o-mini