Guard

Guard checks every call at the gateway, both ways. It can scan the user’s input before the model sees it, and the model’s response before it reaches your code. A typical use: redact credit card numbers from incoming messages, or block responses that look like a leaked API key.

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Two kinds of rule

Open Controls → Guard in platform.opper.ai and add a rule.

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LLM Guard

A custom prompt that asks a model to classify content. Use it for fuzzy things like tone, intent, or categories. Templates: PII, Toxicity, Secrets.

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Regex Guard

Pattern matching. Use it for known formats like credit cards, emails, SSNs, and API keys. Templates: Email, Phone, Credit Card, SSN, API Key.

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Actions

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Where it applies

You can layer rules. For example, run an org-wide secrets check alongside a stricter toxicity check on a customer-facing project. Each rule fires independently.

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Where you see the result

A Guardrail event appears on the trace span with a Shield icon and status:

• Passed: the content was fine.
• Flagged: matched but the action was Flag, so the call proceeded.
• Blocked: the rule rejected the call.

Each event carries the rule name, a family label (LLM guard or Regex guard), and a scope badge. Redacted content appears already replaced in the span’s input or output. In the playground, Guard runs when Project controls is on. Open the trace ↗ link to see the event.