Function wrapOutputGuardrails

Wrap a response stream with guardrail filtering.

Creates an async generator that evaluates each chunk through registered guardrails before yielding to the client. Supports both real-time streaming evaluation and final-only evaluation based on guardrail configuration.

Evaluation Strategy:

• Guardrails with config.evaluateStreamingChunks === true evaluate TEXT_DELTA chunks
• All guardrails evaluate FINAL_RESPONSE chunks (final safety check)
• Rate limiting via config.maxStreamingEvaluations per guardrail

Actions:

• GuardrailAction.BLOCK - Terminates stream immediately with error chunk
• GuardrailAction.SANITIZE - Replaces chunk content with modifiedText
• GuardrailAction.FLAG / GuardrailAction.ALLOW - Passes through

Example

// Wrap output stream with PII redaction
const safeStream = wrapOutputGuardrails(
  [piiRedactor, contentFilter],
  guardrailContext,
  orchestratorStream,
  { streamId: 'stream-123', inputEvaluations }
);

for await (const chunk of safeStream) {
  // Chunks are filtered/sanitized before reaching here
  yield chunk;
}
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