Validating LLM Gateway Responses Beyond HTTP Status Codes

Short summary

Most LLM gateways validate failover success by checking HTTP status and JSON format, ignoring whether content is correct. This creates silent failures: valid responses containing hallucinations, outdated data, or logical contradictions. Add contract validation at the gateway level to enforce field constraints, forbidden patterns, and consistency before returning responses.

• •HTTP 200 + valid JSON doesn't guarantee correct LLM responses during failover.
• •Implement contract validation (field checks, pattern matching, cross-field consistency) at the gateway proxy layer.
• •45µs P50 overhead is negligible vs. typical 700-900ms LLM API call time; catches hallucinations and contradictions automatically.

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