Smart Router Configuration & Cost Failover: Claude Sonnet 5.5 (anthropic/claude-sonnet-5.5) to Gemini 4 Hydrogen (google/gemini-4-hydrogen)

Production LLM API routing configuration, TTFT latency SLA (<400ms), and contribution margin failover benchmark generated by TokenMargin.dev.

1. Pricing & Latency Benchmark Summary

• Primary Model (Claude Sonnet 5.5 — anthropic/claude-sonnet-5.5): $2.00 / 1M input tokens, $10.00 / 1M output tokens | TTFT: 340ms | Throughput: 85 tok/s
• Fallback Model (Gemini 4 Hydrogen — google/gemini-4-hydrogen): $1.50 / 1M input tokens, $7.50 / 1M output tokens | TTFT: 340ms | Throughput: 85 tok/s

2. Zero-Dependency TypeScript / Node.js Smart Router Configuration

export const SMART_ROUTER_CONFIG = {
  slaMaxTtftMs: 400,
  primary: { model: "anthropic/claude-sonnet-5.5", inputPer1M: 2.00, outputPer1M: 10.00 },
  fallback: { model: "google/gemini-4-hydrogen", inputPer1M: 1.50, outputPer1M: 7.50 },
  retryOnStatus: [429, 500, 502, 503, 529]
};

3. LiteLLM / OpenRouter YAML Router Configuration (config.yaml)

model_list:
  - model_name: production-primary
    litellm_params:
      model: openrouter/anthropic/claude-sonnet-5.5
      timeout: 15
  - model_name: cost-fallback
    litellm_params:
      model: openrouter/google/gemini-4-hydrogen
router_settings:
  routing_strategy: latency-based-routing
  fallbacks: [{"production-primary": ["cost-fallback"]}]