Fireworks launches FireRouter with Opus for cache-aware routing across Opus and open models

What changed

Fireworks released FireRouter with Opus on September 28. It routes each turn among Claude Opus 5.5, GLM 5.3 and GLM 5.3 Flash based on task fit, model cost and prompt-cache state, and is available as a standalone serverless router model for the first time. Fireworks reports 57% lower coding-session cost at 98.1% of Opus-only accuracy in internal A/B tests; those figures are vendor-run measurements.