routing.router_missing_default

What it checks

Crux emits this finding when a router() definition has no default route.

Why it matters

Classifier outputs can drift. A default route keeps unexpected outputs deterministic and inspectable instead of producing confusing route decisions or incomplete traces.

How to fix

Add a default entry to the router routes map and point it at the safest fallback model, agent, prompt, or nested routing primitive.

export const modelRouter = router({
  id: 'model-router',
  classify,
  routes: {
    cheap,
    precise,
    default: precise,
  },
})

When to suppress

Suppress only when the classifier is exhaustively constrained by another boundary and unknown keys are impossible by design.

// crux-lint-disable-next-line routing.router_missing_default -- classifier is generated from the same literal route keys
export const modelRouter = router({ id: 'model-router', classify, routes })

Rule metadata

• Rule id: routing.router_missing_default
• Category: composition
• Maturity: preview
• Default profiles: recommended, strict
• Default severity: warning