Router First Architecture

This is an architectural pattern for organizing Claude skills around domain routers that map intents to specific tools. Instead of calling math scripts directly, you route through math-router first, which deterministically maps requests to the right CLI command. The key insight is a two-layer system: broad triggers in skill-rules.json that nudge Claude toward the router, then precise regex patterns in the router itself that find the exact tool. Domain skills co-activate with their router so it's always available. The pattern keeps routing logic centralized and makes individual skills simpler since they don't need their own intent matching.