How do you architect LLM routing workflows for complex vibe-coded web applications?

Question

Tyler Smith · Accepted Answer

When creating web applications using vibe coding - writing software using natural language instructions and reasoning models - a frequent architectural failure is routing all client-side inputs through a single massive foundational model. This creates high operational latency, unpredictable outputs, and unnecessary API overhead.

As outlined in Anthropic's Building Effective Agents design patterns, the most reliable and cost-effective approach is implementing an explicit routing workflow. In this architecture, an initial, low-latency classifier model evaluates user requests before determining the appropriate downstream execution path.

For example, inside a vibe-coded web application, a user interaction might range from a basic layout tweak (such as updating CSS color variables) to a multi-table database schema mutation. An initial router processes the intent and categorizes it into clear buckets:

1. Deterministic Logic: Handled entirely by client-side code or edge functions without calling an LLM.
2. Stylistic Edits: Routed to lightweight, rapid-response models fine-tuned on utility-first component libraries.
3. Architectural and State Updates: Routed to high-reasoning frontier models capable of multi-step tool use and relational data integrity checks.

By decomposing these tasks into modular prompt chains and routing branches, developers avoid the brittleness of monolithic agents. If an update fails, the router isolates the failure to a single component or schema validator, preventing the entire user session from crashing. This composable pattern ensures that vibe-coded websites maintain snappy response times while scaling complex interactive features.