Developer builds multi-agent AI fitness planner in TypeScript using HazelJS framework

A developer has detailed how to build an intelligent fitness workout planner using HazelJS, a TypeScript framework designed for constructing multi-agent AI systems. The solution uses five specialized agents — covering intake, exercise search, workout planning, progress tracking, and coaching — each handling a distinct part of the fitness planning process. Unlike traditional fitness apps that rely on static templates, the agentic approach allows for personalized, adaptive plans based on user goals, fitness level, available equipment, and injury history. HazelJS features such as the @Agent, @Tool, and @Delegate decorators enable agents to collaborate and delegate tasks without tightly coupling their logic. The modular design means individual agents can be improved independently, making the system easier to maintain and scale over time.