Function provider_constructs_agent 

pub fn provider_constructs_agent(
    p: &ProviderDecl,
    is_agent: impl Fn(&str) -> bool,
) -> bool

#2355: whether a bodied provider’s ops construct one of its context’s own agents (is_agent). Such a provider takes a deps even with no given: its agent calls hand this.deps to the agent’s methods, and on Workers the agent factory reads the Worker’s env from it. Syntactic, so the provider class, every composer that builds it, and phase_workers_provider_agent_cross_context agree on the answer; a local shadowing an agent’s name only costs an unused deps. It matches the construction shape Agent(key), the one the emitter’s agent_construct lowers; a new way to reach an agent must be added here too.