Attribute Macro command_service 

#[command_service]

Attach to an impl block whose methods are tagged with #[command].

Rewrites the block so every #[command("id")] method becomes a typed command wrapper struct implementing Command, and adds an inherent register async method to the host type that installs every such command on a &CommandRegistry.

#[command_service]
impl MathService {
    #[command("math.add")]
    async fn add(&self, req: AddReq) -> Result<i64, CommandError> { ... }

    #[command("math.sub")]
    async fn sub(&self, req: SubReq) -> Result<i64, CommandError> { ... }
}

// Registers both commands with one call:
MathService.register(&registry).await?;