Time

Time is host-provided and deterministic. Vela does not read wall-clock time directly from the process; the embedding application installs a clock and grants the time effect.

Installed Clock Functions

When the host calls with_time_clock(now, tick), scripts can call time::now, time::tick, and time::elapsed_since.

fn main() {
    let start = 1_699_999_990;
    return time::elapsed_since(start) + time::tick();
}

time::now() returns the configured timestamp. time::tick() returns the configured logical tick. time::elapsed_since(start) returns time::now() - start and traps on invalid input or overflow.

Capability And Replay

Time functions carry the time effect. Hosts can deny that effect with a capability profile, even if the functions are registered for compilation.

fn main(ctx: Context) {
    if time::tick() > ctx.tick {
        return time::now();
    }
    return ctx.now;
}

For replay and tests, pass the same now and tick values to the engine. The standard context object exposes the same deterministic values through Context.now and Context.tick when the host registers the context schema.