The overlap is real, so be honest about where you sit. A generalist agency and Wavect both ship MVPs, full builds, and retainers. The divergence is structural, not cosmetic.
An agency’s margin comes from junior-on-senior leverage: a senior scopes the work, juniors execute it, a project manager sits between you and the people writing code. That model is efficient when the spec is already correct and you need throughput across parallel workstreams. If you have a CTO or a clear product owner who has already decided what to build, a twenty-person bench will beat us on raw capacity and price.
Where it breaks is when the spec itself is the risk. We bill a weekly outcome instead of tracked hours, put a founder and the senior engineer doing the work on every call, and we tell you when a feature should not ship. That pushback has no line item, but it is the point. The most expensive thing an agency builds is the feature you should have killed.
If your product judgment is solved, take the agency. If “should we even build this?” is still open, that is our work. See how we run build engagements.