Speed changes the bottleneck
An agent can read a repository, propose a change, and produce a plausible patch quickly. Plausible is useful, but it is not the same as correct. The scarce part becomes deciding what should change and recognising when the result only looks finished.
That makes a precise brief more valuable. A good task describes observable behaviour, boundaries, and what must remain untouched.
Ask for evidence
I want a test to fail for the missing behaviour before the implementation exists, then pass for the right reason. For interface work, I also want the rendered page measured and inspected at the sizes people will actually use.
Diffs, tests, browser state, and build output make review concrete. A confident summary without those artefacts is still only a confident summary.
Keep responsibility human
The agent can do more of the typing. It cannot own the consequences. Reviewing the assumptions, the failure modes, and the final experience remains the actual engineering skill.