The sycophancy problem disappears when you stop pushing back on the agent and start having a human review the plan before the agent writes anything. Push back on a human who wrote the plan and their agreement or disagreement will actually be meaningfull. Push back on the agent and you get "you're absolutely right..".

The plan also solves "I can't explain this code" because you wrote the plan before the build, so you can explain it.

After tracking some internal metrics recently we found plan review costs 0.7 hours on average compared to PR review that costs 16 hours. We rejected 13 out of 165 plans meaning no code was written.

The one gap this doesn't close is that the agent drifts from the plan. We run a separate adversarial check that compares the diff against the approved plan and flags anything the plan didn't specify. That catches scope drift without reading every line.