Overview
TDD is strongest where executable behavior can be tested. Visual front-end quality remains difficult. Automated browser and image tools can inspect an interface, but they may not reliably create a polished result in a mature codebase.
A passing test suite can still miss integration setup. In one implementation, automated tests and types passed, but manual use exposed a missing database table or migration state.
Feedback loops reduce blindness; they do not eliminate the need for QA.
Tests can also be badly designed. An agent may test trivial details, mock too much, or wrap every small function in an isolated boundary. Human review of test intent remains essential.