A single prompt that builds an agent harness for your repository. The agent scans the code, asks you a short series of questions, and writes a harness sized to your project rather than adapted from someone else's.
What this one gives you: rules that hold because a script checks them, with the reason for each written down; review by a second model family, briefed on what the product must do rather than how the code does it; plan files that make "done" binary and give executors the right to refuse a bad contract; handoffs so an unfinished session is resumable; routing
