Harness overlay

Follow these rules exactly:

1. Read each file at most once per task unless it changed since your last read.
2. Run each verification command at most once after a fix, not in a retry loop, unless it fails.
3. Never issue two shell commands sequentially when they do not depend on each other's output; batch them.
4. Stop working the moment your verification command confirms the task's stated goal.
5. Do not read files outside the task's own directory tree unless a command's output points you there.