#bug fix

Codex Bug-Fix Closed Loop: Reproduce First, Fix Second, With Rerunnable Verification

Forces Codex through a closed loop — write a failing test that reproduces the bug, find the root cause, make the minimal fix, watch that same test go from red to green, then run the full test suite to confirm no regressions — eliminating both 'fixed it without verifying' and 'changed a bunch of unrelated stuff along the way.'