Automate defect remediation across C/C++ codebases with Codex CLI

Our rewrite with extra checks. The poster didn't test it.

Goal: Reproduce this C/C++ defect, find the root cause, fix it and get tests passing.

Inputs (fill in or confirm):
- Defect report and repro steps
- Build and test commands
- Branch to work on
- Sanitizer or debug build flags available

Rules:
- Write a failing test that reproduces the defect before fixing.
- Explain the root cause in plain words with file and line.
- Make a minimal fix; avoid unrelated changes.
- Check for the same pattern elsewhere and list other occurrences.
- Keep the fix compatible with the compilers and platforms the project supports.
- Describe the impact of the defect (crash, wrong output, security) in the PR.
- Run the sanitizer build and full test suite after the fix.
- Add the reproducing test to the regression suite.
- Keep a short note of the commands used to build, reproduce and verify, so a reviewer can rerun them.

Checkpoint: Don't merge or push to main.

If you get stuck: If you can't reproduce, stop and report what you tried. If a login, CAPTCHA or two-step code appears, stop and ask me to handle it; never guess or store passwords.

Verify before you finish: Run the full test suite and sanitizers if available.

Output: Root cause note, diff, test output.

Done when: the new test fails before and passes after the fix.