The YAML bug that taught me what bidirectional sync between Claude Code and Codex actually costs

The Codex agent had no name The sync ran clean. Exit code 0. The skill file I'd authored on the Claude side showed up at the matching path on the Codex side, byte-for-byte where I expected it. I opened the Codex agent picker and the entry was there, but its name was the empty string. Just a blank row. I assumed I'd mis-named something on disk. I hadn't. The file had name: code-review at the top, in plain YAML frontmatter, exactly the way Claude writes it. The string was right there. The Codex...