False 'missing YAML frontmatter delimited by ---' for valid SKILL.md

Summary

Codex CLI reported a frontmatter error for a skill file that does have valid YAML frontmatter at byte 0.

Observed in the interactive TUI output:

/Users/Morriz/.codex/skills/next-test-analyzer/SKILL.md: missing YAML frontmatter delimited by ---

Environment

• codex-cli 0.98.0
• macOS 26.1 (Darwin 25.1.0, arm64)

Why this looks incorrect

The file starts with --- with no leading bytes/whitespace:

$ head -n 8 /Users/Morriz/.codex/skills/next-test-analyzer/SKILL.md
---
name: next-test-analyzer
description: Review test coverage quality and completeness. Use after creating a PR or adding new functionality to ensure tests adequately cover new code and edge cases.
---

$ xxd -g 1 -l 12 /Users/Morriz/.codex/skills/next-test-analyzer/SKILL.md
00000000: 2d 2d 2d 0a 6e 61 6d 65 3a 20 6e 65  ---.name: ne

Expected behavior

No "missing YAML frontmatter" error should be emitted for this file.

Actual behavior

CLI reports missing frontmatter for this path despite valid delimiter and metadata.

Notes

I saw this in TUI output just before sending another prompt. I have not yet found a deterministic minimal repro; this may be intermittent in skill scanning/parsing.

If helpful, I can capture a debug run (RUST_LOG etc.) once you suggest the best flags.