[codex] Repair invalid skill frontmatter scalars

[charlesgong-openai]

Why

The community marketplace audit found many skill frontmatter parse failures where values were intended as prose, but were not valid YAML. Common examples include unquoted scalar values with : , such as description: Build for AWS: ECS or argument-hint: <duration: e.g. 7d>, and flow-looking values such as tags: [next,@supabase/ssr].

serde_yaml does not expose a permissive mode for this. The parser fails before unknown frontmatter fields can be ignored, so a compatibility repair has to happen before retrying YAML parsing.

What changed

Skill frontmatter loading still uses serde_yaml as the primary parser. If that parse fails, the loader performs a line-oriented repair of scalar frontmatter field values, then retries parsing.

The fallback now:

• applies to any frontmatter mapping field, not just description / short-description
• quotes unquoted scalar values that contain a YAML colon separator such as :
• quotes invalid flow-looking scalar values that start with [, {, @, or backtick
• preserves already quoted values
• skips | / > block scalar bodies so multiline descriptions are not rewritten
• returns the original YAML error if the repaired frontmatter still cannot parse

Examples

This previously failed because the second : was parsed as YAML structure:

description: AWS deployment patterns: ECS Fargate, Lambda, and S3

The fallback now parses it as if it had been written explicitly as:

description: 'AWS deployment patterns: ECS Fargate, Lambda, and S3'

The same repair now applies to ignored frontmatter fields that still need to be valid YAML for the parser to get through the document:

argument-hint: <duration: e.g. 7d, 2w>
tags: [next,@supabase/ssr]

Valid YAML multiline descriptions continue to work through normal parsing without repair:

description: |-
  Build for AWS: ECS
  and Lambda

Validation

• Added loader coverage for unquoted description values containing : .
• Added loader coverage for unquoted metadata.short-description values containing : and an apostrophe.
• Added loader coverage for unrecognized frontmatter fields that need quoting, including argument-hint and tags.
• Added block-scalar coverage to ensure multiline description bodies are preserved while other fields are repaired.
• just test -p codex-core-skills (106 passed)
• just fix -p codex-core-skills

[chatgpt-codex-connector]

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