[DOCS] Skills docs omit that `context: fork` runs in the background by default

Documentation Type

Missing documentation (feature not documented)

Documentation Location

https://code.claude.com/docs/en/skills

Section/Topic

“Run skills in a subagent” and the frontmatter reference for skills with context: fork.

Current Documentation

The page currently says:

Add context: fork to your frontmatter when you want a skill to run in isolation. The skill content becomes the prompt that drives the subagent.

The frontmatter table describes context: fork and agent, but has no background field or default behavior.

What's Wrong or Missing?

Claude Code 2.1.218 changed skills with context: fork to run in the background by default. A skill author can opt out with background: false.

The current page explains isolation but not whether the caller waits for the forked skill, where its progress appears, or how an author can preserve foreground behavior. This is a meaningful execution and interaction change for skills that depend on a result returning before the main turn continues.

Suggested Improvement

Document the background frontmatter field next to context:

• background defaults to true when context: fork is set, so the forked skill runs as background work and its result is reported when it completes.
• Set background: false to keep the forked skill in the foreground when the invoking workflow must wait for the result.

Add an example for both forms and explain how users monitor and stop the resulting background task. Clarify whether the setting affects only context: fork skills or is ignored for inline skills.

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Context |
|------|---------|
| https://code.claude.com/docs/en/skills | context: fork execution and frontmatter reference |
| https://code.claude.com/docs/en/sub-agents | Forked subagent execution and result handling |

Total scope: 2 pages should describe the same forked-skill execution contract.

The behavior was changed in Claude Code v2.1.218.