[DOCS] `/background` docs omit skill-only and custom slash command prompts

Documentation Type

Missing documentation (feature not documented)

Documentation Location

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

Section/Topic

/background [prompt] command reference and background-session prompt examples

Current Documentation

The docs currently say:

/background [prompt] | Detach the current session to run as a background agent and free this terminal. Pass a prompt to send one more instruction before detaching.

Run /background or its alias /bg to move the current conversation into a background session. Pass a prompt such as /bg run the test suite and fix any failures to give one more instruction first.

Related docs explain that slash commands include skills and custom commands:

Skills extend what Claude can do. Create a SKILL.md file with instructions, and Claude adds it to its toolkit. Claude uses skills when relevant, or you can invoke one directly with /skill-name.

A file at .claude/commands/deploy.md and a skill at .claude/skills/deploy/SKILL.md both create /deploy and work the same way.

What's Wrong or Missing?

The /background docs never say that the optional extra instruction can be only a skill or custom slash command. In v2.1.146, /background was fixed so sessions no longer refuse that input form, but the command reference and background-session guide still describe the argument only as a generic prompt and only show plain-text examples.

Users reading the current docs have no explicit guidance that inputs like /bg /debug or /bg /deploy are valid, even though skills and legacy custom commands are documented elsewhere as slash-command prompts.

Suggested Improvement

Add one explicit note anywhere /background [prompt] is documented:

The optional prompt can be plain text or a single slash command, including bundled skills, user or project skills, and legacy custom commands.

Then add at least one example that matches the supported slash-command-only form, such as:

/bg /debug
/bg /deploy

If there are exceptions for specific interactive-only slash commands, document those explicitly instead of leaving the general support implicit.

Impact

Medium - Makes feature difficult to understand

Additional Context

Affected Pages:

| Page | Line(s) | Context |
|------|---------|---------|
| https://code.claude.com/docs/en/commands | 46 | /background [prompt] says only "Pass a prompt" and does not mention slash-command-only prompts |
| https://code.claude.com/docs/en/agent-view | 258-260 | Background-session guidance shows only a free-form text example for the extra instruction |

Cross-references:

| Page | Line(s) | Context |
|------|---------|---------|
| https://code.claude.com/docs/en/skills | 9, 16 | Skills and legacy custom commands are invoked with /... syntax |
| https://code.claude.com/docs/en/hooks | 1087-1095 | UserPromptExpansion describes the slash-command path for skills and custom commands |

Total scope: 2 primary docs pages affected

This behavior change was released in v2.1.146, so the /background docs now need an explicit note and example for slash-command-only prompts.