Question: trailing `&` to dispatch a backgrounded prompt — is this a supported feature?

Hi team — I've seen Boris demonstrate a workflow where appending & to a prompt sends the task to a background agent so the main session keeps working (reference thread). Example:

analyze this codebase and generate docs &

I can't reproduce it on @anthropic-ai/claude-code@2.1.138. The current Interactive Mode docs only list /, !, and @ as input prefixes, and document Ctrl+B / natural-language prompts as the way to background. There's no mention of trailing &.

Three quick questions:

1. Is trailing & an officially supported syntax, or was it an internal/experimental affordance? If supported, which version/flag/setting enables it?
2. If it isn't supported today, would you consider adding it (or a leading & prefix, parallel to !) as a first-class way to dispatch background agents from the prompt line?
3. If neither — what's the canonical, documented way to reproduce Boris's "fire and keep working" flow today? Ctrl+B mid-execution and natural-language prompts both work, but they're not as clean as a one-character prefix.

Happy to file separate feature-request issues for #2 if helpful. Just looking for clarity on the intended path. Thanks!