What
Claude Code's plugin system (which lets extensions run code through "hooks" that respond to events) has a new low-level capability called process.spawn. It lets plugin code launch a subprocess and stream its output back, running through the same sandboxed bridge that mediates what plugins are allowed to do on the host machine.
Why
This gives plugin authors a supported way to run external programs and receive their output as it streams in, rather than only making one-shot request/response calls.
Names in the bundleprocess.spawn
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Confirmed since
Anthropic's documentation has since written up process.spawn, on Mods reference.
Events are grouped by what they concern, each with when it fires and what a hook on it can return. Hooks on `turn.step` and `process.spawn` are async generators, and other hooks are async functions.plugins/mods/reference see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up process.spawn, on Mods reference.