What
Claude Code has named events for things that happen in the box where you type your message, such as prompt.submit, prompt.fill and prompt.suggest. A new one, prompt.compose, now sits alongside them. It is set up to keep track of the model in use and has a step that waits for things to settle.
Why
This adds a new point where something could act while a prompt is being written.
Names in the bundleprompt.compose
Documented inclaude-code/plugins/mods/reference
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 prompt.compose, on Mods reference.
| [`prompt.section`](/docs/en/plugins/mods/events#rewrite-or-add-to-a-prompt) | Once for each named section of the system prompt. `e.name` is the section's `id` in `prompt.compose`. | `{ text }`, or `{ text: null }` to omit the section |plugins/mods/reference see the edit
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear what uses `prompt.compose` or whether plugins or users can reach it.
Anthropic's documentation agrees
Anthropic's documentation has since written up prompt.compose, on Mods reference.