| import { useRef } from 'react'; |
| import type { TurnViewModel } from './materialize.js'; |
| import { |
| createTranscriptProjection, |
| type TranscriptProjection, |
| type TranscriptProjectionInput, |
| } from './transcript-projection.js'; |
| |
| /** |
| * Render-time access to the session's incremental transcript projection. |
| * |
| * Projecting during render (rather than in an effect) keeps the turns the |
| * component renders and the turns the projection last produced the same object |
| * graph — an effect would publish them a commit late and reintroduce the very |
| * re-derivation this replaces. It is safe under React's double-invocation |
| * because `project` is idempotent: identical inputs return the identical |
| * turns array without advancing any owned state. |
| */ |
| export function useTranscriptProjection( |
| input: TranscriptProjectionInput, |
| ): readonly TurnViewModel[] { |
| const projection = useRef<TranscriptProjection>(undefined); |
| projection.current ??= createTranscriptProjection(); |
| return projection.current.project(input); |
| } |
