Function ensureMutable

desktop/src/features/agents/ui/agentSessionTranscript.ts:100–106

Lazily copy items + itemsById on first mutation so callers get new refs.

(d: TranscriptDraft)

/** Lazily copy items + itemsById on first mutation so callers get new refs. */
function ensureMutable(d: TranscriptDraft) {
  if (!d.changed) {
    d.items = [...d.items];
    d.itemsById = new Map(d.itemsById);
    d.changed = true;
  }
}

function replaceItem(d: TranscriptDraft, id: string, updated: TranscriptItem) {
  ensureMutable(d);