Session entry id (user items only). Lets the browser correlate "the
last user message" in the replayed thread with the siblings frame's
entryId, so it knows which DOM node gets the edit/sibling-toggle UI.
Undefined for assistant items — they aren't fork targets.
role
role:"user"|"assistant"
text
text:string
Optionalthinking
thinking?:string
Model reasoning/thinking, kept separate from the final answer.
Session entry id (user items only). Lets the browser correlate "the last user message" in the replayed thread with the
siblingsframe's entryId, so it knows which DOM node gets the edit/sibling-toggle UI. Undefined for assistant items — they aren't fork targets.