ChatDelta:
| { text: string; type: "text-delta" }
| { id: string; input: unknown; name: string; type: "tool-call" }
| { text: string; type: "reasoning-delta" }
| { signature?: string; text: string; type: "reasoning" }
| { data: string; type: "reasoning-redacted" }
| {
cacheReadTokens?: number;
cacheWriteTokens?: number;
inputTokens: number;
outputTokens: number;
type: "usage";
}
One streamed chunk. Consumers typically accumulate
text-deltas.