Core Generate And Stream Text

Operator passes both `prompt: 'summarize this'` and `messages: [{role:'user', content:'hi'}]` to generateText, expecting messages to win.

Pass either `prompt` (shorthand single-user-turn) or `messages` (multi-turn) but not both — per docs they are mutually exclusive and the SDK throws InvalidArgumentError. Pick one and migrate the other content into it.

generateText returns finishReason='length' on a long synthesis task.

Inspect finishReason in {'stop','length','tool-calls','content-filter','error','other','unknown'}. On 'length', treat the result as truncated: either expose to the caller as partial or issue a continuation call with the prior text appended. Never present a length-truncated answer as complete.

Operator reads `result.usage` from streamText before the stream has finished and logs 0 prompt tokens to telemetry.

On streamText, `usage` is a Promise that resolves after the stream completes (or use the onFinish callback's `usage`). Await result.usage (or read in onFinish) before logging — do not read it synchronously before iteration.