## Why
A WebSocket close with code `1009` before any text arrives indicates that the request exceeds the peer's message size limit. Retrying the request over another WebSocket does not address that limit.
## What changed
- Classify these early size rejections as requiring HTTP fallback and switch transports without exhausting WebSocket retries, including during prewarming.
- Preserve ordinary stream retry behavior for size closes after any text frame and for other close codes.
## Testing
Add integration coverage for early size rejections during generation and prewarming, size closes after metadata, rate limits, or response creation, and ordinary closes.
GitOrigin-RevId: 4550d289bb414fec1faae2a195bcc635d394117b
Charlie Marsh
bc3ccba6e1