Streaming and backpressure

Streaming and backpressuremake partial results usable

• Stream tokens as they generate so the user sees motion in hundreds of milliseconds instead of waiting for the whole response.
• Make partial output usable: render the diff as it forms so a reviewer can start reading before it finishes.
• Apply backpressure when the consumer is slower than the stream. The consumer tells the stream to slow down, so a fast model can't flood a slow UI or a downstream tool.

async def stream_edit(req):
    async for token in model.stream(req):       # tokens as they arrive
        await ui.send(token)                    # render incrementally
        if ui.buffer_full():                    # consumer can't keep up
            await ui.drain()                    # wait before pulling more