Read the status before you read the stream.

An authentication or balance error is JSON, not SSE. Check the response first, then process bounded chunks until termination or disconnect.

Start with a non-streaming call Open the error table

curl without client buffering

SSE request

curl -N https://aiwave.live/v1/chat/completions \
  -H "Authorization: Bearer $AIWAVE_API_KEY" -H "Content-Type: application/json" \
  -d '{"model":"deepseek-v4-flash","stream":true,"messages":[{"role":"user","content":"Reply with OK"}]}'

Raw Python handling

httpx

import httpx, json, os

with httpx.stream("POST", "https://aiwave.live/v1/chat/completions",
    headers={"Authorization": f"Bearer {os.environ['AIWAVE_API_KEY']}"},
    json={"model": "deepseek-v4-flash", "stream": True, "messages": [{"role": "user", "content": "Reply with OK"}]},
    timeout=60.0) as response:
    response.raise_for_status()
    if "text/event-stream" not in response.headers.get("content-type", ""):
        raise RuntimeError("expected an SSE response")
    for line in response.iter_lines():
        if not line.startswith("data:"):
            continue
        data = line[5:].strip()
        if data == "[DONE]":
            break
        chunk = json.loads(data)
        # Accumulate content and any route-tested tool-call deltas here.

Wire contract

Signal	Meaning	Handler
HTTP 4xx/5xx	Normal JSON error envelope	Classify before SSE parsing
Content-Type: text/event-stream	Streaming body	Read complete data events
data: {JSON}	One chunk	Accumulate content and tested tool deltas
data: [DONE]	Normal termination	Close the reader
Network disconnect	Completion state unknown	Do not repeat state-changing tool work blindly

Do not replay a request just to estimate tokens.

Save the request ID. Use verified final usage when the route returns it; otherwise reconcile the request ledger. A second generation is a second bill and may produce different output.