- Add /health endpoint that returns 503 until SGLang is ready
- Background task polls SGLang until it accepts connections
- Catch ConnectError/TimeoutException instead of crashing
- Return 503 JSON error when SGLang backend is unavailable
- haproxy health-checks middleware /health, which reflects SGLang state
SGLang's Mistral tool-call parser rejects logprobs/top_logprobs with 422,
while vLLM accepts them. Clients like OpenClaw send these by default.
New architecture: haproxy (port N) → middleware (port N+2) → SGLang (port N+1)
The middleware is a thin FastAPI app that strips incompatible params from
chat completion request bodies and passes everything else through unchanged.
