# 1.3 — Client disconnect propagation (GREEN)

Phase: 1 — Proxy core
Stage: RED
Depends on: [1.2](1.2-streaming-passthrough.md)

- [ ] When a client closes the connection mid-response, the gateway cancels the upstream request immediately
- [ ] The stub upstream observes its request context cancelled, not a request that runs to completion
- [ ] Cancellation happens within a small bounded delay of the client close, not at the route's read timeout
- [ ] The same holds for a non-streaming request abandoned before the upstream replies
- [ ] The disconnect is logged with a reason distinguishing it from an upstream error
- [ ] No goroutine or upstream connection is left alive after the disconnect — the test asserts this, not just the response

This is load-bearing. The `reasoning` upstream runs 2 replicas at `--max-num-seqs=4`,
which is 8 concurrent sequence slots cluster-wide. An orphaned generation holds one of
those 8 until it finishes on its own, which for a 32B model on a Volta GPU can be
minutes. A handful of abandoned browser tabs can starve the entire cluster.

## Verify

```bash
go test ./internal/proxy/... -run TestClientDisconnectCancelsUpstream -race -v
# expected: passes — stub upstream reports context cancellation within 1s of the client
# closing mid-stream, and the post-test goroutine count returns to baseline
```