Can ngrok forward client cancellation to the backend?

Goal

Determine whether ngrok propagates a client‑initiated HTTP abort or WebSocket close frame to the upstream service, and identify the configuration knobs that control this behavior.

Context & Constraints

ngrok’s HTTP API exposes a request timeout setting, but the documentation does not mention how client‑side cancellations are handled. The control API can terminate tunnels, yet it does not signal in‑flight request cancellation. Local server settings such as proxy_read_timeout and proxy_write_timeout influence wait times for data but have no documented effect on client‑side disconnects. Version differences and plan‑based limits may also alter the observed behavior.

Unresolved Questions

• Which ngrok configuration options influence the propagation of client cancellations to the backend?
• Does ngrok support sending an HTTP Abort or WebSocket close frame to the upstream service when the client disconnects?
• How can we reliably verify that the backend receives a close event when a client cancels a long‑running request?