Problem

In the devcontainer /watch endpoint, we only allow a maximum message payload of 32KiB to be read on coderd from the agent. If you have many devcontainers, or a devcontainer with many apps, this limit is easily reached. Once this happens, we fail to detect that the websocket has been closed and then send an empty message over the websocket to the site forever on loop.

Solution

• Increase websocket payload limit
• Detect when the websocket channel is closed and close the websocket.