3.242.0

Changed

• Enabled IPv6 support by default; set feature.network.ipv6: false to
  disable.
• Enabled TCP_NODELAY on every socket used to relay mirrord traffic - layer
  to internal proxy, internal proxy to external proxy and to the agent, agent
  outgoing and passthrough connections, redirected incoming connections, and
  the local sockets used for intercepted and port-forwarded traffic. Relayed
  data was already framed by the app on the other end of the hop, so Nagle's
  algorithm only added latency to small writes.

Fixed

• Added the experimental.guard_std_fds config (off by default), which keeps
  the layer's internal proxy connection from breaking when the process starts
  with a closed standard fd. The connection socket could be assigned fd 0-2 and
  get reconfigured by the app's runtime (e.g. libuv setting O_NONBLOCK on
  stdin), killing the process with "Resource temporarily unavailable." This
  broke Next.js with Turbopack, which spawns its worker processes with stdin
  closed. #4622
• Database branch failures now surface the failure reason instead of a bare
  timeout.
• mirrord operator status now more clearly labels machine session counts.