The built-in WebSocket transport is optional

[genmon]

Two fixes a consumer needs before it can stop holding a WebSocket it does not use.

The built-in WebSocket transport is optional

Courier auto-registers "ws" only when Config::host is set and
defaultTransport is unset or "ws", and it logs the skip otherwise. Sandbox's
constructor did not mirror that: it cached
courier().transport<WebSocketTransport>("ws") unconditionally. So a Sandbox
pointed at another default lane — defaultTransport = "mqtt", for a device
consolidating everything onto one MQTT connection — tripped
Client::transport<T>'s assert, and under NDEBUG bound a null reference that
crashed at the first ws() call instead.

_ws now stays null when Courier did not register one, hasWs() reports it, and
both internal ws() callers are gated on it: the WS-path default in
onCourierTransportsWillConnect, and the mic-stream fallback in
updateMicStream. ws() keeps its assert, so a caller that genuinely needs WS
still fails loudly rather than late.

The message filter runs before the deprecation notice

The legacy un-channelled path logged [deprecated] un-channelled ... and then
offered the frame to onMessageFilter. But the filter is the documented
interposition point, so a host that consumes a frame there never took delivery of
a deprecated message.

It matters for a platform wrapper whose default transport routes its own traffic.
Courier's client hook fires alongside a per-transport hook rather than instead
of it, so a wrapper that routes (say) MQTT by topic sees every inbound frame a
second time on the client lane and consumes it in the filter. Logging each of
those as deprecated was both noise and a lie — and at MQTT message rates, a line
per message.

Verification

Consumed by inanimate-tech/hawthorn-firmware on its voice-over-MQTT branch and
run on hardware (M5Stack StopWatch, ESP32-S3): boots, registers, connects MQTT as
its only persistent transport, and streams a voice session with no WebSocket
present. 481 native tests pass in that repo, including its Sandbox and
message-dispatch suites.

🤖 Generated with Claude Code