What

When AetherSDR is connected to an MQTT broker and the CW decoder is
active, publish each decoded character to the topic
aethersdr/cw/decode as compact JSON:

{"text":"K","freq":14.025,"rx":true}

Fields:

• text — one decoded character (or small chunk, as ggmorse emits it)
• freq — active slice frequency in MHz (omitted if no slice is active)
• rx — true for the RX decoder, false for the TX sidetone decoder

The sensitivity threshold already configured in the CW panel
(m_cwCostThreshold) gates the publish, so the MQTT feed matches
exactly what the decoder window displays — no separate sensitivity
setting is needed.

Why

External tools — contest loggers, automated spotters, skimmers — need
access to the live CW decode stream. AetherSDR already has MQTT
infrastructure for station device control (antenna switches, band
decoders). Extending it to carry decoder output costs nothing in new
dependencies and requires no new port, no new protocol, and no
additional configuration beyond enabling MQTT.

How Other Clients Do It

• SmartSDR — No external CW decode feed of any kind.
• GQRX / SDR++ — No CW decoder; no MQTT.
• WSJT-X / JTDX — Closest analogue: publish decoded QSO data via
  UDP broadcast (wsjtx_status, adif_log datagrams on port 2237).
  Same pattern — decode happens in-app, external tools subscribe.
• AetherSDR — Already publishes nothing automatically; this would
  be the first outbound data topic.

Suggested Behavior

1. When MQTT connects, AetherSDR begins publishing to
   aethersdr/cw/decode automatically — no opt-in toggle needed.
2. Each textDecoded(text, cost) emission from CwDecoder that
   passes the active panel's m_cwCostThreshold is published
   immediately.
3. The TX sidetone decoder (m_cwDecoderTx) publishes the same topic
   with "rx": false so subscribers can distinguish operator keying
   from received traffic.
4. If no slice is active, freq is omitted rather than sending 0.
5. When MQTT disconnects, publishing stops silently — no logged errors,
   no behavior change for users who don't use MQTT.

Protocol Hints

No FlexLib involvement — this is entirely within AetherSDR's client
process. Uses the existing MqttClient::publish(topic, payload) API
already present in src/core/MqttClient.h.

Implementation sketch:

// In MainWindow HAVE_MQTT block, after restoreConnectionState():
connect(&m_cwDecoder, &CwDecoder::textDecoded, this,
    [this](const QString& t, float cost) {
        publishCwDecodeMqtt(t, cost, true);
    });
connect(&m_cwDecoderTx, &CwDecoder::textDecoded, this,
    [this](const QString& t, float cost) {
        publishCwDecodeMqtt(t, cost, false);
    });

A working proof-of-concept lives on branch feat/mqtt-cw-decode-publish.
A minimal Python subscriber (FastAPI + aiomqtt + SSE → browser) confirmed
the pipeline end-to-end against a local Mosquitto broker.

Acceptance Criteria

• Characters visible in the CW decoder panel appear on
  aethersdr/cw/decode within one character period
• Characters suppressed by the sensitivity slider are NOT published
• TX sidetone decoder output appears with "rx": false
• freq contains the active slice frequency in MHz when a slice is active
• No errors or warnings logged when MQTT is disconnected