[feat](trx-core): add decode types and wire protocol for APRS/CW

Add shared DecodedMessage enum (tagged serde), AprsPacket and CwEvent
types for server-side decoding.  Add AUDIO_MSG_APRS_DECODE (0x03) and
AUDIO_MSG_CW_DECODE (0x04) wire protocol constants.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-core/src/audio.rs

@@ -11,6 +11,8 @@ use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
 pub const AUDIO_MSG_STREAM_INFO: u8 = 0x00;
 pub const AUDIO_MSG_RX_FRAME: u8 = 0x01;
 pub const AUDIO_MSG_TX_FRAME: u8 = 0x02;
+pub const AUDIO_MSG_APRS_DECODE: u8 = 0x03;
+pub const AUDIO_MSG_CW_DECODE: u8 = 0x04;
 
 /// Maximum payload size (1 MB) to reject bogus frames early.
 const MAX_PAYLOAD_SIZE: u32 = 1_048_576;

src/trx-core/src/decode.rs

@@ -0,0 +1,48 @@
+// SPDX-FileCopyrightText: 2025 Stanislaw Grams <stanislawgrams@gmail.com>
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+//! Shared types for server-side decoded messages (APRS, CW).
+
+use serde::{Deserialize, Serialize};
+
+/// A decoded message from the server-side decoders.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "type")]
+pub enum DecodedMessage {
+    #[serde(rename = "aprs")]
+    Aprs(AprsPacket),
+    #[serde(rename = "cw")]
+    Cw(CwEvent),
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AprsPacket {
+    pub src_call: String,
+    pub dest_call: String,
+    pub path: String,
+    pub info: String,
+    #[serde(rename = "type")]
+    pub packet_type: String,
+    pub crc_ok: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub lat: Option<f64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub lon: Option<f64>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub symbol_table: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub symbol_code: Option<String>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CwEvent {
+    /// Decoded text fragment (one or more characters)
+    pub text: String,
+    /// Current detected WPM
+    pub wpm: u32,
+    /// Current detected tone frequency (Hz)
+    pub tone_hz: u32,
+    /// Whether a CW tone is currently detected
+    pub signal_on: bool,
+}

src/trx-core/src/lib.rs

@@ -4,6 +4,7 @@
 
 pub mod audio;
 pub mod client;
+pub mod decode;
 pub mod math;
 pub mod radio;
 pub mod rig;