[fix](trx-client): only reset audio reconnect backoff after stable uptime

run_single_rig_audio_client used to reset reconnect_delay to 1 s as soon as TCP connect() succeeded. A peer that fails moments after accepting (broken handshake, oversize history blob, etc.) therefore stayed in a 1 Hz reconnect loop forever — exponential backoff never had a chance to climb.

Capture the moment connect() returns and only reset the backoff once the connection has lived past STABLE_CONNECTION_THRESHOLD (30 s). Defense in depth alongside the chunked history fix.

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/src/audio_client.rs

@@ -7,7 +7,7 @@
 
 use std::collections::{HashMap, HashSet};
 use std::sync::{Arc, Mutex, RwLock};
-use std::time::Duration;
+use std::time::{Duration, Instant};
 
 use bytes::Bytes;
 use flate2::read::GzDecoder;
@@ -36,6 +36,13 @@ use trx_core::audio::{
 use trx_core::decode::DecodedMessage;
 use trx_frontend::VChanAudioCmd;
 
+/// Minimum uptime before a connection is "stable" enough to reset the
+/// reconnect backoff.  Connections that die before this threshold leave the
+/// exponential backoff climbing — protects the server from a tight reconnect
+/// storm when the peer is broken in some way that only manifests after the
+/// TCP handshake.
+const STABLE_CONNECTION_THRESHOLD: Duration = Duration::from_secs(30);
+
 #[derive(Clone, Debug)]
 struct ActiveVChanSub {
     freq_hz: u64,
@@ -289,7 +296,7 @@ async fn run_single_rig_audio_client(
         info!("Audio client [{}]: connecting to {}", rig_id, server_addr);
         match TcpStream::connect(&server_addr).await {
             Ok(stream) => {
-                reconnect_delay = Duration::from_secs(1);
+                let connected_at = Instant::now();
                 if let Err(e) = handle_single_rig_connection(
                     stream,
                     &rig_id,
@@ -311,6 +318,13 @@ async fn run_single_rig_audio_client(
                 {
                     warn!("Audio connection [{}] dropped: {}", rig_id, e);
                 }
+                // Only reset the backoff after a connection survived long
+                // enough to be considered stable.  TCP `connect()` succeeding
+                // is not enough — a peer that fails immediately after
+                // accepting must not be hammered every second.
+                if connected_at.elapsed() >= STABLE_CONNECTION_THRESHOLD {
+                    reconnect_delay = Duration::from_secs(1);
+                }
             }
             Err(e) => {
                 warn!("Audio connect [{}] failed: {}", rig_id, e);