Use bounded hardware CDC for the Full G2 repeater console

src/helpers/SerialPacketLog.h

@@ -130,7 +130,14 @@ class SerialLogLine {
 inline void serialLogBegin() {
 #if defined(ESP32_PLATFORM) && defined(ARDUINO_USB_CDC_ON_BOOT) && \
     (ARDUINO_USB_CDC_ON_BOOT == 1)
+  #if defined(ARDUINO_USB_MODE) && ARDUINO_USB_MODE == 1
+  // Arduino 2.0.17 HWCDC decrements an unsigned retry counter when its
+  // host stops reading. A zero timeout can underflow; retain the bounded
+  // timeout established by prepareUsbLoggingPort().
+  Serial.setTxTimeoutMs(5);
+  #else
   Serial.setTxTimeoutMs(0);
+  #endif
 #endif
 }
 

src/helpers/UsbLogging.cpp

@@ -483,9 +483,16 @@ public:
 
   size_t write(const uint8_t* data, size_t size) override {
     if (data == nullptr || size == 0) return 0;
+    // The shared producer guard excludes other application writers here.
+    // The ISR can only free ring capacity, so one fresh capacity sample keeps
+    // HWCDC::write out of its wait-for-space remainder loop.
+    const int available = Serial.availableForWrite();
+    if (available <= 0) return 0;
+    const size_t attempt = size < static_cast<size_t>(available)
+        ? size : static_cast<size_t>(available);
     noteUsbLoggingTxAttempt();
     esp32_hwcdc_tx_kick_pending.store(true, std::memory_order_release);
-    return Serial.write(data, size);
+    return Serial.write(data, attempt);
   }
 
 private:

variants/station_g2/platformio.ini

@@ -355,6 +355,13 @@ build_src_filter = ${Station_G2.build_src_filter}
 
 [env:Station_G2_repeater_observer_mqtt]
 extends = Station_G2
+; The Full repeater needs a serial console, so use the S3's fixed hardware
+; CDC/JTAG controller instead of TinyUSB's DTR-driven session quarantine.
+; Companion and the other G2 roles retain their existing USB backend.
+build_unflags =
+  ${Station_G2.build_unflags}
+  -DARDUINO_USB_MODE=0
+board_upload.use_1200bps_touch = false
 board_build.partitions = default_16MB.csv ; standard 16MB partition table
 extra_scripts =
   ${esp32_base.extra_scripts}
@@ -363,6 +370,7 @@ board_ssl_cert_source = adafruit-full
 board_build.embed_files = src/certs/x509_crt_bundle.bin
 build_flags =
   ${Station_G2.build_flags}
+  -D ARDUINO_USB_MODE=1
   ; The base observer disables LoRa OTA; build.sh promotes it to FULL and restores OTA.
   -UENABLE_OTA
   -D DISABLE_LORA_OTA=1