Fix comment inaccuracies and restore lint targets

- Clarify sample rate is configurable (8k/12k/16k/24k/48k), not fixed at 48kHz
- Expand mutex comment to include full lifecycle protection scope
- Document that ALSA playback init fails immediately with no fallback
- Add async behavior documentation to audio enable/restart functions
- Restore build_audio_deps target lost during merge
- Restore lint-fix, lint-go, lint-ui Makefile targets
- Fix variable alignment per linter

Makefile

@@ -47,6 +47,10 @@ BIN_DIR := $(shell pwd)/bin
 
 TEST_DIRS := $(shell find . -name "*_test.go" -type f -exec dirname {} \; | sort -u)
 
+# Build ALSA and Opus static libs for ARM in /opt/jetkvm-audio-libs
+build_audio_deps:
+	bash .devcontainer/install_audio_deps.sh
+
 build_native:
 	@if [ "$(SKIP_NATIVE_IF_EXISTS)" = "1" ] && [ -f "internal/native/cgo/lib/libjknative.a" ]; then \
 		echo "libjknative.a already exists, skipping native build..."; \
@@ -137,3 +141,31 @@ release:
 	@shasum -a 256 bin/jetkvm_app | cut -d ' ' -f 1 > bin/jetkvm_app.sha256
 	rclone copyto bin/jetkvm_app r2://jetkvm-update/app/$(VERSION)/jetkvm_app
 	rclone copyto bin/jetkvm_app.sha256 r2://jetkvm-update/app/$(VERSION)/jetkvm_app.sha256
+# Run golangci-lint locally with the same configuration as CI
+lint-go: build_audio_deps
+	@echo "Running golangci-lint..."
+	@mkdir -p static && touch static/.gitkeep
+	golangci-lint run --verbose
+
+# Run both Go and UI linting with auto-fix
+lint-fix: lint-go-fix lint-ui-fix
+	@echo "All linting with auto-fix completed successfully!"
+
+# Run golangci-lint with auto-fix
+lint-go-fix: build_audio_deps
+	@echo "Running golangci-lint with auto-fix..."
+	@mkdir -p static && touch static/.gitkeep
+	golangci-lint run --fix --verbose
+
+# Run UI linting locally (mirrors GitHub workflow ui-lint.yml)
+lint-ui:
+	@echo "Running UI lint..."
+	@cd ui && npm ci && npm run lint
+
+# Run UI linting with auto-fix
+lint-ui-fix:
+	@echo "Running UI lint with auto-fix..."
+	@cd ui && npm ci && npm run lint:fix
+
+# Legacy alias for UI linting (for backward compatibility)
+ui-lint: lint-ui

audio.go

@@ -13,10 +13,10 @@ import (
 )
 
 var (
-	audioMutex       sync.Mutex
-	inputSourceMutex sync.Mutex // Prevents concurrent WebRTC packets from racing during lazy connect + write
-	outputSource     atomic.Pointer[audio.AudioSource]
-	inputSource      atomic.Pointer[audio.AudioSource]
+	audioMutex         sync.Mutex
+	inputSourceMutex   sync.Mutex // Prevents concurrent WebRTC packets from racing during lazy connect + write
+	outputSource       atomic.Pointer[audio.AudioSource]
+	inputSource        atomic.Pointer[audio.AudioSource]
 	outputRelay        atomic.Pointer[audio.OutputRelay]
 	inputRelay         atomic.Pointer[audio.InputRelay]
 	audioInitialized   bool
@@ -257,6 +257,9 @@ func setPendingInputTrack(track *webrtc.TrackRemote) {
 	go handleInputTrackForSession(track)
 }
 
+// SetAudioOutputEnabled enables or disables audio output capture.
+// Returns immediately; when enabling, audio starts asynchronously to prevent UI blocking.
+// Check logs for async operation status.
 func SetAudioOutputEnabled(enabled bool) error {
 	if audioOutputEnabled.Swap(enabled) == enabled {
 		return nil
@@ -274,6 +277,9 @@ func SetAudioOutputEnabled(enabled bool) error {
 	return nil
 }
 
+// SetAudioInputEnabled enables or disables audio input playback.
+// Returns immediately; when enabling, audio starts asynchronously to prevent UI blocking.
+// Check logs for async operation status.
 func SetAudioInputEnabled(enabled bool) error {
 	if audioInputEnabled.Swap(enabled) == enabled {
 		return nil
@@ -329,6 +335,9 @@ func SetAudioOutputSource(source string) error {
 	return nil
 }
 
+// RestartAudioOutput stops and restarts the audio output capture.
+// Returns immediately; restart happens asynchronously to prevent UI blocking.
+// Check logs for async operation status.
 func RestartAudioOutput() error {
 	audioMutex.Lock()
 	hasActiveOutput := audioOutputEnabled.Load() && currentAudioTrack != nil && outputSource.Load() != nil

internal/audio/c/audio.c

@@ -11,7 +11,8 @@
  * Key features:
  * - ARM NEON SIMD optimization for all audio operations
  * - Opus in-band FEC for packet loss resilience
- * - S16_LE stereo, 20ms frames at 48kHz (ALSA resamples non-48kHz sources)
+ * - S16_LE stereo, 20ms frames (sample rate configurable: 8k/12k/16k/24k/48kHz)
+ * - ALSA rate plugin resamples hardware output to match requested Opus-compatible rate
  */
 
 #include <alsa/asoundlib.h>
@@ -75,11 +76,11 @@ static uint32_t max_backoff_us_global = 500000;
 static atomic_int capture_stop_requested = 0;
 static atomic_int playback_stop_requested = 0;
 
-// Mutexes to protect concurrent access to ALSA handles and codecs
+// Mutexes to protect concurrent access to ALSA handles and codecs throughout their lifecycle
 // These prevent race conditions when jetkvm_audio_*_close() is called while
 // jetkvm_audio_read_encode() or jetkvm_audio_decode_write() are executing.
-// The mutexes are held during ALSA I/O and codec operations to ensure
-// handles remain valid throughout the operation.
+// The mutexes protect initialization, cleanup, ALSA I/O, codec operations, and handle validation
+// to ensure handles remain valid from acquisition through release.
 static pthread_mutex_t capture_mutex = PTHREAD_MUTEX_INITIALIZER;
 static pthread_mutex_t playback_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -606,7 +607,7 @@ retry_read:
 /**
  * Initialize INPUT path (Opus decoder → device speakers)
  * Opens ALSA playback device from ALSA_PLAYBACK_DEVICE env (default: hw:1,0)
- * and creates Opus decoder
+ * and creates Opus decoder. Returns immediately on device open failure (no fallback).
  * @return 0 on success, -EBUSY if initializing, -1/-2 on errors
  */
 int jetkvm_audio_playback_init() {