fix: gate native Tauri audio backend

src-tauri/src/commands/audio.rs

@@ -10,9 +10,9 @@ use tauri::{Emitter, State};
 
 use crate::engine::{
     audio_io, AudioDeviceInfo, ClipSchedule, ClipSource, CommandError, CountIn, Engine,
-    EngineConfig, EngineError, EngineStatus, LoopRegion, MetronomeConfig, PositionEmitter,
-    PunchRegion, TempoEvent, TempoMap, TimeSignatureEvent, TimeSignatureMap, TrackParams,
-    POSITION_EVENT_DEFAULT_INTERVAL,
+    EngineConfig, EngineError, EngineStatus, LoopRegion, MeterReading, MetronomeConfig,
+    PositionEmitter, PunchRegion, TempoEvent, TempoMap, TimeSignatureEvent, TimeSignatureMap,
+    TrackParams, POSITION_EVENT_DEFAULT_INTERVAL,
 };
 use crate::engine::slot::SlotHandle;
 
@@ -102,6 +102,14 @@ pub fn audio_start_engine(
         .lock()
         .map_err(|_| EngineError::Open("emitter mutex poisoned".into()))?;
 
+    let current_status = engine.status();
+    if current_status.is_running() {
+        // `Engine::start` returns AlreadyRunning, but the emitter is
+        // already valid in the normal running case. Return the current
+        // status without tearing it down.
+        return Ok(current_status);
+    }
+
     // Stop any leftover emitter BEFORE starting the new engine — so
     // we never have two emitters pushing to the same event name, and
     // we don't leak a thread if `start` fails.
@@ -218,6 +226,48 @@ pub fn audio_set_master_volume(
     engine.set_master_volume(volume)
 }
 
+#[tauri::command]
+pub fn audio_get_track_meter(
+    handle: SlotHandle,
+    state: State<'_, EngineState>,
+) -> Result<MeterReading, CommandError> {
+    let mut engine = state
+        .0
+        .lock()
+        .map_err(|_| CommandError::Disconnected)?;
+    Ok(engine.get_track_meter(handle))
+}
+
+#[tauri::command]
+pub fn audio_get_master_meter(state: State<'_, EngineState>) -> Result<MeterReading, CommandError> {
+    let mut engine = state
+        .0
+        .lock()
+        .map_err(|_| CommandError::Disconnected)?;
+    Ok(engine.get_master_meter())
+}
+
+#[tauri::command]
+pub fn audio_reset_track_clip(
+    handle: SlotHandle,
+    state: State<'_, EngineState>,
+) -> Result<(), CommandError> {
+    let mut engine = state
+        .0
+        .lock()
+        .map_err(|_| CommandError::Disconnected)?;
+    engine.reset_track_clip(handle)
+}
+
+#[tauri::command]
+pub fn audio_reset_master_clip(state: State<'_, EngineState>) -> Result<(), CommandError> {
+    let mut engine = state
+        .0
+        .lock()
+        .map_err(|_| CommandError::Disconnected)?;
+    engine.reset_master_clip()
+}
+
 // ── Transport (3A) ──────────────────────────────────────────────────
 
 #[tauri::command]

src-tauri/src/engine/audio_io.rs

@@ -354,6 +354,14 @@ fn make_audio_callback(
                             bus.enabled = enabled;
                         }
                     }
+                    EngineCommand::ResetTrackClip { handle } => {
+                        if graph.handle_matches(handle) {
+                            meters.track_meters[handle.index()].reset_clip();
+                        }
+                    }
+                    EngineCommand::ResetMasterClip => {
+                        meters.master_meter.reset_clip();
+                    }
                     // Transport commands (3A) — route to the audio-thread
                     // `Transport` instance. Position advance happens at
                     // the tail of the callback, AFTER the drain, so that

src-tauri/src/engine/command.rs

@@ -142,6 +142,13 @@ pub enum EngineCommand {
     /// Enable or disable an aux return bus.
     SetAuxBusEnabled { bus_index: u8, enabled: bool },
 
+    /// Clear the latched clip flag on a track meter.
+    /// Generation-checked like other track-targeted commands.
+    ResetTrackClip { handle: SlotHandle },
+
+    /// Clear the latched clip flag on the master meter.
+    ResetMasterClip,
+
     // ── Transport (3A) ────────────────────────────────────────────────
 
     /// Begin playback from the current position.

src-tauri/src/engine/graph.rs

@@ -252,6 +252,8 @@ impl AudioGraph {
             | EngineCommand::SetTrackSendLevel { .. }
             | EngineCommand::SetAuxBusVolume { .. }
             | EngineCommand::SetAuxBusEnabled { .. }
+            | EngineCommand::ResetTrackClip { .. }
+            | EngineCommand::ResetMasterClip
             | EngineCommand::TransportPlay
             | EngineCommand::TransportStop
             | EngineCommand::TransportPause

src-tauri/src/engine/meter_bank.rs

@@ -68,6 +68,22 @@ impl MeterConsumers {
         drain_into(&mut self.master_consumer, &mut self.master_cache);
         self.master_cache
     }
+
+    /// Clear the latched clip flag from the main-thread cache for a
+    /// track slot. The audio-thread meter is reset by command queue;
+    /// this avoids one stale UI poll before that command drains.
+    pub fn reset_track_clip(&mut self, slot: usize) {
+        if let Some(cons) = self.track_consumers.get_mut(slot) {
+            drain_into(cons, &mut self.track_cache[slot]);
+            self.track_cache[slot].clipped = false;
+        }
+    }
+
+    /// Clear the latched clip flag from the main-thread master cache.
+    pub fn reset_master_clip(&mut self) {
+        drain_into(&mut self.master_consumer, &mut self.master_cache);
+        self.master_cache.clipped = false;
+    }
 }
 
 /// Drain the ring buffer into a cached value. If new entries exist,

src-tauri/src/engine/mod.rs

@@ -497,6 +497,20 @@ impl Engine {
         self.send_command(EngineCommand::SetMasterVolume { volume })
     }
 
+    /// Clear a track meter's latched clip flag.
+    pub fn reset_track_clip(&mut self, handle: SlotHandle) -> Result<(), CommandError> {
+        let running = self.running.as_mut().ok_or(CommandError::NotRunning)?;
+        running.meter_consumers.reset_track_clip(handle.index());
+        self.send_command(EngineCommand::ResetTrackClip { handle })
+    }
+
+    /// Clear the master meter's latched clip flag.
+    pub fn reset_master_clip(&mut self) -> Result<(), CommandError> {
+        let running = self.running.as_mut().ok_or(CommandError::NotRunning)?;
+        running.meter_consumers.reset_master_clip();
+        self.send_command(EngineCommand::ResetMasterClip)
+    }
+
     // ── Transport (3A) ───────────────────────────────────────────────
 
     /// Begin playback from the current position.

src-tauri/src/lib.rs

@@ -5,7 +5,8 @@ use tauri::Manager;
 
 use crate::commands::audio::{
     audio_add_track, audio_clip_get_schedule, audio_clip_set_schedule,
-    audio_get_default_device, audio_get_engine_status, audio_list_devices,
+    audio_get_default_device, audio_get_engine_status, audio_get_master_meter,
+    audio_get_track_meter, audio_list_devices, audio_reset_master_clip, audio_reset_track_clip,
     audio_metronome_get_config, audio_metronome_set_config, audio_metronome_set_enabled,
     audio_remove_track, audio_set_master_volume, audio_set_track_params,
     audio_start_engine, audio_stop_engine, audio_transport_get_count_in,
@@ -55,6 +56,10 @@ pub fn run() {
             audio_remove_track,
             audio_set_track_params,
             audio_set_master_volume,
+            audio_get_track_meter,
+            audio_get_master_meter,
+            audio_reset_track_clip,
+            audio_reset_master_clip,
             audio_transport_play,
             audio_transport_stop,
             audio_transport_pause,

src/components/mixer/LevelMeter.tsx

@@ -1,5 +1,6 @@
 import { useEffect, useRef, useCallback } from 'react';
-import { getAudioEngine } from '../../hooks/useAudioEngine';
+import { getAudioEngine, getTauriPlaybackClockOwner } from '../../hooks/useAudioEngine';
+import { getAudioBridge } from '../../engine/bridge';
 import { METER_CANVAS_STOPS, METER_DB_TICKS, METER_DB_TICKS_MINOR, METER_PADDING_PCT, dbToFill, levelToFill } from '../meter-colors';
 
 const BAR_WIDTH = 4;
@@ -77,6 +78,7 @@ export function LevelMeter({ trackId, masterStage, returnTrackId, stereo, showSc
     };
 
     const engine = getAudioEngine();
+    const bridge = getAudioBridge(engine);
 
     const tick = () => {
       const dpr = window.devicePixelRatio || 1;
@@ -92,8 +94,12 @@ export function LevelMeter({ trackId, masterStage, returnTrackId, stereo, showSc
       let rightLevel = 0;
       let clipped = false;
 
+      const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+        ? bridge
+        : engine;
+
       if (masterStage) {
-        const meter = engine.getMasterMeter(masterStage);
+        const meter = meterSource.getMasterMeter(masterStage);
         leftLevel = meter.level;
         rightLevel = meter.level;
         clipped = meter.clipped;
@@ -103,7 +109,7 @@ export function LevelMeter({ trackId, masterStage, returnTrackId, stereo, showSc
         rightLevel = meter.level;
         clipped = meter.clipped;
       } else if (trackId) {
-        const meter = engine.getTrackMeter(trackId);
+        const meter = meterSource.getTrackMeter(trackId);
         leftLevel = isStereo ? meter.leftLevel : meter.level;
         rightLevel = isStereo ? meter.rightLevel : meter.level;
         clipped = meter.clipped;
@@ -183,12 +189,16 @@ export function LevelMeter({ trackId, masterStage, returnTrackId, stereo, showSc
 
   const resetClip = () => {
     const engine = getAudioEngine();
+    const bridge = getAudioBridge(engine);
+    const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+      ? bridge
+      : engine;
     if (masterStage) {
-      engine.resetMasterClip(masterStage);
+      meterSource.resetMasterClip(masterStage);
     } else if (returnTrackId) {
       engine.resetReturnTrackClip(returnTrackId);
     } else if (trackId) {
-      engine.resetTrackClip(trackId);
+      meterSource.resetTrackClip(trackId);
     }
     clippedRef.current = false;
     clippedStateRef.current = false;

src/components/mixer/__tests__/LevelMeter.test.tsx

@@ -3,6 +3,7 @@ import { render, screen } from '@testing-library/react';
 import { LevelMeter } from '../LevelMeter';
 
 vi.mock('../../../hooks/useAudioEngine', () => ({
+  getTauriPlaybackClockOwner: () => 'web-audio',
   getAudioEngine: () => ({
     getTrackMeter: () => ({ level: 0.5, leftLevel: 0.4, rightLevel: 0.6, clipped: false }),
     getMasterMeter: () => ({ level: 0.3, clipped: false }),

src/components/session/SessionMixerStrip.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useRef, useState } from 'react';
-import { getAudioEngine } from '../../hooks/useAudioEngine';
+import { getAudioEngine, getTauriPlaybackClockOwner } from '../../hooks/useAudioEngine';
+import { getAudioBridge } from '../../engine/bridge';
 import { Knob } from '../ui/Knob';
 
 /** Convert linear level (0..1+) to a 0..1 fill fraction mapping -60dB..0dB */
@@ -45,8 +46,12 @@ export function SessionMixerStrip({
   // Animate meter levels
   useEffect(() => {
     const engine = getAudioEngine();
+    const bridge = getAudioBridge(engine);
     const tick = () => {
-      const meter = engine.getTrackMeter(trackId);
+      const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+        ? bridge
+        : engine;
+      const meter = meterSource.getTrackMeter(trackId);
       setLeftFill(levelToFill(meter.leftLevel));
       setRightFill(levelToFill(meter.rightLevel));
       rafRef.current = requestAnimationFrame(tick);

src/components/session/__tests__/SessionMixer.test.tsx

@@ -9,6 +9,7 @@ vi.mock('../../../services/projectStorage', () => ({
 }));
 
 vi.mock('../../../hooks/useAudioEngine', () => ({
+  getTauriPlaybackClockOwner: () => 'web-audio',
   getAudioEngine: () => ({
     getTrackMeter: () => ({ leftLevel: 0, rightLevel: 0, clipped: false }),
     getTrackLevel: () => 0,

src/components/tracks/FaderMeter.tsx

@@ -1,5 +1,6 @@
 import { useCallback, useEffect, useRef, useState } from 'react';
-import { getAudioEngine } from '../../hooks/useAudioEngine';
+import { getAudioEngine, getTauriPlaybackClockOwner } from '../../hooks/useAudioEngine';
+import { getAudioBridge } from '../../engine/bridge';
 import { METER_GRADIENT_HORIZONTAL, levelToMeterFill } from '../meter-colors';
 
 interface FaderMeterProps {
@@ -33,8 +34,12 @@ export function FaderMeter({ trackId, volume, onVolumeChange, trackName }: Fader
   // Animate meter levels
   useEffect(() => {
     const engine = getAudioEngine();
+    const bridge = getAudioBridge(engine);
     const tick = () => {
-      const meter = engine.getTrackMeter(trackId);
+      const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+        ? bridge
+        : engine;
+      const meter = meterSource.getTrackMeter(trackId);
       setLeftFill(levelToMeterFill(meter.leftLevel));
       setRightFill(levelToMeterFill(meter.rightLevel));
       setClipping((was) => was || meter.clipped);
@@ -46,7 +51,11 @@ export function FaderMeter({ trackId, volume, onVolumeChange, trackName }: Fader
 
   const resetClip = useCallback(() => {
     const engine = getAudioEngine();
-    engine.resetTrackClip(trackId);
+    const bridge = getAudioBridge(engine);
+    const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+      ? bridge
+      : engine;
+    meterSource.resetTrackClip(trackId);
     setClipping(false);
   }, [trackId]);
 

src/components/tracks/StereoMeter.tsx

@@ -1,5 +1,6 @@
 import { useEffect, useRef, useState } from 'react';
-import { getAudioEngine } from '../../hooks/useAudioEngine';
+import { getAudioEngine, getTauriPlaybackClockOwner } from '../../hooks/useAudioEngine';
+import { getAudioBridge } from '../../engine/bridge';
 import { METER_GRADIENT_HORIZONTAL, levelToMeterFill } from '../meter-colors';
 
 interface StereoMeterProps {
@@ -14,9 +15,13 @@ export function StereoMeter({ trackId }: StereoMeterProps) {
 
   useEffect(() => {
     const engine = getAudioEngine();
+    const bridge = getAudioBridge(engine);
 
     const tick = () => {
-      const meter = engine.getTrackMeter(trackId);
+      const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+        ? bridge
+        : engine;
+      const meter = meterSource.getTrackMeter(trackId);
       setLeftFill(levelToMeterFill(meter.leftLevel));
       setRightFill(levelToMeterFill(meter.rightLevel));
       setClipping((was) => was || meter.clipped);
@@ -29,7 +34,11 @@ export function StereoMeter({ trackId }: StereoMeterProps) {
 
   const resetClip = () => {
     const engine = getAudioEngine();
-    engine.resetTrackClip(trackId);
+    const bridge = getAudioBridge(engine);
+    const meterSource = bridge.backend === 'tauri' && getTauriPlaybackClockOwner() === 'native'
+      ? bridge
+      : engine;
+    meterSource.resetTrackClip(trackId);
     setClipping(false);
   };
 

src/components/tracks/__tests__/StereoMeter.test.tsx

@@ -10,6 +10,7 @@ const engine = {
 
 vi.mock('../../../hooks/useAudioEngine', () => ({
   getAudioEngine: () => engine,
+  getTauriPlaybackClockOwner: () => 'web-audio',
 }));
 
 describe('StereoMeter', () => {

src/components/tracks/__tests__/TrackHeader.test.tsx

@@ -23,6 +23,7 @@ vi.mock('../../../services/freezeTrack', () => ({
 }));
 
 vi.mock('../../../hooks/useAudioEngine', () => ({
+  getTauriPlaybackClockOwner: () => 'web-audio',
   getAudioEngine: () => ({
     getTrackLevel: () => 0,
     getTrackMeter: () => ({ level: 0, clipped: false }),

src/components/tracks/__tests__/TrackHeaderAnimation.test.tsx

@@ -18,6 +18,7 @@ vi.mock('../../../services/freezeTrack', () => ({
   flattenTrackToAudio: vi.fn(),
 }));
 vi.mock('../../../hooks/useAudioEngine', () => ({
+  getTauriPlaybackClockOwner: () => 'web-audio',
   getAudioEngine: () => ({
     getTrackLevel: () => 0,
   }),

src/components/tracks/__tests__/TrackHeaderLayout.test.tsx

@@ -19,6 +19,7 @@ vi.mock('../../../services/freezeTrack', () => ({
   flattenTrackToAudio: vi.fn(),
 }));
 vi.mock('../../../hooks/useAudioEngine', () => ({
+  getTauriPlaybackClockOwner: () => 'web-audio',
   getAudioEngine: () => ({
     getTrackLevel: () => 0,
     getTrackMeter: () => ({ level: 0, clipped: false }),

src/components/tracks/__tests__/TrackHeaderMeter.test.tsx

@@ -10,6 +10,7 @@ const engine = {
 
 vi.mock('../../../hooks/useAudioEngine', () => ({
   getAudioEngine: () => engine,
+  getTauriPlaybackClockOwner: () => 'web-audio',
 }));
 
 describe('TrackHeaderMeter', () => {