refactor: extract psysonic-audio crate (M3/7)

Moves all audio playback code (Symphonia decode, rodio output, HTTP
streaming, gapless, previews, and the seven stream/ source-type
submodules from the prior split) out of the top crate into a new
psysonic-audio crate.

  crates/psysonic-audio/                  new lib crate, depends on
                                          psysonic-core + psysonic-analysis
    src/{engine,helpers,decode,…}.rs      flattened layout (no more
                                          extra audio/ namespace level)
    src/stream/                           seven submodules from M0
    src/lib.rs                            re-exports macros from
                                          psysonic-core and the public
                                          API surface

The audio↔analysis edges identified in the dep survey are now real
crate deps (audio depends on analysis directly: AnalysisCache reads,
recommended_gain_for_target, submit_analysis_cpu_seed). Only the
analysis→audio back-edge goes through the PlaybackQueryHandle port
registered in M2.

Cross-crate ref migrations applied via batch sed:
  crate::audio::*               → crate::*       (intra-crate)
  crate::analysis_cache::*      → psysonic_analysis::analysis_cache::*
  crate::submit_analysis_cpu_seed → psysonic_analysis::analysis_runtime::*
  crate::subsonic_wire_user_agent → psysonic_core::user_agent::*

Top crate keeps `crate::audio::*` paths working via
`pub use psysonic_audio as audio;` — lib_commands/cli callers untouched.
`stop_audio_engine` (mac process-exit cleanup) moved into the audio
crate as `pub fn stop_audio_engine` since it reaches AudioEngine
internals; tray.rs now re-exports the moved fn.

Two small visibility promotions in engine.rs:
  pub(crate) fn analysis_track_id_is_current_playback   → pub
  pub(crate) fn ranged_loudness_backfill_should_defer    → pub

Behaviour preserving. Cargo check + clippy --workspace clean.

src-tauri/Cargo.lock

@@ -3609,6 +3609,7 @@ dependencies = [
  "lofty",
  "md5",
  "psysonic-analysis",
+ "psysonic-audio",
  "psysonic-core",
  "reqwest",
  "ringbuf",
@@ -3656,6 +3657,34 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "psysonic-audio"
+version = "1.46.0-dev"
+dependencies = [
+ "biquad",
+ "dasp_sample",
+ "futures-util",
+ "id3",
+ "libc",
+ "lofty",
+ "md5",
+ "psysonic-analysis",
+ "psysonic-core",
+ "reqwest",
+ "ringbuf",
+ "rodio",
+ "serde",
+ "serde_json",
+ "symphonia",
+ "symphonia-adapter-libopus",
+ "tauri",
+ "thread-priority",
+ "tokio",
+ "url",
+ "windows 0.62.2",
+ "zbus 5.15.0",
+]
+
 [[package]]
 name = "psysonic-core"
 version = "1.46.0-dev"

src-tauri/Cargo.toml

@@ -32,6 +32,7 @@ tauri-build = { version = "2", features = [] }
 [dependencies]
 psysonic-core = { path = "crates/psysonic-core" }
 psysonic-analysis = { path = "crates/psysonic-analysis" }
+psysonic-audio = { path = "crates/psysonic-audio" }
 tauri = { version = "2", features = ["tray-icon", "image-png"] }
 tauri-plugin-single-instance = "2"
 tauri-plugin-shell = "2"

src-tauri/crates/psysonic-audio/Cargo.toml

@@ -0,0 +1,41 @@
+[package]
+name = "psysonic-audio"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+publish = false
+
+[dependencies]
+psysonic-core = { path = "../psysonic-core" }
+psysonic-analysis = { path = "../psysonic-analysis" }
+
+tauri = { version = "2" }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+tokio = { version = "1", features = ["rt", "time", "sync"] }
+reqwest = { version = "0.13", default-features = false, features = ["stream", "json", "rustls", "blocking"] }
+futures-util = "0.3"
+rodio = { version = "0.22", default-features = false, features = ["playback", "symphonia-all"] }
+symphonia = { version = "0.5", default-features = false, features = ["flac", "mp3", "pcm", "aac", "alac", "isomp4", "vorbis", "ogg", "wav", "adpcm"] }
+symphonia-adapter-libopus = "0.2.9"
+ringbuf = "0.5"
+biquad = "0.6"
+dasp_sample = "0.11.0"
+md5 = "0.8"
+url = "2"
+thread-priority = "3"
+lofty = "0.24"
+id3 = "1.16.4"
+
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"
+
+[target.'cfg(target_os = "linux")'.dependencies]
+zbus = { version = "5.15", default-features = false, features = ["blocking-api"] }
+
+[target.'cfg(windows)'.dependencies]
+windows = { version = "0.62", features = [
+    "Win32_Foundation",
+    "Win32_System_Com",
+    "Win32_System_Threading",
+] }

src-tauri/crates/psysonic-audio/src/engine.rs

@@ -65,7 +65,7 @@ pub struct AudioEngine {
     pub gapless_switch_at: Arc<AtomicU64>,
     /// Active radio session state.  None for regular (non-radio) tracks.
     /// Dropping the value aborts the HTTP download task via RadioLiveState::Drop.
-    pub(crate) radio_state: Mutex<Option<crate::audio::stream::RadioLiveState>>,
+    pub(crate) radio_state: Mutex<Option<crate::stream::RadioLiveState>>,
     /// URL last committed to `AudioCurrent` — used so `audio_update_replay_gain` can
     /// resolve LUFS / startup trim when the frontend passes `loudnessGainDb: null`
     /// (otherwise `compute_gain` would treat that as unity gain and playback "jumps").
@@ -345,7 +345,7 @@ pub fn create_engine() -> (AudioEngine, std::thread::JoinHandle<()>) {
             reqwest::Client::builder()
                 .timeout(Duration::from_secs(30))
                 .use_rustls_tls()
-                .user_agent(crate::subsonic_wire_user_agent())
+                .user_agent(psysonic_core::user_agent::subsonic_wire_user_agent())
                 .build()
                 .unwrap_or_default(),
         )),
@@ -381,7 +381,7 @@ pub fn create_engine() -> (AudioEngine, std::thread::JoinHandle<()>) {
 }
 /// `analysis_enqueue_seed_from_url` should bail while this track's ranged HTTP buffer
 /// is still filling — playback will seed on completion with the same bytes.
-pub(crate) fn ranged_loudness_backfill_should_defer(engine: &AudioEngine, track_id: &str) -> bool {
+pub fn ranged_loudness_backfill_should_defer(engine: &AudioEngine, track_id: &str) -> bool {
     let tid = track_id.trim();
     if tid.is_empty() {
         return false;
@@ -392,9 +392,22 @@ pub(crate) fn ranged_loudness_backfill_should_defer(engine: &AudioEngine, track_
     matches!(&*g, Some((t, _)) if t.as_str() == tid)
 }
 
+/// Stops the Rust audio engine cleanly (mirrors the logic in `audio_stop`).
+/// Called before process exit on macOS to ensure audio stops immediately.
+pub fn stop_audio_engine(app: &tauri::AppHandle) {
+    use std::sync::atomic::Ordering;
+    use tauri::Manager;
+    let engine = app.state::<AudioEngine>();
+    engine.generation.fetch_add(1, Ordering::SeqCst);
+    *engine.chained_info.lock().unwrap() = None;
+    drop(engine.radio_state.lock().unwrap().take());
+    let mut cur = engine.current.lock().unwrap();
+    if let Some(sink) = cur.sink.take() { sink.stop(); }
+}
+
 /// Subsonic id pinned for the playing source (`audio_play`). Used to prioritize
 /// HTTP loudness backfill for the track the user is listening to.
-pub(crate) fn analysis_track_id_is_current_playback(engine: &AudioEngine, track_id: &str) -> bool {
+pub fn analysis_track_id_is_current_playback(engine: &AudioEngine, track_id: &str) -> bool {
     let needle = track_id.trim();
     if needle.is_empty() {
         return false;

src-tauri/crates/psysonic-audio/src/helpers.rs

@@ -8,8 +8,8 @@ use rodio::Player;
 use serde::Serialize;
 use tauri::{AppHandle, Emitter, Manager};
 
-use crate::audio::engine::AudioEngine;
+use crate::engine::AudioEngine;
-use crate::audio::ipc::{
+use crate::ipc::{
     partial_loudness_should_emit, PartialLoudnessPayload, PARTIAL_LOUDNESS_DELTA_THRESHOLD_DB,
 };
 
@@ -336,7 +336,7 @@ pub(crate) fn resolve_loudness_gain_from_cache_impl(
         }
         return None;
     };
-    let Some(cache) = app.try_state::<crate::analysis_cache::AnalysisCache>() else {
+    let Some(cache) = app.try_state::<psysonic_analysis::analysis_cache::AnalysisCache>() else {
         if opts.log_soft_misses {
             crate::app_deprintln!(
                 "[normalization] resolve_loudness_gain source=no-analysis-cache track_id={}",
@@ -351,7 +351,7 @@ pub(crate) fn resolve_loudness_gain_from_cache_impl(
     }
     match cache.get_latest_loudness_for_track(&track_id) {
         Ok(Some(row)) if row.integrated_lufs.is_finite() => {
-            let recommended = crate::analysis_cache::recommended_gain_for_target(
+            let recommended = psysonic_analysis::analysis_cache::recommended_gain_for_target(
                 row.integrated_lufs,
                 row.true_peak,
                 target_lufs as f64,
@@ -404,7 +404,7 @@ const LOUDNESS_PLACEHOLDER_INTEGRATED_LUFS: f64 = -14.0;
 pub(crate) fn loudness_gain_placeholder_until_cache(target_lufs: f32, pre_analysis_attenuation_db: f32) -> f32 {
     let pre = pre_analysis_attenuation_db.clamp(-24.0, 0.0).min(0.0);
     // `true_peak = 0.0` skips the headroom cap until integrated measurement exists.
-    let pivot = crate::analysis_cache::recommended_gain_for_target(
+    let pivot = psysonic_analysis::analysis_cache::recommended_gain_for_target(
         LOUDNESS_PLACEHOLDER_INTEGRATED_LUFS,
         0.0,
         f64::from(target_lufs),
@@ -551,7 +551,7 @@ pub(crate) async fn fetch_data(
         return Ok(Some(data));
     }
 
-    let response = crate::audio::engine::audio_http_client(&state).get(url).send().await.map_err(|e| e.to_string())?;
+    let response = crate::engine::audio_http_client(&state).get(url).send().await.map_err(|e| e.to_string())?;
     let status = response.status();
     let ct = response.headers()
         .get(reqwest::header::CONTENT_TYPE)
@@ -604,7 +604,7 @@ pub(crate) fn spawn_analysis_seed_from_in_memory_bytes(
     let Some(track_id) = cache_track_id.map(str::trim).filter(|s| !s.is_empty()) else {
         return;
     };
-    if bytes.is_empty() || bytes.len() > crate::audio::stream::TRACK_STREAM_PROMOTE_MAX_BYTES {
+    if bytes.is_empty() || bytes.len() > crate::stream::TRACK_STREAM_PROMOTE_MAX_BYTES {
         return;
     }
     let track_id = track_id.to_string();
@@ -616,12 +616,12 @@ pub(crate) fn spawn_analysis_seed_from_in_memory_bytes(
         track_id,
         bytes.len() as f64 / (1024.0 * 1024.0)
     );
-    let high = crate::audio::engine::analysis_seed_high_priority_for_track(&app, &track_id);
+    let high = crate::engine::analysis_seed_high_priority_for_track(&app, &track_id);
     tokio::spawn(async move {
         if gen_arc.load(Ordering::SeqCst) != gen {
             return;
         }
-        if let Err(e) = crate::submit_analysis_cpu_seed(app.clone(), track_id.clone(), bytes, high).await {
+        if let Err(e) = psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed(app.clone(), track_id.clone(), bytes, high).await {
             crate::app_eprintln!(
                 "[analysis] in-memory play path seed failed for {}: {}",
                 track_id,

src-tauri/crates/psysonic-audio/src/lib.rs

@@ -1,7 +1,10 @@
-//! Audio playback: Symphonia decode, rodio output, HTTP radio/streaming, gapless, previews.
+//! `psysonic-audio` — Symphonia decode, rodio output, HTTP radio/streaming,
-//!
+//! gapless, previews. Submodules (`sources`, `decode`, `stream`, `commands`, …)
-//! Implementation is split into submodules (`sources`, `decode`, `stream`, `commands`, …)
+//! preserve the historical single `audio.rs` partitioning.
-//! for navigation; behavior matches the historical single `audio.rs` file.
+
+// Re-export the logging facade so submodules can keep using
+// `crate::app_eprintln!()` / `crate::app_deprintln!()`.
+pub use psysonic_core::{app_deprintln, app_eprintln, logging};
 
 pub mod autoeq_commands;
 mod codec;
@@ -51,4 +54,4 @@ pub fn register_post_sleep_audio_recovery(app: tauri::AppHandle) {
     let _ = app;
 }
 
-pub(crate) use engine::{analysis_track_id_is_current_playback, ranged_loudness_backfill_should_defer};
+pub use engine::{analysis_track_id_is_current_playback, ranged_loudness_backfill_should_defer, stop_audio_engine};

src-tauri/crates/psysonic-audio/src/play_input.rs

@@ -140,7 +140,7 @@ fn open_local_file_input(
     );
     if let Some(seed_id) = ctx.cache_id_for_tasks {
         let skip_cpu_seed = app
-            .try_state::<crate::analysis_cache::AnalysisCache>()
+            .try_state::<psysonic_analysis::analysis_cache::AnalysisCache>()
             .map(|c| c.cpu_seed_redundant_for_track(seed_id).unwrap_or(false))
             .unwrap_or(false);
         if !skip_cpu_seed {
@@ -174,9 +174,9 @@ fn open_local_file_input(
                     seed_id,
                     data.len() as f64 / (1024.0 * 1024.0)
                 );
-                let high = crate::audio::engine::analysis_seed_high_priority_for_track(&app_seed, &seed_id);
+                let high = crate::engine::analysis_seed_high_priority_for_track(&app_seed, &seed_id);
                 if let Err(e) =
-                    crate::submit_analysis_cpu_seed(app_seed.clone(), seed_id.clone(), data, high).await
+                    psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed(app_seed.clone(), seed_id.clone(), data, high).await
                 {
                     crate::app_eprintln!(
                         "[analysis] local-file seed failed for {}: {}",

src-tauri/crates/psysonic-audio/src/preload_commands.rs

@@ -55,8 +55,8 @@ pub async fn audio_preload(
             track_id,
             data.len() as f64 / (1024.0 * 1024.0)
         );
-        let high = crate::audio::engine::analysis_track_id_is_current_playback(&state, &track_id);
+        let high = crate::engine::analysis_track_id_is_current_playback(&state, &track_id);
-        if let Err(e) = crate::submit_analysis_cpu_seed(app.clone(), track_id.clone(), data.clone(), high).await {
+        if let Err(e) = psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed(app.clone(), track_id.clone(), data.clone(), high).await {
             crate::app_eprintln!("[analysis] preload seed failed for {}: {}", track_id, e);
         }
     }

src-tauri/crates/psysonic-audio/src/preview.rs

@@ -144,7 +144,7 @@ pub async fn audio_preview_play(
     let preview_http = reqwest::Client::builder()
         .timeout(Duration::from_secs(300))
         .use_rustls_tls()
-        .user_agent(crate::subsonic_wire_user_agent())
+        .user_agent(psysonic_core::user_agent::subsonic_wire_user_agent())
         .build()
         .unwrap_or_else(|_| audio_http_client(&state));
     let bytes = preview_http

src-tauri/crates/psysonic-audio/src/stream/ranged_http.rs

@@ -279,9 +279,9 @@ pub(crate) async fn ranged_download_task(
             }
             downloaded += n;
             downloaded_to.store(downloaded, Ordering::SeqCst);
-            if downloaded >= crate::audio::helpers::PARTIAL_LOUDNESS_MIN_BYTES
+            if downloaded >= crate::helpers::PARTIAL_LOUDNESS_MIN_BYTES
                 && total_size > 0
-                && last_partial_loudness_emit.elapsed() >= Duration::from_millis(crate::audio::helpers::PARTIAL_LOUDNESS_EMIT_INTERVAL_MS)
+                && last_partial_loudness_emit.elapsed() >= Duration::from_millis(crate::helpers::PARTIAL_LOUDNESS_EMIT_INTERVAL_MS)
             {
                 last_partial_loudness_emit = Instant::now();
                 if normalization_engine.load(Ordering::Relaxed) == 2 {
@@ -289,14 +289,14 @@ pub(crate) async fn ranged_download_task(
                     let start_db = f32::from_bits(loudness_pre_analysis_attenuation_db.load(Ordering::Relaxed))
                         .clamp(-24.0, 0.0);
                     if let Some(provisional_db) =
-                        crate::audio::helpers::provisional_loudness_gain_from_progress(downloaded, total_size, target_lufs, start_db)
+                        crate::helpers::provisional_loudness_gain_from_progress(downloaded, total_size, target_lufs, start_db)
                     {
-                        let track_key = crate::audio::helpers::playback_identity(&url).unwrap_or_else(|| url.clone());
+                        let track_key = crate::helpers::playback_identity(&url).unwrap_or_else(|| url.clone());
-                        if crate::audio::ipc::partial_loudness_should_emit(&track_key, provisional_db) {
+                        if crate::ipc::partial_loudness_should_emit(&track_key, provisional_db) {
                             let _ = app.emit(
                                 "analysis:loudness-partial",
-                                crate::audio::ipc::PartialLoudnessPayload {
+                                crate::ipc::PartialLoudnessPayload {
-                                    track_id: crate::audio::helpers::playback_identity(&url),
+                                    track_id: crate::helpers::playback_identity(&url),
                                     gain_db: provisional_db,
                                     target_lufs,
                                     is_partial: true,
@@ -368,8 +368,8 @@ pub(crate) async fn ranged_download_task(
             );
         }
         if let Some(track_id) = cache_track_id {
-            let high = crate::audio::engine::analysis_seed_high_priority_for_track(&app, &track_id);
+            let high = crate::engine::analysis_seed_high_priority_for_track(&app, &track_id);
-            if let Err(e) = crate::submit_analysis_cpu_seed(app.clone(), track_id.clone(), data.clone(), high).await {
+            if let Err(e) = psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed(app.clone(), track_id.clone(), data.clone(), high).await {
                 crate::app_eprintln!("[analysis] ranged seed failed for {}: {}", track_id, e);
             }
         }

src-tauri/crates/psysonic-audio/src/stream/track_stream.rs

@@ -132,7 +132,7 @@ pub(crate) async fn track_download_task(
                         }
                     }
                     if !capture_over_limit
-                        && last_partial_loudness_emit.elapsed() >= Duration::from_millis(crate::audio::helpers::PARTIAL_LOUDNESS_EMIT_INTERVAL_MS)
+                        && last_partial_loudness_emit.elapsed() >= Duration::from_millis(crate::helpers::PARTIAL_LOUDNESS_EMIT_INTERVAL_MS)
                     {
                         last_partial_loudness_emit = Instant::now();
                         if normalization_engine.load(Ordering::Relaxed) == 2 {
@@ -141,7 +141,7 @@ pub(crate) async fn track_download_task(
                                 loudness_pre_analysis_attenuation_db.load(Ordering::Relaxed),
                             )
                             .clamp(-24.0, 0.0);
-                            crate::audio::helpers::emit_partial_loudness_from_bytes(&app, &url, &capture, target_lufs, pre_db);
+                            crate::helpers::emit_partial_loudness_from_bytes(&app, &url, &capture, target_lufs, pre_db);
                         }
                     }
                     offset += pushed;
@@ -160,9 +160,9 @@ pub(crate) async fn track_download_task(
                     track_id,
                     capture.len() as f64 / (1024.0 * 1024.0)
                 );
-                let high = crate::audio::engine::analysis_seed_high_priority_for_track(&app, &track_id);
+                let high = crate::engine::analysis_seed_high_priority_for_track(&app, &track_id);
                 if let Err(e) =
-                    crate::submit_analysis_cpu_seed(app.clone(), track_id.clone(), capture.clone(), high).await
+                    psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed(app.clone(), track_id.clone(), capture.clone(), high).await
                 {
                     crate::app_eprintln!("[analysis] track seed failed for {}: {}", track_id, e);
                 }

src-tauri/src/lib.rs

@@ -1,7 +1,6 @@
 // Prevents additional console window on Windows in release, DO NOT REMOVE!!
 #![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]
 
-mod audio;
 pub mod cli;
 mod discord;
 mod lib_commands;
@@ -12,9 +11,7 @@ pub use psysonic_core::user_agent::{
     default_subsonic_wire_user_agent, runtime_subsonic_wire_user_agent, subsonic_wire_user_agent,
 };
 pub use psysonic_analysis::{analysis_cache, analysis_runtime};
-// `crate::submit_analysis_cpu_seed` shorthand kept so the audio modules don't
+pub use psysonic_audio as audio;
-// have to spell out `psysonic_analysis::analysis_runtime::...` until M3.
-pub(crate) use psysonic_analysis::analysis_runtime::submit_analysis_cpu_seed;
 #[cfg(target_os = "windows")]
 mod taskbar_win;
 mod tray_runtime;

src-tauri/src/lib_commands/sync/tray.rs

@@ -1,12 +1,9 @@
-use std::sync::atomic::Ordering;
-
 use tauri::menu::{MenuBuilder, MenuItemBuilder, PredefinedMenuItem};
 use tauri::tray::{MouseButton, TrayIcon, TrayIconBuilder, TrayIconEvent};
 use tauri::{Emitter, Manager};
 #[cfg(not(target_os = "windows"))]
 use tauri::tray::MouseButtonState;
 
-use crate::audio;
 use crate::tray_runtime::{
     tray_state_icon, TrayMenuItems, TrayMenuItemsState, TrayMenuLabels, TrayMenuLabelsState,
     TrayPlaybackState, TrayState, TrayTooltip,
@@ -355,16 +352,7 @@ pub(crate) fn toggle_tray_icon(
     Ok(())
 }
 
-/// Stops the Rust audio engine cleanly (mirrors the logic in `audio_stop`).
+pub(crate) use crate::audio::stop_audio_engine;
-/// Called before process exit on macOS to ensure audio stops immediately.
-pub(crate) fn stop_audio_engine(app: &tauri::AppHandle) {
-    let engine = app.state::<audio::AudioEngine>();
-    engine.generation.fetch_add(1, Ordering::SeqCst);
-    *engine.chained_info.lock().unwrap() = None;
-    drop(engine.radio_state.lock().unwrap().take());
-    let mut cur = engine.current.lock().unwrap();
-    if let Some(sink) = cur.sink.take() { sink.stop(); }
-}
 
 /// Returns `true` if running under a tiling window manager (Hyprland, Sway, i3,
 /// bspwm, AwesomeWM, Openbox, etc.).  Detection is based on environment variables