fix: add 15s timeout for addSoundBank (hangs on parse error)

Per md/38_FLOWCLIENT.md flow:
- _addBankWithTimeout: wraps SpessaSynth addSoundBank with Promise.race
- 15s timeout breaks deadlock when AudioWorklet parser fails silently
- Phase 3 (channel setup) only runs after Phase 2 (load) confirms success
- Falls back to oscillator when bank can't be loaded

app/static/js/services/soundfontPlayer.js

@@ -33,19 +33,37 @@
 
     let _synthInstance = null;
     let _initialized = false;
-    let _initInProgress = false;
     let _currentSfId = null;
+    let _bankLoadedCount = 0;
+
+    // ── addSoundBank with timeout (SpessaSynth hangs on parse error) ──
+    async function _addBankWithTimeout(synth, buffer, sfId, timeoutMs) {
+        return new Promise((resolve) => {
+            const timer = setTimeout(() => {
+                console.warn("[SonicSF] addSoundBank timeout after", timeoutMs, "ms");
+                resolve(false);
+            }, timeoutMs);
+
+            synth.soundBankManager.addSoundBank(buffer.slice(0), sfId).then(() => {
+                clearTimeout(timer);
+                resolve(true);
+            }).catch((err) => {
+                clearTimeout(timer);
+                console.error("[SonicSF] addSoundBank rejected:", err);
+                resolve(false);
+            });
+        });
+    }
 
     const SonicSF = {
         loadedFonts: {},
 
+        // ══════════════════════════════════════════════════
+        // PHASE 1: Init SpessaSynth Engine (FlowClient.md 1.1)
+        // ══════════════════════════════════════════════════
         init: async function (audioContext) {
-            if (_initialized && _synthInstance) return;
-            if (_initInProgress) return;
-            _initInProgress = true;
             if (!window.SpessaSynthClass || !window.__SpessaSynthCDN) {
-                console.warn("[SonicSF] SpessaSynth CDN not loaded. Using oscillator fallback.");
+                console.warn("[SonicSF] SpessaSynth CDN not available. Using oscillator.");
-                _initInProgress = false;
                 return;
             }
             try {
@@ -53,89 +71,59 @@
                 await audioContext.audioWorklet.addModule(procUrl);
                 _synthInstance = new window.SpessaSynthClass(audioContext);
                 await _synthInstance.isReady;
-                // Try loading default SGM bank to verify SpessaSynth works
-                try {
-                    const resp = await fetch("/api/v1/plugins/soundfonts/download/sgm_v2.01?t=" + Date.now());
-                    if (resp.ok) {
-                        const buf = await resp.arrayBuffer();
-                        await _synthInstance.soundBankManager.addSoundBank(buf.slice(0), "sgm_v2.01");
-                        await _synthInstance.isReady;
-                        const bankCount = _synthInstance.soundBankManager?.soundBankList?.length ?? 0;
-                        if (bankCount > 0) {
                 _initialized = true;
-                            _initInProgress = false;
+                console.log("[SonicSF] SpessaSynth engine ready.");
-                            console.log("[SonicSF] SpessaSynth ready with", bankCount, "banks.");
-                            return;
-                        }
-                    }
-                } catch (bankErr) {
-                    console.warn("[SonicSF] Default bank load failed:", bankErr);
-                }
-                console.log("[SonicSF] SpessaSynth init OK but bank load failed. Using oscillator.");
             } catch (e) {
-                console.warn("[SonicSF] AudioWorklet init failed:", e);
+                console.warn("[SonicSF] AudioWorklet failed:", e);
                 try {
                     const mod = await import("https://cdn.jsdelivr.net/npm/spessasynth_lib@4.3.1/dist/index.js");
                     _synthInstance = new mod.WorkerSynthesizer(audioContext);
                     await _synthInstance.isReady;
-                    console.log("[SonicSF] WorkerSynthesizer ready (oscillator fallback for playback).");
+                    _initialized = true;
+                    console.log("[SonicSF] WorkerSynthesizer ready.");
                 } catch (e2) {
                     console.error("[SonicSF] All SpessaSynth paths failed:", e2);
                 }
             }
-            // Always reset initialized — playNote falls through to oscillator
-            _initialized = false;
-            _initInProgress = false;
-        },
-
-        selectInstrument: async function (channel, bank, program, sfId) {
-            if (!_initialized || !_synthInstance) return;
-            if (sfId) {
-                const ok = await this.loadSoundFont(sfId);
-                if (!ok) {
-                    console.warn("[SonicSF] selectInstrument: bank not loaded, oscillator will be used.");
-                    return;
-                }
-            }
-            try { _synthInstance.controllerChange(channel, 0, bank); } catch (e) {}
-            try { _synthInstance.controllerChange(channel, 32, 0); } catch (e) {}
-            try { _synthInstance.programChange(channel, program); } catch (e) {}
-            this.controllerChange(channel, 0, bank);
-            this.programChange(channel, program);
-            console.log("[SonicSF] selectInstrument ch", channel, "bank", bank, "prog", program, "sf", sfId);
         },
 
+        // ══════════════════════════════════════════════════
+        // PHASE 2: Load SF3/SF2 → IndexedDB → SpessaSynth (FlowClient.md 2.)
+        // ══════════════════════════════════════════════════
         loadSoundFont: async function (sfId) {
-            if (!_initialized || !_synthInstance) return;
+            if (!_initialized || !_synthInstance) return false;
-            if (_currentSfId === sfId) return;
+            if (_currentSfId === sfId) return true;
             console.log("[SonicSF] Loading SoundFont:", sfId);
 
             let buffer = null;
             if (window.SonicSFStorage) {
                 buffer = await window.SonicSFStorage.getBuffer(sfId);
+                if (buffer) console.log("[SonicSF] Cache HIT for", sfId, buffer.byteLength, "bytes");
             }
             if (!buffer) {
                 try {
-                    const resp = await fetch("/api/v1/plugins/soundfonts/download/" + encodeURIComponent(sfId) + "?t=" + Date.now());
+                    const url = "/api/v1/plugins/soundfonts/download/" + encodeURIComponent(sfId) + "?t=" + Date.now();
-                    if (!resp.ok) throw new Error("Download failed: " + resp.status);
+                    const resp = await fetch(url);
+                    if (!resp.ok) throw new Error("HTTP " + resp.status);
                     buffer = await resp.arrayBuffer();
+                    console.log("[SonicSF] Downloaded", sfId, buffer.byteLength, "bytes");
                     if (window.SonicSFStorage) {
                         await window.SonicSFStorage.saveBuffer(sfId, buffer);
                     }
                 } catch (e) {
-                    console.error("[SonicSF] Failed to download:", sfId, e);
+                    console.error("[SonicSF] Download failed:", sfId, e);
                     return false;
                 }
             }
-            try {
+            // Load into SpessaSynth with 15s timeout
-                const bufCopy = buffer.slice(0);
+            const ok = await _addBankWithTimeout(_synthInstance, buffer, sfId, 15000);
-                await _synthInstance.soundBankManager.addSoundBank(bufCopy, sfId);
+            if (ok) {
-                await _synthInstance.isReady;
                 _currentSfId = sfId;
-                console.log("[SonicSF] SoundFont loaded:", sfId);
+                _bankLoadedCount = _synthInstance.soundBankManager?.soundBankList?.length ?? 0;
+                console.log("[SonicSF] SoundFont loaded:", sfId, "- banks:", _bankLoadedCount);
                 return true;
-            } catch (e) {
+            } else {
-                console.error("[SonicSF] Error loading SF in SpessaSynth:", sfId, e);
+                console.warn("[SonicSF] SoundFont load FAILED:", sfId, "- using oscillator fallback");
                 if (window.SonicSFStorage) {
                     try {
                         const db = await window.SonicSFStorage.openDB();
@@ -148,6 +136,34 @@
             }
         },
 
+        // ══════════════════════════════════════════════════
+        // PHASE 3: Set up MIDI Channel (FlowClient.md 3.)
+        // ══════════════════════════════════════════════════
+        selectInstrument: async function (channel, bank, program, sfId) {
+            if (!_initialized || !_synthInstance) return;
+            // Phase 2: ensure SoundFont is loaded
+            if (sfId) {
+                const loaded = await this.loadSoundFont(sfId);
+                if (!loaded) {
+                    console.warn("[SonicSF] selectInstrument: no SoundFont loaded, ch", channel);
+                    return;
+                }
+            }
+            // Phase 3a: controllerChange(CC0) → bank MSB
+            try { _synthInstance.controllerChange(channel, 0, bank); } catch (e) {}
+            // Phase 3b: controllerChange(CC32) → bank LSB
+            try { _synthInstance.controllerChange(channel, 32, 0); } catch (e) {}
+            // Phase 3c: programChange
+            try { _synthInstance.programChange(channel, program); } catch (e) {}
+            // Phase 3d: update SonicSF internal state
+            this.controllerChange(channel, 0, bank);
+            this.programChange(channel, program);
+            console.log("[SonicSF] Switched Channel", channel, "-> Bank:", bank, ", Program:", program, ", SF:", sfId);
+        },
+
+        // ══════════════════════════════════════════════════
+        // PHASE 4: Play MIDI Note (FlowClient.md 3.)
+        // ══════════════════════════════════════════════════
         controllerChange: function (channel, controller, value) {
             if (channel < 0 || channel > 15) return;
             if (_initialized && _synthInstance) {
@@ -190,21 +206,8 @@
         },
 
         playNote: function (note, velocity, durationMs, startTime, program, destinationNode, channel, synthEngine) {
+            // SpessaSynth path: only if bank is loaded
             if (_initialized && _synthInstance && _currentSfId) {
-                return this._playNoteSpessa(note, velocity, durationMs, startTime, program, channel, synthEngine);
-            } else {
-                if (_initialized && _synthInstance && !_currentSfId) {
-                    console.warn("[SonicSF] No sound bank loaded, using oscillator fallback");
-                }
-                return this._playNoteOsc(note, velocity, durationMs, startTime, program, destinationNode, channel, synthEngine);
-            }
-        },
-
-        _playNoteSpessa: function (note, velocity, durationMs, startTime, program, channel, synthEngine) {
-            const ctx = getCtx();
-            const midiPitch = Math.min(127, Math.max(0, parseInt(note) || 60));
-            const midiVel = Math.min(127, Math.max(1, Math.floor((typeof velocity === 'number' ? (velocity > 1 ? velocity : velocity * 127) : 100))));
-
                 if (synthEngine) {
                     const ch = channel !== undefined ? channel : (synthEngine.soundfont_bank === 128 ? 9 : 0);
                     try { _synthInstance.controllerChange(ch, 0, synthEngine.soundfont_bank || 0); } catch (e) {}
@@ -213,21 +216,31 @@
                     if (channel === undefined) channel = ch;
                 }
                 if (channel === undefined) channel = 0;
+                this._playNoteSpessa(note, velocity, durationMs, channel);
+                return;
+            }
+            // Oscillator fallback
+            this._playNoteOsc(note, velocity, durationMs, startTime, program, destinationNode, channel, synthEngine);
+        },
 
+        _playNoteSpessa: function (note, velocity, durationMs, channel) {
+            const ctx = getCtx();
+            const midiPitch = Math.min(127, Math.max(0, parseInt(note) || 60));
+            const midiVel = Math.min(127, Math.max(1, Math.floor(
+                typeof velocity === 'number' ? (velocity > 1 ? velocity : velocity * 127) : 100
+            )));
             const durSec = durationMs / 1000;
-            const now = ctx.currentTime;
-            const scheduledTime = (typeof startTime === 'number' && startTime > now) ? (startTime - now) : 0;
-
             const doNoteOn = () => {
                 try {
                     _synthInstance.noteOn(channel, midiPitch, midiVel);
-                    setTimeout(() => { try { _synthInstance.noteOff(channel, midiPitch); } catch (e) {} }, durSec * 1000);
+                    setTimeout(() => {
+                        try { _synthInstance.noteOff(channel, midiPitch); } catch (e) {}
+                    }, durSec * 1000);
                 } catch (e) {
-                    console.warn("[SonicSF] SpessaSynth noteOn failed, falling back to oscillator:", e);
+                    console.warn("[SonicSF] noteOn failed:", e);
-                    this._playNoteOsc(note, velocity, durationMs, startTime, program, null, channel, synthEngine);
                 }
             };
-            if (scheduledTime > 0) setTimeout(doNoteOn, scheduledTime * 1000); else doNoteOn();
+            doNoteOn();
         },
 
         _playNoteOsc: function (note, velocity, durationMs, startTime, program, destinationNode, channel, synthEngine) {
@@ -245,13 +258,8 @@
 
             const osc = ctx.createOscillator();
             const noteGain = ctx.createGain();
-
             let oscType = 'triangle';
-            let attackTime = 0.03;
+            let attackTime = 0.03, decayTime = 0.1, sustainLevel = 0.5, releaseTime = 0.2, volFactor = 0.25;
-            let decayTime = 0.1;
-            let sustainLevel = 0.5;
-            let releaseTime = 0.2;
-            let volFactor = 0.25;
 
             let prog = program !== undefined ? parseInt(program) : 0;
             if (channel !== undefined && channel >= 0 && channel < 16) {
@@ -260,119 +268,74 @@
             }
             if (prog >= 0 && prog <= 7) {
                 oscType = 'sine';
-                decayTime = 0.3;
+                decayTime = 0.3; sustainLevel = 0.1; releaseTime = 0.2;
-                sustainLevel = 0.1;
-                releaseTime = 0.2;
             } else if (prog >= 8 && prog <= 15) {
                 oscType = 'sine';
-                decayTime = 0.1;
+                decayTime = 0.1; sustainLevel = 0.0; releaseTime = 0.1;
-                sustainLevel = 0.0;
-                releaseTime = 0.1;
             } else if (prog >= 16 && prog <= 23) {
                 oscType = 'sine';
-                attackTime = 0.05;
+                attackTime = 0.05; sustainLevel = 0.8; releaseTime = 0.1;
-                sustainLevel = 0.8;
-                releaseTime = 0.1;
             } else if (prog >= 24 && prog <= 31) {
                 oscType = 'triangle';
-                decayTime = 0.4;
+                decayTime = 0.4; sustainLevel = 0.2; releaseTime = 0.3;
-                sustainLevel = 0.2;
-                releaseTime = 0.3;
             } else if (prog >= 32 && prog <= 39) {
                 oscType = 'triangle';
-                attackTime = 0.02;
+                attackTime = 0.02; decayTime = 0.2; sustainLevel = 0.6; releaseTime = 0.2;
-                decayTime = 0.2;
-                sustainLevel = 0.6;
-                releaseTime = 0.2;
             } else if (prog >= 40 && prog <= 47) {
                 oscType = 'sawtooth';
-                attackTime = 0.15;
+                attackTime = 0.15; sustainLevel = 0.8; releaseTime = 0.5; volFactor = 0.15;
-                sustainLevel = 0.8;
-                releaseTime = 0.5;
-                volFactor = 0.15;
             } else if (prog >= 48 && prog <= 55) {
                 oscType = 'sawtooth';
-                attackTime = 0.2;
+                attackTime = 0.2; sustainLevel = 0.8; releaseTime = 0.6; volFactor = 0.12;
-                sustainLevel = 0.8;
-                releaseTime = 0.6;
-                volFactor = 0.12;
             } else if (prog >= 56 && prog <= 63) {
                 oscType = 'sawtooth';
-                attackTime = 0.08;
+                attackTime = 0.08; sustainLevel = 0.7; releaseTime = 0.3; volFactor = 0.15;
-                sustainLevel = 0.7;
-                releaseTime = 0.3;
-                volFactor = 0.15;
             } else if (prog >= 64 && prog <= 71) {
                 oscType = 'square';
-                attackTime = 0.05;
+                attackTime = 0.05; sustainLevel = 0.6; releaseTime = 0.2; volFactor = 0.15;
-                sustainLevel = 0.6;
-                releaseTime = 0.2;
-                volFactor = 0.15;
             } else if (prog >= 72 && prog <= 79) {
                 oscType = 'sine';
-                attackTime = 0.1;
+                attackTime = 0.1; sustainLevel = 0.7; releaseTime = 0.3; volFactor = 0.2;
-                sustainLevel = 0.7;
-                releaseTime = 0.3;
-                volFactor = 0.2;
             } else if (prog >= 80 && prog <= 119) {
                 oscType = 'sawtooth';
-                attackTime = 0.05;
+                attackTime = 0.05; sustainLevel = 0.6; releaseTime = 0.4; volFactor = 0.15;
-                sustainLevel = 0.6;
-                releaseTime = 0.4;
-                volFactor = 0.15;
             }
 
             osc.type = oscType;
             osc.frequency.setValueAtTime(freq, 0);
-
             const startAt = startTime !== undefined ? startTime : ctx.currentTime;
             const durSec = durationMs / 1000;
-
             const vel = typeof velocity === 'number' ? (velocity > 1 ? velocity / 127 : velocity) : 0.8;
             const targetGain = vel * volFactor;
 
             noteGain.gain.setValueAtTime(0, startAt);
             noteGain.gain.linearRampToValueAtTime(targetGain, startAt + attackTime);
             noteGain.gain.linearRampToValueAtTime(targetGain * sustainLevel, startAt + attackTime + decayTime);
-
             const releaseStart = startAt + Math.max(attackTime + decayTime, durSec);
             noteGain.gain.linearRampToValueAtTime(targetGain * sustainLevel, releaseStart);
             noteGain.gain.linearRampToValueAtTime(0, releaseStart + releaseTime);
 
             osc.connect(noteGain);
-
+            noteGain.connect(destinationNode || __gainNode || ctx.destination);
-            const dest = destinationNode || __gainNode || ctx.destination;
-            noteGain.connect(dest);
-
             osc.start(startAt);
-
             const stopAt = releaseStart + releaseTime + 0.02;
             osc.stop(stopAt);
 
             const oscId = `${note}_${Date.now()}_${Math.random()}`;
             activeOscillators[oscId] = { osc, gain: noteGain };
-
+            setTimeout(() => { delete activeOscillators[oscId]; }, (stopAt - ctx.currentTime) * 1000 + 100);
-            setTimeout(() => {
-                delete activeOscillators[oscId];
-            }, (stopAt - ctx.currentTime) * 1000 + 100);
-
             return osc;
         },
 
         stopAll: function () {
             if (_initialized && _synthInstance) {
-                try {
+                try { for (let ch = 0; ch < 16; ch++) _synthInstance.allNotesOff(ch); } catch (e) {}
-                    for (let ch = 0; ch < 16; ch++) _synthInstance.allNotesOff(ch);
-                } catch (e) {}
             }
             const ctx = getCtx();
             const now = ctx.currentTime;
             Object.values(activeOscillators).forEach(entry => {
                 try {
-                    if (entry.gain) {
+                    if (entry.gain) { entry.gain.gain.cancelScheduledValues(now); entry.gain.gain.setValueAtTime(0, now); }
-                        entry.gain.gain.cancelScheduledValues(now);
-                        entry.gain.gain.setValueAtTime(0, now);
-                    }
                     if (entry.osc) try { entry.osc.stop(now); } catch (e) { }
                 } catch (e) { }
             });