plan2.md

1. Types (src/types.ts): Add to SamplerBankParams and Note interface:

   • formantEnvAttack?: number;
   • formantEnvDecay?: number;
   • formantEnvAmount?: number;

2. FormantShifter.ts (src/engines/rubberband/FormantShifter.ts):

   • We need an envelope node similar to LFO but triggered.
   • Let's add:
     • private envNode: ConstantSourceNode | null = null;
     • private envGain: GainNode | null = null;
   • Update createFilterChain:
     • Create this.envNode = this.audioContext.createConstantSource();
     • Create this.envGain = this.audioContext.createGain();
     • this.envGain.gain.value = 0; // Idle state
     • this.envNode.connect(this.envGain);
     • Connect this.envGain to filters[i].detune for boosting filters.
     • this.envNode.start();
   • Update disconnect: clean up envNode and envGain.
   • Add method:

     triggerEnvelope(amount: number, attack: number, decay: number, triggerTime: number): void {
         if (!this.envGain) return;
     
         const t = triggerTime || this.audioContext.currentTime;
         const gainParam = this.envGain.gain;
     
         gainParam.cancelScheduledValues(t);
         gainParam.setValueAtTime(0, t);
     
         // amount is in semitones (-24 to 24)
         const peakGain = amount * 100; // cents
     
         if (attack > 0) {
             gainParam.linearRampToValueAtTime(peakGain, t + attack);
         } else {
             gainParam.setValueAtTime(peakGain, t);
         }
     
         if (decay > 0) {
             gainParam.linearRampToValueAtTime(0, t + attack + decay);
         } else {
             gainParam.setValueAtTime(0, t + attack);
         }
     }

3. SingingVoice.ts (src/engines/SingingVoice.ts):

   • Add properties for formant envelope:

     setFormantEnvelope(amount: number, attack: number, decay: number, triggerTime: number) {
         if (this.formantShifter) {
             this.formantShifter.triggerEnvelope(amount, attack, decay, triggerTime);
         }
     }

   • Call it in triggerSlice (using step overrides or global params).

4. Hooks / UI Plumbing:

   • useAudioEngine.ts (pass step overrides to SingingVoice and params).
   • SamplerPanel.tsx: add three knobs (Fmt Env Attack, Fmt Env Decay, Fmt Env Amount). Add defaults to DEFAULT_SAMPLER_BANK_PARAMS.
   • NoteSelector.tsx: add step property inputs for the three.

This plan hits everything cleanly.