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plugins/library-navigator/skills/sp-audio-fx-plugin-pitch-shifter/SKILL.md

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+---
+name: sp-audio-fx-plugin-pitch-shifter
+description: Pitch shifter FX plugin — time-stretching pitch change without speed alteration. Grain size, overlap, formant preservation. Part of audio-fx-plugin-* family.
+---
+
+# sp-audio-fx-plugin-pitch-shifter
+
+| Symbol | Kind | Responsibility |
+|---|---|---|
+| `PitchShifterPlugin` | Class | Pitch shifter FX plugin extending `AbstractAudioFxPlugin` |
+| `PitchShifterPluginOptions` | Type | Semitones, grain size, overlap, formant preserve, mix |
+| `PitchShifterPluginOptionsSchema` | Schema | Zod schema for options validation |
+| `PitchShifterPresetDataSchema` | Schema | Zod schema for serialisable preset |
+
+**File Structure:** `packages/media/audio-fx/audio-fx-plugin-pitch-shifter/src/{pitch-shifter,schemas}/`
+
+**Sibling packages:**
+- `@suaveplan/audio-fx-plugin-base` — FX plugin foundation
+- `@suaveplan/audio-fx-plugin-glados` — GLaDOS effect (uses pitch shift)
+
+**Patterns:**
+
+*Quick Start:*
+```ts
+import { PitchShifterPlugin } from "@suaveplan/audio-fx-plugin-pitch-shifter";
+const shifter = new PitchShifterPlugin({ semitones: -7, grainSize: 80, overlap: 0.2 });
+```
+
+**Constraints:**
+- Extends `AbstractAudioFxPlugin` from `@suaveplan/audio-fx-plugin-base`
+- Grain-based time-stretching preserves playback speed
+- Formant preservation maintains vocal character during shifts
+- Larger grains = smoother sound, more latency
+- Overlap controls crossfade between grains
+- Mix control for dry/wet blend
+- Preset schema validates all parameters
+
+**Checklist:**
+- [ ] `PitchShifterPlugin` extends `AbstractAudioFxPlugin`
+- [ ] Pitch changes by specified semitones without speed change
+- [ ] Formant preservation maintains vocal character
+- [ ] Grain size tradeoff between quality and latency
+- [ ] Overlap crossfade reduces grain boundary artifacts