Unified target-note controls: key filter + fret window across all modes

- New shared PracticeFilter settings (keyTonic/keyMode/fretWindow), persisted
  via AppSettings.practice, defaults off (behavior unchanged).
- music/targetPool.ts: single source for the effective target pool —
  base playable range ∩ fret window ∩ key/mode pitch classes (9 modes incl.
  pentatonic, same scale machinery as Phrase Mode).
- useGameLogic now builds validNotes via computeTargetPool.
- TargetNoteControls component (key on/off + tonic/mode, fret window on/off +
  min/max) rendered in Controls for all game modes; key is independent of the
  displayed key signature.
- Phrase Mode binds its key/fret-window setup to the same shared filter
  (read/write mirror) and drops the duplicate controls in its setup panel.
- Tests: targetPool.test.ts (7 cases); suite 156/156 green, build ok.

src/music/targetPool.test.ts

@@ -0,0 +1,78 @@
+import { describe, it, expect } from 'vitest';
+import { computeTargetPool } from './targetPool';
+
+const base = {
+    instrumentId: 'guitar',
+    difficulty: 'custom',
+    tuningId: 'standard',
+    customMinFret: 0,
+    customMaxFret: 12,
+    keyEnabled: false,
+    keyTonic: 'C',
+    keyMode: 'major',
+    fretWindowEnabled: false,
+    fretMin: 0,
+    fretMax: 4,
+};
+
+describe('computeTargetPool', () => {
+    it('returns the base playable range when no filters are active', () => {
+        const pool = computeTargetPool(base);
+        expect(pool).toContain(40); // low E
+        expect(pool).toContain(64); // high e (12th fret)
+        expect(pool.length).toBeGreaterThan(30);
+    });
+
+    it('applies the fret window when enabled', () => {
+        const pool = computeTargetPool({ ...base, fretWindowEnabled: true, fretMin: 0, fretMax: 4 });
+        // guitar standard: open strings 40,45,50,55,59,64; window adds up to +4
+        const lo = Math.min(...pool);
+        const hi = Math.max(...pool);
+        expect(lo).toBe(40);
+        expect(hi).toBe(68); // 64 + 4
+        expect(pool).toContain(59); // open g
+        expect(pool).not.toContain(69);
+    });
+
+    it('restricts to pitch classes of the key when key filter is on', () => {
+        const pool = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'major' });
+        const pcs = new Set([0, 2, 4, 5, 7, 9, 11]); // C major
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+        // chromatic notes excluded
+        expect(pool).not.toContain(61); // C# within range
+    });
+
+    it('combines fret window and key filter', () => {
+        const pool = computeTargetPool({ ...base, fretWindowEnabled: true, fretMin: 0, fretMax: 5, keyEnabled: true, keyTonic: 'E', keyMode: 'minor' });
+        const pcs = new Set([4, 6, 7, 9, 11, 0, 2]); // E minor natural: E F# G A B C D
+        expect(pool.length).toBeGreaterThan(0);
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+        // F (pc 5) and F# (pc 6 is in E minor; F natural is not) — F natural excluded
+        expect(pool.some(m => ((m % 12) + 12) % 12 === 5)).toBe(false);
+    });
+
+    it('supports modes beyond the single-note key signatures (dorian)', () => {
+        const pool = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'D', keyMode: 'dorian' });
+        const pcs = new Set([2, 4, 5, 7, 9, 11, 0]); // D dorian: D E F G A B C
+        expect(pool.length).toBeGreaterThan(0);
+        for (const midi of pool) {
+            expect(pcs.has(((midi % 12) + 12) % 12)).toBe(true);
+        }
+    });
+
+    it('falls back to major for an invalid mode id', () => {
+        const a = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'major' });
+        const b = computeTargetPool({ ...base, keyEnabled: true, keyTonic: 'C', keyMode: 'bogus' as string });
+        expect(b).toEqual(a);
+    });
+
+    it('returns an empty pool rather than crashing for a non-fretted window request', () => {
+        const pool = computeTargetPool({ ...base, instrumentId: 'piano', fretWindowEnabled: true });
+        // piano has no fret window: window is ignored, base pool returned
+        expect(pool.length).toBeGreaterThan(0);
+    });
+});

src/music/targetPool.ts

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+/**
+ * Unified target-note pool: base playable range (instrument + difficulty /
+ * fret window) intersected with the optional key-filter (pitch classes of a
+ * tonic+mode) and the optional fret window. Shared by all game modes so the
+ * controls behave identically everywhere.
+ */
+import { keyFor, type ModeId } from './scales';
+import { computePlayableNotes, fretWindowNotes, isFrettedInstrument } from './playableRange';
+import { TUNINGS } from './Tunings';
+
+export interface TargetPoolInput {
+    readonly instrumentId: string;
+    readonly difficulty: string;
+    readonly tuningId: string;
+    readonly customMinFret?: number;
+    readonly customMaxFret?: number;
+    /** Key filter (target-note key, independent of the displayed key signature). */
+    readonly keyEnabled: boolean;
+    readonly keyTonic: string;
+    readonly keyMode: string;
+    /** Fret window (fretted instruments only). */
+    readonly fretWindowEnabled: boolean;
+    readonly fretMin: number;
+    readonly fretMax: number;
+}
+
+/**
+ * Compute the effective target-note pool.
+ *
+ * Order of application:
+ *  1. base playable range (instrument difficulty / custom frets)
+ *  2. fret window (replaces the range for fretted instruments — same
+ *     semantics as Phrase Mode's fret window)
+ *  3. key filter (pitch-class intersection, keeps spelling/degree data intact
+ *     via the same scale machinery Phrase Mode uses)
+ */
+export function computeTargetPool(input: TargetPoolInput): number[] {
+    const tuning = TUNINGS[input.tuningId];
+    const fretted = isFrettedInstrument(input.instrumentId) && !!tuning;
+
+    // 1+2: base pool with optional fret window
+    let base: number[];
+    if (input.fretWindowEnabled && fretted) {
+        base = fretWindowNotes(tuning!, input.fretMin, input.fretMax);
+    } else {
+        base = computePlayableNotes({
+            instrumentId: input.instrumentId,
+            difficulty: input.difficulty,
+            tuningId: input.tuningId,
+            customMinFret: input.customMinFret,
+            customMaxFret: input.customMaxFret,
+        });
+    }
+    if (!input.keyEnabled) return base;
+
+    // 3: key/mode pitch-class filter
+    const mode: ModeId = (['major', 'minor', 'dorian', 'phrygian', 'lydian', 'mixolydian', 'locrian', 'major-pentatonic', 'minor-pentatonic'] as const).includes(input.keyMode as ModeId)
+        ? input.keyMode as ModeId
+        : 'major';
+    const key = keyFor(input.keyTonic, mode);
+    const pcs = new Set(key.pitchClasses);
+    return base.filter(midi => pcs.has(((midi % 12) + 12) % 12));
+}