feat(streaming): Add chord progression pattern detection and improve bar chord accuracy

Enhance streaming chord analysis with known pattern recognition and voting-based bar detection:

Chord Pattern Detection:
- Add library of known progressions (Royal Road, Komuro, Canon, Just the Two of Us, etc.)
- Compute voted pattern by aggregating chords across pattern repetitions
- Score detected progression against known patterns with weighted similarity
- Return all pattern scores sorted by confidence

Bar Chord Improvements:
- Replace chroma averaging with frame-by-frame chord voting for more accurate detection
- Add retroactive bar chord detection using stored chroma history
- Store full chroma history (up to ~35s) for analysis when BPM stabilizes
- Compute bar chords from the start of audio retroactively

API Changes:
- Add votedPattern, patternLength, detectedPatternName, detectedPatternScore, allPatternScores to ProgressiveEstimate
- Add sampleRate() method to StreamAnalyzer
- Change stats() to non-const (triggers final pattern computation)

Testing:
- Add tests for C-G-Am-F progression detection
- Add tests for voted pattern structure and values
- Add tests for pattern detection fields
- Add tests for allPatternScores ordering
- Add tests for reset behavior

Author: libraz

js/index.ts

@@ -172,6 +172,11 @@ interface WasmBarChord {
   confidence: number;
 }
 
+interface WasmPatternScore {
+  name: string;
+  score: number;
+}
+
 interface WasmProgressiveEstimate {
   bpm: number;
   bpmConfidence: number;
@@ -186,6 +191,11 @@ interface WasmProgressiveEstimate {
   barChordProgression: WasmBarChord[];
   currentBar: number;
   barDuration: number;
+  votedPattern: WasmBarChord[];
+  patternLength: number;
+  detectedPatternName: string;
+  detectedPatternScore: number;
+  allPatternScores: WasmPatternScore[];
   accumulatedSeconds: number;
   usedFrames: number;
   updated: boolean;
@@ -223,6 +233,7 @@ interface WasmStreamAnalyzer {
   stats: () => WasmAnalyzerStats;
   frameCount: () => number;
   currentTime: () => number;
+  sampleRate: () => number;
   delete: () => void;
 }
 
@@ -1390,6 +1401,14 @@ export interface BarChord {
   confidence: number;
 }
 
+/**
+ * Pattern score for known chord progressions
+ */
+export interface PatternScore {
+  name: string;
+  score: number;
+}
+
 /**
  * Progressive estimation results for BPM, Key, and Chord
  */
@@ -1407,6 +1426,11 @@ export interface ProgressiveEstimate {
   barChordProgression: BarChord[];
   currentBar: number;
   barDuration: number;
+  votedPattern: BarChord[];
+  patternLength: number;
+  detectedPatternName: string;
+  detectedPatternScore: number;
+  allPatternScores: PatternScore[];
   accumulatedSeconds: number;
   usedFrames: number;
   updated: boolean;
@@ -1583,6 +1607,20 @@ export class StreamAnalyzer {
         })),
         currentBar: s.estimate.currentBar,
         barDuration: s.estimate.barDuration,
+        votedPattern: (s.estimate.votedPattern || []).map((c) => ({
+          barIndex: c.barIndex,
+          root: c.root as PitchClass,
+          quality: c.quality as ChordQuality,
+          startTime: c.startTime,
+          confidence: c.confidence,
+        })),
+        patternLength: s.estimate.patternLength,
+        detectedPatternName: s.estimate.detectedPatternName || '',
+        detectedPatternScore: s.estimate.detectedPatternScore || 0,
+        allPatternScores: (s.estimate.allPatternScores || []).map((p) => ({
+          name: p.name,
+          score: p.score,
+        })),
         accumulatedSeconds: s.estimate.accumulatedSeconds,
         usedFrames: s.estimate.usedFrames,
         updated: s.estimate.updated,
@@ -1604,6 +1642,13 @@ export class StreamAnalyzer {
     return this.analyzer.currentTime();
   }
 
+  /**
+   * Get the sample rate.
+   */
+  sampleRate(): number {
+    return this.analyzer.sampleRate();
+  }
+
   /**
    * Release resources. Call when done using the analyzer.
    */

js/sonare.js.d.ts

@@ -347,6 +347,11 @@ interface WasmBarChord {
   confidence: number;
 }
 
+interface WasmPatternScore {
+  name: string;
+  score: number;
+}
+
 interface WasmProgressiveEstimate {
   bpm: number;
   bpmConfidence: number;
@@ -361,6 +366,11 @@ interface WasmProgressiveEstimate {
   barChordProgression: WasmBarChord[];
   currentBar: number;
   barDuration: number;
+  votedPattern: WasmBarChord[];
+  patternLength: number;
+  detectedPatternName: string;
+  detectedPatternScore: number;
+  allPatternScores: WasmPatternScore[];
   accumulatedSeconds: number;
   usedFrames: number;
   updated: boolean;
@@ -398,6 +408,7 @@ interface WasmStreamAnalyzer {
   stats: () => WasmAnalyzerStats;
   frameCount: () => number;
   currentTime: () => number;
+  sampleRate: () => number;
   delete: () => void;
 }