⚡ Bolt: [성능 개선] O(1) 메모리로 코드 변경 횟수 계산 최적화

.jules/bolt.md

@@ -61,3 +61,6 @@
 ## 2026-07-13 - Array.from mapping optimization
 **Learning:** Using `Array.from({ length: N }).map(...)` creates an intermediate array of `undefined` values which requires memory allocation and garbage collection, adding O(N) unnecessary overhead in frequently re-rendered UI components.
 **Action:** Use `Array.from({ length: N }, (_, index) => ...)` to map elements directly during array creation, avoiding intermediate allocations.
+## 2026-08-14 - Replace zip(lst, lst[1:]) with inline tracking
+**Learning:** Using `zip(lst, lst[1:])` to compute sequential changes in Python creates an intermediate sliced list and requires memory allocation, slowing down analysis of many segments in `section_harmony.py`.
+**Action:** Replace `zip()` with an inline check that tracks `previous_chord` during the main iteration loop. This results in O(1) memory overhead and avoids O(N) list slicing.

patch.diff

@@ -0,0 +1,56 @@
+<<<<<<< SEARCH
+    durations: dict[str, float] = {}
+    overlapping_chords: list[str] = []
+
+    for seg_start, seg_end, chord in segments:
+        overlap = min(seg_end, section_end) - max(seg_start, section_start)
+        if overlap <= 0.0:
+            continue
+        durations[chord] = durations.get(chord, 0.0) + overlap
+        overlapping_chords.append(chord)
+
+    chords: list[ChordDuration] = [
+        {"chord": chord, "duration": duration}
+        for chord, duration in sorted(durations.items(), key=lambda item: (-item[1], item[0]))
+    ]
+
+    main_chord = ""
+    for entry in chords:
+        if entry["chord"] != _NO_CHORD_LABEL:
+            main_chord = entry["chord"]
+            break
+
+    chord_changes = sum(
+        1
+        for previous, current in zip(overlapping_chords, overlapping_chords[1:], strict=False)
+        if previous != current
+    )
+
+    return {
+=======
+    durations: dict[str, float] = {}
+    chord_changes = 0
+    previous_chord = None
+
+    for seg_start, seg_end, chord in segments:
+        overlap = min(seg_end, section_end) - max(seg_start, section_start)
+        if overlap <= 0.0:
+            continue
+        durations[chord] = durations.get(chord, 0.0) + overlap
+        if previous_chord is not None and previous_chord != chord:
+            chord_changes += 1
+        previous_chord = chord
+
+    chords: list[ChordDuration] = [
+        {"chord": chord, "duration": duration}
+        for chord, duration in sorted(durations.items(), key=lambda item: (-item[1], item[0]))
+    ]
+
+    main_chord = ""
+    for entry in chords:
+        if entry["chord"] != _NO_CHORD_LABEL:
+            main_chord = entry["chord"]
+            break
+
+    return {
+>>>>>>> REPLACE

services/analysis-engine/src/bandscope_analysis/chords/section_harmony.py

@@ -84,14 +84,18 @@ def _summarize_one_section(
         the portion of their duration that overlaps the window.
     """
     durations: dict[str, float] = {}
-    overlapping_chords: list[str] = []
+    chord_changes = 0
+    previous_chord = None
 
     for seg_start, seg_end, chord in segments:
         overlap = min(seg_end, section_end) - max(seg_start, section_start)
         if overlap <= 0.0:
             continue
         durations[chord] = durations.get(chord, 0.0) + overlap
-        overlapping_chords.append(chord)
+
+        if previous_chord is not None and previous_chord != chord:
+            chord_changes += 1
+        previous_chord = chord
 
     chords: list[ChordDuration] = [
         {"chord": chord, "duration": duration}
@@ -104,12 +108,6 @@ def _summarize_one_section(
             main_chord = entry["chord"]
             break
 
-    chord_changes = sum(
-        1
-        for previous, current in zip(overlapping_chords, overlapping_chords[1:], strict=False)
-        if previous != current
-    )
-
     return {
         "start_time": section_start,
         "end_time": section_end,