⚡ Bolt: [performance improvement]

.jules/bolt.md

@@ -41,3 +41,7 @@
 ## 2025-02-15 - Replace Array.from(map.values()).map with a for...of loop
 **Learning:** Using `Array.from(map.values()).map(...)` creates an unnecessary intermediate array which wastes memory allocation and garbage collection time, particularly for frequently re-rendered components handling large collections.
 **Action:** Use a `for...of` loop over `map.values()` to iterate and push mapped elements directly into the final array for O(1) memory and avoiding intermediate array allocations.
+
+## 2025-02-15 - Optimize finding min/max with known absolute bounds
+**Learning:** For performance optimizations involving finding a minimum or maximum value with a known absolute bound (e.g., finding a 'low' confidence level), unconditional `.reduce()` calls force an O(N) operation over all elements, wasting CPU cycles on large arrays.
+**Action:** Replace unconditional `.reduce()` calls with a `for...of` loop and an early `break` condition when the known absolute bound is found. This transforms the O(N) operation into one that can short-circuit, yielding measurable performance gains.

apps/desktop/src/App.test.tsx

@@ -293,6 +293,41 @@ describe("App", () => {
     expect(screen.getAllByText(/2 sections/i).length).toBeGreaterThan(0);
   });
 
+  it("summarizes confidence from the lowest-confidence loaded section handling early exit for 'low'", async () => {
+    const baseProject = succeededResult().result;
+    // Clone sections to prevent mutating the shared fixture state and causing flaky tests
+    const loadedProject = {
+      ...baseProject,
+      sections: [
+        {
+          ...baseProject.sections[0],
+          id: "intro-1",
+          label: "intro",
+          confidence: { level: "low" as const, source: "model" as const, notes: "Hard to hear." }
+        },
+        ...baseProject.sections,
+        {
+          ...baseProject.sections[0],
+          id: "chorus-1",
+          label: "chorus",
+          confidence: { level: "high" as const, source: "model" as const, notes: "The chorus form is clear." }
+        }
+      ]
+    };
+    mockLoadProject.mockResolvedValueOnce(loadedProject);
+    render(<App />);
+
+    fireEvent.click(screen.getByRole("button", { name: /open project/i }));
+
+    await waitFor(() => {
+      expect(screen.getByText(/^Low$/i)).toBeTruthy();
+    });
+
+    // Dynamically check the number of sections added
+    const sectionCountText = new RegExp(`${loadedProject.sections.length} sections`, "i");
+    expect(screen.getAllByText(sectionCountText).length).toBeGreaterThan(0);
+  });
+
   it("selects a local audio source and starts a local-audio analysis job", async () => {
     tauriInvoke
       .mockResolvedValueOnce(bootstrapResponse())

apps/desktop/src/App.tsx

@@ -180,15 +180,19 @@ function MetricCard({
 function ConfidenceMetric({ song }: { song: RehearsalSong | null }) {
   const sectionCount = song?.sections.length ?? 0;
   const confidenceOrder = { high: 3, medium: 2, low: 1 } as const;
-  const lowestConfidence = song?.sections.reduce<RehearsalSong["sections"][number]["confidence"]["level"] | null>(
-    (current, section) => {
-      if (!current || confidenceOrder[section.confidence.level] < confidenceOrder[current]) {
-        return section.confidence.level;
+  let lowestConfidence: RehearsalSong["sections"][number]["confidence"]["level"] | null = null;
+
+  if (song?.sections) {
+    for (const section of song.sections) {
+      if (!lowestConfidence || confidenceOrder[section.confidence.level] < confidenceOrder[lowestConfidence]) {
+        lowestConfidence = section.confidence.level;
       }
-      return current;
-    },
-    null
-  );
+      if (lowestConfidence === "low") {
+        break; // Early exit: "low" is the absolute minimum possible value
+      }
+    }
+  }
+
   const confidence = lowestConfidence ? `${lowestConfidence[0].toUpperCase()}${lowestConfidence.slice(1)}` : "Ready";
   const detail = sectionCount > 0 ? `${sectionCount} section${sectionCount === 1 ? "" : "s"}` : "Local analysis";