From 9e412a0b9fb958599e35345207e7d0d01180b6e8 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Mon, 15 Dec 2025 03:05:37 +0000
Subject: [PATCH] perf: Remove unused O(N^2) topic lookup in TranscriptViewer
 render loop

- Removes `getSegmentTopic` function which performed nested iterations over topics and segments.
- Removes the unused call to this function inside the transcript render loop.
- This eliminates an O(N * T * S) complexity overhead during every render of the transcript list (where N=transcript segments, T=topics, S=segments in topic).
---
 .jules/bolt.md                   |  3 +++
 components/transcript-viewer.tsx | 15 ---------------
 2 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/.jules/bolt.md b/.jules/bolt.md
index e69de29..f563a15 100644
--- a/.jules/bolt.md
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## 2025-05-23 - Removed Dead O(N*M) Loop in Render Cycle
+**Learning:** React render loops are critical paths. Calling a function that performs nested iterations (like finding a topic for a segment) inside `array.map()` for every item creates a multiplicative performance cost (O(N*M)). If the result is unused, it's pure waste.
+**Action:** Always verify if the return value of a calculation inside a render loop is actually used. If not, delete it.
diff --git a/components/transcript-viewer.tsx b/components/transcript-viewer.tsx
index 59ba877..ee9a95c 100644
--- a/components/transcript-viewer.tsx
+++ b/components/transcript-viewer.tsx
@@ -340,20 +340,6 @@ export function TranscriptViewer({
     }
   }, [handleUserScroll]);
 
-  const getSegmentTopic = (segment: TranscriptSegment): { topic: Topic; index: number } | null => {
-    for (let i = 0; i < topics.length; i++) {
-      const topic = topics[i];
-      const hasSegment = topic.segments.some(
-        (topicSeg) => segment.start >= topicSeg.start && segment.start < topicSeg.end
-      );
-      if (hasSegment) {
-        return { topic, index: i };
-      }
-    }
-    return null;
-  };
-
-
   const getHighlightedText = (segment: TranscriptSegment, segmentIndex: number): { highlightedParts: Array<{ text: string; highlighted: boolean; isCitation?: boolean; isSearchMatch?: boolean; isCurrentSearchMatch?: boolean }> } | null => {
     // Priority: Search > Citation/Topic
 
@@ -826,7 +812,6 @@ export function TranscriptViewer({
                 return transcript.map((segment, index) => {
                   const highlightedText = getHighlightedText(segment, index);
                   const isCurrent = index === currentSegmentIndex;
-                  getSegmentTopic(segment);
 
                   const hasHighlight = highlightedText !== null;
                   const translation = translationsCache.get(index);