perf(desktop): fix diff sidebar performance with many commits

apps/desktop/src/lib/trpc/routers/changes/status.ts

@@ -11,6 +11,13 @@ import {
 	parseNameStatus,
 } from "./utils/parse-status";
 
+/** Server-side cache to avoid re-running git commands when polled frequently */
+const STATUS_CACHE_TTL_MS = 2_000;
+const statusCache = new Map<
+	string,
+	{ result: GitChangesStatus; timestamp: number }
+>();
+
 export const createStatusRouter = () => {
 	return router({
 		getStatus: publicProcedure
@@ -23,8 +30,14 @@ export const createStatusRouter = () => {
 			.query(async ({ input }): Promise<GitChangesStatus> => {
 				assertRegisteredWorktree(input.worktreePath);
 
-				const git = simpleGit(input.worktreePath);
 				const defaultBranch = input.defaultBranch || "main";
+				const cacheKey = `${input.worktreePath}:${defaultBranch}`;
+				const cached = statusCache.get(cacheKey);
+				if (cached && Date.now() - cached.timestamp < STATUS_CACHE_TTL_MS) {
+					return cached.result;
+				}
+
+				const git = simpleGit(input.worktreePath);
 
 				const status = await getStatusNoLock(input.worktreePath);
 				const parsed = parseGitStatus(status);
@@ -41,7 +54,7 @@ export const createStatusRouter = () => {
 					applyUntrackedLineCount(input.worktreePath, parsed.untracked),
 				]);
 
-				return {
+				const result: GitChangesStatus = {
 					branch: parsed.branch,
 					defaultBranch,
 					againstBase: branchComparison.againstBase,
@@ -55,6 +68,9 @@ export const createStatusRouter = () => {
 					pullCount: trackingStatus.pullCount,
 					hasUpstream: trackingStatus.hasUpstream,
 				};
+
+				statusCache.set(cacheKey, { result, timestamp: Date.now() });
+				return result;
 			}),
 
 		getCommitFiles: publicProcedure

apps/desktop/src/renderer/screens/main/components/WorkspaceView/ChangesContent/components/InfiniteScrollView/components/CommitSection/CommitSection.tsx

@@ -19,7 +19,7 @@ export function CommitSection({
 	onToggleFile,
 	scrollElementRef,
 }: CommitSectionProps) {
-	const [isCommitExpanded, setIsCommitExpanded] = useState(true);
+	const [isCommitExpanded, setIsCommitExpanded] = useState(false);
 
 	const { data: commitFiles } = electronTrpc.changes.getCommitFiles.useQuery(
 		{

apps/desktop/src/renderer/screens/main/components/WorkspaceView/ChangesContent/components/VirtualizedFileList/VirtualizedFileList.tsx

@@ -1,5 +1,5 @@
-import { useVirtualizer } from "@tanstack/react-virtual";
-import { type RefObject, useCallback, useRef } from "react";
+import { defaultRangeExtractor, useVirtualizer } from "@tanstack/react-virtual";
+import { type RefObject, useRef } from "react";
 import type { ChangeCategory, ChangedFile } from "shared/changes-types";
 import { FileDiffSection } from "../FileDiffSection";
 
@@ -36,35 +36,13 @@ export function VirtualizedFileList({
 	isActioning = false,
 }: VirtualizedFileListProps) {
 	const listRef = useRef<HTMLDivElement>(null);
-	const renderedIndicesRef = useRef<Set<number>>(new Set());
-
-	const rangeExtractor = useCallback(
-		(range: { startIndex: number; endIndex: number }) => {
-			const indices = new Set<number>(renderedIndicesRef.current);
-
-			const start = Math.max(0, range.startIndex - OVERSCAN);
-			const end = Math.min(files.length - 1, range.endIndex + OVERSCAN);
-			for (let i = start; i <= end; i++) {
-				indices.add(i);
-			}
-
-			for (const idx of indices) {
-				if (idx >= files.length) {
-					indices.delete(idx);
-				}
-			}
-
-			renderedIndicesRef.current = indices;
-			return Array.from(indices).sort((a, b) => a - b);
-		},
-		[files.length],
-	);
 
 	const virtualizer = useVirtualizer({
 		count: files.length,
 		getScrollElement: () => scrollElementRef.current,
 		estimateSize: () => ESTIMATED_COLLAPSED_HEIGHT,
-		rangeExtractor,
+		rangeExtractor: defaultRangeExtractor,
+		overscan: OVERSCAN,
 		scrollMargin: listRef.current?.offsetTop ?? 0,
 	});