perf(server,web,mobile): Changes tab loads faster on large diffs, 20s -> 1.4s

apps/mobile/src/features/review/ReviewSheet.tsx

@@ -475,6 +475,10 @@ export function ReviewSheet(props: ReviewSheetProps) {
     cwd: selectedThreadCwd,
     selectedSection,
     draftMessage,
+    expandedFileIds: selectedSection?.id
+      ? reviewCache.expandedFileIdsBySection[selectedSection.id]
+      : undefined,
+    enabled: isEnvironmentReady,
   });
   // Expo may return null before registration or in older binaries; use the fallback.
   const NativeReviewDiffView = resolveNativeReviewDiffView();
@@ -567,7 +571,7 @@ export function ReviewSheet(props: ReviewSheetProps) {
   const handleNativeToggleFile = (event: NativeSyntheticEvent<{ readonly fileId?: string }>) => {
     const { fileId } = event.nativeEvent;
     if (fileId) {
-      loadVisibleFile(fileId, true);
+      if (collapsedFileIds.includes(fileId)) loadVisibleFile(fileId, true);
       toggleExpandedFile(fileId);
     }
   };

apps/mobile/src/features/review/reviewFilePatchDemand.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { getReviewFilePatchLookahead } from "./reviewFilePatchDemand";
+
+const files = Array.from({ length: 30 }, (_, index) => ({
+  path: `file-${index}.ts`,
+  previousPath: null,
+  additions: 1,
+  deletions: 1,
+}));
+
+describe("getReviewFilePatchLookahead", () => {
+  it("preserves default expanded viewport lookahead", () => {
+    expect(getReviewFilePatchLookahead(files, 0, undefined)).toEqual([
+      "file-0.ts",
+      "file-1.ts",
+      "file-2.ts",
+    ]);
+  });
+
+  it("does not request collapsed files or scan past the lookahead window", () => {
+    expect(getReviewFilePatchLookahead(files, 10, ["file-11.ts", "file-20.ts"])).toEqual([
+      "file-11.ts",
+    ]);
+    expect(getReviewFilePatchLookahead(files, 0, [])).toEqual([]);
+  });
+
+  it("keeps a requested path valid when another file is inserted before it", () => {
+    const requested = getReviewFilePatchLookahead(files, 10, ["file-10.ts"]);
+    const updated = [{ ...files[0]!, path: "earlier.ts" }, ...files];
+
+    expect(
+      updated.filter((file) => requested.includes(file.path)).map((file) => file.path),
+    ).toEqual(["file-10.ts"]);
+  });
+
+  it("bounds the window at the last file and ignores missing selections", () => {
+    expect(getReviewFilePatchLookahead(files, 29, undefined)).toEqual(["file-29.ts"]);
+    expect(getReviewFilePatchLookahead(files, -1, undefined)).toEqual([]);
+  });
+});

apps/mobile/src/features/review/reviewFilePatchDemand.ts

@@ -0,0 +1,14 @@
+import type { ReviewDiffFileStat } from "@t3tools/contracts";
+
+export function getReviewFilePatchLookahead(
+  files: ReadonlyArray<ReviewDiffFileStat>,
+  startIndex: number,
+  expandedFileIds: ReadonlyArray<string> | undefined,
+): ReadonlyArray<string> {
+  if (startIndex < 0) return [];
+
+  return files
+    .slice(startIndex, startIndex + 3)
+    .filter((file) => expandedFileIds === undefined || expandedFileIds.includes(file.path))
+    .map((file) => file.path);
+}

apps/mobile/src/features/review/useReviewDiffData.ts

@@ -4,6 +4,7 @@ import { formatDiffCount } from "@t3tools/client-runtime/diff-count";
 import { countReviewCommentContexts, parseReviewInlineComments } from "./reviewCommentSelection";
 import { getCachedNativeReviewDiffData } from "./nativeReviewDiffAdapter";
 import { getCachedReviewParsedDiff } from "./reviewState";
+import { getReviewFilePatchLookahead } from "./reviewFilePatchDemand";
 import {
   applyReviewDiffMetadata,
   buildReviewParsedDiff,
@@ -126,6 +127,8 @@ export function useReviewDiffData(input: {
   readonly cwd: string | null;
   readonly selectedSection: ReviewSectionItem | null;
   readonly draftMessage: string;
+  readonly expandedFileIds: ReadonlyArray<string> | undefined;
+  readonly enabled: boolean;
 }) {
   const { draftMessage, selectedSection, threadKey } = input;
   const selectedSectionId = selectedSection?.id ?? null;
@@ -147,17 +150,24 @@ export function useReviewDiffData(input: {
     source?.baseRef,
     source?.diffHash,
   ]);
-  const [requested, setRequested] = useState({ scope, indices: [0, 1, 2] });
-  const indices = useMemo(
-    () => new Set(requested.scope === scope ? requested.indices : [0, 1, 2]),
-    [requested, scope],
+  const initialPaths = useMemo(
+    () => getReviewFilePatchLookahead(lazySource?.files ?? [], 0, input.expandedFileIds),
+    [input.expandedFileIds, lazySource?.files],
+  );
+  const [requested, setRequested] = useState<{ scope: string; paths: ReadonlyArray<string> }>({
+    scope,
+    paths: [],
+  });
+  const requestedPaths = useMemo(
+    () => new Set([...(requested.scope === scope ? requested.paths : []), ...initialPaths]),
+    [initialPaths, requested, scope],
   );
   const queries = useMemo(
     () =>
-      !environmentId || !cwd || !lazySource
+      !input.enabled || !environmentId || !cwd || !lazySource
         ? []
-        : (lazySource.files ?? []).map((file, index) =>
-            indices.has(index)
+        : (lazySource.files ?? []).map((file) =>
+            requestedPaths.has(file.path)
               ? reviewEnvironment.diffFilePatch({
                   environmentId,
                   input: {
@@ -177,7 +187,7 @@ export function useReviewDiffData(input: {
                 })
               : null,
           ),
-    [environmentId, cwd, lazySource, indices, scope],
+    [input.enabled, environmentId, cwd, lazySource, requestedPaths, scope],
   );
   const parsedQuery = useMemo(
     () =>
@@ -203,14 +213,22 @@ export function useReviewDiffData(input: {
         fileId === null ? 0 : (lazySource?.files?.findIndex((file) => file.path === fileId) ?? -1);
       if (index < 0) return;
       setRequested((current) => {
-        const previous = current.scope === scope ? current.indices : [0, 1, 2];
-        const added = [index, index + 1, index + 2].filter((next) => !previous.includes(next));
-        return added.length === 0 ? current : { scope, indices: [...previous, ...added] };
+        const previous = current.scope === scope ? current.paths : initialPaths;
+        const expandedFileIds =
+          retry && fileId !== null && input.expandedFileIds !== undefined
+            ? [...input.expandedFileIds, fileId]
+            : input.expandedFileIds;
+        const added = getReviewFilePatchLookahead(
+          lazySource?.files ?? [],
+          index,
+          expandedFileIds,
+        ).filter((path) => !previous.includes(path));
+        return added.length === 0 ? current : { scope, paths: [...previous, ...added] };
       });
       if (retry && patches[index]?._tag === "Failure" && queries[index])
         registry.refresh(queries[index]);
     },
-    [lazySource, scope, patches, queries, registry],
+    [initialPaths, input.expandedFileIds, lazySource, scope, patches, queries, registry],
   );
   const parsedDiff = useMemo<ReviewParsedDiff>(() => {
     if (!lazySource?.files) return applyReviewDiffMetadata(previewDiff, selectedSection);

apps/mobile/src/features/review/useReviewDiffPrewarming.test.ts

@@ -0,0 +1,69 @@
+import { describe, expect, it, vi } from "vite-plus/test";
+
+import { getCachedNativeReviewDiffData } from "./nativeReviewDiffAdapter";
+import type { ReviewSectionItem } from "./reviewModel";
+import { getCachedReviewParsedDiff } from "./reviewState";
+import { getReviewDiffPrewarmSections, prewarmReviewDiffSection } from "./useReviewDiffPrewarming";
+
+vi.mock("./nativeReviewDiffAdapter", () => ({ getCachedNativeReviewDiffData: vi.fn() }));
+vi.mock("./reviewState", () => ({
+  getCachedReviewParsedDiff: vi.fn(() => ({ kind: "empty" })),
+  getReviewParsedDiffSourceCharacterCount: (input: { diff: string | null }) =>
+    input.diff?.length ?? 0,
+  MAX_CACHED_REVIEW_DIFFS: 8,
+  MAX_CACHED_REVIEW_SOURCE_CHARACTERS: 4_194_304,
+}));
+
+function section(id: string, lazy = false): ReviewSectionItem {
+  return {
+    id,
+    kind: "working-tree",
+    title: id,
+    subtitle: null,
+    diff: "patch",
+    isLoading: false,
+    source: {
+      id,
+      kind: "working-tree",
+      title: id,
+      diff: "patch",
+      diffHash: id,
+      truncated: lazy,
+      files: [],
+      baseRef: null,
+      headRef: null,
+    },
+  };
+}
+
+describe("review diff prewarming", () => {
+  it("skips truncated stat-backed neighbors whose bodies use file queries", () => {
+    const sections = [section("selected"), section("lazy", true), section("complete")];
+
+    expect(
+      getReviewDiffPrewarmSections({
+        threadKey: "thread",
+        sections,
+        selectedSectionId: "selected",
+      }).map((item) => item.id),
+    ).toEqual(["complete"]);
+  });
+
+  it("does not parse or prepare a lazy source even when invoked directly", () => {
+    vi.clearAllMocks();
+
+    prewarmReviewDiffSection({ threadKey: "thread", section: section("lazy", true) });
+
+    expect(getCachedReviewParsedDiff).not.toHaveBeenCalled();
+    expect(getCachedNativeReviewDiffData).not.toHaveBeenCalled();
+  });
+
+  it("still prewarms complete section bodies", () => {
+    vi.clearAllMocks();
+
+    prewarmReviewDiffSection({ threadKey: "thread", section: section("complete") });
+
+    expect(getCachedReviewParsedDiff).toHaveBeenCalledOnce();
+    expect(getCachedNativeReviewDiffData).toHaveBeenCalledOnce();
+  });
+});

apps/mobile/src/features/review/useReviewDiffPrewarming.ts

@@ -35,12 +35,16 @@ function cancelIdle(handle: number): void {
   clearTimeout(handle);
 }
 
-function prewarmReviewDiffSection(input: {
+export function prewarmReviewDiffSection(input: {
   readonly threadKey: string;
   readonly section: ReviewSectionItem;
 }): void {
   const { section, threadKey } = input;
-  if (section.diff === null || section.diff.length > MAX_CACHED_REVIEW_SOURCE_CHARACTERS) {
+  if (
+    section.diff === null ||
+    section.diff.length > MAX_CACHED_REVIEW_SOURCE_CHARACTERS ||
+    (section.source?.truncated && section.source.files)
+  ) {
     return;
   }
 
@@ -52,7 +56,7 @@ function prewarmReviewDiffSection(input: {
   getCachedNativeReviewDiffData({ parsedDiff, comments: [] });
 }
 
-function getReviewDiffPrewarmSections(input: {
+export function getReviewDiffPrewarmSections(input: {
   readonly threadKey: string;
   readonly sections: ReadonlyArray<ReviewSectionItem>;
   readonly selectedSectionId: string | null;
@@ -80,7 +84,11 @@ function getReviewDiffPrewarmSections(input: {
         return pendingSections;
       }
       const section = sections[index];
-      if (!section || section.diff === null) {
+      if (
+        !section ||
+        section.diff === null ||
+        (section.source?.truncated && section.source.files)
+      ) {
         continue;
       }
       const sectionCharacterCount = getReviewParsedDiffSourceCharacterCount({

apps/mobile/src/features/review/useReviewSections.ts

@@ -95,7 +95,7 @@ export function useReviewSections(input: {
 
   const selectedCheckpoint =
     selectedSectionId === null ? undefined : checkpointBySectionId.get(selectedSectionId);
-  const activeCheckpoint = selectedCheckpoint ?? readyCheckpoints[0] ?? null;
+  const activeCheckpoint = selectedCheckpoint ?? null;
   const activeSectionId = activeCheckpoint
     ? getReviewSectionIdForCheckpoint(activeCheckpoint)
     : null;