fix(code-review): scroll to next file after viewing

apps/code/snapshots.yml

@@ -27,7 +27,7 @@ snapshots:
     archive-archivedtasksview--many-tasks--dark:
         hash: v1.k4693efd2.40d24f07a24c6400c32ae68b39fd908a056beb5dc6df8bcb237ec2ab2b494f4a.l2vjfSQDalCPRtDNV7pbfTKGlMsQoI81jI-UdJfLHWE
     archive-archivedtasksview--many-tasks--light:
-        hash: v1.k4693efd2.52ec9963bfe6f248ffcdaa4c26945d2b7e303115825b65d978aa5aefd4af1007.ZLtOfTZUrznhYeB-N2SIHzQWRzF6TDSaipNkfd8uzjM
+        hash: v1.k4693efd2.74c25b303262f2d4c0f22890d351e76f482827548548f7c023bc309327c927b8.DP9VVrvBz1naIJMwHORkfqm69BlO785ulOt4o6zFs94
     archive-archivedtasksview--mixed-modes--dark:
         hash: v1.k4693efd2.d94039b8cc17a4ad1b720364f41fee58a4843aa9a901443997ba62602f698794.441LWZhT-2WQZJHni4LoOgQsOSr2O103NZOk1pF8ME4
     archive-archivedtasksview--mixed-modes--light:

packages/core/src/code-review/reviewShellGeometry.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, it } from "vitest";
 import {
   buildItemIndex,
+  findNextScrollKey,
   getDeferredMessage,
   splitFilePath,
   sumHunkStats,
@@ -45,6 +46,18 @@ describe("buildItemIndex", () => {
   });
 });
 
+describe("findNextScrollKey", () => {
+  it.each([
+    ["a", "b"],
+    ["b", null],
+    ["missing", null],
+  ])("finds the next file after %s", (currentKey, expected) => {
+    const items = [{ scrollKey: "a" }, {}, { scrollKey: "b" }, {}];
+
+    expect(findNextScrollKey(items, currentKey)).toBe(expected);
+  });
+});
+
 describe("getDeferredMessage", () => {
   it("returns the line-limit message", () => {
     expect(getDeferredMessage("line-limit")).toContain("5,000-line");

packages/core/src/code-review/reviewShellGeometry.ts

@@ -37,6 +37,20 @@ export function buildItemIndex(
   return index;
 }
 
+export function findNextScrollKey(
+  items: { scrollKey?: string }[],
+  currentKey: string,
+): string | null {
+  const currentIndex = items.findIndex((item) => item.scrollKey === currentKey);
+  if (currentIndex === -1) return null;
+
+  for (let i = currentIndex + 1; i < items.length; i++) {
+    const key = items[i].scrollKey;
+    if (key) return key;
+  }
+  return null;
+}
+
 export function getDeferredMessage(reason: DeferredReason): string {
   switch (reason) {
     case "line-limit":

packages/ui/src/features/code-review/components/ReviewShell.tsx

@@ -1,4 +1,5 @@
 import { WorkerPoolContextProvider } from "@pierre/diffs/react";
+import { findNextScrollKey } from "@posthog/core/code-review/reviewShellGeometry";
 import { useService } from "@posthog/di/react";
 import type { Task } from "@posthog/shared/domain-types";
 import { useArchivedTaskIds } from "@posthog/ui/features/archive/useArchivedTaskIds";
@@ -187,26 +188,40 @@ export function ReviewShell({
     if (prState === "merged") clearTasks([taskId]);
   }, [prState, taskId, clearTasks]);
 
-  const viewedContextValue = useMemo(
-    () => ({
-      viewedRecord,
-      currentSignatures,
-      toggleViewed: onToggleViewed,
-    }),
-    [viewedRecord, currentSignatures, onToggleViewed],
-  );
-
   const scrollRequest = useReviewNavigationStore(
     (s) => s.scrollRequests[taskId] ?? null,
   );
   const clearScrollRequest = useReviewNavigationStore(
     (s) => s.clearScrollRequest,
   );
+  const requestScrollToFile = useReviewNavigationStore(
+    (s) => s.requestScrollToFile,
+  );
   const setActiveFilePath = useReviewNavigationStore(
     (s) => s.setActiveFilePath,
   );
   const clearTask = useReviewNavigationStore((s) => s.clearTask);
 
+  const toggleViewed = useCallback(
+    (key: string, signature: string | null) => {
+      onToggleViewed(key, signature);
+      if (signature === null) return;
+
+      const nextKey = findNextScrollKey(items, key);
+      if (nextKey) requestScrollToFile(taskId, nextKey);
+    },
+    [items, onToggleViewed, requestScrollToFile, taskId],
+  );
+
+  const viewedContextValue = useMemo(
+    () => ({
+      viewedRecord,
+      currentSignatures,
+      toggleViewed,
+    }),
+    [viewedRecord, currentSignatures, toggleViewed],
+  );
+
   useEffect(() => {
     return () => {
       if (navigationFrameRef.current !== null) {