fix(ui): fill the review stream on first paint (0.20.x)

.changeset/fix-startup-file-window.md

@@ -0,0 +1,5 @@
+---
+"hunkdiff": patch
+---
+
+Fill the review stream on first paint instead of leaving it blank until the user scrolls.

src/ui/App.tsx

@@ -296,6 +296,10 @@ export function App({
   const layoutToggleScrollTopRef = useRef<number | null>(null);
   const cancelCopySelectionRef = useRef<(() => void) | null>(null);
   const [layoutToggleRequestId, setLayoutToggleRequestId] = useState(0);
+  const [scrollEdgeRequest, setScrollEdgeRequest] = useState<{
+    id: number;
+    edge: "top" | "bottom";
+  }>({ id: 0, edge: "top" });
   const [transientNoticeText, setTransientNoticeText] = useState<string | null>(null);
   const [layoutMode, setLayoutMode] = useState<LayoutMode>(bootstrap.initialMode);
   const [themeId, setThemeId] = useState(
@@ -1395,6 +1399,15 @@ export function App({
     delta: number,
     unit: "step" | "viewport" | "content" | "half" = "viewport",
   ) => {
+    if (unit === "content") {
+      if (delta !== 0) {
+        setScrollEdgeRequest((current) => ({
+          id: current.id + 1,
+          edge: delta > 0 ? "bottom" : "top",
+        }));
+      }
+      return;
+    }
     if (unit === "half") {
       const scrollBox = diffScrollRef.current;
       if (!scrollBox) return;
@@ -2407,6 +2420,7 @@ export function App({
             wrapToggleScrollTop={wrapToggleScrollTopRef.current}
             layoutToggleScrollTop={layoutToggleScrollTopRef.current}
             layoutToggleRequestId={layoutToggleRequestId}
+            scrollEdgeRequest={scrollEdgeRequest}
             selectedFileTopAlignRequestId={review.selectedFileTopAlignRequestId}
             selectedHunkRevealRequestId={review.selectedHunkRevealRequestId}
             cursorLine={cursorLine}

src/ui/AppHost.interactions.test.tsx

@@ -433,6 +433,14 @@ async function flush(setup: Awaited<ReturnType<typeof testRender>>) {
   });
 }
 
+/** Let initial viewport measurement enable row windowing before testing imperative scroll jumps. */
+async function settleViewportMeasurement(setup: Awaited<ReturnType<typeof testRender>>) {
+  await act(async () => {
+    await Bun.sleep(32);
+    await setup.renderOnce();
+  });
+}
+
 /** Let wrap-toggle renders and follow-up layout retries settle before asserting on the frame. */
 async function settleWrapToggle(setup: Awaited<ReturnType<typeof testRender>>) {
   await flush(setup);
@@ -2462,6 +2470,7 @@ describe("App interactions", () => {
 
     try {
       await flush(setup);
+      await settleViewportMeasurement(setup);
       let frame = setup.captureCharFrame();
       expect(frame).toContain("line01 = 1001");
 
@@ -2485,6 +2494,39 @@ describe("App interactions", () => {
     }
   });
 
+  test("G supersedes a pending selected-hunk reveal", async () => {
+    const setup = await testRender(
+      <AppHost bootstrap={createCrossFileHunkNavigationBootstrap()} />,
+      {
+        width: 120,
+        height: 16,
+      },
+    );
+
+    try {
+      await flush(setup);
+      await settleViewportMeasurement(setup);
+      await pressHunkNavigationKey(setup, "]", 1);
+
+      await act(async () => {
+        await setup.mockInput.pressKey("g", { shift: true });
+      });
+      await flush(setup);
+      await act(async () => {
+        await Bun.sleep(160);
+        await setup.renderOnce();
+      });
+
+      const frame = setup.captureCharFrame();
+      expect(frame).toContain("export const mid = 4;");
+      expect(frame).not.toContain("line 021 changed");
+    } finally {
+      await act(async () => {
+        setup.renderer.destroy();
+      });
+    }
+  });
+
   test("pager mode also supports G and g top/bottom jumps", async () => {
     const before =
       Array.from(
@@ -2525,6 +2567,7 @@ describe("App interactions", () => {
 
     try {
       await flush(setup);
+      await settleViewportMeasurement(setup);
       let frame = setup.captureCharFrame();
       expect(frame).toContain("line01 = 1001");