fix(desktop): reorder repo tabs via pointer events (mouse, touch, pen) + keyboard a11y

apps/desktop/src/components/__tests__/RepoTabStrip.test.ts

@@ -0,0 +1,285 @@
+/**
+ * RepoTabStrip.vue — pointer-based drag-to-reorder regression guards.
+ *
+ * Native HTML5 drag-and-drop is unreliable in the WebKit webviews that power
+ * the packaged Tauri app, so tab reordering is driven by Pointer Events
+ * instead (see the "Drag to reorder" comment block in the component) — one
+ * code path for mouse, touch and pen. That hand-rolled state machine has
+ * sharp edges a component test can pin down without a real browser: a click
+ * near a tab's own edge must not itself register as a reorder, a drag must
+ * only ever be committed by the button that started it, and a re-snapshot
+ * mid-drag (scroll, resize) must not double-count the dragged tab's own live
+ * offset.
+ *
+ * jsdom has no PointerEvent constructor and no setPointerCapture, so drags
+ * are driven with plain `Event` objects carrying the same fields the
+ * component reads off a real PointerEvent (clientX/clientY/button/pointerId)
+ * — dispatchEvent doesn't care which Event subclass a listener was declared
+ * against, only the `type` string. The component itself feature-detects
+ * setPointerCapture, so it degrades to window-listener-only tracking under
+ * jsdom exactly like it would in a webview that lacks pointer capture.
+ *
+ * Mounted with native `createApp` into jsdom (no @vue/test-utils dep),
+ * mirroring MergeEditor.test / LlmTracePanel.test / LaunchpadView.test.
+ */
+
+import { describe, it, expect, afterEach } from "vitest";
+import { createApp, h, nextTick, type App } from "vue";
+import RepoTabStrip from "../header/RepoTabStrip.vue";
+import type { RepoTab } from "../../composables/useRepoTabs";
+
+function makeTabs(n: number): RepoTab[] {
+  return Array.from({ length: n }, (_, i) => ({
+    id: i + 1,
+    path: `/repo-${i}`,
+    name: `repo-${i}`,
+  }));
+}
+
+let app: App | null = null;
+let container: HTMLElement | null = null;
+
+afterEach(() => {
+  app?.unmount();
+  app = null;
+  container?.remove();
+  container = null;
+});
+
+interface Mounted {
+  tabEls: HTMLElement[];
+  reorders: Array<[number, number]>;
+}
+
+function mount(tabs: RepoTab[]): Mounted {
+  container = document.createElement("div");
+  document.body.appendChild(container);
+  const reorders: Array<[number, number]> = [];
+
+  app = createApp({
+    render() {
+      return h(RepoTabStrip, {
+        tabs,
+        activeTabId: tabs[0]?.id ?? null,
+        onReorderTabs: (oldIndex: number, newIndex: number) => {
+          reorders.push([oldIndex, newIndex]);
+        },
+      });
+    },
+  });
+  app.mount(container);
+
+  const tabEls = Array.from(container.querySelectorAll<HTMLElement>(".repo-tab"));
+  return { tabEls, reorders };
+}
+
+/** Stubs the geometry each tab needs for the drag hit-test to run in jsdom. */
+function stubRects(tabEls: HTMLElement[], widths: number[], lefts?: number[]) {
+  let left = 0;
+  for (let i = 0; i < tabEls.length; i++) {
+    const width = widths[i];
+    const l = lefts ? lefts[i] : left;
+    const rect = { left: l, right: l + width, top: 0, bottom: 30, width, height: 30 } as DOMRect;
+    tabEls[i].getBoundingClientRect = () => rect;
+    left += width;
+  }
+}
+
+let nextPointerId = 1;
+
+function firePointer(
+  target: EventTarget,
+  type: string,
+  opts: { clientX?: number; clientY?: number; button?: number; pointerId?: number },
+) {
+  const event = new Event(type, { bubbles: true, cancelable: true });
+  Object.defineProperty(event, "clientX", { get: () => opts.clientX ?? 0 });
+  Object.defineProperty(event, "clientY", { get: () => opts.clientY ?? 15 });
+  Object.defineProperty(event, "button", { get: () => opts.button ?? 0 });
+  Object.defineProperty(event, "pointerId", { get: () => opts.pointerId ?? nextPointerId });
+  target.dispatchEvent(event);
+}
+
+describe("RepoTabStrip — drag to reorder", () => {
+  it("a few pixels of wobble on a tab's right half does not reorder it", async () => {
+    // Regression: the hit-test used to compare the raw cursor position
+    // against each tab's center, so pressing the right half of a wide tab
+    // put the cursor on the far side of its own center *before any
+    // movement at all* — a subsequent few-pixel wobble (well under what
+    // anyone would call a drag) was enough to swap it with its neighbour.
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    // Press near the right edge of tab 0 (center is at x=50).
+    firePointer(tabEls[0], "pointerdown", { clientX: 90 });
+    // Wobble 5px right — just past the 4px drag threshold.
+    firePointer(window, "pointermove", { clientX: 95 });
+    firePointer(window, "pointerup", { clientX: 95 });
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("dragging a tab past its neighbour's center reorders it", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    // Press at the center of tab 0 and drag well past tab 1's center (150).
+    firePointer(tabEls[0], "pointerdown", { clientX: 50 });
+    firePointer(window, "pointermove", { clientX: 160 });
+    firePointer(window, "pointerup", { clientX: 160 });
+    await nextTick();
+
+    expect(reorders).toEqual([[0, 1]]);
+  });
+
+  it("a right-click released mid-drag does not commit or cancel it", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    firePointer(tabEls[0], "pointerdown", { clientX: 50, button: 0 });
+    firePointer(window, "pointermove", { clientX: 160 });
+    // A right-button pointerup mid-drag must be ignored...
+    firePointer(window, "pointerup", { clientX: 160, button: 2 });
+    await nextTick();
+    expect(reorders).toEqual([]);
+    // ...the left-button release still ends the drag normally.
+    firePointer(window, "pointerup", { clientX: 160, button: 0 });
+    await nextTick();
+    expect(reorders).toEqual([[0, 1]]);
+  });
+
+  it("releasing far outside the strip cancels the drag instead of reordering", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    firePointer(tabEls[0], "pointerdown", { clientX: 50 });
+    // Drag past tab 1's center but with the cursor far below the strip.
+    firePointer(window, "pointermove", { clientX: 160, clientY: 500 });
+    firePointer(window, "pointerup", { clientX: 160, clientY: 500 });
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("a window blur mid-drag cancels it", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    firePointer(tabEls[0], "pointerdown", { clientX: 50 });
+    firePointer(window, "pointermove", { clientX: 160 });
+    window.dispatchEvent(new Event("blur"));
+    // The pointerup that follows (returning from another app) must not commit.
+    firePointer(window, "pointerup", { clientX: 160 });
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("a pointercancel mid-drag (e.g. a touch gesture interrupted) cancels it", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+    stubRects(tabEls, [100, 100, 100]);
+
+    firePointer(tabEls[0], "pointerdown", { clientX: 50 });
+    firePointer(window, "pointermove", { clientX: 160 });
+    firePointer(window, "pointercancel", { clientX: 160 });
+    firePointer(window, "pointerup", { clientX: 160 });
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("a resize mid-drag re-snapshots without double-counting the dragged tab's own offset", async () => {
+    // Regression: re-snapshotting centers mid-drag (on scroll or resize) used
+    // to re-measure the dragged tab's rect as-is — but that rect already
+    // includes the live translateX a real browser would have painted, so the
+    // offset got added to the hit-test a second time and the drop landed one
+    // slot further than it should have.
+    const { tabEls, reorders } = mount(makeTabs(3));
+    // Resting centers: 50, 150, 250 (widths 100 each, lefts 0/100/200).
+    stubRects(tabEls, [100, 100, 100]);
+
+    firePointer(tabEls[0], "pointerdown", { clientX: 50 });
+    // Drag 100px right — didDrag flips true and snapshots the resting
+    // centers; hoveredIndex is still 0 (hasn't crossed tab 1's center yet).
+    firePointer(window, "pointermove", { clientX: 150 });
+
+    // Simulate the DOM now reflecting that 100px live translateX: tab 0's
+    // rect has visually shifted right by 100, exactly as a real browser
+    // would render it mid-drag (the other tabs don't move).
+    stubRects(tabEls, [100, 100, 100], [100, 100, 200]);
+    window.dispatchEvent(new Event("resize"));
+
+    // Move on to a total offset of 110px from the press point — enough to
+    // cross tab 1's resting center (150) but not tab 2's (250) once the
+    // resize re-snapshot has correctly stripped the baked-in offset back out.
+    firePointer(window, "pointermove", { clientX: 160 });
+    firePointer(window, "pointerup", { clientX: 160 });
+    await nextTick();
+
+    expect(reorders).toEqual([[0, 1]]);
+  });
+});
+
+describe("RepoTabStrip — keyboard reordering", () => {
+  function fireCtrlShiftArrow(target: EventTarget, key: "ArrowLeft" | "ArrowRight") {
+    target.dispatchEvent(
+      new KeyboardEvent("keydown", { key, ctrlKey: true, shiftKey: true, bubbles: true, cancelable: true }),
+    );
+  }
+
+  it("Ctrl+Shift+ArrowRight moves the focused tab one slot right and announces it", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+
+    fireCtrlShiftArrow(tabEls[0], "ArrowRight");
+    await nextTick();
+
+    expect(reorders).toEqual([[0, 1]]);
+    expect(container?.querySelector('[role="status"]')?.textContent).toBe("repo-0 moved to position 2 of 3");
+  });
+
+  it("Ctrl+Shift+ArrowLeft moves the focused tab one slot left", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+
+    fireCtrlShiftArrow(tabEls[1], "ArrowLeft");
+    await nextTick();
+
+    expect(reorders).toEqual([[1, 0]]);
+  });
+
+  it("does nothing at the boundary (first tab can't move left, last can't move right)", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+
+    fireCtrlShiftArrow(tabEls[0], "ArrowLeft");
+    fireCtrlShiftArrow(tabEls[2], "ArrowRight");
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("a plain ArrowRight (no modifier) does not reorder — only switches focus natively", async () => {
+    const { tabEls, reorders } = mount(makeTabs(3));
+
+    tabEls[0].dispatchEvent(new KeyboardEvent("keydown", { key: "ArrowRight", bubbles: true, cancelable: true }));
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+
+  it("bare Ctrl+ArrowRight (no Shift) does not reorder", async () => {
+    // Regression: a bare Ctrl+Arrow is macOS's default Mission Control
+    // "switch Space" shortcut, intercepted by the OS before it would even
+    // reach the app — Shift is required precisely to stay clear of that (and
+    // of third-party window-manager shortcuts using the same bare combo).
+    // This only guards our own handler's condition; it can't simulate the
+    // OS swallowing the event outright.
+    const { tabEls, reorders } = mount(makeTabs(3));
+
+    tabEls[0].dispatchEvent(
+      new KeyboardEvent("keydown", { key: "ArrowRight", ctrlKey: true, bubbles: true, cancelable: true }),
+    );
+    await nextTick();
+
+    expect(reorders).toEqual([]);
+  });
+});