fix(downloads): make package disclosure motion visible

Keep the explicitly requested 300 ms package transition active when Chromium reports reduced motion, and separate the prepared and active disclosure states by a painted frame. Add focused regression coverage and an opt-in motion mode for the visual harness while keeping normal captures deterministic.

src/renderer/views/downloads/VirtualizedDownloadsBody.tsx

@@ -5,6 +5,7 @@ import {
   DOWNLOAD_DISCLOSURE_DURATION_MS,
   mergeDownloadDisclosureRows,
   prepareDownloadDisclosureTransition,
+  scheduleDownloadDisclosureActivation,
   type DownloadDisclosureRow
 } from "./download-disclosure-transition";
 import type { DownloadsViewActions, DownloadsViewModel } from "./DownloadsView";
@@ -114,7 +115,7 @@ export function VirtualizedDownloadsBody({ actions, model, state }: { actions: D
     transitionRowsRef.current = prepared.rows;
     setTransitionRows(prepared.rows);
     let settleTimer = 0;
-    const animationFrame = window.requestAnimationFrame(() => {
+    const cancelActivation = scheduleDownloadDisclosureActivation(window.requestAnimationFrame.bind(window), window.cancelAnimationFrame.bind(window), () => {
       const active = activateDownloadDisclosureTransition(transitionRowsRef.current ?? prepared.rows);
       transitionRowsRef.current = active;
       setTransitionRows(active);
@@ -125,7 +126,7 @@ export function VirtualizedDownloadsBody({ actions, model, state }: { actions: D
       }, DOWNLOAD_DISCLOSURE_DURATION_MS);
     });
     return () => {
-      window.cancelAnimationFrame(animationFrame);
+      cancelActivation();
       if (settleTimer) window.clearTimeout(settleTimer);
     };
   }, [model.disclosureRevision, model.displayMode]);

src/renderer/views/downloads/download-disclosure-transition.ts

@@ -4,6 +4,22 @@ import { DOWNLOAD_FILE_ROW_HEIGHT } from "./download-virtualizer";
 export const DOWNLOAD_DISCLOSURE_DURATION_MS = 300;
 export const DOWNLOAD_DISCLOSURE_MAX_ANIMATED_ITEMS = 64;
 
+export function scheduleDownloadDisclosureActivation(
+  requestFrame: (callback: FrameRequestCallback) => number,
+  cancelFrame: (frame: number) => void,
+  activate: () => void
+): () => void {
+  let paintFrame = 0;
+  let activationFrame = 0;
+  paintFrame = requestFrame(() => {
+    activationFrame = requestFrame(activate);
+  });
+  return () => {
+    cancelFrame(paintFrame);
+    if (activationFrame) cancelFrame(activationFrame);
+  };
+}
+
 export type DownloadDisclosurePhase = "stable" | "entering" | "leaving";
 
 export type DownloadDisclosureRow = DownloadLogicalRow & {

src/renderer/views/downloads/downloads.css

@@ -583,6 +583,14 @@
 }
 
 @media (prefers-reduced-motion: reduce) {
+  .downloads-virtual-spacer {
+    transition-duration: 300ms !important;
+  }
+
+  .downloads-virtual-row {
+    transition-duration: 300ms, 300ms, 300ms !important;
+  }
+
   .downloads-table.is-column-drag-active [data-download-column],
   .downloads-table.is-column-drag-settling [data-download-column] {
     transition-duration: 220ms !important;

tests/downloads-view.test.tsx

@@ -23,6 +23,7 @@ import {
   activateDownloadDisclosureTransition,
   mergeDownloadDisclosureRows,
   prepareDownloadDisclosureTransition,
+  scheduleDownloadDisclosureActivation,
   stableDownloadDisclosureRows
 } from "../src/renderer/views/downloads/download-disclosure-transition";
 import {
@@ -224,6 +225,32 @@ describe("virtualisierte Paketanimation", () => {
     renderLimit: 100
   }));
 
+  it("zeichnet den Startzustand in einem eigenen Frame vor der Aktivierung", () => {
+    const frames: FrameRequestCallback[] = [];
+    const cancelled: number[] = [];
+    const activated = vi.fn();
+    let frameId = 0;
+    const requestFrame = vi.fn((callback: FrameRequestCallback) => {
+      frames.push(callback);
+      frameId += 1;
+      return frameId;
+    });
+    const cancelFrame = vi.fn((frame: number) => cancelled.push(frame));
+
+    const cancel = scheduleDownloadDisclosureActivation(requestFrame, cancelFrame, activated);
+
+    expect(activated).not.toHaveBeenCalled();
+    expect(frames).toHaveLength(1);
+    frames.shift()?.(16);
+    expect(activated).not.toHaveBeenCalled();
+    expect(frames).toHaveLength(1);
+    frames.shift()?.(32);
+    expect(activated).toHaveBeenCalledTimes(1);
+
+    cancel();
+    expect(cancelled).toContain(2);
+  });
+
   it("fährt neue Unterzeilen von null auf ihre feste Höhe aus und verschiebt Folgepakete unter stabilen IDs", () => {
     const collapsed = logicalRows([packageA.id]);
     const expanded = logicalRows([]);
@@ -246,6 +273,13 @@ describe("virtualisierte Paketanimation", () => {
     ]);
   });
 
+  it("behält die ausdrücklich gewünschte Paketbewegung auch bei reduzierten Systemanimationen bei", () => {
+    const css = fs.readFileSync(path.join(process.cwd(), "src/renderer/views/downloads/downloads.css"), "utf8");
+
+    expect(css).toMatch(/@media \(prefers-reduced-motion: reduce\)[\s\S]*\.downloads-virtual-spacer\s*\{[^}]*transition-duration:\s*300ms !important;/s);
+    expect(css).toMatch(/@media \(prefers-reduced-motion: reduce\)[\s\S]*\.downloads-virtual-row\s*\{[^}]*transition-duration:\s*300ms, 300ms, 300ms !important;/s);
+  });
+
   it("behält ausfahrende Unterzeilen bis zum Animationsende und reduziert ihre Höhe auf null", () => {
     const expanded = logicalRows([]);
     const collapsed = logicalRows([packageA.id]);

tests/visual/index.html

@@ -4,10 +4,13 @@
     <meta charset="UTF-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>Multi Debrid Downloader Visual Harness</title>
+    <script>
+      if (new URLSearchParams(location.search).has("motion")) document.documentElement.dataset.visualMotion = "true";
+    </script>
     <style>
-      *,
-      *::before,
-      *::after {
+      html:not([data-visual-motion="true"]) *,
+      html:not([data-visual-motion="true"]) *::before,
+      html:not([data-visual-motion="true"]) *::after {
         animation: none !important;
         caret-color: transparent !important;
         transition: none !important;