fix: stabilize media progress and cancel controls

src/store/downloadStore.test.ts

@@ -1,6 +1,10 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { initDownloadListener, useDownloadProgressStore } from './downloadStore';
-import { useDownloadStore } from './useDownloadStore';
+import {
+  clearDownloadControlIntents,
+  setDownloadControlIntent,
+  useDownloadStore
+} from './useDownloadStore';
 import * as ipc from '../ipc';
 
 vi.mock('../ipc', () => ({
@@ -13,6 +17,7 @@ describe('useDownloadProgressStore', () => {
     vi.clearAllMocks();
     vi.mocked(ipc.invokeCommand).mockResolvedValue(undefined);
     useDownloadProgressStore.setState({ progressMap: {} });
+    clearDownloadControlIntents();
   });
 
   it('prunes terminal progress entries', () => {
@@ -233,4 +238,70 @@ describe('useDownloadProgressStore', () => {
     expect(useDownloadStore.getState().downloads[0].status).toBe('completed');
     release();
   });
+
+  it('ignores a stale paused event during resume and accepts the new active state', async () => {
+    const handlers: Record<string, (event: any) => void> = {};
+    vi.mocked(ipc.listenEvent).mockImplementation((event, handler) => {
+      handlers[event] = handler as (event: any) => void;
+      return Promise.resolve(vi.fn());
+    });
+    useDownloadStore.setState({
+      downloads: [{
+        id: 'resume-race',
+        url: 'https://example.com/file',
+        fileName: 'file.bin',
+        status: 'queued',
+        category: 'Other',
+        dateAdded: ''
+      }]
+    });
+    setDownloadControlIntent('resume-race', 'resume');
+
+    const release = await initDownloadListener();
+    handlers['download-state']({ payload: {
+      id: 'resume-race',
+      status: 'paused'
+    } });
+    expect(useDownloadStore.getState().downloads[0].status).toBe('queued');
+
+    handlers['download-state']({ payload: {
+      id: 'resume-race',
+      status: 'downloading'
+    } });
+    expect(useDownloadStore.getState().downloads[0].status).toBe('downloading');
+    release();
+  });
+
+  it('allows a later genuine pause after consuming the stale resume event', async () => {
+    const handlers: Record<string, (event: any) => void> = {};
+    vi.mocked(ipc.listenEvent).mockImplementation((event, handler) => {
+      handlers[event] = handler as (event: any) => void;
+      return Promise.resolve(vi.fn());
+    });
+    useDownloadStore.setState({
+      downloads: [{
+        id: 'resume-pause-race',
+        url: 'https://example.com/file',
+        fileName: 'file.bin',
+        status: 'queued',
+        category: 'Other',
+        dateAdded: ''
+      }]
+    });
+    setDownloadControlIntent('resume-pause-race', 'resume');
+
+    const release = await initDownloadListener();
+    handlers['download-state']({ payload: {
+      id: 'resume-pause-race',
+      status: 'paused'
+    } });
+    expect(useDownloadStore.getState().downloads[0].status).toBe('queued');
+
+    handlers['download-state']({ payload: {
+      id: 'resume-pause-race',
+      status: 'paused'
+    } });
+    expect(useDownloadStore.getState().downloads[0].status).toBe('paused');
+    release();
+  });
 });

src/store/downloadStore.ts

@@ -5,7 +5,11 @@ import type { DownloadItem } from '../bindings/DownloadItem';
 import { categoryForFileName } from '../utils/downloads';
 import { useDownloadProgressStore } from './downloadProgressStore';
 
-import { useDownloadStore } from './useDownloadStore';
+import {
+  clearDownloadControlIntent,
+  downloadControlIntentFor,
+  useDownloadStore
+} from './useDownloadStore';
 
 export { useDownloadProgressStore } from './downloadProgressStore';
 
@@ -78,6 +82,28 @@ const startDownloadListeners = async () => {
       }
       const status = payload.status as DownloadStatus;
 
+      // resume_download queues the row before the backend can emit its new
+      // active state. A paused event already emitted by the old lifecycle may
+      // arrive in that gap. Do not let it overwrite the queued transition;
+      // otherwise the guard below would reject the legitimate downloading
+      // event and leave the row visibly paused forever.
+      if (status === 'paused' &&
+          current.status === 'queued' &&
+          downloadControlIntentFor(payload.id) === 'resume') {
+        // Consume only the stale pause event that caused the resume race.
+        // A later real pause must be allowed through even if the backend has
+        // not emitted a new active state yet.
+        clearDownloadControlIntent(payload.id, 'resume');
+        return;
+      }
+      if (status === 'downloading' || status === 'processing' ||
+          status === 'completed' || status === 'failed') {
+        clearDownloadControlIntent(payload.id, 'resume');
+      }
+      if (status === 'paused') {
+        clearDownloadControlIntent(payload.id, 'pause');
+      }
+
       // Prevent stale lifecycle events from moving a paused row back into an
       // active state. A pause request can finish before one already-emitted
       // worker event reaches the frontend. Resume paths set the row to queued

src/store/useDownloadStore.ts

@@ -24,6 +24,29 @@ const queueStartPromises = new Map<string, Promise<string[]>>();
 const queueControlGenerations = new Map<string, number>();
 let pendingStartupResume: Promise<void> | null = null;
 
+type DownloadControlIntent = 'pause' | 'resume';
+const downloadControlIntents = new Map<string, DownloadControlIntent>();
+
+// State events do not carry a lifecycle generation. Keep the intent that
+// initiated a control transition long enough for the listener to discard an
+// already-emitted event from the previous transition.
+export const setDownloadControlIntent = (id: string, intent: DownloadControlIntent): void => {
+  downloadControlIntents.set(id, intent);
+};
+
+export const clearDownloadControlIntent = (id: string, intent?: DownloadControlIntent): void => {
+  if (intent === undefined || downloadControlIntents.get(id) === intent) {
+    downloadControlIntents.delete(id);
+  }
+};
+
+export const downloadControlIntentFor = (id: string): DownloadControlIntent | undefined =>
+  downloadControlIntents.get(id);
+
+export const clearDownloadControlIntents = (): void => {
+  downloadControlIntents.clear();
+};
+
 const waitForPendingStartupResume = async (): Promise<void> => {
   const pending = pendingStartupResume;
   if (pending) await pending.catch(() => undefined);
@@ -871,6 +894,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
   },
   removeDownload: async (id, deleteFile = false, preserveResumable = false) => {
     await waitForPendingStartupResume();
+    clearDownloadControlIntent(id);
     const { pendingDispatch } = await invalidateDispatch(id);
     if (pendingDispatch) {
       await pendingDispatch;
@@ -898,17 +922,23 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
   },
   pauseDownload: async (id) => {
     await waitForPendingStartupResume();
+    if (!get().downloads.some(download => download.id === id)) return;
+    setDownloadControlIntent(id, 'pause');
     const { generation, pendingDispatch } = await invalidateDispatch(id);
-    if (pendingDispatch) {
-      await pendingDispatch;
-    }
+    try {
+      if (pendingDispatch) {
+        await pendingDispatch;
+      }
 
-    await invoke('pause_download', { id });
+      await invoke('pause_download', { id });
 
-    if (!isCurrentDownloadLifecycle(id, generation)) return;
-    const current = get().downloads.find(download => download.id === id);
-    if (current && current.status !== 'completed' && current.status !== 'failed') {
-      get().updateDownload(id, { status: 'paused', speed: '-', eta: '-' });
+      if (!isCurrentDownloadLifecycle(id, generation)) return;
+      const current = get().downloads.find(download => download.id === id);
+      if (current && current.status !== 'completed' && current.status !== 'failed') {
+        get().updateDownload(id, { status: 'paused', speed: '-', eta: '-' });
+      }
+    } finally {
+      clearDownloadControlIntent(id, 'pause');
     }
   },
   redownload: async (id) => {
@@ -925,6 +955,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
     const url = targetItem.url?.trim();
     if (!url) throw new Error('Cannot redownload: original URL is missing.');
 
+    setDownloadControlIntent(id, 'resume');
     await invalidateAndWaitForDispatch(id);
 
     // Remove from backend to clear its state and delete the existing file so we can overwrite
@@ -933,6 +964,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
       get().unregisterBackendIds([id]);
     } catch (e) {
       console.warn("Could not remove old download from backend", e);
+      clearDownloadControlIntent(id, 'resume');
       throw e;
     }
 
@@ -951,6 +983,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
     if (!await dispatchItem(id)) {
       console.error("Failed to enqueue redownload");
       get().updateDownload(id, { status: 'failed' });
+      clearDownloadControlIntent(id, 'resume');
     } else {
       get().updateDownload(id, { hasBeenDispatched: true });
       info(`Download ${id} redownloaded (queued)`);
@@ -961,6 +994,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
     const targetItem = get().downloads.find(d => d.id === id);
     if (!targetItem) return false;
 
+    setDownloadControlIntent(id, 'resume');
     try {
       if (targetItem.status === 'ready' || targetItem.status === 'staged') {
         get().updateDownload(id, { status: 'queued', hasBeenDispatched: true });
@@ -968,6 +1002,7 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
           return true;
         }
         get().updateDownload(id, { status: targetItem.status });
+        clearDownloadControlIntent(id, 'resume');
         return false;
       }
 
@@ -1002,11 +1037,13 @@ export const useDownloadStore = create<DownloadState>((set, get) => ({
       } else {
         console.error("Failed to re-enqueue for resume");
         get().updateDownload(id, { status: prevStatus });
+        clearDownloadControlIntent(id, 'resume');
         return false;
       }
     } catch (e) {
       console.error("Failed to resume download:", e);
       get().updateDownload(id, { status: targetItem.status });
+      clearDownloadControlIntent(id, 'resume');
       return false;
     }
   },