fix(downloads): close audit lifecycle gaps

Prevent duplicate Add Window submissions and preserve discard confirmation.

Reject duplicate backend primary-path ownership and clear stale lifecycle progress.

src/store/downloadStore.test.ts

@@ -113,4 +113,47 @@ describe('useDownloadProgressStore', () => {
     expect(useDownloadProgressStore.getState().progressMap).toEqual({});
     release();
   });
+
+  it('drops stale progress when a download returns to a queued lifecycle', 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: 'reused',
+        url: 'https://example.com/file',
+        fileName: 'file.bin',
+        status: 'downloading',
+        category: 'Other',
+        dateAdded: ''
+      }]
+    });
+
+    const release = await initDownloadListener();
+    handlers['download-progress']({ payload: {
+      id: 'reused',
+      fraction: 0.8,
+      speed: '1 MB/s',
+      eta: '2s',
+      size: '8 MB',
+      size_is_final: false
+    } });
+    handlers['download-state']({ payload: {
+      id: 'reused',
+      status: 'queued'
+    } });
+    handlers['download-progress']({ payload: {
+      id: 'reused',
+      fraction: 0.9,
+      speed: '2 MB/s',
+      eta: '1s',
+      size: '9 MB',
+      size_is_final: false
+    } });
+
+    expect(useDownloadProgressStore.getState().progressMap).toEqual({});
+    release();
+  });
 });

src/store/downloadStore.ts

@@ -38,9 +38,10 @@ const startDownloadListeners = async () => {
         return;
       }
       // A sidecar can flush one last progress chunk after a pause, failure,
-      // or completion event. Do not let that stale chunk repopulate the live
-      // progress map or overwrite a later lifecycle's first frame.
-      if (current && ['completed', 'failed', 'paused'].includes(current.status)) {
+      // completion, or lifecycle reset. Do not let that stale chunk repopulate
+      // the live progress map or overwrite a later lifecycle's first frame.
+      if (!['downloading', 'processing'].includes(current.status)) {
+        useDownloadProgressStore.getState().clearDownloadProgress(payload.id);
         return;
       }
       useDownloadProgressStore.getState().updateDownloadProgress(payload.id, payload);
@@ -74,6 +75,9 @@ const startDownloadListeners = async () => {
         return;
       }
 
+      if (['queued', 'retrying', 'completed', 'failed', 'paused'].includes(status)) {
+        useDownloadProgressStore.getState().clearDownloadProgress(payload.id);
+      }
       const progress = useDownloadProgressStore.getState().progressMap[payload.id];
       const updates: Partial<DownloadItem> = {
         status,
@@ -109,7 +113,7 @@ const startDownloadListeners = async () => {
       } else if (status === 'completed' || status === 'failed') {
         mainStore.unregisterBackendIds([payload.id]);
       }
-      if (status === 'completed' || status === 'failed' || status === 'paused') {
+      if (['queued', 'retrying', 'completed', 'failed', 'paused'].includes(status)) {
         useDownloadProgressStore.getState().clearDownloadProgress(payload.id);
       }
     }),