fix: Bug - Sending files and attachment issues (cross-transport auto-download race)

Re-queue attachment auto-downloads when the chat message arrives, since
file-announce (WebRTC) can beat chat-message (websocket) and the announce-time
pass gives up on an unknown room. Gate stalled-download resets on chunk-progress
staleness so an active transfer is never cancelled mid-stream, which deadlocked
the retry against the sender's active-transfer dedupe.

Co-authored-by: Cursor <cursoragent@cursor.com>

toju-app/src/app/domains/attachment/domain/logic/attachment-autodownload.rules.spec.ts

@@ -1,20 +1,52 @@
-import { shouldResetStalledAttachmentDownload } from './attachment-autodownload.rules';
+import { ATTACHMENT_STALLED_DOWNLOAD_THRESHOLD_MS, shouldResetStalledAttachmentDownload } from './attachment-autodownload.rules';
+
+const NOW_MS = 1_750_000_000_000;
 
 describe('attachment autodownload rules', () => {
-  it('resets stalled partial downloads that are no longer actively transferring', () => {
+  it('does not reset an actively transferring download with recent chunk progress', () => {
+    // Regression: the pending-request marker is deleted on the first received
+    // chunk, so an in-flight multi-chunk transfer has receivedBytes > 0 and no
+    // pending request - it must NOT be treated as stalled while chunks flow.
     expect(shouldResetStalledAttachmentDownload({
       available: false,
-      receivedBytes: 128
-    }, false)).toBe(true);
+      receivedBytes: 128,
+      lastUpdateMs: NOW_MS - 100
+    }, false, NOW_MS)).toBe(false);
+  });
 
+  it('resets partial downloads with no progress past the stall threshold', () => {
+    expect(shouldResetStalledAttachmentDownload({
+      available: false,
+      receivedBytes: 128,
+      lastUpdateMs: NOW_MS - ATTACHMENT_STALLED_DOWNLOAD_THRESHOLD_MS - 1
+    }, false, NOW_MS)).toBe(true);
+  });
+
+  it('treats partial downloads without a progress timestamp as stalled', () => {
     expect(shouldResetStalledAttachmentDownload({
       available: false,
       receivedBytes: 128
-    }, true)).toBe(false);
+    }, false, NOW_MS)).toBe(true);
+  });
+
+  it('never resets downloads with a pending request or already available', () => {
+    expect(shouldResetStalledAttachmentDownload({
+      available: false,
+      receivedBytes: 128,
+      lastUpdateMs: NOW_MS - ATTACHMENT_STALLED_DOWNLOAD_THRESHOLD_MS - 1
+    }, true, NOW_MS)).toBe(false);
 
     expect(shouldResetStalledAttachmentDownload({
       available: true,
-      receivedBytes: 128
-    }, false)).toBe(false);
+      receivedBytes: 128,
+      lastUpdateMs: NOW_MS - ATTACHMENT_STALLED_DOWNLOAD_THRESHOLD_MS - 1
+    }, false, NOW_MS)).toBe(false);
+  });
+
+  it('never resets downloads that have not received any bytes', () => {
+    expect(shouldResetStalledAttachmentDownload({
+      available: false,
+      receivedBytes: 0
+    }, false, NOW_MS)).toBe(false);
   });
 });