Fix beta desktop download selection

backend/routers/updates.py

@@ -333,13 +333,23 @@ async def download_latest_desktop_release(
 ):
     """
     Redirect to the latest desktop release DMG installer.
-    Resolves from GitHub release assets filtered by channel.
+    Stable resolves from the latest stable-tagged release.
+    Beta always resolves from the newest desktop GitHub release, regardless of channel metadata.
     Defaults to stable channel (for macos.omi.me). Use channel=beta for QA.
     """
     desktop_releases = await _get_live_desktop_releases(platform)
     if not desktop_releases:
         raise HTTPException(status_code=404, detail=f"No live desktop releases found for platform: {platform}")
 
+    if channel == "beta":
+        # Beta downloads should always expose the newest GitHub desktop build,
+        # even if the release-channel promotion metadata is stale.
+        for entry in desktop_releases:
+            dmg_url = _get_dmg_download_url(entry["release"])
+            if dmg_url:
+                return RedirectResponse(url=dmg_url, status_code=302)
+        raise HTTPException(status_code=404, detail="No DMG installer found for latest beta release")
+
     # Find latest release matching the requested channel
     for entry in desktop_releases:
         if entry["channel"] != channel:

backend/tests/unit/test_desktop_updates.py

@@ -515,7 +515,28 @@ async def test_beta_no_fallback(self):
         with patch("routers.updates._get_live_desktop_releases", new_callable=AsyncMock, return_value=mock_releases):
             async with AsyncClient(transport=ASGITransport(app=_test_app), base_url="http://test") as client:
                 resp = await client.get("/v2/desktop/download/latest?channel=beta")
-        assert resp.status_code == 404
+        assert resp.status_code == 302
+        assert resp.headers["location"] == "https://example.com/stable.dmg"
+
+    @pytest.mark.asyncio
+    async def test_beta_uses_latest_release_even_if_marked_stable(self):
+        mock_releases = [
+            {
+                "channel": "stable",
+                "release": {"assets": [_dmg_asset("https://example.com/latest.dmg")]},
+            },
+            {
+                "channel": "beta",
+                "release": {"assets": [_dmg_asset("https://example.com/older-beta.dmg")]},
+            },
+        ]
+        with patch("routers.updates._get_live_desktop_releases", new_callable=AsyncMock, return_value=mock_releases):
+            async with AsyncClient(
+                transport=ASGITransport(app=_test_app), base_url="http://test", follow_redirects=False
+            ) as client:
+                resp = await client.get("/v2/desktop/download/latest?channel=beta")
+        assert resp.status_code == 302
+        assert resp.headers["location"] == "https://example.com/latest.dmg"
 
     @pytest.mark.asyncio
     async def test_404_when_no_dmg_asset(self):