Add Site discovery cannot subscribe to existing Reddit feed result

Summary

I hit a case where Add + Discover Sites can find and preview an existing Reddit feed, but the Add/Subscribe actions fail instead of subscribing to that resolved feed.

Reproduction

1. Open NewsBlur and go to Add + Discover Sites.
2. Search for cycling in the Reddit tab.
3. NewsBlur shows the direct-add fallback for https://www.reddit.com/r/cycling/.rss.
4. Click Add.
5. The button changes to Error and then resets to Add.
6. Switch to the Search tab and search cycling.
7. NewsBlur finds the existing feed result bikeit! for the cycling subreddit.
8. Click Add on that result.
9. The same Error state appears.
10. Click Try on that same result.

What I observed

The Try action opens the existing feed page and loads current stories successfully. In my case it opened /site/19/bikeit and displayed current r/cycling stories, so the feed itself appears to exist and fetch content correctly.

Both Add paths failed with this browser console message:

Subscribe error: There was a problem trying to add this site. Please try a different URL.

Using the feed page's Subscribe button opened the generic "Add any site or feed" modal. Submitting https://www.reddit.com/r/cycling/.rss there routed into the Web Feed flow and reported Anthropic API key not configured.

Expected behavior

Once discovery/search has resolved an existing feed result, clicking Add should subscribe to it.

Notes

This may be around the boundary between discovery cards and the generic URL add path. The result appears to have a feed id that works for previewing stories, while the Add action appears to depend on adding by URL.

Relevant areas may include:

• media/js/newsblur/views/add_site_view.js
• media/js/newsblur/common/assetmodel.js
• apps/reader/views.py
• apps/reader/models.py

Thanks for maintaining NewsBlur. I wanted to report this with the concrete repro since it looks like a normal UI path rather than a local data issue.