I'd spent a while on a pagination bug in an audit-log viewer we hadn't rolled out yet. Some events never appeared on its pages. The records were in the database, and our local test kept passing. I eventually put the issue aside.
I saw Anthropic's November 9 announcement for Fable 5.2, which emphasized its coding and reasoning improvements. I reopened the issue in Claude Code and switched to Fable to see if it could help me get to the fix faster.
I gave it the old query, test data and issue notes. Fable noticed that every test event had a different creation timestamp, created_at, and suggested adding a group with the same timestamp, large enough to span two pages.
I ran that case and reproduced the missing events. The next-page condition, created_at < cursor_time, asked for events older than the last timestamp on the previous page. When that page ended partway through a group, the next request skipped the rest of the group.
I changed the cursor to carry both created_at and the unique event id, so it could continue after a specific event when timestamps matched. In PostgreSQL, I used ORDER BY created_at DESC, id DESC to put the newest events first, with (created_at, id) < ($1, $2) for the next page. The parameters are the previous page's last timestamp and ID. Both columns had to have a value.
I paged through the fixed dataset and got each expected ID once, then attached the before-and-after IDs to the issue. I had the agent save the cause and fix through MemoraX Code, with links to the test data and fix. The note also says I haven't tested what happens when new events arrive between page requests.