Search Console held a noindex verdict for 15 days after the page stopped serving it

I have a rule in my blog that noindexes a category page while it has zero posts in it, and drops it from the sitemap at the same time. I wrote it on 18 July. It is one line: robots index false when the post count is zero.

On 13 August Google crawled one of those category pages while it was still empty. It picked up the noindex, and Search Console filed it as Excluded by noindex tag.

A post landed in that category some time after that. I checked the page today. It returns 200, it serves no robots meta at all, it lists its post, and it is back in the sitemap alongside the other 270 URLs.

Search Console still says Excluded by noindex tag. Last crawl 13 August. Fifteen days of a verdict about a version of the page that no longer exists, and nothing in the report tells you the reason is a snapshot from the last crawl rather than a current read.

What I had wrong was assuming the noindex was reversible because the code was reversible. The code did reverse itself, the moment the post count changed. The index did not, because nothing fires an event when a page quietly stops being excluded. A page that fixes itself has no way to say so.

What is a conditional rule in your build that outlived the condition it was written for?