Six checkers were all green and three things were broken

This piece is the record of one session worked through with an AI. Every number below can be verified in this repository.

This site has six automatic checkers. They check whether the colours are easy to see, whether the writing rules hold, whether the styling order is right, whether the motion is safe, whether a page is too heavy, and whether it is fit to publish.

In one session I added support for several languages and several new effects. All six were green while three things were broken.

1. The preview picture for shared links vanished

Paste an address into a messenger and a preview picture appears. It disappeared on every page.

That picture works by putting a file in a fixed place so it gets attached automatically. But if a page sets its own title and description, it overwrites the picture setting too.

Only the first screen survived, because only the first screen does not set its own title.

There was no error and no warning. Every shared link was missing its picture.

No checker could have caught this. The publishing checker confirms titles and descriptions, but the preview picture was not on its list. What is not on the list is not checked.

2. The big title on the first screen was invisible

I added an effect where a band of orange passes through the letters. It works by making the letters transparent so the background behind them shows through.

In the same session, to make each line appear on its own beat, I wrapped every line in one more box. But that box inherits the transparent letter colour and does not inherit the background. With no background to show through, nothing was visible.

The important part here is that the checkers were not wrong.

The question the motion checker asks is "is this effect safely gated?" The effect was correctly gated. It does not ask whether the result is visible.

The colour checker is the same. It is a tool that measures the colours on a fixed list; letters that became transparent are outside its scope.

Both did exactly what they promised.

3. Clicking a bar in the graph led to a missing page

There is a screen that shows records as bars, and clicking a bar should take you to that entry. The code that builds the address was building it in the old shape.

The picture was drawn correctly and the data was right. What broke was the single action a visitor takes inside it. Nothing on the page was wrong; only what happens next was.

The checkers themselves were giving stale answers

Changing the address structure quietly broke three checkers, and one of them was actively giving a wrong answer — it reported "there is no preview picture anywhere," when in fact every page had one.

A wrong warning is worse than no warning. The next real warning in that same place gets ignored too.

All three were fixed by replacing hand-written paths with finding them directly. A hand-written path eventually goes stale.

The checkers also caught me

In the same session I was blocked three times, and all three times the checker was right. The code it blocked either did not need to exist or needed to be written differently.

And I ignored a checker

Once, the check had already failed and I shipped anyway.

The command that ran the check skimmed the output for a few words and never looked at whether it succeeded or failed before moving on. The error lines that did not match simply scrolled past.

Going on as though a checker passed when it failed is worse than having no checker at all. Without one you check by hand; with one you believe you checked.

What is left

All three problems were found differently.

• The shared picture — while building a table to measure things myself
• The big title — by a person using the site
• The bar click — by a person using the site, clicking

None of the three was the kind a checker could catch. A checker answers only the question it asks.

So I got one more line out of it —

A checker passing is only the answer to the question that checker asks, and what that question is has to be managed from outside the checker.

Every check added this time was deliberately broken first, confirmed to actually fire, and only then kept. A check confirmed only by passing still guarantees nothing.