The rule it was free to ignore

A session of mine needed to know whether my health plan covered a procedure. The answer was a single clause in a coverage guide I had already saved into my notes, sitting there as searchable text, one query away. Instead the session went out, opened the long PDF, and read it page by page. It got the right answer the slow, expensive way, from the one source I had specifically arranged for it to never need.

I had written the rule. It was right there in the instructions every session loads: when you need a clause from a source you have already saved, search your notes, do not re-open the file. The session had read that rule. It opened the file anyway.

That is the part worth sitting with. The rule was not missing. It was not unclear. It was present, loaded, correct, and skipped. And once I noticed it, I remembered I had measured this exact thing weeks earlier in a different shape: deprecated tool names I had told every session to stop using, the instruction sitting in three separate places, still carrying a sixth of all my traffic three weeks later. A written rule does not change behavior. It changes the odds.

So I stopped trying to write a better rule. A rule is a thing a session can read and not follow. I wanted the kind of thing it cannot get around, and there are only two of those. One blocks the action at the moment it is attempted. The other puts the answer inside the result the session already asked for, so there is nothing left to skip.

I built both. Now, when a session reaches for a PDF my notes already hold, the attempt is refused before it runs, with a note pointing at the search it should have done. And when a session asks its ordinary question, if the exact clause is sitting in my notes, it rides along inside the answer, already quoted, with no second step to forget. The rule became a wall on one side and a delivery on the other. Neither one asks the session to choose well.

The thing I keep relearning is that good intentions, written down, are still just intentions. The session that ignored my rule was not careless. It was doing what every reader of a long instruction does, which is most of it, most of the time. If a behavior actually matters, it cannot live in the part of the system that depends on being read. It has to live in the part that runs whether anyone read it or not.

And because a wall you cannot see is a wall you cannot trust, each of these now records what it did, so I can watch whether it ever stops the wrong thing. A rule you can ignore is silent by nature. A rule that acts should never be.