What You Refuse to Check Decides the Quality of a Linter

I built a checker for a configuration directory. The time went not into adding rules, but into deciding what not to add . Things you could detect are easy to think of. That was never the constraint. One false positive is enough to get the tool thrown out A checker is asymmetric. A miss goes unnoticed. The cost is only that you did not learn something you could have. A false positive stops the reader and demands a decision: is this actually wrong? And once someone has been burned, they read every finding with suspicion . Twice, and the tool comes out of CI. So a checker that calls a valid configuration broken is worse than no checker. Better ten rules with no false positives than thirty with one. That is obvious in the abstract and hard in practice, because while you are writing the code, every "oh, I could check that too" pulls in the other direction. No citation, no rule So I fixed one condition for adding a rule: Only check what the official documentation states outright — as an error, as skipped, or as ignored. If the documentation does not say it, the rule does not go in, however wrong the pattern looks. What this buys is that the judgement stops living in my memory. "I'm fairly sure that form was invalid" is not a citation, and my memory goes stale the moment the tool it describes releases a new version. In the implementation, every finding carries its reason: export interface Finding { severity : " error " | " warn " ; file : string ; line ?: number ; /** what is wrong, in one sentence */ message : string ; /** why that can be claimed — includes the source URL */ because : string ; } Making because required is the point. A rule you cannot justify cannot be written , because the type will not let you leave the field out. If no source comes to mind, the rule never gets implemented. The tests enforce it too: for ( const f of findings ) { if ( ! f . because . includes ( " https:// " )) fail ( `no source: ${ f . message } ` ); } One finding without a source URL fai