A --check run of the env generator exits non-zero when the committed catalog drifts

The check does not validate the committed YAML against a schema. It runs the generator a second time in `--check` mode, holds the result in memory, compares it with the file on disk, and exits non-zero on any difference ^[5]. The failing case is an ordinary pull request: someone adds a field to a config struct, the committed catalog still describes the old set, and the job stops the merge. "A generated file that nobody regenerates is just a stale file with better formatting," Anton Brilliantov wrote ^[9].

The count justifies the tooling. Fifty-nine variables in one service, one repository ^[1]. Three quarters came in with the platform library ^[2], which leaves roughly 44 variables the service inherits against about 15 it declares itself ^[14]. Brilliantov puts the failure of the hand-written version this way: "At fifty-nine, hand-written documentation survives exactly until the next pull request - someone adds a field to a config struct, nobody touches the README, and from that moment the README is confidently wrong" ^[10].

Six fields per record, and the post stops at six ^[7]. `schema_version: 1` sits at the top because the file is read by machines as well as people, so consumers have something to branch on when the record shape changes ^[8]. The `secret` flag is there for the same audience: tools that dump configuration can read which variables must never appear in a log ^[15]. According to Brilliantov, the `defined_in` line closes questions; without it, "do we still need this one?" turns into a search across the repository run by whoever is unlucky ^[16].

The catalog is the file that falls out of the service manifest covered in part one of the series, one declaration the runtime reads instead of a pile of wiring code ^[13]. Brilliantov is a software engineer working mostly in PHP/Symfony and Go, carving a live PHP monolith into Go services ^[12].

He is explicit about scope. "As always: this is what I'm doing on one codebase right now, with the price attached. Not a recommendation for yours," he wrote ^[11]. The published post does not give a CI time for the extra generator run, and it does not estimate the work of keeping the generator in step with the platform library ^[17].

Two conditions have to hold for this to transfer. Variables have to be declared somewhere a generator can enumerate; `internal/daemon/worker/retention/config.go:16` implies that is how the service-side records are found ^[4]. And the platform library has to ship its own catalog, or the three quarters cannot be generated at all ^[2]. A service that reads configuration through bare `os.Getenv` calls scattered across handlers gives the generator nothing to walk, and the four triggers ^[6] then fire a job that can only confirm a partial list.