Find dead entries

Report map entries whose removal changes nothing, so layered files do not silt up with lines a template already implies.

Rendered from docs/how-to/find-dead-entries.md in the engine repository, where a correction belongs, and where the test suite executes every example on this page.

Layered files silt up: an entry written before the template existed now repeats what the template already says, and deleting it by eye is a bet. aontu trim --check settles the bet by evaluation: each map entry is deleted in turn, the document re-evaluated, and the entries that made no difference are reported as paths. Write services.aon:

services: {
  &: { tier: standard }
  auth:    { tier: standard, replicas: 3 }
  billing: { replicas: 1 }
}

Now check it:

$ aontu trim --check services.aon
verdict: redundant

$.services.auth.tier
$ echo $?
1

auth.tier restates the &: template, so the document means the same thing without it. The test is evaluate-and-compare, not pattern matching, which covers everything the fixpoint can see: spread templates, references, duplicate-key merges. (A removal that makes the document error is not redundant: the document does not stand up without that entry.)

Delete the dead line yourself (trim only reports) and re-declare services.aon:

services: { &: { tier:standard } auth:replicas:3 billing:replicas:1 }

$ aontu trim --check services.aon
verdict: clean
$ echo $?
0

Exit 0 is clean and exit 1 is redundant, so the verb gates a lint job as it stands; --format json gives the paths as a redundant array. Two limits to know: list elements are never candidates (removing one renumbers the rest, a different document rather than a leaner one), and --check is required: a bare aontu trim that silently did something other than trimming would be worse than refusing.

The candidate rules and the error verdict’s report shape are under aontu trim. Run it beside your schema gate when you validate in CI; when a reported path surprises you, explain the value to see which template is doing the implying.