Codes of check

Every line the check command prints carries a stable code (Check\CheckItem::$code). The code is what check --json consumers, deploy pipelines and alert rules match on; the text is not API and gets improved between versions, the same way Reason is the identifier of a Result and Result::$error the sentence. A code names the check, not the outcome: key_file.status is ok when the key file answers 200 with the right body and error when it does not, so a rule written as "fail the deploy when key_file.status is not ok" survives a rewording.

Codes are added in minor versions when a check is added (a new line in the table below), and never renamed or removed before 1.0 without an entry under "Changed" in the changelog. A code is a dotted lower-case identifier; the first segment is the area. Lines about one host carry it in CheckItem::$host ("host" in the JSON), the global lines have null there.

Core (Check\Checker)

Code	Levels	Line
config.enabled	warning	enabled: false: nothing will be submitted
config.dry_run	warning, error	dry_run is on (error when the environment is production)
environment.name	ok, warning	the environment: … line; warning outside production when real requests leave
environment.non_production_submits	warning, error	a non-production environment with a key and dry_run off: error when dry_run was left unset, warning when it says false explicitly
config.strict_hosts	ok, warning	strict_hosts on; or off next to a hosts map / in production
config.base_url	ok, warning	base_url set or missing
config.engines	ok	the resolved engine list
config.delivery	ok	dispatch, debounce window, batch size, throttle, timeout
config.hosts	error	no host to check at all (no base_url, no hosts)
http.client	warning	a custom http.client fetches the key files: if it follows redirects, a 30x to a catch-all page looks like a 200
key.missing (host)	error	no key for the host
key.invalid (host)	error	the key fails KeyValidator
key_file.location (host)	error	key_location points to another host (engines answer 422)
key_file.served_externally (host)	warning	key_file.enabled: false and no key_location: the web server must serve the file
key_file.status (host)	ok, error	GET /<key>.txt: ok on 200 with the key as body; error on any other status
key_file.body (host)	error	200 with a body that is not the key (a catch-all route)
key_file.fetch (host)	error	the key file could not be fetched (network error, no HTTP client)
key_file.content_type (host)	ok, warning, error	after a matching key file: text/plain ok; no Content-Type header warning; another type error; one neutral ok line when the transport exposes no headers
key_file.cache_control (host)	ok, warning	after a matching key file: Cache-Control lifetime (s-maxage, else max-age) or Age above key_file.cache_max_age is a warning (a rotation would serve the old key for that long); absent header: no line
key_file.robots (host)	ok, warning	robots.txt (when it answers 200): a Disallow covering the key file path for every bot or an engine's bot is a warning
key_file.previous (host)	ok, warning	previous_key set: the old key file still answers 200 with the old key (ok: rotation window open), or not (warning)
probe.config (host)	error	--live: the live configuration cannot be built
probe.response (host)	ok, warning, error	--live: one line per engine: 200 ok, 202 warning (verification pending), anything else error
check.failed	error	a registered CheckInterface threw; the line names the class
debounce.store	ok, warning, error	Check\DebounceStoreCheck: off, none, memory (warning), a shared store probed ok, or unusable (error)
<feature>.installed	ok, warning	Adapter\OptionalPackage: an optional package of the family is not installed (sitemap.installed); warning when its block is configured and ignored

Adapters

Code	Package	Levels	Line
wiring.messenger	symfony-bundle	warning	dispatch: messenger without a routed transport
wiring.doctrine	symfony-bundle	ok, warning	entity hooks active or not
queue.dispatch	laravel, yii2	ok	dispatch is not queue: what happens instead
queue.connection	laravel	error	the queue connection is not defined
queue.component	yii2	error	the yii2-queue component does not exist
queue.driver	laravel, yii2	ok, warning	the queue driver: sync (warning, nothing is retried) or a real one
eloquent.enabled	laravel	ok, warning	model observers active or not
active_record.enabled	yii2	ok, warning	ActiveRecord hooks active or not
url_manager.key_file	yii2	ok, error	the key file is not served by the application, or key_file is misconfigured
url_manager.pretty_url	yii2	error	enablePrettyUrl is off, /<key>.txt cannot be routed
url_manager.rule	yii2	ok, error	the key file URL rule is registered, or missing (component not in bootstrap)
sitemap.spool	sitemap	ok, warning, error	where sitemap documents are spooled; error when spool: disk has no writable directory

Application checks (CheckInterface implementations you register) choose their own codes; leave the core areas (config, environment, key, key_file, probe, debounce) to the core. A line without a code is allowed but appears as "code": null in the JSON.