Backward compatibility

indexnowkit/yii2 follows SemVer. Before 1.0, minor versions may contain breaking changes; every one is listed under "Changed" in CHANGELOG.md with the migration. After 1.0 the rules below become the promise. The core's tiers ("call", "implement", "may grow") apply to every core class you touch through this package: core bc.md.

What the package keeps stable

Surface	Promise
Component options ('options' => [...] of IndexNowComponent, configuration.md)	Keys and their meaning stay; new keys are only added with a default. A rename ships the old key as deprecated for one minor and is listed in the changelog.
Component properties options, transport, debounceStore, dispatcher, urlResolver, logger, checks, environment, sitemapInstalled and the accessors config(), kit(), rules(), keys(), transport(), submitter(), collector(), dispatcher(), debounceStore(), staging(), services(), sitemapPackage(), sitemapInstalled()	Names and types stay; new properties and accessors are only added.
Console actions and options (indexnow/check, indexnow/key-generate, indexnow/submit, indexnow/submit-record, indexnow/explain, indexnow/sitemap)	Names, arguments and options come from the core Console\Definitions; new options are only added. Output is not a contract except the exit codes and the --json shape of the core formatter.
Bootstrap ('bootstrap' => ['indexnow']), the controller id indexnow, the key file controller indexnow-key-file and its URL rule <key>.txt	Ids and the rule stay.
Behavior ActiveRecord\IndexNowBehavior, ActiveRecord\IndexNowObserver	The behavior stays a drop-in; the observer's public hooks keep their names.
Queue job Queue\SubmitUrlsJob	Its public properties and the serialized shape stay, so jobs pushed before an upgrade still run after it.
Check classes Check\QueueCheck, Check\UrlManagerCheck, Check\ActiveRecordCheck, Check\CacheProbe and the checks property	Names stay; adding a CheckInterface keeps working.

Not a contract: log message texts (their context keys are), the exact wording the actions print (exit codes and levels are), and the Wiring / References helpers the component builds its graph with.

Pinning

composer require indexnowkit/yii2:^0.7 gets every 0.7.x patch. Read the changelog before a minor.