Backward compatibility

indexnowkit/laravel 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
config/indexnow.php keys (configuration.md)	Keys and their meaning stay; new keys are only added with a default. A published config file from an older minor keeps working; a rename ships the old key as deprecated for one minor and is listed in the changelog.
Environment variables the config file reads (INDEXNOW_KEY, INDEXNOW_BASE_URL, INDEXNOW_DRY_RUN, …)	Names stay; new ones are only added.
Artisan commands and options (indexnow:check, indexnow:key:generate, indexnow:submit, indexnow:submit-model, indexnow:explain, indexnow:sitemap, indexnow:history, indexnow:status)	Names, arguments and options come from Console\Definitions of indexnowkit/console (and the sitemap and history packages); new options are only added. The model argument of submit-model and explain stays. Output is not a contract except the exit codes and the --json shape of the core formatter. The classes are the packages' since 0.15.0 — IndexNowKit\Console\Command\*, Sitemap\Console\SitemapCommand, History\Console\{History,Status}Command — each bound in the container under its class name (extending.md "Replacing a command").
Container bindings listed in extending.md	Each abstract stays bound to an implementation of the same interface; rebinding and decorating stay possible.
Facade Facades\IndexNowKit and IndexNowManager (kit(), rules(), observe(), submit(), submitModel(), submitModels(), urlsFor(), urlsForAll(), explain(), collect(), flush())	Method names and parameter names stay; new parameters are appended with defaults.
Trait Eloquent\IndexNowable, Eloquent\IndexNowObserver, Eloquent\RouteBindingFieldsInterface	The trait stays a drop-in; the observer's public hooks keep their names; the interface gets no new method without a major.
Queue job Queue\SubmitUrlsJob	Its constructor and the serialized shape stay (new parameters are appended with a default), so jobs queued before an upgrade still run after it.
Route indexnow.key_file (or key_file.route_name, {key}.txt)	Name and shape stay.
Check classes Check\QueueCheck, Check\EloquentCheck, Check\CacheStoreProbe and the indexnowkit.check tag	Names stay; adding a tagged CheckInterface keeps working. A tagged service of another type is a ConfigurationException. The router.locales line is the core's Check\LocalesCheck since 0.15.0 (Check\RouterCheck of this package is gone: same code, same texts).
Exceptions	Configuration mistakes are IndexNowKit\Exception\ConfigurationException, a bad command argument is IndexNowKit\Exception\InvalidArgumentException — both from the core, both IndexNowException.

Not a contract: log message texts (their context keys are), the exact wording the commands print (exit codes and levels are), and the service provider's private methods.

Pinning

composer require indexnowkit/laravel:^0.9 gets every 0.9.x patch. Read the changelog before a minor.