Backward compatibility

indexnowkit/console follows SemVer and the tiers of the core's docs/bc.md. Before 1.0, minor versions may contain breaking changes, listed under "Changed" in CHANGELOG.md.

Tier	Members
Call — signatures only grow by appended, defaulted parameters; pass anything past the first argument by name	CheckRunner, ConfigRunner, SubmitRunner, SubmitSubjectsRunner, ExplainRunner, KeyGenerateRunner (constructors and run()), ResultRenderer, Vocabulary (constructor: named arguments), ClassNameResolver, SubjectSampler (the --sample-class sampler over the adapter's loader; PER_CLASS), Definitions::*
Commands — final classes over the runners, registered by an adapter on symfony/console; constructors take named arguments and grow only by appended, defaulted parameters	Command\SubmitCommand, Command\SubmitSubjectsCommand, Command\ExplainCommand, Command\CheckCommand, Command\ConfigCommand, Command\KeyGenerateCommand, Command\SitemapNotInstalledCommand, Command\HistoryNotInstalledCommand, Command\StatusNotInstalledCommand. The name of each is a contract (#[AsCommand], or Vocabulary::$submitSubjects for SubmitSubjectsCommand); the description is not. SubmitSubjectsCommand and ExplainCommand take string $classArgument = 'class' (since 0.5.0): the name of the class argument as the adapter's command always called it (model in Laravel) — positional on the command line either way. Command\NotInstalledCommand is the one abstract class of the package: extend it for a stub of your own optional command, the message is its only constructor argument
Implement — methods are not added without a major version	SubjectLoaderInterface, ResultFormatterInterface, ConfigSourceInterface (new in 0.5.0: before 1.0 a method may still be appended in a minor, listed under "Changed"), AbstractSubjectLoader (new in 0.5.0: the skeleton of an ORM loader — findOne() and findMany() are what you implement, resolveClass(), byIds(), all() and guard() are final; a protected method is not added without a major version)
Value objects — final readonly, properties only appended with defaults	CommandDefinition, ArgumentDefinition, OptionDefinition, SubmitSubjectsOptions
Constants — referenced, not hard-coded	ExitCode::SUCCESS, FAILURE, INVALID, OptionDefinition::FLAG, VALUE, OPTIONAL_VALUE, LIST, CheckRunner::CONFIG_INVALID
Documents — the shape only grows by optional members	docs/check.schema.json, the JSON of check --json (status, environment, items[].{level, code, message, host}); the codes are the core's docs/check-codes.md

Command surface. The argument and option names, defaults and descriptions in Definitions are what the adapters render into their commands, so they are the public API of every adapter's CLI: an option is renamed only with a deprecation window on the adapter side. CommandDefinition::laravelSignature() is gone in 0.5.0 (artisan registers the command classes of this package since Laravel 0.15; the renderer had no other consumer). Descriptions and the printed texts of the runners are not API (they are written for humans and get improved); exit codes are.

Not covered: log and exception message texts, anything under tests/.

The package pins indexnowkit/core ^0.13: the runners take the core's Config, Checker, Adapter\SubmitterFactoryInterface and Submission\ResultSummary, so a core minor that changes them ships with a console minor.