Backward compatibility

indexnowkit/verify 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	VerifyingSubmitter (constructor, submit(), prepare(), addListener()), VerifyConfig (constructor, fromArray(), disabled(), loadOrDisabled(), toArray(), transportConfig(), userAgent(), defaultUserAgent()), PageSignals::fromResponse(), UrlReference::resolve(), RobotsCache (constructor, disallows(), key()), VerifyingSubmitterFactory (constructor, create(), inner()), Check\SampleCheck
Value objects — final readonly, properties only appended with defaults	PageSignals, VerifyConfig
Constants — referenced, not hard-coded; values may change in a minor	VerifyConfig::OPTIONS, DEFAULT_*, MAX_DELAY, PageSignals::MAX_BYTES, SOURCE_*, SampleCheck::CODE
Enum — closed sets	RedirectPolicy, NonCanonicalPolicy, OriginErrorPolicy
Texts that are a contract	the log-line prefixes of operations.md (operators grep them); the Reason cases of the skipped results (Noindex, RobotsDisallowed, NonCanonical, Redirected, OriginError) and the check codes verify.installed, verify.dispatch, verify.sample

Not covered: Verdict (@internal), the error sentences of the results and the exception messages, anything under tests/.

The package pins indexnowkit/core ^0.10: the Reason cases it uses and Retry\ForbiddenCounter's sibling Http\TransportFactory::lazy(..., $extraHeaders) appeared there.