Backward compatibility

indexnowkit/testing 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	KeyFileAssertions::*, CheckOutputAssertions::*, ReadmeAssertions::* and their constants (SECTION_EN, SECTION_RU, FAMILY_COMMANDS, CROSS_ADAPTER_KEYS grow, never shrink)
Extend — the abstract driver methods of a kit only grow by appended methods with a default implementation; a scenario is only added, never removed or renumbered, in a minor	CoreConformanceTestCase, OrmConformanceTestCase
Resource — the file path and the scenario names are stable; scenarios are added, not renamed	resources/mock-server/router.php (X-Mock-Scenario: ok200, pending202, bad400, forbidden403, unprocessable422, ratelimit429, ratelimit429-then-ok, flaky500-then-ok, timeout; GET /_mock/requests, DELETE /_mock/requests; MOCK_KEYS)

The conformance identifiers (C01–C22, A01–A21, H01–H06) are a cross-language contract of the specification: they are frozen at 1.0 of the family. What an assertion accepts may become stricter in a minor when the specification does (listed in the changelog); what it rejects never becomes accepted silently.

Not covered: the failure-message texts of the assertions, anything under tests/.

The package pins indexnowkit/core ^0.7: it reads Config::OPTIONS and the test doubles of the core, so a core minor that renames them ships with a testing minor.