Accept proven transactional table backends for identity reservation

[chubes4]

Summary

The maintainer approved this generic capability API; the previous hold is lifted. This is backend-neutral application integration, not proof that MDI implements the original MySQL-specific consumer contract unchanged.

• Ask optional wpdb::supports_transactional_tables(array $tables) about the exact reservation and posts table set.
• Accept only strict true. Missing methods, incomplete coverage, false-like answers and exceptions fail closed.
• Preserve schema column/index validation, the default MySQL/InnoDB verification and SQLite safeguards.
• Introduce no MDI class dependency or fake InnoDB label.

Engine prerequisite: Automattic/markdown-database-integration#403. Track remaining MySQL parity separately in Automattic/markdown-database-integration#377.

Verification

Data Machine 4432c2433dbce2985654cc88f57dc3d5abc411f0 passed the following runs. Current b6fe3762ea92a31b30d63cb72607dfaaa8582b4f adds only a PHPCS assignment-alignment fix; its lint, audit, refactor and all four test shards passed. MDI prerequisite #403 is merged as d4907227f4c252d1f781134bd79f00f4e1a112b1.

• Dedicated reservation tests on MySQL: 26 passed, 0 failed, 1 skipped / 27.
• Full DME with the native provider and this consumer adapter: 1040 passed, 4 failed, 9 skipped / 1053.
• Full DME with physical MySQL and this consumer adapter: 1046 passed, 0 failed, 7 skipped / 1053.

All 15 prior identity/upsert failure identities disappear with the adapter. The four remaining native failures require physical mysqli connections or handles. The native provider is tested at dcfe6b4; restored PR403 head 34057b0 has the identical tree. Its transaction behavior is bounded coarse serialization, not MVCC.

With the repository's configured WordPress PHPUnit database and fixtures:

vendor/bin/phpunit --configuration phpunit.xml tests/Unit/Core/Database/PostIdentityReservations/PostIdentityReservationsTest.php

The managed test runner used tests/fixtures/phpunit-isolation.php and the shared WP-CLI bootstrap. The capability fake tests routing and failure handling, not transactional behavior of MyISAM. Independent-process conformance belongs to the native prerequisite.

Operator-retained evidence: transaction-capability-full-native-dcfe6b4-4432c243, transaction-capability-full-mysql-dcfe6b4-4432c243, and dm-post-identity-mysql-4432c243-dedicated, with full JUnit and effective recipes. No consumer assertions were weakened. No release or deployment is included.

AI Assistance

OpenAI GPT-6 Astra (openai/gpt-6-astra) via OpenCode investigated transactional requirements, implemented and reviewed the generic adapter through isolated agents, corrected test-double/bootstrap and lint issues, and ran dedicated MySQL and paired native/MySQL consumer verification under maintainer direction.