fix: preserve native transaction and lock semantics

[chubes4]

Summary

Repair native savepoint semantics outside transactions, add root-scoped advisory locks with logical connection ownership, and support conditional option-value updates under the existing mutation lock.

Lock files remain stable across ownership transfer to avoid split-inode races. Reentrant acquisition, release/close, stale-file handling and multisite ownership have independent-process coverage. Supported waits are explicitly bounded to10 seconds. Conditional option updates use supported ASCII nonbinary collation semantics; explicit BINARY comparison remains byte-exact. Unsupported Unicode collation remains an explicit limitation.

Verification

Exact candidate:3fb04a00c169895f861c0f4dde9ea531cdb237b7, based on main91ef5e7.

• Parent independently passed option-query, advisory-lock, WPDB lifecycle and transaction probes on Linux at the exact candidate.
• Cross-process CAS contenders produce one affected row and one winner. The pre-opened lock-waiter test prevents regression of the split-inode race.
• Savepoint behavior was compared with MariaDB11.4 for autocommit on/off and preserves inactive-session state.
• Real paired DME VenueProfileMutationsTest on WordPress7.1/PHP8.3.32/PHPUnit9.6.35: native24 total =19 passed,1 failed,3 errors,1 skipped; MySQL8.4 control24 total =23 passed,1 skipped.
• Prior lock and conditional-update failures no longer recur. Loaded candidate hashes were checked in the actual managed runtime during investigation, separately from recipe revision metadata.

Remaining venue differences are explicit: native accepts a foreign-site attachment that MySQL rejects; three tests require physical mysqli access. Event-upsert unit tests rewrite lock queries to SELECT1, whose support is separate work in #393. No full consumer-parity claim is made.

Reproduction

php tests/smoke-native-option-query.php
php tests/smoke-native-advisory-locks.php
php tests/smoke-native-wpdb-lifecycle.php
php tests/probe-native-transaction-semantics.php

For the paired consumer run, use wp-codebox's managed multisite wordpress.phpunit command with plugin-slug=data-machine-events, test-file=tests/Integration/VenueProfileMutationsTest.php, database-type=mdi-native versus mysql, the pinned DME source88d55a907b12638e88baee5b492501dbed5c2665, Data Machine dependency31befb659aaa5268e79a0c28a16321c3ee5e1108, and managed wp-phpunit harness. Override the MDI extra-plugin source with this candidate without retaining the bundled archive digest, and verify loaded PHP file hashes.

Supports #377, which remains open. No release or deployment is included.

AI Assistance

OpenAI GPT-5.6 Terra (openai/gpt-5.6-terra) via OpenCode implemented repairs and ran paired consumer verification. GPT-6 Astra (openai/gpt-6-astra) via OpenCode reviewed lock races, result semantics, source provenance and collation, independently reran the exact candidate's Linux gates, and finalized this scoped improvement under Chris Huber's direction.