Summary

• document createPipeline and rebuild its supporting internals around dedicated type definitions for diagnostics and runners
• introduce a typed extension coordinator module to centralise lifecycle execution, rollback, and commit handling
• add a regression test covering rollback metadata delivery when extension rollbacks fail after builder errors

Testing

• pnpm --filter @wpkernel/pipeline test
• pnpm --filter @wpkernel/pipeline typecheck
• pnpm --filter @wpkernel/ui build
• pnpm --filter @wpkernel/core build
• pnpm --filter @wpkernel/php-driver build
• pnpm --filter @wpkernel/test-utils build
• pnpm --filter @wpkernel/e2e-utils build
• pnpm --filter @wpkernel/php-json-ast build
• pnpm --filter @wpkernel/wp-json-ast build
• pnpm --filter @wpkernel/cli build

Codex Task