Add real-D1 coverage for core migrations and queries

[khoinguyenpham04]

This Roadmap discussion mirrors #1689: Add real-D1 coverage for core migrations and queries.

Use this discussion to upvote the roadmap item and discuss priority, use cases, and product feedback. Keep implementation tracking, reproduction details, and PR-specific feedback on the source issue.

• Source issue: #1689
• Status: Open
• Labels: None
• Original author: ascorbic

Original Issue

Goal

Core migration and query behavior should be tested against real D1 before 1.0.

Scope

Extend the existing D1 test patterns to packages/core so migration and query bugs caused by D1-specific behavior are caught before release.

Acceptance criteria

• packages/core has a real-D1 test path for migrations.
• Representative query helpers run against real D1.
• The setup works in CI or has a documented opt-in path with clear coverage expectations.
• Tests cover at least the classes of D1-specific bugs seen in previous production issues.
• The test utilities make it hard to accidentally run only sqlite/postgres for D1-sensitive code.