Migrations that Alchemy can apply to D1 and Durable Objects #59

Signal

We use Alchemy for all Cloudflare resources. We want effect-orm migrations in a format that Alchemy applies. For D1, that is D1Database({ migrationsDir }). For Durable Objects, it is a bundled list the object runs at start.

Why (MyRemotely / CAFE)

• One source of truth: table definitions → generated SQL → Alchemy deploy. No second tool such as wrangler or drizzle-kit.
• PR feat(sqlite): generate migrations #51 adds SQLite migration generation. This issue is about the delivery path.

Scope

• Output layout that Alchemy D1 reads (ordered .sql files, journal).
• A DO helper: Migrations.runOnStart(storage, bundledMigrations) with a ledger table inside the object.
• Per-tenant fan-out: apply one migration to N tenant databases, with resume after a partial failure (the ClickHouse runner has a journal and resume already).

Done when

• alchemy deploy creates a D1 database and applies effect-orm migrations to it.
• A DO applies new migrations when it starts after a deploy.

Part of #52: the CAFE-stack roadmap signal from MyRemotely. This shows the direction we want, and it is not a demand. We can send a PR if you accept the idea.