# opencode database guide

## Database

- **Schema**: Drizzle schema lives in `src/**/*.sql.ts`.
- **Naming**: tables and columns use snake*case; join columns are `<entity>_id`; indexes are `<table>*<column>\_idx`.
- **Migrations**: generated by Drizzle Kit using `drizzle.config.ts` (schema: `./src/**/*.sql.ts`, output: `./migration`).
- **Command**: `bun run db generate --name <slug>`.
- **Output**: creates `migration/<timestamp>_<slug>/migration.sql` and `snapshot.json`.
- **Tests**: migration tests should read the per-folder layout (no `_journal.json`).

# opencode Effect rules

Use these rules when writing or migrating Effect code.

See `specs/effect-migration.md` for the compact pattern reference and examples.

## Core

- Use `Effect.gen(function* () { ... })` for composition.
- Use `Effect.fn("Domain.method")` for named/traced effects and `Effect.fnUntraced` for internal helpers.
- `Effect.fn` / `Effect.fnUntraced` accept pipeable operators as extra arguments, so avoid unnecessary outer `.pipe()` wrappers.
- Use `Effect.callback` for callback-based APIs.
- Prefer `DateTime.nowAsDate` over `new Date(yield* Clock.currentTimeMillis)` when you need a `Date`.

## Schemas and errors

- Use `Schema.Class` for multi-field data.
- Use branded schemas (`Schema.brand`) for single-value types.
- Use `Schema.TaggedErrorClass` for typed errors.
- Use `Schema.Defect` instead of `unknown` for defect-like causes.
- In `Effect.gen` / `Effect.fn`, prefer `yield* new MyError(...)` over `yield* Effect.fail(new MyError(...))` for direct early-failure branches.

## Runtime vs Instances

- Use the shared runtime for process-wide services with one lifecycle for the whole app.
- Use `src/effect/instances.ts` for per-directory or per-project services that need `InstanceContext`, per-instance state, or per-instance cleanup.
- If two open directories should not share one copy of the service, it belongs in `Instances`.
- Instance-scoped services should read context from `InstanceContext`, not `Instance.*` globals.

## Preferred Effect services

- In effectified services, prefer yielding existing Effect services over dropping down to ad hoc platform APIs.
- Prefer `FileSystem.FileSystem` instead of raw `fs/promises` for effectful file I/O.
- Prefer `ChildProcessSpawner.ChildProcessSpawner` with `ChildProcess.make(...)` instead of custom process wrappers.
- Prefer `HttpClient.HttpClient` instead of raw `fetch`.
- Prefer `Path.Path`, `Config`, `Clock`, and `DateTime` when those concerns are already inside Effect code.
- For background loops or scheduled tasks, use `Effect.repeat` or `Effect.schedule` with `Effect.forkScoped` in the layer definition.

## Instance.bind — ALS for native callbacks

`Instance.bind(fn)` captures the current Instance AsyncLocalStorage context and restores it synchronously when called.

Use it for native addon callbacks (`@parcel/watcher`, `node-pty`, native `fs.watch`, etc.) that need to call `Bus.publish`, `Instance.state()`, or anything that reads `Instance.directory`.

You do not need it for `setTimeout`, `Promise.then`, `EventEmitter.on`, or Effect fibers.

```typescript
const cb = Instance.bind((err, evts) => {
  Bus.publish(MyEvent, { ... })
})
nativeAddon.subscribe(dir, cb)
```