# 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 InstanceState

- Use `makeRuntime` (from `src/effect/run-service.ts`) for all services. It returns `{ runPromise, runFork, runCallback }` backed by a shared `memoMap` that deduplicates layers.
- Use `InstanceState` (from `src/effect/instance-state.ts`) for per-directory or per-project state that needs per-instance cleanup. It uses `ScopedCache` keyed by directory — each open project gets its own state, automatically cleaned up on disposal.
- If two open directories should not share one copy of the service, it needs `InstanceState`.
- Do the work directly in the `InstanceState.make` closure — `ScopedCache` handles run-once semantics. Don't add fibers, `ensure()` callbacks, or `started` flags on top.
- Use `Effect.addFinalizer` or `Effect.acquireRelease` inside the `InstanceState.make` closure for cleanup (subscriptions, process teardown, etc.).
- Use `Effect.forkScoped` inside the closure for background stream consumers — the fiber is interrupted when the instance is disposed.

## 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.

## Effect.cached for deduplication

Use `Effect.cached` when multiple concurrent callers should share a single in-flight computation rather than storing `Fiber | undefined` or `Promise | undefined` manually. See `specs/effect-migration.md` for the full pattern.

## 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` 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)
```
