# `registerSqliteMemoryEngine`

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_(no submodules)_
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## Purpose

Registers the in-memory SQLite adapter under `engine: "sqlite-memory"` in the open `@suaveplan/api-db-adapter` engine registry. Once called, any consumer that constructs an adapter via `createDbAdapter({ engine: "sqlite-memory", ... })` receives an instance produced by this package. The TypeScript-side declaration-merge into `DatabaseEngineRegistry` means the engine name is accepted as a string-literal-typed argument with no cast.

This is the bridge that lets `@suaveplan/api-host/testing`'s Stage-5 `createTestHost` boot a plugin entirely against an in-memory SQLite without changing any of The adapter code paths. The registration is idempotent — calling twice replaces the previous factory — and the function returns a disposer so tests can unregister the engine in `afterEach`.

## Features

- Type-level: `declare module` extends `DatabaseEngineRegistry` with `"sqlite-memory": true`.
- Runtime: `registerEngine("sqlite-memory", factory)` against the api-db-adapter registry.
- Factory honours `DbAdapterOptions.url` → `filename` so callers may write `engine: "sqlite-memory"` + `url: ":memory:"` (or a file path).
- Forwards `tenantColumn` + `autoInjectInserts` so The wrapper composes correctly on top.
- Returns a disposer `() => boolean` that unregisters the engine.

## Usage: Basic

```ts
import { createDbAdapter } from "@suaveplan/api-db-adapter";
import { registerSqliteMemoryEngine } from "@suaveplan/api-db-sqlite-memory/engine";

const dispose = registerSqliteMemoryEngine();
const adapter = await createDbAdapter({
    engine: "sqlite-memory",
    url: ":memory:",
});
await adapter.admin.execute("CREATE TABLE t (id INTEGER PRIMARY KEY)");
await adapter.close();
dispose();
```

## Usage: Advanced

Test lifecycle with deterministic registry teardown:

```ts
import {
    afterEach,
    beforeEach,
    describe,
    it,
} from "@suaveplan/testing/runner";
import { createDbAdapter } from "@suaveplan/api-db-adapter";
import { registerSqliteMemoryEngine } from "@suaveplan/api-db-sqlite-memory/engine";

describe("plugin install", () => {
    let dispose: () => boolean;
    beforeEach(() => {
        dispose = registerSqliteMemoryEngine();
    });
    afterEach(() => {
        dispose();
    });

    it("resolves the engine sentinel", { timeout: 5000 }, async () => {
        const adapter = await createDbAdapter({
            engine: "sqlite-memory",
            url: ":memory:",
            tenantColumn: "tenant_id",
        });
        await adapter.close();
    });
});
```

## API Reference

- `registerSqliteMemoryEngine()` — returns a disposer `() => boolean`.

## Implementation Notes

The declaration-merge happens inside this module so the type extension is only visible after the consumer imports from `@suaveplan/api-db-sqlite-memory/engine` (or the package root, which re-exports). That keeps the engine sentinel scoped to plugins that opt in, matching the design intent of the open `DatabaseEngineRegistry`. The factory normalises an empty or `"sqlite-memory:"` url to `":memory:"` because `createDbAdapter`'s Zod schema requires `url` to be non-empty — without this normalisation, callers would have to write `url: ":memory:"` redundantly even when the engine name already implies it.