# defaultClock (schema-registry)

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## Purpose

`defaultClock` is the single point in `@suaveplan/bitpacker-schema/registry` where the wall clock is read. The `SchemaRegistry` class accepts an injectable `Clock` for stamping `createdAt`/`updatedAt` on registered entries; when no clock is provided, it falls back to this default.

Centralising the `Date.now()` call this way matches the pattern used by `@suaveplan/bitpacker-streaming` and `@suaveplan/bitpacker-network`. suaveplan enforces a "no module-scope `Date.now()`/`Math.random()`" rule outside allow-listed defaults — this file is one of those defaults.

## Features

- Single named export `defaultClock: Clock` typed via `@suaveplan/types`.
- Pure function — no side effects beyond reading the wall clock.
- Idiomatic Suaveplan convention for clock injection.

## Usage: Basic Example

```ts
import { defaultClock } from "@suaveplan/bitpacker-schema";

const now = defaultClock();
```

## Usage: Advanced Example

```ts
import type { Clock } from "@suaveplan/types";
import { SchemaRegistry } from "@suaveplan/bitpacker-schema";

// Inject a deterministic clock for reproducible test timestamps.
let t = 0;
const fakeClock: Clock = () => {
    t += 1000;
    return t;
};

const registry = new SchemaRegistry(undefined, { clock: fakeClock });
await registry.registerSchema(
    { id: "uuid" },
    { namespace: "events", name: "user-created" }
);
```

## API Reference

### `defaultClock: Clock`

Returns `Date.now()` — the current wall-clock time in milliseconds.

## Implementation Notes

The `Clock` type is `() => number`. suaveplan prefers function types over class instances for monotonic primitives because they are trivially serialisable, comparable, and substitutable in tests without dependency-injection frameworks.

The reason this lives in `registry/defaults/` rather than as a static class member is the lint rule that bans module-scope `Date.now()` calls in production code. By scoping the call to a single named, lint-allow-listed module, we keep the rest of the package free of static analysis exceptions.