# `Mailglass.Clock`
[🔗](https://github.com/szTheory/mailglass/blob/v0.1.0/lib/mailglass/clock.ex#L1)

The single legitimate source of wall-clock time in mailglass (TEST-05).
Phase 6 `LINT-12 NoDirectDateTimeNow` forbids `DateTime.utc_now/0`
outside this module.

## Three-tier resolution (D-07)

1. If `Process.get(:mailglass_clock_frozen_at)` is a `%DateTime{}` → return it.
2. Else if `Application.get_env(:mailglass, :clock)` is set → delegate to
   that impl's `utc_now/0`.
3. Else delegate to `Mailglass.Clock.System.utc_now/0` (wraps `DateTime.utc_now/0`).

Per-process isolation makes `async: true` tests safe — freezing the
clock in one test does not affect sibling tests. Runtime (not
compile-time) impl config so host apps don't recompile for test
harnesses.

# `utc_now`
*since 0.1.0* 

```elixir
@spec utc_now() :: DateTime.t()
```

Returns the process-frozen time if set, else delegates to the configured impl.

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*Consult [api-reference.md](api-reference.md) for complete listing*