# `Mutare.Report.HarnessDiagnostic`
[🔗](https://github.com/foxbenjaminfox/mutare/blob/v0.2.1/lib/mutare/report/harness_diagnostic.ex#L1)

Compact diagnostics for mutants that ended as `:harness_error`.

The runner already captures the raw `mix test` output, but the final reports
need a short, stable summary rather than an entire suite log. This module is the
shared presentation layer for human, JSON, live, and abort messages.

This module formats the diagnostic. `Mutare.Sandbox.Command.Output` parses
Mix's output: `salient_line/1` selects the line to show, and `boot_failure?/1`
identifies the known boot crash.

# `line`

```elixir
@spec line(Mutare.Result.t()) :: String.t()
```

Return a site-prefixed diagnostic line suitable for multi-error summaries.

# `summary`

```elixir
@spec summary(Mutare.Result.t()) :: String.t()
```

Return a one-line diagnostic for a harness-errored result.

Includes the exit status when known plus the output's salient line
(`Mutare.Sandbox.Command.Output.salient_line/1`), truncated. The known
self-erasing boot crash gets a cause-specific summary because its output is
explicitly not useful for recovering the original exception.

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