What an OS process did: exit status, captured output, and termination evidence.

:status is the exit code for a normal exit, or {:signal, number} when the process died from a signal, where number is the signal number (for example {:signal, 15} for the SIGTERM Forcola itself sends on timeout). The only atom case is {:signal, :unconfirmed}, which means the shim could not confirm death before its own deadline; treat it as leaked and investigate.

:evidence defaults to nil for source-compatible struct construction. Forcola.run/2 populates a map with these independent observations:

• :child_status / :child_signal - raw direct-child exit code or signal, or nil when unavailable. These survive unconfirmed cleanup.
• :termination - :exit, :malformed_exit, :backstop, {:transport, port_status}, or {:spawn, reason}.
• :reason - nil, :timeout, :idle_timeout, :max_output_bytes, or :observer_overflow. Early JSON on stdout does not override this reason.
• :output_truncated - true, false, or :unknown when not reported.
• :cleanup - :confirmed, :unconfirmed, or :unknown. Only an explicit, valid native EXIT confirmation yields :confirmed.
• :scope - :process_group, :active_cgroup, or :unknown. Process-group confirmation says nothing about descendants that escaped that group. It never confirms an entire process tree on macOS.
• :guard_close - :ok or {:error, :guard_close_timeout}. Closing the transport is separate from native cleanup confirmation.

Without new options, a legacy shim's EXIT missing confirmed retains its original status projection; its evidence still records unknown cleanup. Missing or malformed EXIT never supplies positive cleanup evidence.