--debug

Controls the minimum severity of log messages the slicer emits during a CLI run. The argument is a single integer, and the six named values map to standard log severity levels: 0 = fatal, 1 = error, 2 = warning, 3 = info, 4 = debug, 5 = trace. Setting --debug to a value installs a global severity filter; any message below that threshold is silently discarded, never written. Values of 5 and above all map to trace — the implementation uses a default branch in its level-to-severity switch, so no integer is out of range and none produces an error.

When --debug is absent entirely, the CLI defaults to 2 (warning). This is set explicitly in the startup code path — not derived from the option's declared schema default of 1 — so "no flag" and "--debug 1" produce different output: the former shows warnings and above, the latter shows only errors and fatals. Level 2 is appropriate for routine automation. Level 3 (info) adds slice-progress milestones and file-load confirmation. Levels 4 and 5 add internal engine diagnostics and are useful when a slice fails unexpectedly or produces wrong output and you need to trace which config keys were applied, which plates were processed, and where the engine diverged.

--debug controls verbosity only; it does not govern where log output is written. The output destination is determined by whatever log sink the slicer has registered, and in CLI mode no explicit console or file sink is configured by the startup code. In practice, log output goes to wherever the default log sink directs it; the source does not make this explicit.