brief-command
A deny rule: it refuses a spawn or continuation brief that teaches a command the guard denies, and names what to run instead.
What it catches
A spawn or continuation brief that teaches a command the guard denies.
Why
A worker runs the commands in its brief as written, so a denied one is refused in every worker the brief reaches, or teaches each of them a way around the refusal. Measured 2026-09-24: 33 briefs seeded 462 prefixes of a retired variable. Only what the brief presents as a command is graded, a fenced shell block or an inline code span, with the same rules a shell line gets. A line naming a command to forbid it (never, do not, denied, instead of) is passed over, and a <placeholder> reads as a word rather than a redirect.
Seeing it
A verdict names its rule in brackets, which is how you got here:
deny [brief-command]: ...
magus describe rule brief-command prints the same entry at a terminal, and
magus describe rules lists every rule this workspace enforces.