The 41-line comment on logLevelRules tripped the comment-block lint
(30-line max). Move the detailed walkthrough (why each rule shape is
what it is, the three silent-failure modes, the query a level button
emits) into docs/scheduler/observability.md's existing 'Log severity'
section, which already covered the mapping at a higher level. The nix
comment now carries the short why/contract and points at the doc for
the full detail — no information dropped, just relocated.
da1f80c2ef