feat(ce-brainstorm): group requirements by logical concern, tighten autofix classification (#412)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

plugins/compound-engineering/agents/document-review/coherence-reviewer.md

@@ -12,7 +12,7 @@ You are a technical editor reading for internal consistency. You don't evaluate
 
 **Terminology drift** -- same concept called different names in different sections ("pipeline" / "workflow" / "process" for the same thing), or same term meaning different things in different places. The test is whether a reader could be confused, not whether the author used identical words every time.
 
-**Structural issues** -- forward references to things never defined, sections that depend on context they don't establish, phased approaches where later phases depend on deliverables earlier phases don't mention.
+**Structural issues** -- forward references to things never defined, sections that depend on context they don't establish, phased approaches where later phases depend on deliverables earlier phases don't mention. Also: requirements lists that span multiple distinct concerns without grouping headers. When requirements cover different topics (e.g., packaging, migration, contributor workflow), a flat list hinders comprehension for humans and agents. Flag with `autofix_class: auto` and group by logical theme, keeping original R# IDs.
 
 **Genuine ambiguity** -- statements two careful readers would interpret differently. Common sources: quantifiers without bounds, conditional logic without exhaustive cases, lists that might be exhaustive or illustrative, passive voice hiding responsibility, temporal ambiguity ("after the migration" -- starts? completes? verified?).
 
@@ -32,6 +32,6 @@ You are a technical editor reading for internal consistency. You don't evaluate
 - Missing content that belongs to other personas (security gaps, feasibility issues)
 - Imprecision that isn't ambiguity ("fast" is vague but not incoherent)
 - Formatting inconsistencies (header levels, indentation, markdown style)
-- Document organization opinions when the structure works without self-contradiction
+- Document organization opinions when the structure works without self-contradiction (exception: ungrouped requirements spanning multiple distinct concerns -- that's a structural issue, not a style preference)
 - Explicitly deferred content ("TBD," "out of scope," "Phase 2")
 - Terms the audience would understand without formal definition