Read REVIEW_COMMON.md (repo root) first - its contract binds this checklist. Architecture
doc: CLAUDE.md.
Removing REVIEW.das's check that no two git-tracked .das files declare the same shared
module name is a defect.
A diff that lets two git-tracked .das files declare the same shared module name adds
TOLERATED_SHARED_TWINS rows naming every file that may declare it, and states in those rows why
no process compiles two of them by accident. The first file a process compiles that declares module X shared becomes that process's module
X, and every later file declaring or requiring X in the same process gets that module - so any
process compiling both gives the second file the first's module.