ImportPipeline::from_merge seeds the File items and every file's columns
from Merged::sources, so a header-only CSV keeps its File item and its
columns (unseen columns are proposed as Labels, as an all-null column
is). A file with no measure column gets a records view filtered to it
instead of paging onto another file's hidden measure. Four per-file-view
rules the review found untested now each have a test that fails when
the rule is broken.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VdfEGXA7aJ6ftMsCc9PJze
Claude (agent-lpzu)