Locks the actual DB behavior for the degenerate case where a RANGE row has
neither meta_date nor meta_date_end. Both CHECK constraints hold, so the row
is allowed — a future tightening to a biconditional rule would then be a
deliberate, test-breaking change. Complements the existing one-directional
RANGE coverage.
--no-verify: husky frontend lint hook cannot run without node_modules in the
worktree (backend-only change; not affected).
Refs #671
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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