Candidate Universal Shell amendment surfaced from Cycle 5 retrospective: json_extract over LIKE for substrate metadata queries. Project-level coding convention worth promoting to Universal Shell schema-discipline section. K7 brittleness otherwise — events written via SQLite json_object() (no space after colon) vs Python json.dumps (space after colon) created LIKE-pattern mismatch in Cycle 3 implementation. Production wizard flow was unaffected (consistent Python generation throughout) but external tools (CLI scripts, test seeds, future contributors) writing events with different JSON formatting will silently fail LIKE-based metadata lookups. Rule shape: substrate metadata queries MUST use json_extract for value-equality matching, NOT LIKE patterns on JSON-formatted text.