The first cut tested `relative_to(TOPIC_DIR)`, which also matches the LEGACY
multi-record topic files -- so every record in workflow-process.md et al. lost its
anchor and linked to the top of the file instead of to its own record. Caught by
`build_decisions_catalog --check` going stale on the unmigrated corpus, not by
reading. Narrowed to `RECORDS_DIR in src.parents`, which by construction only
matches one-record-per-file.