Extract VaultEntry struct to entry.rs (64 lines), YAML parsing to frontmatter.rs (323 lines), and file I/O helpers to file.rs (59 lines). Tests moved to mod_tests.rs. mod.rs reduced from 1679 to 189 lines, now purely orchestration (parse_md_file, reload_entry, scan_vault). All 612 tests pass, public API unchanged. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>