pub fn load_dir(dir: &Path) -> Result<MigrationGraph>Expand description
Walk dir and load all NNNN_*.json sidecar files into a sorted
MigrationGraph.
Only files whose stems match the four-digit prefix pattern
([0-9][0-9][0-9][0-9]_*) and whose extension is .json are loaded.
.py files and any other non-matching files are skipped. The resulting
MigrationGraph is sorted by file stem (lexicographic / discovery
order), which matches Python’s discover() sort.
This is the dir-native loader consumed by the Rust CLI (sub-plan 08).
It does not invoke Python, does not exec_module, and opens no
transaction.
§Errors
Returns MigrationError::Loader when the directory cannot be read or
a matching sidecar file cannot be read or deserialized.