test_lambda_image_copies_full_import_closure caught this: importing the Historic
EPC S3 repo drags datatypes/epc/domain/historic_epc_matching.py into the handler's
init-time closure, and that reaches back into the legacy address matcher —
backend/address2UPRN/scoring.py and utils/pandas_utils.py. The image COPYed
neither, so the Lambda would have died at cold start with Runtime.ImportModuleError.
Copied file-by-file rather than `COPY backend/ backend/`: backend/ is the whole
legacy engine and the closure needs only these seven files. Their third-party
deps (pandas, requests) are already in requirements.txt, so no new pip installs.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
