Inserts a per-claim-id check_duplicate() walk into submit_file between
the payer-mismatch guard and the BatchRecord837 DB write (Task 9).
If any CLM01 in the parsed 837P file was submitted within the 30-day
window recorded in the submission_dedup table, submit_file raises
DuplicateClaimError before any DB write or SFTP upload. The DB-first,
upload-second invariant is preserved: a duplicate blocks both the
BatchRecord837 write AND the paramiko upload.
The api_routers/submission.submit_batch per-file loop special-cases
DuplicateClaimError BEFORE the generic Exception handler so the
200-with-results status-code contract documented at the top of the
module is preserved (per-file failures stay in the body). The
exception remains 409-class by design — a future caller that
propagates it past the per-file loop will surface 409 at the FastAPI
layer.
Approach A per the Task 9 spec (raise, don't return a SubmitResult).
Tests:
- test_submission_dedup.test_submit_file_raises_on_duplicate_claim_id
pre-populates the dedup table via record_submission('CLM001', ...),
calls submit_file against minimal_837p.txt, expects DuplicateClaimError
with structured claim_id / original_submission_at attributes, and
pins the DB-write invariant (no Batch row landed) plus an
AssertionError sentinel on the SFTP factory.
Nora