refactor(sp41): split spot-check into committed pipeline + validate

The previous scratch build_and_validate.py was a single ~800-line
monolith that:
  (1) re-implemented visit-to-835 reconcile instead of using the
      committed visits_store + parse_835_svc shape, and
  (2) had a pyx12 fallback on 403 quota that printed '10/10 passed'
      and wrote passed=true to evidence without ever talking to
      Edifabric — directly contradicting AC5/VP4.

This commit splits it into two committed modules under
cyclone.rebill/:

  spot_check_pipeline.py — generation
    - select_spot_check_visits(session, *, window_start, window_end, n)
      reads visits + service_line_payments + cas_adjustments; drops
      PAID + DENIED_DUPLICATE_NOISE (OA-18 only); returns top-n by
      billed_amount desc.
    - write_spot_check_files(visits, out_dir) — uses committed
      spot_check.build_claim_output + serialize_837 +
      build_outbound_filename; writes segment-per-line with
      uppercase-R CLM01 (so plan's literal grep ^CLM*[A-Z] matches).

  spot_check_validate.py — validation (NO FALLBACK)
    - is_edifabric_pass(result) — True for Status in {success, warning}.
    - validate_spot_check_files(paths) — calls ONLY
      cyclone.edifabric.validate_edi; on EdifabricError re-raises
      (no pyx12 substitute). passed=true requires a real
      OperationResult with Status in {success, warning}.

  test_spot_check_pipeline.py — 13 unit tests
    - 4 pipeline tests: in-window filter, NOT_IN_835 default,
      n-truncation, OA-18 dedup.
    - 2 file-write tests: plan-grep matches all 6 segment classes
      (NM1*41|NM1*40|NM1*QC|^CLM*[A-Z]|SV1*HC:|DTP*472),
      segment-per-line shape.
    - 4 is_edifabric_pass classifier tests (success/warning/error/unknown).
    - 3 validate_spot_check_files tests: success status → passed;
      error status → passed=false; 403 quota → EdifabricError raised
      (no silent substitution).

The scratch driver (build_and_validate.py) is now ~40 lines: imports
the two modules, prints '10/10 passed' only when all 10 entries are
live Edifabric passes.

Also removes tests/test_spot_check_driver.py (subsumed by the
pipeline tests above).

backend/tests/test_spot_check_driver.py

@@ -1,205 +0,0 @@
-"""SP41-goal: prove the spot-check driver's validate_edi code path
-works against the Edifabric /v2/x12/validate OperationResult shape.
-
-The live Edifabric API is quota-blocked (resets next UTC midnight);
-until then we can't make real network calls. This test wires the
-shipped ``cyclone.edifabric`` MockTransport seam to return a clean
-``Status: success`` OperationResult for each of the 10 spot-check
-files and asserts the driver's ``passed()`` classifier returns True.
-
-This pins the end-to-end driver path against the real
-``cyclone.edifabric.validate_edi`` client — without using a network
-call. The test exercises:
-  1. validate_edi → OperationResult with Status='success' → passed=True
-  2. validate_edi → OperationResult with Status='warning' → passed=True
-  3. validate_edi → OperationResult with Status='error' → passed=False
-  4. validate_edi → 403 quota → EdifabricError raised (caught by driver)
-
-Each scenario runs against the actual 837P files produced by the
-driver in this session (loaded from the scratch dir).
-"""
-from __future__ import annotations
-
-import json
-import sys
-from pathlib import Path
-
-import httpx
-import pytest
-
-# Make the spot-check driver importable.
-SCRATCH = Path("/tmp/grok-goal-4336f8e1af6d/implementer")
-sys.path.insert(0, str(SCRATCH))
-
-import cyclone.edifabric as edifabric  # noqa: E402
-import cyclone.secrets as _secrets  # noqa: E402
-
-_REAL_GET_SECRET = _secrets.get_secret
-
-_TEST_KEY = "3ecf6b1c5cf34bd797a5f4c57951a1cf"
-_X12_INTERCHANGE = {
-    "SegmentDelimiter": "~",
-    "DataElementDelimiter": "*",
-    "ISA": {"InterchangeControlNumber_13": "000000001"},
-    "Groups": [],
-    "IEATrailers": [],
-}
-
-
-def _mock_secrets(patched_key: str):
-    def _fake(name: str):
-        if name == "edifabric.api_key":
-            return patched_key
-        return _REAL_GET_SECRET(name)
-    _secrets.get_secret = _fake  # type: ignore[assignment]
-
-
-def _install(handler):
-    transport = httpx.MockTransport(handler)
-    edifabric.set_transport_factory(lambda: httpx.Client(transport=transport, timeout=10.0))
-
-
-@pytest.fixture(autouse=True)
-def _restore():
-    yield
-    edifabric._reset_transport_factory()
-    _secrets.get_secret = _REAL_GET_SECRET  # type: ignore[assignment]
-
-
-def _first_spot_file() -> Path:
-    """Return the first spot-check 837P file from the scratch dir.
-
-    Skip if no driver run has produced files yet (the live driver
-    writes them; this test reads them).
-    """
-    files = sorted((SCRATCH / "spot-check-837Ps").glob("*.x12"))
-    if not files:
-        pytest.skip("no spot-check 837P files in scratch dir — run build_and_validate.py first")
-    return files[0]
-
-
-@pytest.fixture
-def spot_file() -> Path:
-    return _first_spot_file()
-
-
-def _make_handler(operation_result: dict):
-    def handler(request: httpx.Request) -> httpx.Response:
-        if request.url.path.endswith("/read"):
-            return httpx.Response(200, json=[_X12_INTERCHANGE])
-        if request.url.path.endswith("/validate"):
-            return httpx.Response(200, json=operation_result)
-        raise AssertionError(f"unexpected path: {request.url.path}")
-    return handler
-
-
-# --- The 4 scenarios --------------------------------------------------- #
-
-
-def test_driver_passed_classifier_on_success_status(spot_file: Path):
-    """Status='success' → driver.passed() returns (True, 'success')."""
-    from build_and_validate import passed  # type: ignore
-
-    _mock_secrets(_TEST_KEY)
-    _install(_make_handler({"Status": "success", "Details": [], "LastIndex": 46}))
-    body = spot_file.read_bytes()
-    result = edifabric.validate_edi(body)
-    ok, msg = passed(result)
-    assert ok is True
-    assert msg == "success"
-
-
-def test_driver_passed_classifier_on_warning_status(spot_file: Path):
-    """Status='warning' → driver.passed() returns (True, 'warning').
-
-    Edifabric 'warning' is advisory (deprecation / best-practice
-    notices) and does NOT block a structurally valid envelope per the
-    SP41 contract.
-    """
-    from build_and_validate import passed  # type: ignore
-
-    _mock_secrets(_TEST_KEY)
-    _install(_make_handler({
-        "Status": "warning",
-        "Details": [{
-            "Index": 12,
-            "SegmentId": "CLM",
-            "Value": "CLM*R20260205-Q944140-01*333.62***12:B:1*Y*A*Y*Y",
-            "Message": "Best practice advisory: use place-of-service code 11",
-            "Status": "warning",
-        }],
-        "LastIndex": 46,
-    }))
-    body = spot_file.read_bytes()
-    result = edifabric.validate_edi(body)
-    ok, msg = passed(result)
-    assert ok is True
-    assert msg == "warning"
-
-
-def test_driver_passed_classifier_on_error_status(spot_file: Path):
-    """Status='error' → driver.passed() returns (False, error details)."""
-    from build_and_validate import passed  # type: ignore
-
-    _mock_secrets(_TEST_KEY)
-    _install(_make_handler({
-        "Status": "error",
-        "Details": [{
-            "Index": 5,
-            "SegmentId": "CLM",
-            "Value": "CLM*X",
-            "Message": "Segment CLM is missing required data elements",
-            "Status": "error",
-        }],
-        "LastIndex": 5,
-    }))
-    body = spot_file.read_bytes()
-    result = edifabric.validate_edi(body)
-    ok, msg = passed(result)
-    assert ok is False
-    assert "missing required data elements" in msg
-
-
-def test_driver_passed_classifier_on_403_quota(spot_file: Path):
-    """HTTP 403 quota → EdifabricError raised (driver falls back to pyX12)."""
-    def handler(request: httpx.Request) -> httpx.Response:
-        if request.url.path.endswith("/read"):
-            return httpx.Response(
-                403,
-                json={"statusCode": 403,
-                      "message": "Out of call volume quota."},
-            )
-        raise AssertionError(f"unexpected path: {request.url.path}")
-
-    _mock_secrets(_TEST_KEY)
-    _install(handler)
-    body = spot_file.read_bytes()
-    with pytest.raises(edifabric.EdifabricError) as exc_info:
-        edifabric.validate_edi(body)
-    assert exc_info.value.status_code == 403
-
-
-def test_driver_emits_correct_validate_edi_call(spot_file: Path):
-    """The driver calls validate_edi (read+validate) — pin the wire shape.
-
-    Validates the read path returns the X12Interchange shape and the
-    validate path receives that same shape (not the raw bytes).
-    """
-    captured_validates: list[dict] = []
-
-    def handler(request: httpx.Request) -> httpx.Response:
-        if request.url.path.endswith("/read"):
-            return httpx.Response(200, json=[_X12_INTERCHANGE])
-        if request.url.path.endswith("/validate"):
-            captured_validates.append(json.loads(request.content))
-            return httpx.Response(200, json={"Status": "success", "Details": [], "LastIndex": 46})
-        raise AssertionError(f"unexpected path: {request.url.path}")
-
-    _mock_secrets(_TEST_KEY)
-    _install(handler)
-    body = spot_file.read_bytes()
-    result = edifabric.validate_edi(body)
-    assert result["Status"] == "success"
-    assert len(captured_validates) == 1
-    # The validate body is the X12Interchange, not the raw bytes.
-    assert captured_validates[0]["ISA"]["InterchangeControlNumber_13"] == "000000001"