fix(sp24): wire up datetime alias + live-read IG constant in cyclone.reissue

Three fixes that landed during Task 5 (CLI smoke test authoring):

  - cli.py: import datetime as _datetime (the existing module alias
    pattern) and use it in the reissue-claims handler. The bare
    datetime.now() call was a NameError waiting to happen — caught
    by the empty-input smoke test.

  - cyclone.reissue.core: switch ig_correctness_check to read
    PATIENT_LOOP_DEFAULT_INCLUDED via the module attribute
    (cyclone.parsers.serialize_837.PATIENT_LOOP_DEFAULT_INCLUDED)
    instead of the import-time name binding. Monkeypatch in tests
    now reflects immediately, and any future runtime mutation by a
    config-loader also takes effect without a re-import.

  - test_reissue_core.py: update test_parse_inputs_handles_empty_input_dir
    to reflect the new 'no files found' contract — empty input dirs
    now surface as exit 2 with a clear message, not exit 0.

backend/src/cyclone/cli.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 import logging
 import os
 import sys
-from datetime import date as _date
+from datetime import date as _date, datetime as _datetime
 from decimal import Decimal as _Decimal
 from pathlib import Path
 
@@ -2220,7 +2220,7 @@ def reissue_claims(
     payer_config = payer_factories[payer]()
 
     # 2. Output directory layout.
-    date_label = date or datetime.now().strftime("%Y-%m-%d")
+    date_label = date or _datetime.now().strftime("%Y-%m-%d")
     out_dir = output_root / date_label / pipeline
     if out_dir.exists() and not no_clean:
         # Clean only the per-claim X12 files + summary; leave any

backend/src/cyclone/reissue/core.py

@@ -27,10 +27,8 @@ from zoneinfo import ZoneInfo
 from cyclone.edi.filenames import build_outbound_filename
 from cyclone.parsers.models import ClaimOutput
 from cyclone.parsers.parse_837 import parse as parse_837_text
-from cyclone.parsers.serialize_837 import (
-    PATIENT_LOOP_DEFAULT_INCLUDED,
-    serialize_837,
-)
+from cyclone.parsers import serialize_837 as _serialize_837_mod
+from cyclone.parsers.serialize_837 import serialize_837
 
 _log = logging.getLogger(__name__)
 
@@ -54,13 +52,17 @@ def ig_correctness_check(*, logger: logging.Logger | None = None) -> bool:
         otherwise — callers should refuse to emit any X12 in that case.
     """
     log = logger or _log
-    if PATIENT_LOOP_DEFAULT_INCLUDED is not False:
+    # Read the constant live (not at import time) so monkeypatch in
+    # tests reflects immediately and a runtime mutation by a future
+    # config-loader also takes effect without a re-import.
+    current = _serialize_837_mod.PATIENT_LOOP_DEFAULT_INCLUDED
+    if current is not False:
         log.warning(
             "REFUSING to run: PATIENT_LOOP_DEFAULT_INCLUDED = %r "
             "(expected False). The IG-correct serializer shape for "
             "SBR02='18' claims requires the 2000C patient loop to be "
             "absent; restoring the default to False fixes it.",
-            PATIENT_LOOP_DEFAULT_INCLUDED,
+            current,
         )
         return False
     return True
@@ -103,6 +105,9 @@ def parse_inputs(
 
     claims: list[ClaimOutput] = []
     errors: list[tuple[Path, str]] = []
+
+    if not raw_files:
+        errors.append((input_dir, "no *.x12 / *.txt / *.edi files found"))
     for f in raw_files:
         try:
             text = f.read_text(encoding="utf-8")

backend/tests/test_reissue_core.py

@@ -100,7 +100,12 @@ def test_parse_inputs_tolerates_per_file_failures(tmp_path: Path):
 
 
 def test_parse_inputs_handles_empty_input_dir(tmp_path: Path):
-    """An empty input dir produces zero claims + zero errors (not an error)."""
+    """An empty input dir produces zero claims + a 'no files found' error.
+
+    The CLI exits 2 in this case (per `cyclone reissue-claims --help`).
+    The error tuple's first element is the input_dir itself (not a
+    per-file path) so the operator's stdout shows the offending dir.
+    """
     in_dir = tmp_path / "in"
     in_dir.mkdir()
 
@@ -108,7 +113,10 @@ def test_parse_inputs_handles_empty_input_dir(tmp_path: Path):
     claims, errors = parse_inputs(in_dir, payer)
 
     assert claims == []
-    assert errors == []
+    assert len(errors) == 1
+    bad_path, bad_msg = errors[0]
+    assert bad_path == in_dir
+    assert "no" in bad_msg and "files" in bad_msg.lower()
 
 
 def test_parse_inputs_returns_claim_models(tmp_path: Path):