Audit batch 6: B1 zero-gate sentinel, I1 known-to-lack marker, I2 wire error returns row status, M1 max-rounds label, M2 chosen-last convention, M5 escalate write retry, M6/M7 clear/pass CAS tests

cloud/routing_shadow.py

@@ -69,6 +69,13 @@ _DETAIL_RE = re.compile(
     # parse, and legacy suggested-with-whitespace rows still land
     # in the unparseable bucket (counted, batch 2) rather than
     # being silently lost.
+    # Audit batch 6 (M2): the "chosen is last" placement is a
+    # standing convention, not an accident — (.+?) runs to end
+    # of line, so any field appended after chosen would be
+    # swallowed into chosen and misparsed. Writers (the two
+    # worker_routing audit sites in cloud/worker.py) must keep
+    # chosen as the final field; a test in test_audit_batch6.py
+    # locks both sites to that shape.
     r"(?:\s+chosen=(?P<chosen>.+?))?\s*$")