fix: make corporate actions atomic and recoverable

tests/test_issue34_regressions.py

@@ -44,6 +44,23 @@ def test_canonical_hash_same_payload_and_changed_payload_differ():
     assert canonical_payload_hash(a) != canonical_payload_hash(b)
 
 
+def test_default_resume_flag_preserves_pre_recovery_idempotency_hash():
+    request = CorporateActionRequest(
+        effective_date=date(2026, 1, 2),
+        quantity_before=Decimal(10),
+        quantity_after=Decimal(5),
+        evidence_ref="ev",
+    )
+    legacy_payload = request.model_dump(mode="json", exclude={"resume_partial"})
+    explicit_default_payload = {**legacy_payload, "resume_partial": False}
+
+    assert canonical_payload_hash(request) == canonical_payload_hash(legacy_payload)
+    assert canonical_payload_hash(explicit_default_payload) == canonical_payload_hash(legacy_payload)
+    assert canonical_payload_hash(
+        request.model_copy(update={"resume_partial": True})
+    ) != canonical_payload_hash(legacy_payload)
+
+
 def test_runtime_schema_has_one_corporate_action_ddl_and_replay_mapping_starts_at_18():
     source = Path("app/repositories/postgres.py").read_text()
     assert source.count("CREATE TABLE IF NOT EXISTS portfolio_corporate_actions") == 1