feat: pause campaign batches on SMTP failure

tests/test_synchronous_delivery_policy.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+from contextlib import contextmanager
 from types import SimpleNamespace
 from unittest.mock import Mock, patch
 
@@ -23,7 +24,9 @@ from govoplan_campaign.backend.sending.jobs import (
     QueueCampaignResult,
     SynchronousSendRejected,
     _ensure_synchronous_send_count_allowed,
+    _pause_jobs_after_systemic_smtp_failure,
     _preflight_synchronous_send_batch,
+    _synchronous_smtp_batch_manager,
     queue_campaign_jobs,
     send_campaign_now,
     synchronous_send_candidate_jobs,
@@ -364,6 +367,72 @@ def test_batch_preflight_checks_every_message_before_provider_effects() -> None:
     provider.send_campaign_email_bytes.assert_not_called()
 
 
+def test_smtp_batch_manager_preflights_combined_recipients_and_frozen_transport() -> None:
+    snapshot = SimpleNamespace(
+        uses_mail=True,
+        mail_profile_id="profile-1",
+        smtp_transport_revision="revision-1",
+        smtp_server_id="server-1",
+        smtp_credential_id="credential-1",
+    )
+    jobs = [
+        SimpleNamespace(
+            id="one",
+            tenant_id="tenant-1",
+            campaign_id="campaign-1",
+            delivery_channel_policy="mail",
+            resolved_recipients={"from": {"email": "sender@example.test"}},
+        ),
+        SimpleNamespace(
+            id="two",
+            tenant_id="tenant-1",
+            campaign_id="campaign-1",
+            delivery_channel_policy="mail",
+            resolved_recipients={"from": {"email": "sender@example.test"}},
+        ),
+    ]
+    contexts = {
+        "one": SimpleNamespace(snapshot=snapshot, envelope_from="sender@example.test", envelope_recipients=["one@example.test"]),
+        "two": SimpleNamespace(snapshot=snapshot, envelope_from="sender@example.test", envelope_recipients=["two@example.test", "one@example.test"]),
+    }
+    state = SimpleNamespace(connection_count=1, reconnect_count=0)
+
+    @contextmanager
+    def batch(_session, **kwargs):
+        batch.kwargs = kwargs
+        yield state
+
+    provider = SimpleNamespace(campaign_smtp_batch=batch)
+    with patch("govoplan_campaign.backend.sending.jobs.mail_integration", return_value=provider):
+        with _synchronous_smtp_batch_manager(object(), jobs=jobs, contexts=contexts) as opened:  # type: ignore[arg-type]
+            assert opened is state
+
+    assert batch.kwargs["envelope_recipients"] == ["one@example.test", "two@example.test"]
+    assert batch.kwargs["expected_smtp_transport_revision"] == "revision-1"
+
+
+def test_systemic_failure_pauses_only_remaining_queued_jobs() -> None:
+    session = Mock()
+    session.query.return_value.filter.return_value.update.return_value = 3
+    campaign = SimpleNamespace(id="campaign-1", tenant_id="tenant-1", status="sending")
+    session.get.return_value = campaign
+    with patch("govoplan_campaign.backend.sending.jobs.audit_event") as audit:
+        paused = _pause_jobs_after_systemic_smtp_failure(
+            session,
+            campaign_id="campaign-1",
+            exclude_job_id="failed-job",
+            reason_code="smtp_authentication_failed",
+        )
+
+    assert paused == 3
+    assert campaign.status == "ready_to_queue"
+    session.commit.assert_called_once_with()
+    assert audit.call_args.kwargs["details"] == {
+        "reason_code": "smtp_authentication_failed",
+        "paused_count": 3,
+    }
+
+
 def test_rejected_synchronous_preflight_rolls_back_staged_queue_before_audit() -> None:
     session = Mock()
     campaign = SimpleNamespace(id="campaign-1", current_version_id="version-1")