feat: govern attachment exceptions and ownership transfers

tests/test_attachment_building.py

@@ -100,9 +100,9 @@ class CampaignAttachmentBuildTests(unittest.TestCase):
         cases = {
             "block": ("build_failed", "blocked", 0, "block", False),
             "ask": ("built", "needs_review", 0, "ask", True),
-            "drop": ("built", "excluded", 0, "drop", True),
+            "drop": ("built", "needs_review", 0, "ask", True),
             "warn": ("built", "warning", 1, "warn", True),
-            "continue": ("built", "ready", 1, None, True),
+            "continue": ("built", "warning", 1, None, True),
         }
         for behavior, (build_status, validation_status, queueable_count, issue_behavior, has_mime) in cases.items():
             with self.subTest(behavior=behavior):
@@ -133,6 +133,71 @@ class CampaignAttachmentBuildTests(unittest.TestCase):
                         self.assertEqual(coverage_issues[0].behavior, issue_behavior)
                     self.assertEqual(result.built_messages[0].mime is not None, has_mime)
 
+    def test_required_missing_policy_cannot_be_loosened_by_rule(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            campaign_file = root / "campaign.json"
+            campaign_file.write_text("{}", encoding="utf-8")
+            config = self._no_attachment_config(
+                behavior="continue",
+                configure_missing_rule=True,
+            )
+            rule = config.attachments.global_[0]
+            rule.required = True
+            rule.missing_behavior = "continue"
+            config.attachments.missing_behavior = "continue"
+
+            result = build_campaign_messages(
+                config,
+                campaign_file=campaign_file,
+                output_dir=root / "out",
+                write_eml=True,
+            )
+
+            message = result.report.messages[0]
+            self.assertEqual(message.validation_status.value, "blocked")
+            issue = next(
+                item
+                for item in message.issues
+                if item.code == "missing_required_attachment"
+            )
+            self.assertEqual(issue.behavior, "block")
+            self.assertEqual(
+                issue.details["effective_policy"]["requirement_policy"],
+                "block",
+            )
+            self.assertEqual(
+                message.attachments[0].missing_policy["effective_behavior"],
+                "block",
+            )
+
+    def test_optional_missing_policy_warns_by_default(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            campaign_file = root / "campaign.json"
+            campaign_file.write_text("{}", encoding="utf-8")
+            config = self._no_attachment_config(
+                behavior="continue",
+                configure_missing_rule=True,
+            )
+            config.attachments.global_[0].missing_behavior = None
+
+            result = build_campaign_messages(
+                config,
+                campaign_file=campaign_file,
+                output_dir=root / "out",
+                write_eml=True,
+            )
+
+            message = result.report.messages[0]
+            self.assertEqual(message.validation_status.value, "warning")
+            issue = next(
+                item
+                for item in message.issues
+                if item.code == "missing_optional_attachment"
+            )
+            self.assertEqual(issue.behavior, "warn")
+
     def test_missing_pattern_does_not_create_zip_member_or_count_as_attachment(self) -> None:
         with tempfile.TemporaryDirectory() as tmp:
             root = Path(tmp)