feat(campaign): govern attachment reuse

tests/test_review_decisions.py

@@ -92,6 +92,43 @@ def test_attachment_block_cannot_be_overridden_by_review_decision() -> None:
     assert decisions == []
 
 
+def test_attachment_reuse_review_requires_reason_and_captures_policy() -> None:
+    job = _job(
+        issues=[{
+            "code": "duplicate_attachment_reuse",
+            "behavior": "ask",
+            "source": "attachments:reuse_policy",
+            "details": {
+                "file_fingerprint": "f" * 64,
+                "policy": {"action": "review", "allow_within": "none"},
+            },
+        }]
+    )
+
+    with pytest.raises(CampaignPersistenceError, match="require an explicit reason"):
+        _normalize_review_issue_decisions(
+            [job],
+            [],
+            user_id="reviewer-1",
+            build_token="build-1",
+        )
+
+    decisions = _normalize_review_issue_decisions(
+        [job],
+        [{
+            "job_id": job.id,
+            "decision": "accept",
+            "reason": "The shared statutory notice is intentionally identical.",
+        }],
+        user_id="reviewer-1",
+        build_token="build-1",
+    )
+
+    assert decisions[0]["issue_codes"] == ["duplicate_attachment_reuse"]
+    assert decisions[0]["reason"] == "The shared statutory notice is intentionally identical."
+    assert len(decisions[0]["issue_fingerprint"]) == 64
+
+
 def _job(*, issues: list[dict[str, object]]) -> SimpleNamespace:
     return SimpleNamespace(
         id="job-1",